Disc Brake Project

 

CHAPTER 1

INTRODUCTION Brakes are most important safety parts in the vehicles. Generally all of the vehicles have their own safety devices to stop their car. Brakes function to slow and

stop sto p th thee  rota rotatio tion n of th thee wheel wheel.. To stop stop th thee wheel wheel,, br brak akin ing g pa pads ds are are fo forc rced ed mechanically against the  rotor disc on both surfaces. They are compulsory for all of  the modern vehicles and the  safe operation of vehicles. In short, brakes transform the kinetic energy of the car into heat  energy energy,, thus slowing its speed. Brakes Bra kes have have been been retune retuned d and improv improved ed ever ever since since their their invent invention ion.. The The increases in traveling speeds as well as the growing weights of cars have made these improvements essential. The faster a car goes and the heavier it is, the harder it is to stop. An effective braking system is needed to accomplish this task with challenging term where material need to be lighter than before and performance of the brakes must be improved. Today's cars often use a combination of disc brakes and drum  brakes. For normal sedan car, normally disc brakes are located on the front two wheels and drum brakes on the back two wheels. wheels. Clearly shows that, together together with the steering components components and tyres represent the most important important accident accident avoidance avoidance systems syst ems present present on a motor motor vehicl vehiclee which which must must reliab reliably ly operate operate under under variou variouss conditions. However, the effectiveness of braking system depends on the design itself and also the right selection of material. It is important to do some analysis on a disc brake rotor which has been designed to predict the behavior of the systems than follow fol low with with some some improv improveme ements nts.. In order order to unders understan tand d the behav behavior iorss of brakin braking g system, there are three functions that must be complied for all the time

a) The brakin braking g system system must be decelerat deceleratee a veh vehicl iclee in a controlle controlled d and repeatabl repeatablee fashion and when appropriate cause the vehicle to stop.  b) The braking should permit the vehicle to maintain a constant speed when traveling downhill. c) The braki braking ng system system must hold hold the vehicl vehiclee stationar stationary y when on the flat flat or on a gradient. 1

 

1.1 Brak Brakee System System Revie Review w In this section History of brake system, Vehicle Brake System, Types of  Brakes, Advantages, Disadvantages and Applications of brake system are explained in the following sections

1.1. 1.1.11 Hist Histor oryy ooff Bra Brake ke Sy Syst stem em In the early days of the automobile, drum brakes were standard. Drum brakes offered several advantages over other types of brakes. One of these was that the drum could keep out water and dust, materials that could damage disc brakes which were out in the open. Major advancement in brake technology came in 1918 with the invention of  four wheel hydraulic brake systems by Malcolm Longhead. The hydraulic brake system replaced the mechanical brake system that was in use at this time. The mechanical system had numerous disadvantages. It made it difficult to break all the wheels evenly, often causing a loss of control. In addition, it required drivers to exert tremendous amounts of force on the brake pedal to slow the car. T The he hydraulic brake system multiplied the force that was applied to the brake, lessening the amount of  force needed to be applied to the brake pedal by the driver. This system was first used in the 1918 Duisenberg. Its advantages quickly caught on and by 1929, four  wheel hydraulic braking systems were standard equipment on higher priced cars. Thee main Th main pr prob oble lem m wi with th dr drum um br brak akes es is th that at th thee he heat at is no nott ef effi ficie cient ntly ly disbursed. The heat that is produced inside the drum does not escape easily since the drum prevents wind from drawing it away. However, disc brakes killed the issues when it allowed the heat to be carried away which increased the efficiency of the  brake. However, their use was limited up until the 1950's since their efficiency was not required and they required more pedal pressure to operate. The reason for the high higher er pe peda dall pr pres essu sure re is th that at disc disc br brak akes es ha have ve no self-s self-serv ervo o ef effec fectt or no selfselfenergizing capacity that the drum brakes have. The self-servo effect is caused by the forward motion of the car. This forward motion helps pull the brake shoe into contact with the drum. This helped lower the required pedal pressure. Now that their  efficiency was needed and the hydraulic brake system multiplied the force applied to the brake pedal, disc brakes seemed to be the better alternative. Chrysler was the 2

 

first to widely introduce the disc brake in its cars in the early 1950's. The system did not have much success till automaker Studebaker to reintroduce the system in 1964. This time it saw much more success and in a few years, disc brakes were common on most new cars. One of the reasons that disc brakes were a success with the Studebaker and not the Chrysler was due to the development of the power braking system. Power   brakes became common in the 195Ots, after Chrysler had developed and dropped its disc brake program. The system assisted the movement of the piston in the master  cylinder which meant that the driver needed to apply less peddle pressure to get the same braking effectiveness. Therefore, since ease of braking was no longer an issue, the adoption of the more efficient disc brake became widespread.

1.1. 1.1.22 Veh ehic icle le Br Brak akee Sy Syst stem em It is know that, the basic functions of the brake system are to slow down a vehicle speed to the point we need. It is also help to maintain acceleration during moving mov ing downhi downhill ll and keep keep the vehicl vehiclee on static static condit condition ions. s. Brakes Brakes operat operatee by converting the kinetic energy (motion) of an automobile into heat energy. A typical vehicle braking system is shown in Figure 1.1

Figure 1.1: Vehicle Brake System   Driver exerts a force on brake pedal which is further amplified by power   booster. The force on brake pedal pressurizes brake fluid in a master cylinder; brake fluid is designed for extreme conditions, generally a silicon based DOT5 brake fluid 3

 

is recommended. The hydraulic force developed by brake fluid is transmitted to a wheel cylinder or caliper at each wheel which is used to force friction material against the drum or rotor. The friction between the friction material and rotating drum or rotor causes the rotating part to slow and eventually stop. In the passenger or commercial vehicle, there are always two main types of   brake assemblies have been used. Those types of brakes are drum and disc brakes which have been described as below.

1.2 Types of Br Brakes akes  

Brakes are of two types. They are Drum brakes and Disc brakes

1.2.1 Drum brakes Drum brakes (Figure (Figure 1.2 and Figure 1.3) have their pads located inside of a drum. Like the disc in disc brakes, drum brakes also are attached to the wheels. Usuall Usu ally y, main main compon component entss of drum drum brake brake for passen passenger ger or commer commercial cial vehicle vehicle consist of brake shoes, backing plate, parking brake cable and wheel cylinder. When the brake pedal is pressed the curved brake shoes (pads) are pushed outward so that they make contact with the rotating drum. Retracting spring is used in this type of   brake. Just as with disc brakes, this causes friction which turns kinetic energy into heat energy, thus slowing and stopping the car to the right point. There is an advantage of using drum brakes, where there is low cost of common parts. However, there are also some disadvantages, such as the drum heats up and expands away from the lining lining material material which increasing increasing fading. It is also have lower efficiency efficiency in wet braking action.

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Figure 1.2: Components of Drum Brake

Figure1.3: Figure1. 3: Drum Brake System 5

 

1.2.2 Disc brakes Disc brakes (Figure 1.4) operate in a similar step of bicycle. It involves  pushing a block against a spinning wheel. This contact causes friction, which changes chang es kinetic kinetic energy energy into heat energy energy.. Usually Usually, components components of disc brake for   passenger or commercial vehicle consist of disc pads (brake pads), brake caliper and  brake disc rotor. rotor. Normal vehicle use two of these pads, one on each side of the wheel, which helps keep the wheel more stable. When the brake pedal is pushed, the  pads (often called brake shoes) push up against the wheel disc. The wheel that attached with the rotor will affected by force from pads and makes the wheel stop rotate. Those for both of disc and drum brakes are refer to mechanical, hydraulic and  power brake systems in order to make the brake systems function smoothly. smoothly. According Accord ing to many researchers, researchers, disc brake system has many advantages advantages over drum  brakes. The major part of rotor is exposed to air; therefore there is sufficient air flow overr brakes ove brakes to dissip dissipate ate the heat generat generated ed resulti resulting ng in coolin cooling g down down of rotor  rotor  temperature easily. The rotor expands in the direction of the friction material in disc  brakes as opposed to drum brakes. The pressure applied on the rotor is more uniform resulting in even braking action as compared with drum brakes. It is also possible on wet stopping when water slide off the rotor surface.

Figure 1.4: Components of Disc Brake 6

 

1.2.2.1

Disc Calipers There are two types of disc calipers where further classified as floating and

fixed caliper.

Figure 1.5: Floating Caliper Design Figure 1.5 shows a type of floating caliper. This type of brake uses only a single piston to squeeze the brake pad against the rotor. The reactive force shifts the caliper housing and presses opposite side of braking pad against rotor. Referring to Figure 1.5, the brake fluid pushes the piston when the brake is applied to the left of  the piston and immediately pushes the inner pads and presses it against the rotor  disc, the sliding caliper housing reacts by shifting towards right pushing the left pad against the disc. Other type of disc calipers is a fixed caliper. Figure 1.6 shows a type of fixed caliper. In these types of brakes, the caliper body is fixed and uses two or more  pistons on each side of the rotor. rotor. The pistons are located in each eac h half section of the fixed caliper. Hydraulic pressure is applied during braking to each of the piston. Each of the pistons pistons has a function to press against the brake pads of the brake disc. Shaped piston seals will retract the piston when the brakes are released. Referring to Figure 1.6, the brake fluid pushes the both piston when the brake is applied to the left and the right of the piston and immediately pushes the both inner pads and  presses it against the rotor disc. Normally, Normally, these types of brake caliper are used in high performance and heavy duty vehicle due to high physical strength. 7

 

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Figure 1.6: Fixed Caliper Design 1.2.2.2

Brake Pads As shown in Figure 1.7, brake pads consist of steel carrier which the pad are

 bonded to the steel carrier. According According to organically bonded pads consist of metallic, ceramic or organic friction materials in a bonded mass such as rubber or synthetic resin. The bonded friction materials can withstand temperatures up to 750°c, with short term peaks-up to 950'~ where the friction coefficient is between 0.25 and 0.5. 8

 

There is an advantage of brake pads, where most of them are poor to thermal conductivity which protects the hydraulic actuating elements from overheating. It is also als o ea ease se to manu manufac factu ture re an and d lo low w co cost st.. Howe Howeve verr, th thee pa pads ds ne need edss to in insp spec ectt frequ fre quen entl tly y du duee to ra rapi pid d wear wear as resul resultt from from hi high gher er te temp mpera eratu tures res an and d co cont ntact act  pressures associated with the operation of a brake disc.

 

Figure 1.7: A Sample of Brake Pads 1. 1.22.2.3 .2.3

Brake ake D Diisc / D Dis iscc Bra Brake ke Roto Rotorr Figure 1.8, shows the heat generated on the surfaces of disc brake rotor when

 brake applied. Materials of disc brake rotor usually are made from cast iron, spheroidal-graphite cast iron or cast steel. It is chosen as a rotor material due to low cost of material and performs high thermal resistance. This type of material normally suit to normal passenger vehicle but not for high performance car. Once brake pads contacts to rotating rotor, there will be huge amount of heat generated to stop or  slow down the vehicle.

Figure 1.8: Heat Generated on Rotor Surfaces

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1. 1.22.2.4 .2.4

Dis iscc B Brrake Ro Roto torr D Deesc scrripti iption on Overal Ove ralll idea idea on vehicle vehicle brake brake system system and disc disc brake brake theori theories es has been

described as above. As similar to the type disc brake described above, the author  used the disc brake rotor from normal passenger vehicle. The disc brake rotor was taken from normal passenger vehicle which having type of ventilated disc (Figure 1.9). Basically Basically, disc brake rotor consists of rotating rotating circular plate and cylinder cylinder disc (hat) attached and rotated to wheel hub.

1 .3

Figure 1.9: Non Ventilated Disc Brake Rotor Advantages aan nd D Diisadvantages

1.3.1 Advantages 1. Ceramic Ceramic brake discs discs are 50% 50% lighter lighter than metal brake brake discs. discs. As a result, result, they they can reduce the weight of car by up to 20kg. In case of a high speed ICE like train with 36 brake discs, these savings amount to 6 tons. And apart from saving fuel, this also means a reduction in unsprung masses with a further improvement of  shock absorber response and behavior. 2. The ceramic ceramic brake disc disc ensures very very high and, and, in particular particular,, consistent consistent frictional frictional values throughout the entire deceleration process. With Porsche ceramic brake discs, a car was able to decelerate from 100Km to 0Km in less than 6 seconds. In the case of Daewoo’s Nexia, it takes about 8 seconds to stop the vehicle. 3. Brake temperat temperature ure – a factor factor crucial crucial to stopping stopping distances distances with metal metal brake brake discs  – is now only a minor factor, both the brake lining and ceramic brake disc retaining their high level of friction regardless of whether they are hot or cold. This not only shortens stopping distances by a couple of – often decisive –  meters, but also spares the driver unpleasant surprises whenever having to apply the brakes, say, from a high speed.

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4. Cera Cerami mics cs reta retain in thei theirr re resi sist stan ance ce up to 20 2000 00 de degr gree ee Cels Celsiu ius. s. Only Only if th thee temperature is excess of this, they loose their dimensional stability. 5. Initia Initiall field studi studies es have shown shown that ceramic ceramic brake brake discs can still reliabl reliably y bring an automobile to standstill even after 300,000 kilometers. Brake disc changes will in future be unnecessary. unnecessary. 6. They are are not subject subject to wear, wear, are are maintenance maintenance free free and are heat heat and rust rust resistant. resistant. 7. Heavil Heavily y commerci commercial al vehicles vehicles can be braked braked safely safely over long long distance distancess withou withoutt ha havi ving ng to un unde derg rgo o br brak akee main mainte tena nanc nce. e. This This di disp spen enses ses with with th thee ne need ed fo for  r  expensive maintenance. 8. Ceramic Ceramic brake discs do do not rust under under high high oxygen oxygen concent concentration ration.. 9. Dry and and wet perform performances ances are are excellent. excellent. Ceramics Ceramics are water water proof proof materials materials and the brake pads always remain dry.

1.3.2

Disadvantages The main disadv disadvant antage age of cerami ceramicc brake brake discs discs is their their high high initial initial cost.

Initially the ceramic matrix composite brake discs will be more expensive than the current technology metal ones due to the low manufacturing volumes and high cost of production. production. But, because of the advantages advantages listed above, above, the ceramic brakes will work out to be cheaper in the long run.

1.3.3

Applications

1. It was was firs firstt intr introd oduc uced ed in Form Formul ulaa One, One, bu butt ap appl plyi ying ng to ro road ad ca cars rs se seem emss impr im prac actic tical al (F1 (F1 cars cars ha have ve warm warm up lap lap to br brin ing g th thee di discs scs in into to ap appr prop opria riate te workin wor king g temper temperatu ature), re), alt althou hough gh the short-l short-live ived d French French sports sports car special specialists ists Venturi made history by applying it to its road cars in the mid-90s 2. The new 911 911 GT2 comes comes with the most effecti effective ve braking braking system system ever featured featured on a production Porsche: the Porsche Ceramic Composite Brake (PCCB) - a  powerful new technology designed to cope with even the most extreme conditions on racetrack and road? 3. Mercedes-Benz Mercedes-Benz’’s the futuristic futuristic Vision Vision GST GST concept concept car features features 22 inch inch wheels, 'butterfly' doors, three-dimensional instruments, a 360 horsepower 5.5 litre V8 engine, and carbon-fiber reinforced ceramic disc brakes. Mercedes Benz SLR IS ALSO available with ceramic disc brakes.

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CHAPTER 2

LITERATURE REVIEW The research contributions available around 21 articles are reviewed on the DISC BRAKE on various materials and methods are discussed. Though lot of work  ha hass be been en in pr prog ogre ress ss th there ere is a ne neces cessit sity y in th thee in inve vesti stiga gati tion on of pe perfo rform rman ance ce characteristics of different materials used as disc brake.

G P Voller, et. al, [1] (2003)  Analysis of automotive disc brake cooling ch char aract acteri eristi stics cs ha have ve in inve vest stig igat ated ed ab abou outt ch chara aract cteri eristi stics cs ex expe peri rime ment ntall ally y us usin ing g a sp speci ecial ally ly de deve velo lope ped d sp spin in rig and nu nume meri rical cally ly us usin ing g

fini finite te el elem emen entt (FE) (FE) an and d

computational fluid dynamics (CFD) methods. All three modes of heat transfer  (conduction, convection and radiation) have been analysed along with the design features of the brake assembly and their interfaces. The spin rig proved to be very valuable equipment; experiments enabled the determination of the thermal contact resistan resi stance ce betwee between n the disc disc and wheel wheel carrier carrier.. The analys analyses es demon demonstra strated ted the sensiti sens itivit vity y of this this mode mode of heat heat transfe transferr to clampi clamping ng pressu pressure. re. For convec convectiv tivee coolin coo ling, g, heat heat transfe transferr coeffi coefficien cients ts were measur measured ed and very very simila similarr results results were were obtained from spin rig experiments and CFD analyses.

Abd Ab d Ra Rahi him m AbuB AbuBaaka karr an and d Hu Huaj ajia iang ng Ou Ouya yang ng [2]( [2](20 2006 06))  Complex eigenvalue analysis and dynamic transient analysis in predicting disc brake squeal have investigated The positive real parts of complex eigenvalues indicate the degree of instability of the disc brake and are thought to associate with squeal occurrence or  noise intensity. On the other hand, instability in the disc brake can be identified as an initially initial ly divergent divergent vibration response using transient analysis. From the literature literature it appears that the two approaches were performed separately, and their correlation was not much investigated. In addition, there is more than one way of dealing the frictional contact in a disc brake. This paper explores a proper way of conducting  both types of analyses and investigates the correlation between them for a large degree-of-freedom disc brake model. Anal alys ysis is of he heat at Farama Far amarz rz Tala alati ti and Sal Salman man Jal Jalali alifar far [3](20 [3](2009) 09)  An conduction in a disk brake system have investigated the governing heat equations for  the disk and the pad are extracted in the form of transient heat equations with heat 13

 

ge gene nera rati tion on th that at is de depe pend ndan antt to time time an and d space space.. In th thee de deri riva vati tion on of th thee he heat at equations, equati ons, parameters such as the duration duration of braking, braking, vehicle velocity velocity,, geometries geometries and the dimensions of the brake components, materials of the disk brake rotor and the pad and contact pressure distribution have been taken into account. The problem is solved analytically using Green’s function approach.

Pyung Hwang and Xuan Wu [4](2009)  Investigation of temperature and thermal stress in ventilated disc brake based on 3D thermo-mechanical coupling model have investigated Ventilated Ventilated disc brakes are widely used for reducing re ducing velocity due to their braking stability, controllability and ability to prove a wide ranging  brake torque. During braking, the kinetic energy and potential energies of a moving vehicle are converted into thermal energy through friction heating between the brake disc and the pads. The object of the present study is to investigate the temperature and thermal stress in the ventilated disc-pad brake during single brake. The brake disc is decelerated at the initial speed with constant acceleration, until the disc comes to a stop. The ventilated pad-disc brake assembly is built by a 3D model with a thermo mechanical coupling boundary condition and multi-body model technique.

M.Z. Akop, et. al, [5](2009) Thermal Stress Analysis of Heavy Truck Brake Disc Rotor have have investi investigate gated d for steady steady state state and transient transient condit condition ion.. The heat heat dissipated dissip ated along the brake disc surface during during the periodic braking via conduction, conduction, convection and radiation. In order to get the stable and accurate result of element size, time step selection is very important and all of these aspects are discussed in this paper. The findings of this research provide a useful design tool to improve the  brake performance of disc brake system.

Saw Chun Lin, et. al, [6](2009)   Supressing Disc Brake Squeal Through Structural Modification have investigated proposes proposes a solution to suppress disc brake using the finite element method. First a three dimensional finite element (FE) model of a real disc brake assembly is developed and validated. Then, complex eigenvalue an anal alys ysis is made made av avai ailab lable le in co comm mmer erci cial al FE soft softwa ware re pa pack ckag agee is pe perfo rform rmed ed to determine stability of the brake system where positive real parts of the complex eigenvalue indicate unstable system and in turn exhibit squeal generation in the  brake assembly. assembly. Then, various disc modifications are proposed to reduce the brake squeal. 14

 

Pevec.M , et. al, [7](2010)  Numerical Temperature Analysis Of Brake Disc Considering Consi dering Cooling have investigated investigated the temperature temperature numerical calculation calculation of a ventilated front brake disc. The goal was to simulate the sequent vehicle brake test th that at co comp mpri rises ses 10 stops stops from from 10 100 0 km/h km/h.. The The fil film m co coef effic ficie ient nt facto factors rs fo forr th thee ventila ven tilated ted brake brake disc disc were calculated calculated using using the CFD CFD softwa software re and afterwa afterwards rds considered in thermal numerical simulation.

Adam Adamowicz and Piotr Grzes [8](2010)  Analys Analysis is of Disc Brake Brake Temperature Distribution During Single Braking Under Non-Axisymmetric Load have investigated the temperature distributions caused by mutual sliding of two memb me mber erss of th thee disc disc br brak akee syste system m ba basi sing ng on tw twoo- an and d th thre ree-d e-dim imen ensio siona nall FE modelling techniques and complexity of the phenomenon. First step of the analysis  based on the previously developed model where the intensity of heat flux was assumed to be uniformly distributed on the friction surface of disc during braking  process, and the heat is transferred exclusively e xclusively in axial direction, whereas during the second, the three-dimensional rotor is subjected to the non-axisymmetric thermal load to simulate realistic thermal behaviour of the brake action.

M.A. Maleque , et. al, [9](2010) Material Selection Method in Design of  Automotive Brake Disc have investigated the material selection method and select the optimum material for the application of brake disc system emphasizing on the substitution of this cast iron by any other lightweight material. Two methods are introduced for the selection of materials, such as cost per unit property and digital logic methods. Material performance requirements were analyzed and alternative solutions were evaluated among cast iron, aluminium alloy, titanium alloy, ceramics and composites. composites. Mechanical properties properties including including compressive compressive strength, strength, friction friction coefficient, wear resistance, thermal conductivity and specific gravity as well as cost, were used as the key parameters in the material selection stages. Surface Temperature emperature distribution distribution in a A.A.. Adebi A.A Adebisi si , et. al, [10 [10](2 ](2010 010))  Surface Composite Comp osite Brake Rotor have investigated investigated the frictional heat generated generated on the rotor  surface can influence excessive temperature rise which in turn leads to undesirable effe effects cts such such as th therm ermal al elast elastic ic in insta stabi bili lity ty (TEI (TEI), ), pr prem ematu ature re wear wear,, br brak akee fluid fluid vaporization (BFV) and thermally excited vibrations (TEV). The purpose of this study is to investigate the temperature distribution profile for brake calliper pressure 15

 

application of 0.5, 0.10, 1.5 and 2.0 MPa with a speed of 60km/h braking condition on the disc rotor surface. The brake rotor assembly is built by using a 3 dimensional finite element model of a real car brake rotor. To verify the simulation results, an experimental investigation is carried out.

Mohd Mo hd Fird Firdau auss Ab Abu u Baka Bakarr , et. et. al al,, [11] [11](2 (201 011) 1)  Therm Thermal al Analys Analysis is of  Ventilated Disc Brake Rotor for UTeM Formula Varsity Race Car have investigated the Compacted graphite cast iron (CGI) was proposed as the material for the disc  brake rotor. Thermal analysis was performed in this project to assess the component  performance using ABAQUS/CAE v6.7-1 finite element analysis software both in transient condition. Results from the analysis show that the maximum temperature generated on the disc brake surface at the end of the braking procedure for transient condit con dition ion was within within the allowab allowable le service service temper temperatu ature re of the ventil ventilate ated d rotor  rotor  material.

Sharath Kumar T. and S.Vinodh [12](2012) Novel Design and Analysis of  a Brake Rotor have investigated the propose a new automotive brake rotor design and to compare compare it with automotive automotive vented disk rotor. rotor. Static structural structural and transient thermal analysis have been carried out on the vented disk rotor and proposed rotor  designs to evaluate and compare their performance. Finite element analysis was employed for both static structural and transient thermal analysis. Structural analysis was carried out to study the stress and deformation pattern of the rotors under  extreme loads. Time varying temperature load was applied on the rotors and the temperature distribution was analysed considering cooling parameters (convection and radiation).

G. Babukanth and M. Vimal Teja [13](2012)  Transient Analysis of Disk  Brake Bra ke By using using Ansys Softwa Software re have have investi investigat gated ed the compu computati tationa onall results results are  presented for the distribution of heat flux and temperature on each friction surface  between the contacting bodies. Also, thermo elastic instability (TIE) phenomenon (the unstable growth of contact pressure and temperature) is investigated in the  present study, study, and the influence of the material properties on the thermo elastic  behaviors (the maximum temperature on the friction surfaces) is investigated to facilitate facilita te the conceptual conceptual design of the disk brake system. system. Based on these numerical results, the thermo elastic behaviors of the carbon-carbon composites with excellent mechanical properties are also discussed. 16

 

Haripal Singh an and d Har Harshdeep shdeep Shergill [14](2012) Thermal Analysis of  Disc Brake Using Comsol have investigated the heat generation and dissipation in a disc brake of an car during panic braking and the following release period by using computer aided engineering software for three different materials of rotor disc. The objective of this work is to investigate and analyze the temperature distribution of  rotor disc during operation using comsol multiphysics. The work uses the finite element analysis techniques to predict the temperature distribution on the brake disc and to identify the critical temperature of the brake rotor disc. All three modes of  heat transfer (conduction, convection and radiation) have been analyzed. The results obtained from the analysis shows that different material on the same retardation of  the car during panic braking shows different temperature distribution. Simulatio tion n of fully fully Ali belh belhocine ocine and moste mostefa fa bouchetar bouchetaraa [13](2 [13](2012) 012)  Simula couple cou pled d thermo thermo mechani mechanical cal analysis analysis of disc disc brake brake rotor have investig investigated ated

The The

frictional heat generated during braking application can cause numerous negative effects on the brake assembly such as brake fade, premature wear, thermal cracks and disc thickness variation (DTV). In the past, surface roughness and wear at the  pad interface have rarely been considered in studies of thermal analysis of a disc  brake assembly using finite element method.. The ventilated pad-disc brake assembly is built by a 3D model with a thermo-mechanical coupling boundary condit con dition ion and multi-b multi-body ody model model techniq technique. ue. The nu numer merical ical simula simulatio tion n for the coupled transient thermal field and stress field is carried out by sequentially thermalstructural coupled method based on ANSYS to evaluate the stress fields and of  deformations which are established in the disc had with the pressure of the pads and in the conditions of tightening of the disc thus the contact pressures distributions field in the pads which is another significant aspect in this research.

Ameer Ame er Faree Fareed d Bas Basha ha Shaik and

Ch Ch.La .Laksh kshmi mi Sriniv Srinivas as [14](2012 [14](2012))

Structural And Thermal Analysis Of Disc Brake With And Without Crosse drilled Rotor Of Race Car have investigated The disc brake used in Honda Civic. Coupled Coupled field analysis (Structural+Thermal) is done on the disc brake. The materials used are Cast Iron. Analysis is also done by changing the design of disc brake. Actual disc  brake has no holes; design is changed by giving holes in the disc brake for more heat dissipation. Modeling is done in Catia and Analysis is done in ANSYS. 17

 

V.M.M.Thilak [15](2012) transient analysis of rotor disc of disc brake using ansys have investigatio investigation n into usage of new materials is required required which improve improve  braking efficiency and provide greater stability s tability to vehicle. This investigation can be done using ANSYS software. ANSYS is a dedicated finite element package used for  determining the temperature distribution, variation of the stresses and deformation across the disc brake profile. In the present work, an attempt has been made to investigate the suitable hybrid composite material which is lighter than cast iron and has good Young’s modulus, Yield strength and density properties. Aluminium base metal matrix composite and High Strength Glass Fiber composites have a promising friction and wear behaviour as a Disk brake rotor.

S Naveen Kumar and Dr Dr.. M B Kiran [16](2012 [16](2012))   Redesign of Disc Brake Assembly Assemb ly with Lighter Material have investigation investigation the evaluating the performance performance of disc brake of a car under severe braking conditions and there by assist in disc rotor design and analysis. analysis. An attempt is made to suggest suggest an alternative alternative material for  disc brake disc brake by compar comparing ing the results results obtain obtained ed for differe different nt materi materials als Cast Iron, Iron, Carb Ca rbon on fibr fibree rein reinfo forc rced ed cera cerami micc comp compos osit ite, e, ba base sed d on whic which h yi yiel elds ds a lo low w temperature variation across the rotor, less deformation, good heat dissipation and minimum von-misses stress possible.

Moses Mos es Omolay Omolayoo Pe Petin tinrin rin and John John Oghene Ogheneort ortega ega Oji [17 [17](2 ](2012 012))  Numerical Simulation of Thermo elastic Contact Problem of Disc Brake with Frictional Frictio nal Heat Generation have investigatio investigation n the braking braking action by investigatin investigating g  both the thermal and elastic actions occurring during the friction between the two sliding surfaces, represented by the maximum temperature on the contact surface. Brake pad and disc were selected, and parameters set to certain values from existing literatures. Three dimensional thermo mechanical analysis model of the disc brake sy syste stem m was was creat created ed,, an and d go gove vern rnin ing g dy dyna nami mics cs an and d he heat at eq equa uati tion onss de desc scrib ribed ed.. Compar Com pariso ison n was also made made of the selected selected pad material material (aramid (aramid)) with with that that of  asbestos to ascertain its viability as an effective substitute and to improve conceptual designs. Performance Investigat Investigation ion of the UTeM UTeM M. K. Khalid, et. al, [18](2012)   Performance Eco- Car Disc Brake System have investigation investigation The disc brake system utilized utilized a single cross-drilled cross-drilled rotor with fixed calliper desig design. n. The brake system performance performance in term term of its its th ther erma mall pr prop oper erty ty was was de dete term rmin ined ed in tran transi sien entt co cond ndit itio ion n us usin ing g ABAQUS CAE finite element analysis software. 18

 

Ştef Ştefan an VO VOLO LOAC ACĂ Ă and and Gh Gheo eorg rghe he FR FRĂŢ ĂŢIL ILĂ Ă [19] [19](2 (201 012) 2)  concerns regard reg arding ing temper temperatu ature re distri distribut bution ion obtain obtained ed by experi experimen ments ts and finite finite element element analys ana lyses es for two types types of brake brake discs discs have have invest investiga igatio tion n the analys analyses es causes causes of  thermal stress which appears in two different brake discs, with different geometries. A case study was made for an intensive braking from 100 km/h. It was possible to study stu dy,, to co comp mpar aree an and d to ex expl plain ain the the te temp mpera eratu ture re di distr strib ibut utio ion n ob obta tain ined ed by experim exp eriments ents and finite finite element element analys analyses es (FEA). (FEA). Furthe Furtherr the study study encomp encompasse assess temperature distribution inside the studied brake discs obtained by finite element analyses, highlighting some thermal stress influence factors. It was observed the non-uniform repartition of radiation and conduction over the surfaces and inside the  brake discs, due to characteristics of material, their processing and the braking severity.

Guru Murthy Nathi , et. al, [20](2012)  coupled structural thermal analysis of disc brake have investigation investigation the performance performance under severe braking braking conditions conditions and there by assist in disc rotor design and analysis. This study is of disc brake used for cars. ANSYS package is a dedicated finite element package used for determining the temperature distribution, variation of stresses and deformation across the disc  brake profile. In this present work, an attempt has been made to investigate the effect of stiffness, strength and variations in disc brake rotor design on the predicted stress and temperature distributions. By identifying the true design features, the extended service life and long term stability is assured. A transient thermal analysis has been carried out to investigate the temperature variation across the disc using axisymmetric elements. Further structural analysis is also carried out by coupling thermal analysis.

S. Sarip [21](2013)  Design Development of Lightweight Disc Brake for  Regenerative Braking – Finite Element Analysis have investigation the automotive industry has for many years identified weight reduction as a way of improving  product competitiveness and thus the ability to make profits. One area that has been examin exa mined ed for weight weight reduct reduction ion is vehicle vehicle with with Regene Regenerati rative ve Brakin Braking g System System (RBS) (RB S) .The .The greate greatest st advant advantage agess of electri electricc vehicl vehicles es (EVs), (EVs), and hybrid hybrid electric electric vehicles (HEVs) is their ability to recover significant amounts of braking energy using a RBS. Regenerative braking is an effective method to extend brake disc life, 19

 

minimise disc rotor weight, minimise brake pad wear and to extend the working range of an EV or HEV. HEV. Regenerative braking would extend the working range of an EV or HEV provided that any extra energy consumption e.g. from increased vehicle mass and system losses did not outweigh the saving from energy recuperation, also reduce duty levels on the brakes themselves, giving advantages including extended  brake rotor and friction material life, but more importantly reduced brake mass, mini mi nimi mise se br brak akee pa pad d wear wear.. The The ob objec jecti tive ve of th this is re rese searc arch h is to de defi fine ne th therm ermal al  performance on lightweight disc brake models. Thermal performance was a key fact factor or whic which h was was st stud udie ied d usin using g the the 3D mode modell in Fini Finite te Elem Elemen entt Anal Analys ysis is simulations. Ultimately a design method for lightweight brakes suitable for use on an any y car-si car-sized zed hy hybr brid id ve vehi hicl clee was was us used ed from from pr prev evio ious us an anal alys ysis. is. The The de desi sign gn requir req uireme ement, nt, includ including ing reduci reducing ng the thickn thickness, ess, would would affect affect the temper temperatu ature re dist distrib ribut utio ion n an and d in incr creas easee str stres esss at th thee cr crit itic ical al ar area. ea. Based Based on th thee re rela lati tion onsh ship ip obtained between rotor weight, thickness, undercut effect and offset between hat and friction ring, criteria have been established for designing lightweight brake discs in a vehicle with regenerative braking. The contribut contribution ionss of variou variouss research research and experts experts contai contained ned in so many many artic art icles les in th thee fi field eld of Fini Finite te Elem Elemen entt Anal Analys ysis is of Spur Spur di disc sc br brak akee ha have ve be been en reviewed. The advantages and limitations of 3-D models have been brought-out. Further the advantages of 3-Dimensional simulation model over the experimental studies were highlighted. The software such as ANSYS, RADIOSS ABACUS, LSDYNA are available for static and thermal analysis of disc brake. In the present work RADI work RADIOS OSS S is us used ed.. Based Based on the the de detai taile led d an anal alys ysis is of th thee lite literat ratur ure, e, th thee objective of the present work has been brought-out as given below 1. To design the model model of disc brake brake using using CATIA CATIA V5R20. V5R20. 2. To analyze analyze the the model for displace displacement ment and and stress stress using using Hyper Hyper Mesh Mesh 11 11 3. To analyze analyze the model model for grid temperat temperature ure using using Hyper Hyper Mesh 11 4. To fi find nd the be best st materia materiall fo forr disc disc brake brake amon among g th thee selec selected ted materi materials als using comparative study. study.

20

 

CHAPTER 3 METHODOLOGY 

3.1 Introduction to CATIA CATIA CA TIA (Computer (Computer Aided Three-dimen Three-dimensional sional Interactive Interactive Application) Application) (in Engl En glis ish h us usua uall lly y pr pron onou ounc nced ed)) is a multi multi-p -pla latfo tform rm CAD/ CAD/CAM/ CAM/CAE  CAE  commercial softwaree suite developed softwar suite developed by the French company Dassault Systems. Written Systems.  Written in the C++   programming language, C++ language, CATIA is the cornerstone of the Dassault Systems  product lifecycle management software management software suite.

3.1.1

About CATIA V5 CATIA CA TIA versio version n 5 is a process process-cen -centric tric comput computer er-aid -aided ed design design/co /compu mputer ter--

assisted manufacturing/computer-aided engineering (CAD/CAM/CAE) system that fully uses next generation object technologies and leading edge industry standards. Seamlessly integrated with Dassault Systems Product Lifecycle Management (PLM) solutions, it enables users to simulate the entire range of industrial design processes from initial concept to product design, analysis, assembly, and maintenance. The CATIA CA TIA V5 produc productt line line covers covers mechan mechanical ical and shape shape design design,, stylin styling, g, produ product ct synthesis, synth esis, equipment and systems systems engineering engineering,, NC manufacturi manufacturing, ng, analysis analysis and simulation, and industrial plant design. In addition, CATIA CATIA Knowledge ware enables  broad communities of users to easily capture and share know-how, know-how, rules, and other  intellectual property (IP) assets. CATIA V5 builds on powerful smart modelling and morphing concepts to enable the capture and reuse of process specifications and intelligence. The result is an easily scaleable, Web-enabled system that covers all user requirements within the digital extended enterprise, from the simplest design to the most complex processes. This capability allows optimization of the entire product development process while controlling change propagation. CATIA V5 moves beyond traditional parametric or  variati var iation on approa approache ches, s, acceler acceleratin ating g the design design process process and helpin helping g designe designers, rs, engineers, and manufacturers increase their speed and productivity. productivity. CATIA V5 has an innovative and intuitive user interface that unleashes the designer's design er's creativity creativity.. Context-sen Context-sensitive sitive integrated integrated workbenches workbenches provide provide engineers engineers 21

 

with the tools they need for the task at hand, and they are beneficial for multidiscipline discip line integration integration.. The workbenches workbenches have powerful powerful keyboard-fre keyboard-freee direct object object manipulators that maximize user productivity. productivity. CATIA V5 applications are based on a hybrid modelling technology. These applications provide expanded digital product definitions, process definitions, and revie rev iew w func functi tion onss capab capable le of op opera erati ting ng on pr proj oject ectss wi with th an any y de degr gree ee of de desi sign gn comple com plexit xity y. CATIA CATIA V5 has produc produced ed domain domain-spe -specifi cificc applic applicati ations ons that that have have addressed global digital enterprise requirements that span the areas of mock-up, manufacturing, plant, and operations. CATIA V5 expands scalability across processes, functions, and platforms to de deli live verr th thee right right so solu luti tion on to th thee de desk skto top p of ea each ch te team am memb member er in th thee pr prod oduc uctt development chain. Tailored solutions meet the needs of a broad range of users, from a small supplier shop to a large multinational corporation.

3.2 Part Modelling Modelling is a pre-processor tool, the modelling of disc brake rotor are created using the Computer aided a ided three-dimensional interactive application (CATIA) (CATIA) V5 R20 software tool. CATIA helps us to draw the disc brake rotor parts. There are various platform and workbench features are available to design disc brake. Main workbe wor kbench nches es availa available ble in CATIA CATIA are part part workbe workbench nch,, wire wire frame frame workbe workbench nch,, surface design, assembly design and drafting workbench etc. A feature is defined as the smalles smallestt buildi building ng that that can be modifie modified d indivi individua dually lly,, block. block. The differe different nt workbenches designs are saved in CATIA are sketcher, part design, wire frame and surface design: CAT CAT Part, Assembly design: .CAT .CAT Part, Cat drawing: .CAT .CAT drawing. The reason for selecting CATIA software, this software a user tool makes it possible for mechanical designers to create quickly. Sketch required ideas, experimentally with features, dimensions and models and drawings. The modelling of disc brake rotor are created using the two dimensional drawing designed for the disc brake rotor, the models are created using varies commands in the CATIA CATIA work bench. CATIA CA TIA V5 is a feature-based feature-based,, parametric parametric solid modelling modelling design tool that takes tak es advant advantage age of the easy-to easy-to-lea -learn rn Windows indows graphi graphical cal user user interfa interface. ce. We can create fully associative associative 3D solid models, with or without without constraints, constraints, while using automatic autom atic or user-define user-defined d relations relations to capture the design intent. intent.  Generative Shape 22

 

Design is used to model the rotor blade. It is a complete surfacing tool used to create complex shape parts such as steam turbine blades. The geometrical module of the rotor and blade is created using CATIA V5 R20 software, CATIA is a pre-processor were the solid geometry is created using 2D drawings, module created in CATIA is exported as IGES file for the next pre processor for meshing. mes hing. The figure 3.2 contains the disc brake rotor and the stages s tages of  th thee Mode Modeli ling ng of disc disc br brak akee ro roto torr is do done ne by impo importi rting ng no noda dall da data ta en ente tere red d in Microsoft excel sheet into CATIA v5 generate shape design work bench by running micros.

Figure 3.1 Part design of the Disc brake in Catia 3.3

Disc Brake Modeling In Part Design Part and Shape design are the basic modules of design in CATIA software.

They are based on several tools for easy and qualitative modeling of any kind of  machine elements. First step of design any part is to define position (plane) of  Sketch and to draw profile in chosen Sketch. After that there are several groups of  options that give designers opportunity to make a 3D model: Sketch-Based Features are entities you combine to make up your part. The features are obtained by applying co comm mman ands ds on in init itia iall pr prof ofil iles es creat created ed in th thee Sket Sketch cher er work workbe benc nch, h, or in th thee Generative Shape Design workbench as well as surfaces. Some operations consist in adding material, others in removing material like 23

 

Create a Pad, Create a Pocket, Create a Shaft, Create a Hole, Create a Loft etc.

3.3.1 Dress-Up Features Applying commands to one or more supports does dressing up features. CATIA provides a large number of possibilities to achieve the features meeting your  needs. The application lets you create the following dress-up features: Create an Edge Fillet, Create a Chamfer, and Create a Shell, Create Basic Draft etc.

3.3.2 Transformat ransformation ion Features These features are very useful for different transformations such as: Create a Trans ranslat latio ion, n, Cr Crea eate te a Rotat Rotatio ion, n, Cr Crea eate te Symm Symmet etry ry,, Creat Createe a Circu Circula larr Pa Patt tter ern, n, Exploding Patterns, Create a Scaling etc.,

3.4

Displaying and Editing Proper Properties ties You must use bodies as entities you will eventually associate to the Part

Body using the capabilities described below to finish the design of your part. Here are Displaying and Editing Parts Properties, Bodies and Features Properties.

3.4.1 Special tools This Th is co comm mman ands ds ar aree us usee fo forr so some me an anal alys ysis is such such as Pe Perfo rform rm a Surf Surfac acee Curvature Analysis, Analyze Disc brake , Apply a Material, Display Parents and Children, Define an Axis System, Publish Elements etc. For designing simplest Disc  brake it is first right sketch to define, where should be imported involutes profile

3.4.2 Fundamentals CATIA CA TIA V5 employs two operating modes for part modeling, model made for  modeling 3Dparametric parts and drawing mode for creating 2D drawings of them. These modes operate independently but share the same design data. Part modeling requires beginning the design work in model mode where a model of the part is immediately built. Then the drawing mode can be used at any point to document the design. In traditional CUMPUTER AIDED DESIGN, a 2D drawing is created at the  beginning and then 3D model model is built to analyze, and verify the initial concept.

3.5. Flow chart of Disc brake optimization 24

 

Figure 3.2

25

 

CHAPTER 4 FINITE ELEMENT METHOD

4.1

Introductio Introduction n to Finite Element Method The finite element method is a powerful tool to obtain the numerical solution

of wide range of engineering problems. The method is general enough to handle any complex shape or geometry, for any material under different boundary and loading conditions. The generality of the finite element method fits the analysis requirement of today’s complex engineering systems and designs where closed form solutions of  govern gov erning ing equili equilibri brium um equati equations ons are usuall usually y not availa available ble.. In additi addition, on, it is an efficient design tool by which designers can perform parametric design studies by conside con siderin ring g variou variouss design design cases, cases, (diff (differen erentt shapes shapes,, materia materials, ls, loads, loads, etc.) etc.) and analyze them to choose the optimum design. The method originated in the aerospace industry as a tool to study stress in a complex airframe structures. It grows out of what was called the matrix analysis method used in aircraft design. The method has gained increased popularity among  both researchers and practitioners. The basic concept of finite element method is that a body or structure may be divided into small elements of finite dimensions called “finite “fin ite elemen elements”. ts”. The origin original al body body or the structure structure is then then consid considered ered,, as an assemblage assembl age of these elements connected connected at a finite number of joint jointss called nodes or  nodal points.

4.2

History of Finite Element Method

The concept of finite element element method method has been used several centuries centuries back, although it has named recently. Basic ideas of the finite element method originated from the aircraft structural analysis, the concept of finite element method was first used by courant in 1943. He used the principle of stationary potential energy and  piece-wise polynomial interpolation over triangular sub regions, to study the torsion tors ion  problems. In 1956 Turner and Clough derived stiffness matrices for truss, beam and other elements in their presentation. The term finite element was first coined and used by Clough in 1960. Paper presented by the Clough and Turner presents the application of simple finite elements for the analysis of aircraft structure and is considered as one of the key contribution in the development of the finite element method. The digital computer provided performs many calculations rapidly involved 26

 

in the finite element analysis and make the method practical viable. Along with development of high-speed digital computers, the application of the finite element method met hod also progre progressed ssed at a very very impress impressive ive rate. rate. Large Large general general-pu -purpo rpose se finite finite element computer program emerged during the late 1960s and early1970s. In the early 1960s, engineers used the method for approximate solution of   problems in stress analysis, fluid flow, flow, heat transfer and other areas. The book by Prezemieniecki presented the finite element method as applied to the solution of  stress analysis problems. Zienkiewicz and Cheung presented the broad interpretation of the method and its applicability to any general field problem. In the late 1960s and early 1970s finite element analysis was applied to non-linear problems and large deformations. In 1963, the finite element method gained popularity, when it was recognized as having a sound s ound mathematical foundation. In 1970s study is focused on new element development and convergence studies. With this broad interpretation of  the finite element method, it has been found that using a weighted weighted residual method such as Gale kin method or least squares approach can also derive finite element equations. With all the progress, today the finite element method or least squares approach appro ach is considering considering as one of the well-established well-established and convenient convenient analysis tool  by engineers and applied scientists.

4.3

General Proced Procedure ure of Finite Element Method The finite element method is a method of piecewise approximation in which

the structure or body is divided into small elements of finite dimensions called finite elements and then the original body or the structure is considered as an assemblage of these elements elements connected connected at finite number number of joints called nodal points points or nodes. Since the actual variation of field variables like displacement, stress, temperature,  pressure or velocity inside the continuum are not known, the variation of the field variable inside a finite element can be approximated by a simple function. These approximation functions called interpolation models are defined in terms of the values of the field variables of the nodes. nodes. The nodal values of the field variable variable are obtained by solving the field equations, which are generally in the form of matrix equations. Once the nodal values are known, the approximating functions define the field fiel d variab variable le throug throughou houtt the assemb assemblag lagee of element elements. s. The soluti solutions ons of general general continuum problems by the finite element method always follow an orderly step-bystep process.

27

 

The step-by-step procedure for static structural problem can be stated as follows:

Step 1:- Description of Structure (Domain). The first step in the finite element method is to divide the structure of solution region in to sub divisions or  elements.

Step 2:- Selecti Selection on of proper proper interp interpola olatio tion n model. model. Since Since the displa displacem cement ent (field (field va vari riab able) le) solu soluti tion on of a co comp mplex lex struc structu ture re un unde derr an any y speci specifi fied ed lo load ad conditions cannot be predicted exactly, some suitable solution, is assumed within an element to approximate the unknown solution. The assumed solu soluti tion on must must be simpl simplee an and d it shoul should d sa satis tisfy fy certa certain in co conv nver erge genc ncee requirements. Derivation ation of element element stiffness stiffness matrices (characteristi (characteristicc matrices) matrices) and load Step 3:- Deriv vectors. From the assumed displacement model the stiffness matrix [K(e)] and the load vector P(e) of element „e‟ are to be derived by using either  equilibrium conditions or a suitable Variation Variation principle.

Step 4:- Assemblage of element equations to obtain the equilibrium equations. Since the structure is composed of several finite elements, the individual element stiffness matrices and load vectors are to be assembled in a suitable manner  and the overall equilibrium equation has to be formulated as [K]φ = P Where [K] is called assembled stiffness matrix,  Φ is called the vector of nodal displacement P is the vector or nodal force for the complete structure .

Step 5:- Solution of system equation to find nodal values of displacement (field variable) the overall equilibrium equations have to be modified to account for the boundary conditions of the problem. After the incorporation of the  boundary conditions, the equilibrium equilibrium equations can be expressed as

[K]φ = P 28

 

For linear problems, the vector „φ‟ can be solved very easily. But for nonlinear problems, the solution has to be obtained in a sequence of steps, each step involving the modification of the stiffness matrix [K] and „φ‟ or the load vector P. P. Computati ation on of element element strains strains and stresse stresses. s. From From the known known nodal nodal Step 6:- Comput disp displa lace ceme ment nts, s, if requi require red, d, th thee elem elemen entt strai strains ns an and d str stress esses es can be co comp mput uted ed by us usin ing g th thee ne neces cessar sary y eq equa uati tion onss of soli solid d or str struc uctu tura rall mechanics. In the above steps, the words indicated in brackets implement the general FEM step-by-step procedure.

4.4

Convergence Requirement The finite element method provides a numerical solution to a complex problem.

It ma may y ther theref efor oree be ex expe pect cted ed that that the the so solu luti tion on must must co conv nver erge ge to th thee ex exac actt formulation of the structure. Hence as the mesh is made finer the solution should converge to the correct result and this would be achieved if the following three conditions are satisfied by the assumed displacement function. 

The displacement function must be continuous within the element. Choosing  polynomials for the displacement model can easily satisfy this condition.



Thee disp Th displac lacem emen entt fu func ncti tion on must must be capab capable le of re repr prese esent ntin ing g rigid rigid bo body dy displacement of the element. This is when the nodes are given such displacement corresponding to a rigid body motion; the element should not experience and hence leads to zero nodal forces. The constant terms in the polynomials used for  displacement models would usually ensure this condition.



The displacement function must be capable of representing constant strain states within the element. The reason for the requirement can be understood if we imagine the Condition when the body or structure is divided in to smaller and smaller elements. As these elements approach infinitesimal size the strain in each element also approach constant strain states. For one, two and three-dimensional elastic ela sticity ity proble problems ms the linear linear terms terms presen presentt in the polyno polynomia mials ls satisfy satisfy the requirement. However, in constant curvature instead of constant strains.

4.4.1 Advantages of FEM 29

 

The proper properties ties of each each element element are evalua evaluated ted separat separately ely,, so an obviou obviouss advantage advan tage is that we can incorporate incorporate different material properties properties for each element. Thus almost any degree of non-homogeneity can be included. There is no restriction on to the shape of medium; hence arbitrary and irregular shapes cause no difficulty likee all numeric lik numerical al approx approxima imatio tions ns FEM is based based on the concep conceptt of descrip descriptio tion. n.  Nevertheless as either the variations or residual approach, the technology te chnology recognizes the multidimensional continuous but also requires no separate interpolation process to extend the approximate solution to every point with the continuum. One of the important advantages of FEM is that it makes use of boundary conditions in the form of assembled equations. This is relatively an easy process and requires requir es no special technology technology.. Rather than requiring requiring every trial solution to satisfy  boundary conditions, one prescribes the conditions after obtaining the algebraic equations for individual

s finite elements.

’

4.4.2 Limitations of FEM FEM reached high level of development as solution technology; however the method yields realistic results only if coefficient or material parameters that describe  basic phenomena are available. The most tedious aspects of use of FEM are basic process of sub-dividing the continuum of generating error free input data for f or computer.

4.4.3 Applications of FEM The finite finite element element method method was develo developed ped origin originally ally for the analys analysis is of  aircraft structures. However, the general nature of its theory makes it applicable to wide variety of boundary value problem in engineering. A boundary value problem is one in which a solution is sought in domain or region of a body subject to the satisfaction of prescribed boundary conditions. Finite element method is the best tooll in investi too investigat gation ion of aircraf aircraftt str struct ucture uress involv involving ing static static analys analysis is of wings, wings, structures of rockets and missiles, dynamic analysis, response to random loads and  periodic loads. In mechanical design, stress concentration problems, stress analysis of pressure vessels, dynamic analysis of mechanical linkages can be effectively dealt using finite element method.

30

 

The specific application of the finite element method in the three major  categories catego ries of boundary boundary value problems, namely equilibrium equilibrium of steady state or time in inde depe pend nden entt pr prob oble lems ms,, Eige Eigen n va valu luee pr prob oble lems ms,, an and d pr prop opag agat atio ion n or tran transi sien entt  problems. In the equilibrium problems steady state displacement or stress distrib dis tributi ution on is found found for a solid solid mechan mechanics ics proble problem, m, temper temperatu ature re or heat heat flux flux distribution in the case of heat transfer problem. Referring to Eigen value problems in solid mechanics or structural problem, natural frequencies, buckling loads and mode shapes are found, stability stability of laminar laminar flows is found if it is a fluid mechanics  problem and resonance characteristics are obtained if it is an electrical circuit  problem, while for the propagation or transient problem, the response of the body under time varying force is found in the area of solid mechanics. Finite element method finds its application in the field of civil engineering in carrying out the static analysis of trusses, frames and bridges. The dynamic analysis of the structure is to obtain natural frequencies, modes and response of the structures to periodic loads. Nuclear engineering also uses finite element method concept in the static static and dy dynam namic ic charac characteri terizati zation on of its system systemss such such as nuclear nuclear pressu pressure re ve vesse ssels, ls, co cont ntai ainm nmen entt str struc uctu ture re an and d dy dyna nami micc respo respons nsee of re react actor or co comp mpon onen entt containment structures. Even the Bio-medical engineering applies finite element method, for impact analysis of skulls. Finite element method can be applied to an anal alys ysis is of ex exca cava vati tion on,, un unde derg rgro roun und d op open enin ings gs an and d dy dyna nami micc an anal alys ysis is of da dam m reservoir systems, which come under Geo-mechanics.

4.5

Hypermesh 11

Fastest, Solver Neutral CAE Environment for High Fidelity Modeling

Figure 4.1 Hypermesh 31

 

Altair Alt air HyperMe HyperMesh sh is a high-p high-perfo erforma rmance nce finite finite elemen elementt pre-pr pre-proce ocessor ssor to  prepare even the largest models, starting from import of CAD geometry to exporting an analysis run for various disciplines. HyperMesh enables engineers to receive high quality meshes with maximum accuracy in the shortest time possible. A complete set of geometry editing tools he help lpss to effic efficien ientl tly y pr prep epar aree CAD CAD mode models ls fo forr th thee me mesh shin ing g pr proc oces ess. s. Meshi Meshing ng algorithms algori thms for shell and solid elements provide provide full level of control, control, or can be used in automatic mode. Altair’s BatchMeshing technology meshes hundreds of files  precisely in the background to match user-defined standards. HyperMesh offers the  biggest variety of solid meshing capabilities in the market, including domain specific methods such as SPH, NVH or CFD meshing. A long list of CAD formats ensures a high level of CAD interoperability. Altair’s connector technology automatically assembles individual parts with their  Finite Element representation. HyperMesh is entirely customizable. An extensive APII libr AP librar ary y ca can n be us used ed to au auto toma mate te repe repeat atin ing g tas tasks ks or do co comp mpli licat cated ed math math operations for model generation. With a focus on engineering productivity, HyperMesh is the user-preferred environment for:  • Solid Geometry Modeling

  • Surface Surface Geometry Modeling

 • Shell Meshing

  • Solid Solid Mesh Generation Generation

 • Model Morphing

  • Automatic Mid-surface Generation

 • Detailed Model Setup

  • Batch Meshing

4.5.1 Benefits

Figure 4.2 A Powerful FEA Modeling Solution for the Enterprise

32

 



With the broadest set of direct CAD and CAE interfaces and the ability to define custom cus tom integr integrati ations ons,, HyperMe HyperMesh sh works works seamless seamlessly ly within within any engine engineeri ering ng environment.



HyperMesh provides a robust, common FEA modeling framework across the corporation - minimizing niche modeling tool investments and training costs.

High-speed, High-quality Meshing 

With automatic and semi-automatic shell, tetra, and hexa meshing capabilities, HyperMesh simplifies the modeling process of complex geometries.

Increase End-user Efficiency with Batch Meshing and Automated Model Assembly 

Batch Bat ch Mesher Mesher techno technolog logy y eli elimin minates ates the need need to perfor perform m manual manual geomet geometry ry cleanup and meshing thus accelerating the model development process.



Highly Highl y automated automated methods for rapid model assembly including including the assignment assignment and management of connections such as bolts spot welds, adhesives and seam welds. Interac Int eractiv tivee Featur Featuree and Volume-b olume-based ased Morphi Morphing ng for Geomet Geometric ric Shape Shape

Changes and Design Variable Variable Definition Def inition 

A flexible flexible set of morphing morphing tools allows users to modify legacy meshes without without re-meshing to automate the investigation new design proposals.

Close the Loop between CAD and FEA 

Extract shell meshes straight from a thin solid geometry including thickness assignments with the powerful Mid-map Mesh Generation tools.



Extract composite data from geometry files and transfer it to finite element data with minimal user interaction.



Retrieve 3D CAD geometries from finite element models to communicate design direction to design and engineering teams.

33

 

4.5.2 Capabilities

Figure 4.3 Capabilities Best In Class Meshing HyperMesh presents users with an advanced suite of easy-to-use tools to  build and edit CAE models. For 2D and 3D model creation, users have access to a va vari riety ety of mesh mesh-ge -gene nera rati tion on capab capabil ilit ities ies,, as well well as Hype HyperM rMesh esh’’s po powe werfu rfull automeshing module. High Fidelity Meshing 

Surface meshing



Solid map hexa meshing



Tetra meshing



CFD meshing



SPH meshing

4.5.2.1 Mesh Morphing HyperMo Hyp erMorph rph is powerf powerful ul solutio solution n for interac interactiv tively ely and parame parametric trically ally changing the shape of a finite element model. Its unique approach enables rapid shape variations on the finite element mesh without sacrificing mesh quality. During the morphing process, HyperMorph also allows the creation of shape variables, which can be used for subsequent design optimization studies.

4.5.2.2 Batch Meshing Using Altair BatchMesher™ is the fastest way to automatically generate high-quality high-q uality finite element meshes for large large assemblies. assemblies. By minimizing minimizing manual 34

 

meshing tasks, this auto-meshing technology provides more time for value-added engineering simulation activities. BatchMesher provides user-specified control over  meshing criteria and geometry clean-up parameters as well as the ability to output to customized model file formats.

4.5.2.3 CAD Interoperability HyperMesh provides direct readers for industry-leading CAD data formats for  generating finite-element models. Moreover, HyperMesh has robust tools to clean up imported impor ted geometry geometry containing surfaces with gaps, overlaps overlaps and misalignments misalignments that  prevent high-quality mesh generation. By eliminating misalignments and holes, and suppressing the boundaries between adjacent surfaces users can mesh across larger, more logical regions of the model while improving overall meshing speed and quality. Boundary conditions can be applied to these surfaces for future mapping to underlying element data. 

CATIA V5



IGES



PRO-ENGINEER 



PARASOLID



UNIGRAPHICS



STEP



ACIS



JT Precise

4.5.2.4 Connectors Connectors are geometric entities used to connect geometry or FE entities. They are used to create spot- and seamwelds, adhesives, bolts or masses. Connectors can can be real realiz ized ed fr from om geo geometr metric ic en enti titi ties es in into to var ario ious us so solv lver er sp spec ecif ific ic FE representations. It is possible to unrealize them to change the representation to a different type or solver profile on the next realization. Connectors contain their  locati loc ation, on, linkin linking g partne partners, rs, connec connectio tion n rules rules and realizat realization ion types. types. They They can be created crea ted manual manually ly,, absorb absorbed ed from from FE existi existing ng FE connec connectio tions ns or import imported ed and generated from text files. 35

 

4.5.2.5 Composites HyperMesh holds strong features for modeling highly complex composites structu stru ctures. res. Ply entiti entities es all allow ow defini defining ng the shape shape of indivi individua duall layers layers based based on geometry or elements. The laminate entity defines the stacking order of a composite  part. The composites definition is generic and can be realized into many solver   profiles. Forr revie Fo review w pu purp rpos oses es co comp mposi osite tess st stru ruct ctur ures es can be vi visu sual alize ized d in 3D, 3D, individual layers isolated and ply orientations visualized graphically. graphically. For a highly efficient workflow the CATIA reader has been enhanced to read composite definitions, such as ply shapes, material and ply orientations, directly from the geometry file. Fibersim drape data can be imported in a very similar way. way. HyperMesh offers sophisticated mapping algorithms to transfer the geometric input data to an FE mesh and associated properties.

4.5.3 CAE Solver Solver Interfacing HyperMesh supports a host of different solver formats for both import and export exp ort.. Along Along with with fully fully suppor supported ted solver solvers, s, HyperMe HyperMesh sh provid provides es a comple completel tely y tailored environment (user profile) for each supported solver. It also provides the flexibi flex ibilit lity y to suppor supportt additio additional nal solver solverss throug through h a unique unique and straigh straightfo tforwa rward rd interfacing language

4.5.3.1 Collaboration Tools HyperMesh Hyper Mesh Collaborati Collaboration on Tools Tools are available available with the standard standard installation installation an and d work work ou out-o t-off-th thee-bo box. x. User Userss ar aree en enab able led d to work work in a po powe werfu rfull an and d trul truly y co coll llab abor orati ative ve en envi viro ronm nmen ent. t. The The Expl Explor oree dialo dialog g is tigh tightl tly y in integ tegrat rated ed in into to al alll Hype Hy perMe rMesh sh file file dial dialog ogss an and d allo allows ws fo forr effi effici cient ent search searchin ing g of da data taba base sess an and d retrieving of files. The Organize Browser helps to structure simulation data and file versions. Personal or team data can be efficiently managed to ensure that always the latest late st file versions versions will will be used. used. Keywor Keyword d search search allows allows ef effici ficient ent research research of  databases. Connect is the connection to a common team database or corporate PLM systems. Files can be retrieved or uploaded from or to the database. 36

 

4.5.3.2 Customize HyperMesh to Fit Your Environment 

Configure the HyperMesh Interface:



  Custom Customize ize your your modeli modeling ng experi experienc encee throug through h an easy-to easy-to-us -usee interfa interface ce contain con taining ing drag-an drag-and-d d-drop rop toolba toolbars, rs, config configura urable ble pull-do pull-down wn menus menus and keyboard-controlled shortcuts.



Custom Utilities: Create custom applications that are fully integrated within the HyperMesh interface.



Solver Input Translators: Users can extend HyperMesh’s interface support by adding input translators to read different analysis data decks.



Solver Export Templates: Templates: Export templates allow the HyperMesh database to  be written out to user defined formats for non-supported solvers. solvers.

4.6 Radioss Altair RADIOSS is a leading structural analysis solver for highly non-linear   problems under dynamic loadings. It is highly differentiated for Scalability, Quality and Robustness, Robustness, and consists of features features for multiphysics multiphysics simulation simulation and advanced advanced materials such as composites. RADIOSS is used across all industry worldwide to improve the crashworthiness, safety, and manufacturability of structural designs. Forr ov Fo over er 20 ye years ars,, RADI RADIOS OSS S ha hass estab establi lish shed ed itsel itselff as a le lead ader er an and d an indust ind ustry ry standar standard d for automo automotiv tivee crash crash and impact impact analys analysis. is. Automo Automotiv tivee and aeros aer ospa pace ce co comp mpan anie iess va valu luee the the co cont ntri ribu buti tion on it make makess in un unde derst rstan andi ding ng an and d  predicting design behavior in complex environments such as automotive crash simula sim ulatio tion. n. In recent recent years years thru thru the additi addition on of implici implicitt finite finite elemen elementt solver  solver  capabilities RADIOSS has become a viable option also for standard analyses and linear dynamics. The tight integration with Hyper Works environment makes RADIOSS a  powerful design tool. Aside from modeling and visualization, RADIOSS models are ready for optimization. Transition to the optimization solver OptiStruct and Hyper  Study is easy. 37

 

4.6.1 Aerospace

Figure 4.4 Aerospace Every design organization in the aerospace industry struggles day by day to deliver on-time and on-budget products of the highest technical complexity which meet the most severe safety and performance requirements. To succeed in this task, the aerospace product developers and their extended enterprise need to exploit full potential of CAE; on one side early in the process to  predict performances supporting decision making, and on the other to accurately verify ver ify design designss to meet meet requir requireme ements nts.. Altair Altair HyperW HyperWork orkss provid provides es best-in best-in-cla -class ss simulation tools to the aerospace industry for: 

Minimum weight design



Composite Design 



Modern structural modeling



Stress, mechanism and vulnerability simulation



Automated design processes HyperView , OptiStruct  OptiStruct  and RADIOSS RADIOSS   are CAE tool toolss like like HyperMesh, HyperMesh,  HyperView,

 becoming the new standard bringing aerospace simulation to the next generation. EADS companies such Airbu Airbus, s, EADS Defence and Security Security,, Eurocopter Eurocopter.. EADS Innovation works as well as Boeing, Embraer, Bombardier Aerospace, GE Aviation, Pratt & Witney and many more have all chosen to work with Altair to improve their design processes.

38

 

4.6.2 Automotive

Figure 4.5 Automotive In Automotive CAE, Altair is the recognized leader, with more than 20 ye year arss of pr prov ovid idin ing g be bestst-in in-c -cla lass ss mode modeli ling ng,, solu soluti tion on an and d op opti timi mizat zatio ion n to tool ols. s. HyperWorks is used by most of the world’s leading automotive companies and their suppliers, who employ our common licensing model for maximum value. HyperWorks HyperW orks offer the widest span of solutions in Automotive CAE, including: 

Design Optimization



Crash and safety simulation



 Noise and vibration simulation



Durability analysis



Vehicle dynamics simulation s imulation



Computational fluid dynamics



Manufacturing simulation HyperWorks has a proven track record of success in a variety of automotive

systems applications, including: 

Interiors: Seats, Instrument Instr ument Panels, Trim



Body: BIW, Closures, Trim



Powertrain systems 39

 



Chassis systems



Climate control systems



Energy management and safety restraint systems



Electrical and control systems Sustainable Mobility: Aerodynamic performance, low mass structures, low

rolling resistance/high driveline efficiency and reduced accessory loads 

HyperWorks has the widest array of best-in-class software products for  automotive:



 and HyperCrash) HyperCrash) Finite element modeling and setup (HyperMesh (HyperMesh and



(OptiStruct)) Crash (RADIOSS (RADIOSS)) , NVH (OptiStruct



Multi-body dynamics solution (MotionView (MotionView and  and MotionSolve MotionSolve))



 and HyperStudy) HyperStudy) Optimization (OptiStruct (OptiStruct and



Computational Fluid Dynamics(AcuSolve Dynamics(AcuSolve)) HyperWorks Enabled Partner  products HyperWorks  products offer additional benefit to HyperWorks HyperWorks

unique licensing model, including solutions in Occupant simulation, Fatigue analysis, Electromagnetics and CFD.

4.7

Hyper view High-perfor Highperformance mance Post-process Post-processing ing and Visualization isualization Environme Environment nt for CAE

and Test Data:

Figure 4.6 Hyper view 40

 

Alta Altair ir

Hype HyperV rVie iew w

is

a

co comp mple lete te

po post st-p -pro roce cess ssin ing g

an and d

vi visu sual aliz izat atio ion n

environment for finite element analysis, multi-body system simulation, digital video, and engineering data. HyperView combines advanced animation and XY plotting features with window synching to enhance results visualization. HyperView also saves 3D animation results in Altair's compact H3D format, so users can visualize and share CAE results within a 3D web environment using Altair HyperView HyperView Player. Amazingly fast 3D graphics and unparalleled functionality set a new standard for speed and integration of CAE results post-processing. Coupling these features with HyperView’s advanced process automation tools dramatically improves results visualization and reporting.

4.7.1 Benefits of Hyper view 

HyperView is a complete visualization environment for FEA, CFD, and multi body system simulation data.



Through a complete, extendable library of direct model and results readers, users can post-process any CAE analysis.



HyperV Hyper View’s iew’s animation animation capabilities capabilities and speed make it ideal for working working with extremely large models and results files.



A multi-window, multi-page environment enables users to study several model configurations simultaneously. simultaneously.



To check for correlations between two models or simulation and reality, results can be overlaid with a model or video within the same window.



The Results Browser enables enables users to efficiently efficiently navigate though complicated complicated models. The Results View gives quick access to all analysis results. Plot styles help to efficiently generate contour plots based on common settings.



Resu Re sult ltss Math Math is a po powe werf rful ul to tool ol to ge gene nerat ratee ne new w re resu sult ltss from from ex exist istin ing g simulations by using mathematical expressions or external scripting languages. Time consuming result manipulation tasks can be performed in batch using HVTrans and saved in H3D. 41

 



All post-processing sessions can be stored in a session file or a report template. Session files help to reopen a complete session spanning across multiple pages and applications. Report templates similarly reopen previous sessions but can  be used to generate sessions for model variations or similar simulations.



Users can explore explore CAE models with Hype HyperV rView’ iew’ss in-depth in-depth model and results interrogation tools that are based on user-defined criteria.



HyperView’s synchronization capabilities help users gain insight into model integrity and behavior. This allows users to synchronize and visualize FEA results, multi-body systems results, XY plotting (simulation or test data) and digital video data.



HyperView HyperV iew enables users to share CAE results within a 3D web environment or  Microsoft PowerPoint using Altair HyperView Player® via Altair’s compact .h3d file.



Export HyperView session reports directly to HTML or PowerPoint including text, images, AVIs AVIs & .h3d files.



Users can create custom model views such as section section cuts and exploded exploded views  by combining functionality from HyperView’s HyperView’s comprehensive post-processing tool and utility set.



HyperView contains HyperGraph, a powerful XY plotting and data analysis  package that is tightly integrated within the HyperView HyperView environment.



HyperV Hyp erView iew contai contains ns a comple completely tely open open enviro environme nment nt that that enable enabless users users to expand the

Post-Processing Toolset in Virtually any way. Users can: 

Generate plot macros to capture and replay often-used mathematical curves.



Create custom math functions and algorithms.



Completely customize the GUI to cater to the user’s preferences and needs.



Automate any post-processing procedure and embed logical control through the

42

 

command layer and Tcl/Tk Tcl/Tk programming. 

Automate the generation and presentation of standard animations, plots and tables, as well as quickly compare results and correlation studies using the Overlay Results option.

4.7.2 Capabilities

Figure 4.7 CAE Animation HyperView delivers a complete suite of interactive animation, data plotting and digital digital video video functio functional nality ity that that dramat dramatical ically ly improv improves es results results visual visualizat ization ion,, analys ana lysis is and correl correlatio ation. n. Its synchr synchroni onizati zation on capabi capabiliti lities es enable enable users users to explor exploree detailed detail ed model integrity and behavior behavior.. By utilizing utilizing HyperView’ HyperView’ss extensive extensive post processing platform users can easily synchronize, compare and visualize FEA results, multi-body systems results, XY plotting (simulation or test data) and digital video data simultaneously in the same environment.

Animations 

Contours (Scalar & Tensor) Tensor)



Vector plots



Tensor plots



Deformation plots



CFD streamline plots

43

 



Deformed animations



Linear animations



Modal animations



Transient animations



Multi-body dynamics animations with flex-bodies

4.7.3 Solver Interfacing HyperV Hyp erView iew suppor supports ts many many popula popularr CAE solver solver format formatss throug through h direct direct readers, read ers, provid providing ing a flexibl flexiblee and consist consistent ent high-p high-perf erform ormanc ancee post-p post-proc rocessi essing ng environment for animating and plotting CAE simulation results. Additional solver  formats can be supported through user defined results translators, that convert results into the Altair H3D compressed binary format. HyperWorks also offers two translators, HvTrans and HgTrans, for working with any type of engineering data. HvTrans allows you to extract, translate, and compress CAE results while HgTrans enables you to convert, compress and process data files using custom math expressions that can be built from the embedded math function library. Solvers Supported Include: 

Radioss



OptiStruct



MotionSolve



ABAQUS



LS-DYNA



 NASTRAN



ANSYS



PAMCRASH



Adams 44

 



MADYMO



DADS



SIMPACK 



MOLDFLOW



MARC



 NIKE3D



LLNL DYNA



Others

4.7.4 Report Generation Generating a standard report is made easy with HyperView by using the “P “Pub ubli lish sh Sessi Session on”” ca capa pabi bili lity ty alon along g with with th thee repor reportt Templ emplate atess fu func ncti tion onal ality ity.. HyperView allows the user to export the active session to a HTML or PowerPoint XML report and provides users with the control to decide which information gets exported and in which format.

4.8



Report export — HTML, PowerPoint



Animation export — AVI, H3D



Image export — BMP, BMP, JPEG, PNG, TIFF



Summary data export — Multi-column, customizable formatting.

Step by Step process in FEM

For using any commercial software there are 3 steps 1. Preprocessing Preprocessing-- Consume Consumess most most the out of the the three three steps. steps. 2. Processing Processing (or (or solution) solution) - just click on “Solve"& “Solve"& it's the the software's software's turn to to do the job

45

 

3. Post Post processi processingng- Resul Resultt viewing viewing & interpr interpretat etation ion

Step 1 - Pre processing  

a) CAD data

 

b) Meshing (or discretization to convert infinite dof to finite one)

  C) Boundary conditions In early stage of industrial applications of Finite Element Analysis, CAD, meshing & analysis al1 used to be carried out by   a single engineer only. Soon it was realized that separation of the jobs &forming dedicated subgroups i.e. CAD group, Meshing group & Analysis or calculation group is necessary for optimum output and efficiency. CAD & Meshing -There are specialized software’s for CAD, Meshing & Analysis. CAD & meshing consumes most of the time For example - Typical time for  a single person to mode1 (CAD) 4cylinder engine block is 6 weeks & for brick  meshing 7 weeks (For tetra mesh about 2 weeks). Boundary Boun dary Conditions Conditions -Consumes -Consumes least time but it is the most Important Important step (typically applying load cases is about 1 day job). 3 months hard work of meshing & CAD data preparation of engine block would be undone in just 1 day if boundary conditions are not applied properly. Afte Af terr co comp mple leti tion on of pr prep epro roce cessi ssing ng i.e. i.e.,, CAD, CAD, Mesh Meshin ing g an and d Boun Bounda dary ry conditions, software internally forms mathematical equations of the form [F] = [K] [δ].

Step 2 - Proce Processing ssing or Solution During preprocessing user has to work hard while solution step is the turn of  computer to do the job. User has to just click on solve icon & enjoy a cup of tea! Intern Int ernall ally y softwar softwaree carries carries out matrix matrix format formation ions, s, inversi inversion, on, multip multiplica licatio tion n & solution for unknown e.g. displacement & then find strain stress for static analysis. Today FEA being used just because of availability of computers. FEM has  been known to Mathematicians & engineers right from late 50's but since solving so many equations manually was not possible, in true sense FEA got recognition only 46

 

after emergence of high capacity Computers.

Step 3 - Post processing Post process Post processing ing is viewin viewing g results results,, verific verificati ations ons,, conclu conclusio sions ns & thinki thinking ng about what steps could be taken to improve the design. Consider a simple example which involves al1 the above Steps Probably at the moment you are sitting on a chair or stool & reading this book. In this example we will analyse analysess the stool stool its itself elf for stress stress & displa displacem cement ent for a load load of 200 kg (assuming it could be used for sitting as well as supporting any object up to max. 200 kg wt.) 

47

 

CHAPTER 5

RESUL RESU LTS AND DI DISCUSSION SCUSSIONS S

5.1 Assumptions Review paper (20) 1. The analysis analysis is done done taking taking the distribu distribution tion of the the braking braking torque torque between between the front and rear axle is 70:30 2. Brakes Brakes are are appli applied ed on all the the four four whee wheels. ls. 3. The The anal analys ysis is is base based d on pure pure ther therma mall lo load adin ing g .The .The an anal alys ysis is do does es no nott determine the life of the disc brake. 4. The kinet kinetic ic energy energy of the vehicl vehiclee is lost lost through through the the brake discs discs i.e. i.e. no heat loss between the tyres and the road surface and the deceleration is uniform. 5. The disc disc brake brake model model used is of solid solid type type and not the the ventilated ventilated one. one. 6. The The ther therma mall co cond nduc ucti tivi vity ty of th thee mate materia riall us used ed for th thee an anal alysi ysiss is unifor uniform m throughout. 7. The specif specific ic heat of the materia materiall used is constant constant throug throughou houtt and does not not change with the temperature. 8. Heat flux flux on each front front wheel wheel is applied applied on one one side of of the disc only only.. 9. Displa Displacem cement ent in axial axial directio direction n on flang flangee is constr constrain ained ed in one side of the disc.

5.2

Static Calculations

Weight of car W = 1.4 tons Wheel diameter =19 inches  

= 19*25.4

 

= 482.6 mm

( 1inch=25.4mm)

Time to come rest = t=6 sec 48

 

5.2.1 For Velocity 60 kmph: Velocity of car = 16.6 m/s=60 kmph Stopping distance (D) =  

D= 16.66*6

 

D=99.96 meters

Torque T=F.r 

Stopping force a=2.77 m/sec2   F = 1400*2.77(kg.m/sec2)   F=3878 N

Torque =F.r    = 3878* (482.6/2)  

= 935761.4 N-mm

  = 935.761 N- m Brake set=4 Torque per brake = Torque/4  

= 233.94 N-m

Breaking normal force  Tf =µ N r m  N=

 N=

49

 

µ=0.4 from the review paper (20) r m= disc brake mean radius

 

=

mm

  r m =0.131 m

  N=  N=4464 N

Pressure (P) =

=

= 0.579 MPa 5.2.2 For Velocity 100 kmph Velocity of car = 27.77 m/s=100 kmph Stopping distance (D) =  

D= 27.77*6

 

D=166.62 meters

Torque T=F.r 

Stopping force

50

 

 

a=4.6283 m/sec2

  F = 1400*4.6283   F=6479.62 N

Torque =F.r    = 6479.62* (482.6/2)  

= 1563532.306 N-mm

  = 1563.53 N- m Brake set=4 Torque per brake = Torque/4  

= 390.88 N-m

Breaking normal force Tf =µ N r m  N=

 N= r m= disc brake mean radius

 

=

mm

  r m =0.131 m

  N=

51

 

  N=7459.54 N

Pressure (P) =

= = 0.9636 MPa

5.3 Thermal Calculations 5.3.1 Disc Brake Calculations for 100 kmph: Given Data: Velocity of the vehicle =100 km/h

 

 υ = 27.77 m/s

 

υ2= (27.77)2 = 771.17

Time for stopping the vehicle = 6 seconds Mass of the vehicle = 1400 kg.

Step-1: Kinetic Energy (K.E) = ½ * m * υ2 2

   

= ½ * 1400 *(27.77) = 539821.03 Joules

The above said is the Total Kinetic Energy induced while the vehicle is under  motion.

Step-2: The total kinetic energy = the heat generated Qg = 539821.03 Joules

52

 

Step-3: The area of the rubbing faces A = 15482.202 mm2 (calculated from drawings per disc) 2

  = 61928.808 mm  (for 4 discs’)

Step-4: Heat Flux (q) = Heat Generated / Second / rubbing area  

= 539821.03/6/ 61928.808

 

= 1.3014 Watts / mm2

The analysis is done by taking the distribution of braking torque between the front and rear axle is 70:30 Thus Heat Flux on each front wheel = (1.3014* 0.7)/2  

= 0.4559 Watts / mm2

5.3.2 Disc Brake Calculations for 60 kmph:  Given Data: Velocity of the vehicle =60 km/h

 

 υ = 16.66 m/s

 

υ2= (16.66)2 = 277.55

Time for stopping the vehicle = 6 seconds Mass of the vehicle = 1400 kg.

Step-1: Kinetic Energy (K.E) = ½ * m * υ2    

= ½ * 1400 *(16.66)2 = 194288.42 Joules

The above said is the Total Kinetic Energy induced while the vehicle is under  motion.

53

 

Step-2: The total kinetic energy = the heat generated Qg = 194288.42 Joules

Step-3: The area of the rubbing faces A = 10321.456mm2 (calculated from drawings per disc)   = 41285.824 mm2 (for 4 discs’)

Step-4: Heat Flux (q) = Heat Generated / Second / rubbing area  

= 194288.42/6/ 41285.824

 

=0.7843 Watts / mm2 The analysis is done by taking the distribution of braking torque between the

front and rear axle is 70:30 Thus Heat Flux on each front wheel = (0.7843* 0.7)/2  

= 0.2745 Watts / mm2

5.4 The properti properties es of mater materials ials : The Properties of the materials selected for present study is shown in table 5.1. Table5.1 Properties of materials used

Properties

Steel

Aluminum 2014-T6

Aluminum based metal matrix composite

Dens De nsit ity( y( ) iin n kg kg/m /mm m3

7.9e-6

2.8e-6

2.765e-6

Young’s Modulus(E) in MPa

210e3

72.4e3

98.5e3

Thermal Conductivity in W/mm 0C

1.6e-2

155e-3

181e-3

Specific Heat in J/kg

500

880

836.6

0

C 54

 

Poisson’s Ratio Coefficient of Thermal Expansion in /0C

0.3

0.3

0.33

1e-5

2.3e-5

17.6e-6

5.5 5.5 Stat Static ic R Res esul ults ts  

The static results such as stress, displacement at velocity 60 Kmph and 100

Kmph are given in table 5.2.

Table-5.2 Static Results Velocity 60kmph Velocity 100kmph Displacement Stress in Displacement in Stress in in 2 mm N/mm2 N/mm mm

Material Steel Aluminum 2014-T6 Aluminum  based Metal Matrix Composite

0.5923

7.09e-5

0.9857

1.18e-4

0.5923

2.06e-4

0.9857

3.42e-4

0.5897

1.56e-4

0.9815

2.60e-4

5.6 Static Analysis for displacement and str stress ess of disc using Hyper Hyper Mesh Static analysis for displacement and stress have been carried out for materials such as steel, Alumin Aluminum um and Alumin Aluminum um matrix material material composite composite at velocities velocities 60kmph and 100kmph are given in the sub sections

 At velocity 60kmph

 Fig5.1: Displacement of Steel disc at 60 kmph

55

 

 Fig 5.2: Stress of Steel disc at 60 kmph

 Fig 5.3: Displacement of Al disc at 60 kmph

 Fig 5.4: Stress Stress of Al disc at 60 kmph

56

 

 Fig 5.5: Displacement of AlMMC AlMMC disc at 60 kmph

 Fig5.6: Stress of AlMMC disc at 60 kmph

At velocity 100kmph

 Fig5.7: Displacement of Steel disc at 100 kmph

57

 

 Fig5.8: Stress of Steel disc at 100 100 kmph

 Fig 5.9: Displacement of Al disc at 100 kmph

 Fig5.10: Stress Stress of Al disc at 100 kmph

58

 

 Fig5.11:  Fig5.1 1: Displacement of AlMMC disc at 100 kmph kmph

 Fig5.12: Stress Stress of AlMMC disc at 100 kmph

Static Sta tic load loadss

are thos thosee which which are applie applied d

to a struct structure ure very very gradu graduall ally y,

in incre creasi asing ng from zero to th their eir fin final al va valu luee an and d th then en ei eith ther er do not ch chan ange ge

th thei eir  r 

magnitude, magni tude, direction direction or point point of application application with time time at all or change change them very slightly, so that accelerations occurred in this case can be neglected.

5.7 5.7 Ther Therma mall Re Resu sult ltss  The Grid temperature at 60 and 100kmph for three selected materials are given in the table 5.3 Table 5.3 Thermal Resuls

Velocity 60kmph

Velocity 100kmph

Grid Temperatures Temperatures in 0C

Grid Temperatures in in 0C

59

 

Steel

1079

433

Aluminum

508

204

Aluminum based Metal Matrix Composite

435

174

5.8 Thermal Analysis for Grid Temperatur emperaturee of disc using Hyper Mesh Thermal Therm al analysis analysis for Grid temperature temperature has been ca carried rried out for materials materials such as steel, Aluminu Aluminum m and Alumin Aluminum um matrix material material composite for velocities velocities 60kmph and 100kmph are given in the sub sections

At velocity 60kmph

 Fig5.13: Grid Temperature Temperature of Steel disc at 60 kmph

 Fig5.14: Grid Temperature Temperature of A All disc at 60 kmph

60

 

 Fig5.15: Grid Temperature Temperature of AlMMC disc at 60 kmph

At velocity 100kmph

 Fig5.16: Grid Temperature Temperature of Steel disc at 100 kmph

61

 

 Fig5.17: Grid Temperature Temperature of Al disc at 100 kmph

 Fig5.18: Grid Temperature Temperature of AlMMC AlMMC disc at 100 kmph 

The above analysis refers to a treatment of allowable stress at acceptable  performances. At high temperatures, there is a modification of the strength of  materials. If this high temperature is maintained for a long time, structural changes takes place which further affect the strength of and other properties of material. Also at high temperatures there will be continuous increase in strain or deformation of the material under the action of the applied load.

5.9 Comparative study The following following graphs graphs shows the comparativ comparativee study of radial distance distance Vs stress , deformation Vs thickness and Radial distance Vs Temperature for the three selected materials at 60 and 100kmph

 At 60 kmph:

62

 

Fig 5.19 Stress distribution along radial distance at 60kmph

Fig 5.20 Deformation along Thickness at 60kmph

At 100 kmph:

63

 

Fig 5.21 Stress distribution along radial distance for 100 kmph

Fig 5.22 Deformation along Thickness for 100kmph At 60 Kmph

64

 

Fig 5.23 Grid Temperature along Radial Thickness at 60kmph

At 100 kmph:

Fig 5.24 Grid Temperature along Radial Thickness at 100 kmph

65

 

CHAPTER-6

CONCLUSION & FUTURE WORK 

6.1 Conclusion Thee pr Th prese esent nt study study ca can n pr prov ovid idee a us usefu efull de desig sign n an and d impr improv ovee th thee br brak akee  performance of disc brake using three different materials Steel, Aluminum, Aluminum Alumi num based metal matrix compo composite. site. The design was analyzed considering considering the effects effec ts of thermal expansion and pressure load separately separately.. This is done to study the amount of deformation due to pressure loading individually. individually. These results are used to study the increase in deformation. The following conclusions are drawn from the  present study. study. 1. Comp Compar arat ativ ively ely the the yiel yield d str stren engt gth h of Alum Alumin inum um an and d Alum Alumin inum um ba based sed meta metall 66

 

matrix composite are high and hence maximum stress obtained is low for the materials. 2. Even though though stress stress and displace displacement ment for Aluminum Aluminum and Aluminum Aluminum based based metal matrix composite are almost equal to steel but the nodal temperatures for the applied heat flux are very high in the disc made of steel. 3. From the the study it is concluded concluded that that all values values obtained obtained from from the analysis analysis are less less than their allowable values. 4. The The ca calc lcul ulat ated ed resu result ltss ar aree sa sati tisf sfac acto tory ry co comm mmon only ly fo foun und d in th thee lite litera ratu ture re investigations. Thus conclusion is made from the above analysis stating that the brake disc made of Aluminum and Aluminum based metal matrix composite can be used as alternative materials.

6.2 Future Work  In today’s fast paced world, CAD/CAM systems have become an essential elem elemen entt in manu manufa factu cturin ring g co comp mpan anies ies th thro roug ugho hout ut th thee worl world. d. Tec echn hnol olog ogy y an and d communication are changing rapidly, driving business methods for organizations and requiring capitalization in order to maintain competitiveness. Knowledge prior to investing into a system is crucial in order to maximize the benefits received from changing CAD/CAM systems. Alon Along g wi with th the the mode modern rn manu manufa fact ctur urin ing g in indu dust stry ry with with

hi high gh sp spee eed d

development, many materials are used to design the Disc brake system, such as  plastic and polymer material and thickness also a lso is one of the important factors for the Disc brake dynamic analysis. So comparison should be done for material property of  Disc brake system under low and high speed and time variation. 67

 

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