Module No 5 of Ae (Be.mech Sem8)

2011-2012

MECHANICAL ENGINEERING

MODULE NO 5. BODY ENGINEERING

AUTOMOBILE ENGINEERING | Mr. Vaibhav V Naik

BODY ENGINEERING

Automobile Engineering

MODULE NO5. BODY ENGINEERING 1. BODY DESIGN a. Importance of body design b. Material for body construction c. Styling forms d. Coach and bus style e. Layout of passenger cars, bus and truck bodies.

2. Aerodynamic of the vehicle a. Aerodynamic drag b. Aerodynamic lifts and pitching moment c. Side force d. Yawing moments and rolling moments

3. Basic dimension a. Geometrical relations to driver seat b. Dimension of foot and pedal control, c. Passenger seats d. Vehicle dimension and visibility

4. Overall criteria for vehicle comparison 5. Chassis types and structure types : a. Open , b. Semi integral and c. Integral bus structure 6. Frame : a. Function and types of Frames b. Load on the frames c. Load and distribution of structure d. Location of power plant

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

BODY DESIGN a. Importance of body design b. Material for body construction c. Styling forms d. Coach and bus style e. Layout of passenger cars, bus and truck bodies.

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Q.1: - What are the main features of the automobile body?

Ans: Main feature of automobile body are

1. Torsional stiffness : To avoid the flexing of body on bad roads, it must resist twisting between the front and back.

2. Beam stiffness Body should not get sagged in the middle of vehicle resulting jamming of the door

3. Resistance to side impact Side member and doors of vehicle should be sufficient stong to resist t he side impact.

4. Safety glasses The glass used for front and rear vision and in door is provided with lamination

5. Less resistance to overflowing wind Vehicle should have minimum resistance to wind , therfore the vehicle body is provided with aerodynamic sha pe.

6. Safe guarding components from weather The components of engine and other systems are safeguarded from weather by automobile body

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Q.2: - What are the requirements of Bodies for various types of vehicles?

Ans: REQUIREMENTS OF BODIES FOR VARIOUS TYPES OF VECHILE: The body of the most vehicles should fulfill the following requirements: 1. The body should be light. 2. It should have minimum number of components. 3. It should provide sufficient space for passengers and luggage. 4. It should withstand vibrations while in motion. 5. It should offer minimum resistance to air. 6. It should be cheap and easy in manufacturing. 7. It should be attractive in shape and colour. 8. It should have uniformly distributed load. 9. It should have long fatigue life 10. It should provide good vision and ventilation.

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Q.3: - State the different bodies used in automobiles: Ans: The Automobile bodies are divided in two groups BODY

Passenger Body

Commercial Body

Figure: Types of Layout

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

B. According to Chassis design the body can divided into 1) Conventional Type 2) Integral Type 3) Semi- Integral Type C. According to other usage: 1) Light vehicle Bodies - cars, jeeps 2) Heavy vehicle Bodies – Busses, Lorries 3) Medium vehicle Bodies - Vans, Matadors

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Q.4: Explain various safet y features in body, which can be incorporated during design Ans:1) Crashworthy Crashworthy systems and devices prevent or reduce the severity of injuries when a crash is imminent or actually happening. Much research is carried out using anthropomorphic cra sh test dummies.

2) SEATBELTS Seatbelts limit the forward motion of an occupant, stretch to slow down the occupant's deceleration in a crash, and prevent occupants being ejected from the vehicle.

3) AIRBAGS Airbags inflate to cushion the impact of a vehicle oc cupant with various parts of the vehicle's interior.

4) LAMINATED WINDSHIELDS Laminated windshields remain in one piece when impacted, preventing penetration of unbelted occupants' heads and maintaining a minimal but adequate transparency for control of the car immediately following a collision. Tempered glass side and rear windows break into granules with minimally sharp edges, rather than splintering into jagged fragments as ordinary glass does.

5) CRUMPLE ZONES Crumple zones absorb and dissipate the force of a collision, displacing and diverting it away from the passenger compartment and reducing the impact force on the vehicle occupants. Vehicles will include a front, rear and maybe side crumple zones (like Volvo SIPS) too.

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

6) SIDE IMPACT PROTECTION B EAMS.

7) Collapsible universally jointed steering columns , (with the steering system mounted behind the front axle - not in the front crumple zone), reduce the risk and severity of driver impalement on the column in a frontal crash.

8) Pedestrian protection systems. Padding of the instrument panel and other interior parts of the vehicle likely to be struck by the occupants during a crash.

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

2. AERODYNAMIC OF THE VEHICLE a. Aerodynamic drag b. Aerodynamic lifts and pitching moment c. Side force d. Yawing moments and rol ling moments

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Q1. Explain Aerodynamic drag and aerodynamic lift with moments acting on the vehicle? Ans:- AERODYNAMIC DRAG AND AERODYNAMIC LIFT 1) A breakdown of the factors causing aerodynamic dra g. 2) Aerodynamic drag of rotating wheels may be omitted in the consideration of utilitarian or utility vehicles as it only gives a component of drag without considering at speeds a bove 150km/h (93 mph). 3) The total aerodynamics drag of a vehicle includes many factors such as profile drag, induced drag, skin friction drag, interference drag & cooling and ventilation system drag. 4) The total aerodynamic drag can be written in usual form:

Px = Cx .ρ.v2.A/2

where Cx = dimensionless drag coefficient, ρ = air density V = velocity of the vehicle & A = cross-sectional area of the vehicle (When viewed from front)

Skin friction drag 1. Drag due to tangential stress exerted on the surface of the body as the viscous fluid 2. Slips as a body (i.e.), the drag caused due to the friction between the aircraft’s outer surface & air. 3. Friction forces between an object & air through which it is moving produces skin friction drag. 4. The magnitude of skin friction drag depends on surface area of the Aircraft. 5. The whole surface of the aircraft experience s a surface (or) skin friction drag as it moves through the air

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

INDUCED DRAG 1. The drag caused due to induced lift. 2. Induced drag is a bi-product of lift and is closely related to the angle of attack. 3. Induced drag is separate from the parasite drag. 4. Due to the development of lift a wing will have both induced and parasite drag. 5. Actually induced drag is directly proportional to lift and inversely proportional to speed. Effects of induced drag: 1. Induced drag increases with increase in weight 2. Induced drag decreases with wing span i.e., high aspect ratio reduces induced drag 3. Speed increases, induced drag decreases

INTERFERENCE DRAG 1) It is caused by interference (i.e.) a term applied to the aerodynamic influence of bodies & parts of an aircraft on one anoth er. 2) When the aircraft parts are far apart the interference drag effect will be less. 3) If gap between a biplane wing decreases then interference increases. 4) Total drag is greater than the sum of the drag on the individual parts of the aircraft. 5) This is due to the flow interference at the junction of various surface, such as the wing, fuselage junction, tail fuselage ju nction or engine wing junction. 6) This Flow interference creates additional drag which is interference drag. 7) It is not directly associated with production of lift i.e., it is a parasite drag. Suitable fairing and streamlining of shapes to control local pressure gradient that can minimize interference drag. 8) Fairing is a part of the skin of an aircraft added to encourage streamline flow, thereby reducing eddies. 9) Hence, decreasing drag.At zero speed, there is no relative motion be tween the aircraft and the air.

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

10)Therefore there is no parasite drag. As the speed inc reases skin friction drag, formdrag and interference drag increases about half the p arasite drag on aircraft due to the wing.

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

3. BASIC DIMENSION a. Geometrical relations to driver seat b. Dimension of foot and pedal control, c. Passenger seats d. Vehicle dimension and visibility

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Q.1: - Short notes on Visibility and Blind Spots? Answer: A. Visibility 1. In transport, driver visibility is the maximum distance a t which the driver of a vehicle can see and identify prominent objects around the v ehicle. 2. Visibility is primarily determined by weather condition s (see visibility) and by a vehicle's design. 3. The parts of a vehicle that influence visibility include the wi ndshield, the dashboard and the pillars. 4. Good driver visibility is essential to safe road traffic. 5. Good all round visibility is one of the main requirements of the body design. It depends upon the size of the window opening and their position relative to the occupants.

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

B. Blind spots 1. Blind spots may occur in the front of the driver when the A -pillar (also called the windshield pillar), side-view mirror, and interior rear -view mirror block a driver's view of the road. 2. Behind the driver, there are additional pillars, headrests, passengers, and cargo that may reduce visibility. 3. Blind spots are affected directed by vehicular speed, since they increase substantially the faster one goes.

A-pillar blind spot

Forward visibility 1. This diagram shows the blocked view in a horizontal -plane in front of the driver. 2. The front-end blind spots caused by this can create problems in traffic situations, such as in round about, intersections, and road crossings. 3. Front-end blind spots are influenced by the following design criteria: a. Distance between the driver and the pillar b. Thickness of the pillar c. The angle of the pillar in a vertical plane side view d. The angle of the pillar in a vertical plane front view e. the form of the pillar straight or arc -form f. Angle of the windshield g. Height of the driver in relation to the dashboard h. Speed of the opposite car

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Effects of A-pillar angle on visibility 1. Most passenger cars have a diagonal pillar as shown in this side view. 2. The angle between the horizon and A -pillar is approximately 40 degrees with a straight pillar that is not too thick. 3. This gives the car a strong, aerodynamic body with an adequately sized front door.

40° angle A-pillar bar blind spots

Vertical A-pillar having small blind spots

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Q.2: - Short notes on Ergonomics Ans: Ergonomic 1. Ergonomics is the study of designing equipment and d evices that fit the human body, its movements, and its cogn itive abilities. 2. The International Ergonomics Association defines ergonomics as follows:

Ergonomics (or human factors) is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profe ssion that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance.

3. Ergonomics is employed to fulfill the two goals of health and productivity. 4. It is relevant in the design of such thing s as safe furniture and easy-to-use interfaces to machines. 5. Proper ergonomic design is necessary to prevent repetitive strain injuries, which can develop over time and can lead to long -term disability.

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Q.3: - Short notes on Drivers seat geometry Answer: Driver’s seat geometry

1. A correct driving position is important in the vehicle layout and the seat position in relation to the steering wheel, foot controls and other secondary control is of fundamental importance in body des ign. 2. Seating position has an influence not only on the drivers comfort but also on road safety. 3. The driver’s seat should be adjustable -45mm horizontally and 30mm vertically. Inclination of the steering column has a direct influence on the forces which can be applied by the driver. 4. A vertical steering column allows the driver to use the maximum force because the whole body is involved in the work of turning the wheel, not just the shoulders, as is the case when steering column is horizontal. 5. Forces of varying magnitude can be exerted on the foot pedals, depending on the angles α and β of the inclination of the seat and the back rests. 6. The distance between the floor and seat also has some influence on these forces. It should also be noted that harder seat allow the driver to use more force when controlling the vehicles. 7. These facts influence the design of controls and seating layout for different categories of vehicle. 8. Trucks have control which requires large forces and it is therefore usual vertical steering columns and a seating position that allows the driver to exert his full weight on the pedals. 9. Large fore are not acceptable in passenger cars and in consequence the controls are designed for the comfort.

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

CHASSIS a. Types and structure types : b. open , c. semi integral and d. integral bus structure

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

CHASSIS

Chassis is a French term which is now denotes the whole vehicle except body in case of heavy vehicles. In case of light vehicles of mono construction, it denotes the whole vehicle except additional fittings in the body.

“Chassis consists of en gine, power train, brakes, steering system and wheels mounted on a frame .”

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Q.1: - Draw the layout of the CHASSIS? List the main components of the Chassis? Answer: -LAYOUT OF CHASSIS AND ITS MAIN COMPONENTS:

Figure: Layout of chassis The following main components of the Chassis are 1. Frame: it is made up of long two members called side members riveted together with the help of number of cross members. 2. Engine or Power plant: It provides the source of power 3. Clutch: It connects and disconnects the power from the engine fly wheel to the transmission system. 4. Gear Box 5. U Joint 6. Propeller Shaft and Differential

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Q.3: - List the various load acting on the CHASSIS? Ans:- LOAD ACTING ON THE CHASIS Various loads acting on th e frame are 1) Short duration Load - While crossing a broken patch. 2) Momentary duration load – while taking a curve 3) Impact loads –Due to collision of the vehicle 4) Inertia loads –While applying the brakes 5) Static loads-load due to chassis parts 6) Over loads – beyond design capacity.

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

FRAME Frame: a. Function and types of Frames b. Load on the frames c. Load and distribution of structure d. Location of power plant

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Q.1: - List out the types of Chassis frame? Explain them? Ans: TYPES OF CHASSIS FRAMES : A. CONVENTIONAL FRAME : 1. It has two long side members and 5 to 6 cross members joined together with the help of rivets and bolts. 1) The frame sections are used generally. a. Channel Section - Good resistance to bending b. Tabular Section - Good resistance to Torsion c. Box Section - Good resistance to both bending and Torsion B. Integral Frame: 1) This frame is used now days in most of the cars. 2) There is no frame and all the assembly units are attached to the body. 3) All the functions of the frame carried out by the body itself. 4) Due to elimination of long frame it is cheaper and due to less weight most economical also. Only disadvantage is repairing is difficult. C. Semi - Integral Frame: 1) In some vehicles half frame is fixed in the front end on which engine gear box and front suspension is mounted. 2) It has the advantage when the vehicle is met with accident the front frame can be taken easily to replace the damaged chassis frame. 3) This type of frame is used in FIAT cars and some of the European and American cars.

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Q.2: - State the function of the CHASSIS FRAME? Ans:- FUNCTIONS OF THE CHASSIS FRAME: 1) To carry load of the passengers or goods carried in the body. 2) To support the load of the body, engine, gear box etc., 3) To withstand the forces caused due to the sudden braking or acceleration 4) To withstand the stresses caused due to the bad road condition. 5) To withstand centrifugal force while cornering .

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Q.3: - Short notes on FRAME ? Ans:-FRAME

1. It is structure to furnish supports for transmission system ,th e body and other units such as shock absorber ,spring and shackles.etc 2. It also maintains the correct relationship between the other related parts in order to perform their normal functions and freedom from strain. 3. It takes all static and dynamic loads with out undue twist and deflection. 4. The frame is the main part of the chassis on which remaining parts of chassis are mounted. 5. The frame should be extremely rigid and strong so that it can withstand shocks, twists, stresses and vibrations to which it is subje cted while vehicle is moving on road. It is also called underbody. 6. The frame is supported on the wheels and tyre assemblies. 7. The frame is narrow in the front for providing short turning radius to front wheels. 8. It widens out at the rear side to provide la rger space in the body.

Load coming on the frame 1. Weight of vehicle and passengers, which causes vertical bending of the side members. 2. Vertical loads when vehicle comes across a bump or pot hole of road. 3. Inertia load due to sudden application of sudden br akes. 4. Engine torque and braking torque. TYPES OF FRAME There are three types of frames: 1. Conventional frame, 2. Semi-integral frame, and 3. Integral frame (or unit frame)

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

A. CONVENTIONAL FRAME 1. It is non-load carrying frame. 2. The loads of the vehicle are tra nsferred to the suspensions by the frame. 3. This suspension in the main skeleton of the vehicle which is supported on the axles through springs. 4. The body is made of flexible material like wood and isolated frame by inserting rubber mountings in between. 5. The frame is made of channel section or tubular section of box section. Example: This type of frame is used for trucks.

B. SEMI-INTEGRAL FRAME 1. In this case the rubber mountings used in conventional frame between frame and suspension are replaced by more s tiff mountings. 2. Because of this some of the vehicle load is shared by the frame also. 3. This type of frame is heavier in construction. Example: Popular in European and American car.

C. INTEGRAL FRAME OR FRAME -LESS CONSTRUCTION 1. In this type of construction, th ere is no frame. 2. It is also called unitized frame -body construction. 3. In this case, the body shell and underbody are welded into single unit. 4. The underbody is made of floor plates and channel and box sections welded into single unit. This assembly replaces the frame. 5. This decreases the overall weight compared to conventional separate frame and body construction.

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Q.4.List the advantage and disadvantages of frame less construction?

Ans:- The advantage and disadvantages of frame less construction  Advantages of frame less construction 1. Reduced weight of vehicle. 2. Lower manufacturing cost. 3. Shock absorbing capacity of vehicle increases, which improves the safety of passengers. 4. Stability of vehicle increases due to lower position of vehicles.  Disadvantages of frame less construction 1. Reduction in strength and durability. 2. Increased cost of repairs in case of damage due to accidents. 3. Topless cars are difficult to provide frame less construction. 4. Economical only in case of mass production.

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Q5.Give the classification of motor vehicle on the basis of location of power plant Solution:

CLASSIFICATION OF MOTOR VEHICLE ON THE BASIS OF LOCATION OF POWER PLANT

The engine is typically placed in one of three locations. In the vast majority of vehicles, it is located as the front of the vehicle, in front of the passenger compartment. Front -mounted engines can be positioned either longitudinally or transversely with respect to the vehicle The second engine location is a mid -mount position between the passenge r compartment and rear suspension. Mid -mount engines are normally transversely mounted. The third, and least common, engine location in the rear of the vehicle. The engines are typically opposed -type engines. Each of these engine locations offers advantages and disadvantages:1. Front Engine Longitudinal a. In this type of vehicle, the engine, transmission, front suspension, and steering equipment are installed in the front of the body, and the differential and rear suspension are installed in the rear of the b ody. b. Most front engine longitudinal vehicles are rear -wheel drive. c. Some front-wheel-drive cars with a transaxle have this configuration, and most four-wheel-drive vehicles are equipped with a transfer case and have the engine mounted longitudinally in the front of the vehicle. d. Total vehicle weight can be evenly distributed between the front and rear wheels with this configuration. e. This lightens the steering force and equalizes the braking load. f. With this design, it is possible to independently remove and install the engine, propeller shaft, differential, and suspension. g. Longitudinally mounted engines require large engine compartments. h. The need for a rear-drive propeller shaft and differential also cuts down passenger compartment space.

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

2. Front Engine Transverse a. Front engines that are mounted transversely sit sideways in the engine compartment. b. They are used with transaxles that combine transmission and differential gearing into a single compact housing, fastened directly to the engine. c. Transversely mounted engines reduce the size of the engine compartment and overall vehicle weight. d. Transversely mounted front engines allow for downsized, lighter vehicles with increased interior space. e. However most of the vehicle weight is toward the front of the vehicle.Th is provides for increased traction by the drive wheels. f. The weight also places a greater load on the front suspension and brakes

3. Mid-engine Transverse a. In this design, the engine and drive train are positioned between the passenger compartment and rear axl e. b. Mid-engine location in used in smaller, rear -wheel-drive, highperformance sports cars for several reasons. c. The central location of heavy components results in a center of gravity very d. near the center of the vehicle. e. This vastly improves steering and handling. Since the engine is not under the hood, the hood can be sloped downward, improving aerodynamics and increasing the driver’s field of vision. f. However, engine access and cooling efficiency are reduced. g. A barrier is also needed to reduce the transf er of noise, heat, and vibration to the passenger compartment.

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Vaibhav Vithoba Naik

BODY ENGINEERING

Automobile Engineering

Q6.Explain the various loads acting on the chassis frame ? Ans: Various loads acting on the frame are 1) Short duration Load - While crossing a broken patch. 2) Momentary duration Load - While taking a curve. 3) Impact Loads - Due to the collision of the vehicle. 4) Inertia Load - While applying brakes. 5) Static Loads - Loads due to chassis parts. 6) Over Loads - Beyond Design capacity.

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Vaibhav Vithoba Naik