Project Report Groundnut Harvester

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DESIGN, ANALYSIS AND DEVELOPMENT OF GROUNDNUT HARVESTER A dissertation Submitted in partial fulfilment of the requirements for the award of the degree of

MASTER OF TECHNOLOGY in

DESIGN ENGINEERING Submitted by

SANGRAM SHIVAJIRAO BHOSALE 2012AMD2607 Under the guidance of

Dr. B. P. PATEL

DEPARTMENT OF APPLIED MECHANICS INDIAN INSTITUTE OF TECHNOLOGY DELHI HAUZ KHAS, NEW DELHI-110016 May- 2014

Certificate This is to certify that the thesis entitled “Design, Analysis and Development of Groundnut

Harvester”

being

submitted

by

Mr.

Sangram

Shivajirao

Bhosale

(2012AMD2607) to the Department of Applied Mechanics, Indian Institute of Technology Delhi, in partial fulfilment of the requirements for the award of Master of Technology in Design Engineering, is a record bonafide work carried out by him under my guidance and supervision. The contents of this thesis have not been submitted to any other University or Institute for the award of any degree or diploma.

Dr. B.P.Patel Associate Professor Department of Applied Mechanics Indian Institute of Technology Delhi Hauz-Khas, New Delhi-110016

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Acknowledgements I would like to thank my supervisor, Dr. B.P. Patel, for his valuable guidance, kind help throughout completion of this project work. I would like to express my deep sense of gratitude to him for supporting me throughout the year. I would like to thank all the faculty and staff members of Applied Mechanics Department who contributed by making provision for necessary arrangements and facilities. I wish to express my thanks to friends for their heartiest co-operation in every stop of my project work. Lastly I would like to express deep gratitude to my father, Shri Shivajirao Bhosale for his guidance, co-operation, understanding, moral support and constant encouragement which inspired me to complete this thesis.

Sangram Shivajirao Bhosale

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Abstract The main objective of the project is to develop groundnut harvester considering needs of Indian farmers. Among the field operations concerned with groundnut cultivation, harvesting is the most laborious and costly endeavour. Existing harvesters are too huge to be useful for small scale farmers and in scenario like multi-cropping. Initially survey of typical groundnut farm field has been done followed by literature survey, patent study, kinematic analysis, static analysis, fabrication, testing and design modifications. The developed groundnut harvester is very cost effective and can also be used as tiller. By replacing the existing teeth it can be used for harvesting other underground crops as well.

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Table of Contents Certificate .................................................................................................................................... I Acknowledgements ................................................................................................................... II Abstract ..................................................................................................................................... III Table of Contents ..................................................................................................................... IV List of Figures ..........................................................................................................................VII List of Tables ............................................................................................................................ IX Chapter 1 Introduction and Literature survey ........................................................................1 1.1 Introduction .........................................................................................................................1 1.1.1 Human uses...................................................................................................................2 1.1.2 Process description .......................................................................................................2 1.1.3 Conventional harvesting technique .............................................................................3 1.2 Literature survey .................................................................................................................3 1.2.1 PATENT US4607703 ...................................................................................................5 1.2.2 PATENT US4687064 ..................................................................................................6 1.3 Need of the product .............................................................................................................7 1.3.1 Land acquired by Indian farmers ..................................................................................7 1.3.2 Mixed / Inter / Multi-cropping......................................................................................7 1.3.3 Labour Cost ..................................................................................................................8 1.3.4 Any delay in harvesting causes huge loss ....................................................................9 1.4 AMP777 course work..........................................................................................................9 1.4.1 Problem statement ......................................................................................................11 Chapter 2 Design Upgradation ................................................................................................12 2.1 Different ways of processing.............................................................................................13 2.2 Updated designs ................................................................................................................14 2.2.1 Groundnut Harvester 1 (GH1) ....................................................................................14 2.2.2 Groundnut Harvester 2 (GH2) ....................................................................................15 IV

2.2.3 Groundnut Harvester 3 (GH3) ....................................................................................16 2.3 Material selection and torque calculations........................................................................17 Chapter 3 Analysis of GH3 ......................................................................................................19 3.1 Kinematic analysis ............................................................................................................19 3.1.1 Analytical calculations ...............................................................................................19 3.1.2 Modelling in ADAMS ................................................................................................20 3.1.3 Validation ...................................................................................................................20 3.2 Static analysis of GH3 rotor assembly ..............................................................................23 3.2.1 Twisting case for GH3 rotor assembly .......................................................................23 3.2.2 Reconsideration of design ..........................................................................................26 3.2.3 Twisting case for NGH3 rotor assembly ....................................................................27 3.2.3 Convergence study for twisting case NGH3 rotor assembly ......................................28 3.2.4 Shear case for NGH3 rotor assembly .........................................................................29 3.2.5 Convergence study for shear case NGH3 rotor assembly ..........................................30 Chapter 4 Fabrication, Assembly and Testing .......................................................................31 4.1 Casting of blade-hand........................................................................................................31 4.1.1 Pattern making ............................................................................................................31 4.1.2 Casting and drilling ....................................................................................................31 4.1.3 Drum assembly ...........................................................................................................31 4.2 Trial 1 ................................................................................................................................32 4.2.1 Observations ...............................................................................................................33 4.2.2 Causes of failure .........................................................................................................33 Chapter 5 Design Modifications, Analysis and Testing .........................................................34 5.1 Weight reduction of rotor ..................................................................................................34 5.2 Static analysis of modified rotor assembly .......................................................................34 5.2.1 Twisting case for GH4 rotor assembly .......................................................................39 5.2.2 Convergence study of GH4 rotor assembly for twist case .........................................41 V

5.2.3 Shear Case for GH4 rotor assembly ...........................................................................41 5.2.4 Convergence study of GH4 rotor assembly for shear case .........................................43 5.3 Frame analysis ...................................................................................................................43 5.4 RPM reduction ..................................................................................................................45 5.5 Trial 2 ................................................................................................................................45 Chapter 6 Costing, Features and Scope for Improvement ...................................................47 6.1 Cost estimation ..................................................................................................................48 6.2 Features .............................................................................................................................48 6.3 Scope for improvement .....................................................................................................49 References ..................................................................................................................................50

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List of Figures Fig. 1 Global Peanut Production Distribution in 2011-2012 [2] ..................................................1 Fig. 2 Groundnut produced (metric tonne) in world verses Year [2] ...........................................2 Fig. 3 Schematic diagram of transmission shaft and fracture point for peanut harvester [6] .......3 Fig. 4 Groundnut digger cum separator [7] ..................................................................................4 Fig. 5 US Patent no. 4,607,703 .....................................................................................................6 Fig. 6 US Patent no. 4,687,064 .....................................................................................................7 Fig. 7 Sole crop yields and actual and expected intercrop yields of groundnut and millet [12]...8 Fig. 8 Primary design of TWGH and developed TWGH ...........................................................10 Fig. 9 Plain Shovel......................................................................................................................12 Fig. 10 Segmented Shovel..........................................................................................................12 Fig. 11 Bucket wheel excavator ..................................................................................................12 Fig. 12 Different possible ways of processing ............................................................................12 Fig. 13 Groundnut harvester 1 ....................................................................................................14 Fig. 14 Groundnut Harvester 2 ...................................................................................................15 Fig. 15 Groundnut Harvester 3 ...................................................................................................16 Fig. 16 Close View of GH3 rotor................................................................................................18 Fig. 17 Model for kinematic analysis in ADAMS ......................................................................20 Fig. 18 'X' coordinate of trajectory versus Time .........................................................................20 Fig. 19 ‘Y’ coordinate of trajectory versus Time .......................................................................21 Fig. 20 ‘Y’ coordinate of trajectory versus ‘X’ coordinate of trajectory ....................................21 Fig. 21 ‘X’ coordinates of trajectory versus Time ......................................................................22 Fig. 22 ‘Y’ coordinates of trajectory versus Time ......................................................................22 Fig. 23 ‘Y’ coordinates of trajectory versus ‘X’ coordinates of trajectory .................................22 Fig. 24 Loading and boundary conditions on GH3 rotor assembly ............................................23 Fig. 25 Fixed edge boundary condition .....................................................................................24 Fig. 26 von Mises stress distribution in shaft region ..................................................................24 Fig. 27 von Mises stress distribution in the blade region ...........................................................25 Fig. 28 Fixed blade surface boundary condition .........................................................................25 Fig. 29 von Mises stress distribution in sectional view of shaft and ribs ...................................25 Fig. 30 von Mises stress distribution around blade surface ........................................................26 Fig. 31 NGH3 and GH3 rotor assembly .....................................................................................26 Fig. 32 von Mises stress distribution around shaft .....................................................................27

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Fig. 33 von Mises stress distribution around blade surface ........................................................28 Fig. 34 Graph of von Mises stress versus Point number marked in region A (Fig. 32) .............29 Fig. 35 Surface traction applied on blade surface and fixed shaft boundary condition ..............29 Fig. 36 von Mises stress distribution around the shaft................................................................30 Fig. 37 Graph of von Mises stress versus Point number marked in region A (Fig. 36) .............30 Fig. 38 Designed and fabricated wooden pattern........................................................................31 Fig. 39 Designed blade-hand and casted blade-hand ..................................................................31 Fig. 40 Total assembled NGH3 rotor design and actual fabricated NGH3 rotor assembly........32 Fig. 41 Arrangements for Trial 1 ................................................................................................32 Fig. 42 Photograph of failed plywood plate................................................................................33 Fig. 43 von Mises stress distribution in NGH3 rotor assembly ..................................................34 Fig. 44 Skeleton rotor design ......................................................................................................34 Fig. 45 Deflection distribution in rotor teeth without ribs under twisting case ..........................35 Fig. 46 Deflection distribution in rotor teeth with ribs under twisting case ...............................35 Fig. 47 Flow chart for design, modifications done in the rotor assembly ..................................36 Fig. 48 von Mises stress distribution in shaft region ..................................................................37 Fig. 49 Problem in sprocket support ...........................................................................................37 Fig. 50 GH4 rotor assembly ........................................................................................................38 Fig. 51 Difference between rotor assembly of NGH3 and GH4.................................................38 Fig. 52 Close view of blade surface ............................................................................................39 Fig. 53 Loading and boundary conditions ..................................................................................40 Fig. 54 Partial edge of blade tooth fixed .....................................................................................40 Fig. 55 von Mises stress distribution in blade region .................................................................40 Fig. 56 Graph of ‘von Mises stress’ versus ‘Point number marked in region A (Fig. 55) ’ .......41 Fig. 57 Boundary and loading conditions ...................................................................................42 Fig. 58 von Mises stresses observed in sectional view of blade .................................................42 Fig. 59 Graph of von Mises stress versus Point number marked in region A (Fig. 58) .............43 Fig. 60 Loading and boundary conditions for frame ..................................................................44 Fig. 61 Deflection distribution in frame .....................................................................................44 Fig. 62 Deflection observed in frame with 10 mm plate ............................................................45 Fig. 63 Conceptual gear train ......................................................................................................45 Fig. 64 Arrangements for Trial 2 ................................................................................................46 Fig. 65 GH4 model .....................................................................................................................47 Fig. 66 Photograph of actual developed groundnut harvester ....................................................47 VIII

List of Tables Table 1 Existing patents regarding groundnuts [8] .......................................................................5 Table 2 Various intercropping systems.........................................................................................8 Table 3 Average Daily Wage Rate for Farm Labour (in Rs.)[13] ................................................9 Table 4 Components and their functions of GH1 .......................................................................14 Table 5 Components and their functions of GH2 .......................................................................15 Table 6 Components and their functions of GH3 .......................................................................16 Table 7 Comparative study of proposed designs ........................................................................17 Table 8 Shear strengths of different soil types [15] ....................................................................17 Table 9 Comparison of analytical and ADAMS results .............................................................23 Table 10 No. of elements used in different meshes (NGH3 twist) .............................................28 Table 11 No. of elements used in different meshes (NGH3 Shear)............................................30 Table 12 No. of elements used in different meshes twisting case for GH4 rotor assembly .......41 Table 13 No. of elements for different meshes shear case for GH4 rotor assembly ..................43 Table 14 Cost estimation for GH ................................................................................................48

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Chapter 1 Introduction and Literature survey 1.1 Introduction Peanuts, or "groundnuts" as they are known in some parts of the world, are the edible seeds and they are high in protein, oil and fibre. Peanuts are mostly used in food and confection products, but more than 50 per cent of the worldwide production is crushed for its oil [1]. World’s total peanut production is approximately 29 million metric tons per year with India being the world’s largest producer after China. Worldwide peanut exports are approximately 1.25 million metric tons. The India is one of the world’s leading peanut exporters, with average annual exports of between 200,000 and 250,000 metric tons. Argentina and China are other significant exporters. Countries such as India, Vietnam and several African countries enter the world market depending upon their crop quality and world market demand [1]. The global peanut production distribution in 2011-2012 is given in Fig. 1 and yearly production of groundnuts is given in Fig. 2.

Fig. 1 Global Peanut Production Distribution in 2011-2012 [2]

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Fig. 2 Groundnut produced (metric tonne) in world verses Year [2]

1.1.1 Human uses Groundnut oil is also used for pharmaceuticals, soaps, cold creams, cosmetics, dyes, paints, pomades and lubricants, emulsions for insect control, and fuel for diesel engines. Peanut hulls are used for furfural, fuel and as filler for fertilisers [3]. Value-added products have also been developed with a number of applications including bakery, confectionery and the general consumer market. Among these are [3]: 1) Peanut Flavour 2) Peanut Oil 3) Roasted Peanuts 4) Peanut Butter 1.1.2 Process description The production of high quality, flavourful and wholesome peanuts begins at the farm level. The quality of the peanuts delivered by farmers to the buying point dictates to a large degree the value of peanuts to the producer. The producer is an important industry component in the production of high quality peanuts for the consumer.  Soil requirement: Groundnuts grow best in well, red well-drained fertile sandy soil with pH value ranging from 5.5 to 7.0. Shallow and compacted soils are not preferred as the tap root of groundnut required to penetrate to the soil depth of about 10-12 cm [4].  Climatic requirements: Groundnuts require a high temperature and a frost-free period of about 120 to 160 days depending upon the seed. Groundnuts germinate 95% at soil

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temperatures ranging from 18° to 30°C. The suitable vegetative growth temperature ranges from 20° to 35°C. However at 33°C, this declines to 84%. The temperature favorable for flowering and pod formation is about 28°C. Rainfall of about 500-700 mm per annum will be satisfactory for good yields of groundnuts. Wider rows are advisable in low rainfall areas whilst the narrow rows are suitable in higher rainfall area [5]. 1.1.3 Conventional harvesting technique: • Harvest is the process of gathering mature crops from the fields. Harvesting usually consists of a series of operations comprising digging, lifting, windrowing, stocking and threshing. • Among the field operations concerned with groundnut cultivation, harvesting is the most laborious and costly endeavour. • When the plant has matured and the peanuts are ready to be harvested, the farmer waits until the soil is neither too wet nor too dry before digging. • The bunch type of groundnut is mostly harvested by pulling out the plants with manual labour in India. Usually 18 to 20 labours can harvest half-acre area of groundnut crop in one day.

1.2 Literature survey: The patents and available papers are reviewed. There are only limited number of papers available regarding harvesting of groundnuts. Tseng and Lin [6] in their paper about ‘The processing and fracture analysis on transmission shaft of a peanut harvester’ examined shaft failure. The transmission shaft is shown in Fig. 3.

Fig. 3 Schematic diagram of transmission shaft and fracture point for peanut harvester [6]

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The power of peanut harvester was 43 HP and the rotational speed of transmission shaft ranged from 75 RPM to 228 RPM in service. The diameter of transmission shaft was 40mm. According to the service condition, stress analysis of transmission shaft has been conducted by analytical approach and finite element simulation using ANSYS. It has been found that bending stress induced in the transmission shaft was 58 MPa, and shear stress 260 MPa. The shear stress resulted from torsion of transmission shaft. Because shear stress is much larger than bending stress, the fracture of transmission shaft is in torsion condition. On the basis of the examination of the fracture surface and stress analysis, they concluded that the fracture mode of transmission shafts is torsional fatigue [6]. In another case study, Singhal [7] of Grassroots Innovations Augmentation Network – North (GIAN - North), has analysed ‘Groundnut digger cum separator’ developed by innovator Khan [7]. Developed digger cum separator is shown in Fig. 4.

Fig. 4 Groundnut digger cum separator [7]

The conventional ground nut diggers leave 15-20 % of nut beneath the soil and additional manpower is required to avoid this loss. They only dig and cut groundnut crops while the studied innovation digs out remaining 15-20% groundnuts and separates it from the soil through the vibrating sieve. Khan [7] has developed a machine which is capable of separating the pods from the soil that comes in the path on which it is moving, moreover it does digging and filtering of the soil in one go. Specifications of digger cum separator are • Traction vehicle:- Tractor (35HP or more) • Working width – 6 feet • Working Depth – 6 inches • Size – 4ft x 6ft x 6ft 4

• Weight – approx. 300 - 400 kg • Container Capacity – 4 cubic meter The patents related to groundnut processing are listed in Table 1. Table 1 Existing patents regarding groundnuts [8] Sr. no.

Patent No.

Patent Name

1. 2. 3. 4.

4,000,747 4,136,507 4,142,348 4,166,505

5.

4,188,772

6. 7. 8.

4,227,538 4,607,703 4,687,064

Feed mechanism for peanut combine Peanut combine Speed control unit for driving the pick-up reel of a peanut combine Method and apparatus for harvesting green peanuts Hydraulic speed control system for the pick-up reel of a peanut combine Separator conveyor for peanut combine Peanuts harvester and its harvesting method Green peanut harvester

As one can observe from Table 1 that there are only two patents regarding harvesting of groundnuts. The brief descreption of patent numbers US4607703 and US4687064 is given in Fig. 5 and Fig. 6 respectively. 1.2.1 PATENT US4607703: This patent was registered on 26th August 1986 by Wang [8] .This peanut harvester includes truck body, two pairs of stalk straightners,two peanut diggers, a plant feeder, tilled conveyor , a horizontal conveyer, a peanut stripper and a peanut collector. By using this harvester soil can be automatically dug, lifted, stripped, screened and finally picked peanuts are collected into the bags. Another advantage of this harvester is that it provides a harvesting method through dividing the rows of peanut plants, straightening of stalks, digging peanuts under soil, screening and removing dust of the stripped peanuts, finally conveying and collecting the peanuts into bags for automatic integrated harvesting operation [8].

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Fig. 5 US Patent no. 4,607,703

1.2.2 PATENT US4687064 : This patent was registered on 18th August 1987 by Johnson [8]. It is actually an attachment for tractor or similar vehicle.

In this invention a pair of rubber V-belt is

positioned back-to-back and synchronized with vehicle motion. The plant conveyor belts carry the harvested plants rearward and upward to cause the roots of the plants containing the peanuts to pass over a pair of picking elements. A plurality of toothed picking combs is mounted transversely to the flat belts such that the combs move across the plant for contacting the roots and stripping the peanuts. In addition to the harvesting and picking system of this invention, Johnson [8] also provided blowing and shaking provisions for removing dirt and debris from picked peanuts such that the stored peanuts would be relatively clean.

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Fig. 6 US Patent no. 4,687,064

1.3 Need of the product: 1.3.1 Land acquired by Indian farmers: Agricultural land is scarce in India even though the country has a land area of about 328 million hectares which is the seventh largest land area among the countries of the world. India is burdened with a population of 1210 million as per the 2011 census, which grew from 345 million in 1947 with a growth rate of 1.76 in the last decade. Population density has increased from 117 per sq.km in 1951 to 368 in 2011. The population to land ratio is what makes the land accounting a matter linked to human development concerns. As the pace of growth in non-farm employment avenues lagged behind the population growth, it forced upon more than half of the population (58%) to take out their living from agriculture and allied activities [9]. India's per capita availability of agricultural land has shrunk to 0.3 hectare per farmer compared to over 11 hectares in the developed world [10]. So, it is uneconomical / infeasible to use existing huge harvesters in India. 1.3.2 Mixed / Inter / Multi-cropping: Mixed cropping is growing of two or more crops simultaneously on the same piece of land. It is also known as multiple cropping. This type of cropping leads to an improvement in 7

the fertility of the soil and increases in crop yield. The products and refuse from one crop plant help in the growth of the other crop plant and vice-versa. Mixed cropping is an insurance against crop failure in abnormal weather conditions. It also helps the farmer to improve its yield and economy and avoid crop failure which was very common in India and Asian countries [11]. In the developing world, groundnuts are commonly grown in intercropping systems, especially by small farmers who use traditional combinations often involving up to 5-6 crops [11]. Moreover intercropping leads to increase in yield. Groundnut is generally intercropped with sunflower, pigeon pea & millet. Few results of groundnut and millet intercropping are given in Fig. 7. Various intercropping system are listed in Table 2.

Fig. 7 Sole crop yields and actual and expected intercrop yields of groundnut and millet [12]

Table 2 Various intercropping systems

1.3.3 Labour Cost: During the Eleventh Five year Plan (2007‐12), nominal farm wages in India increased by 17.5 per cent per annum, and real farm wages by 6.8 per cent per annum, registering the fastest growth since economic reforms began in 1991. The average daily wage rate for farm labours is given in Table 3. Farming being labour intensive, this rapid increase in farm wages

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has raised cost of production of agri-commodities across the board. No wonder, farmer’s organizations have been demanding higher and higher minimum support prices (MSPs) to cover increased costs of production [13]. Table 3 Average Daily Wage Rate for Farm Labour (in Rs.)[13]

Such high wages not only squeeze farmers’ margins, but also crimp availability of labour. Above data shows that there is a need of automated machine which can minimize labour cost incurred in harvesting. 1.3.4 Any delay in harvesting causes huge loss: Conventional way of harvesting groundnuts is just holding and pulling the plant so that we can pick groundnuts. There could be delay in harvesting due to any of following reasons: a) Prolonged /Extended / Unexpected raining b) Unavailability of labour c) Personal reason of farmer Due to any of the above reason if harvesting is delayed then plant stem gets weaker which we can’t handle in traditional way & which finally results in huge loss to the farmer. So, there is a necessity of machine which can dig out groundnuts even though upper plant weakened.

1.4 AMP777 course work: By using M-80 scooter engine and tools available in the workshop of Applied Mechanics Department under the supervision of Dr. B.P. Patel, ‘Three Wheeler Groundnut Harvester (TWGH)’ was developed in the course of Product Design II (AMP777). Primary design and actual product are shown in Fig. 8. 9

A survey has been carried out in Satara , Maharashtra by taking into consideration 1 acre of farm field & following observations are made :  Maximum depth: 9 inch.  Max. dia. of spread: 9 inch.  Soil type: Soft soil (easily indented by fingers)  Average nuts: 40-100.  Weight of a plant with nuts: 300-600g.  Usual gap between two plants: 12-15 inch.  Crop period : 90 to 140 days.

Fig. 8 Primary design of TWGH and developed TWGH

The realized product had the following problems: 1. Weld joint is not strong enough for digging. 2. Inefficient in collection. 3. Unable to separate soil. The detailed design modifications are carried out and are discussed next.

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1.4.1 Problem statement: From the literature survey and patent study, we can conclude that the commercially available groundnut harvesters are huge in size, require high power and usually coupled with tractor. These are the three factors which indicate us why it is inconvenient to use existing patents, machines for small scale Indian farmers. Difficulties and problems faced in harvesting groundnuts are main reasons for farmers to forbid thinking of groundnut crop. It will be encouraging for farmers if there is groundnut harvester which would work in small workspace & would be simple and inexpensive. The objectives set for the study are: 1. Study of typical Groundnut Farm Field. 2. Design and Development of Groundnut Harvester. 3. Fabrication and Testing. 4. Design Modifications.

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Chapter 2 Design Upgradation We had with us a Bajaj M80 4.5 bhp engine with gearbox and decided to use this engine to develop ‘Groundnut Harvester (GH)’. Based on the literature survey, existing patent study and field survey the designed product should do following the processes: a) Digging: This can be done by various means like using curved blades or using drill.

Fig. 9 Plain Shovel

Fig. 10 Segmented Shovel

Fig. 11 Bucket wheel excavator

b) Separation of soil from pod: For this purpose, we can either use porous teeth or provide separate vibratory platform. c) Collecting pods: In case of wet conditions, collecting drum or box should be able to carry together weight of pods and soil. There should be an arrangement for separating soil from pod. Different ways of digging and separating soil from pods are given in Fig. 12.

Fig. 12 Different possible ways of processing

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2.1 Different ways of processing: A) Digging mechanism: This mechanism will dig out groundnuts with plant (pods) from ground. The different teeth profiles are discussed next: A1. Plain shovel: It is shown in Fig. 9. If we choose teeth profile as plain shovel then teeth ultimately will carry lot of undesirable weight of soil. Comparatively it is the strongest profile among all. A2. Segmented shovel: It is shown in Fig.10. This type of teeth profile will support separation of soil from pods but it is the weakest profile among all. A3. Bucket wheel excavator: It is shown in Fig. 11. Though it is more reliable and efficient, power requirement for this type of rotor will be the highest among all. B) Separation of soil from pods: When we dig out groundnuts, they will come along with lot of dust and debris. So it is important to separate dust and debris from pods. The different ways of separating soil from pods discussed next. B1. Separate conveyor: For separating soil from pod we can use vibrating conveyor. This mechanism can be incorporated after digging mechanism. B2. Modified collector: Instead of using normal box for collection of pods, one can use box with the porous base. For separation purpose, one can add long vertical nails with downside up position, so that when pods with dust and debris fall onto it, dust and debris will get separated and passed though porous base. B3. Porous teeth: Instead of using plain shovel (Fig.9) like teeth profile if we use porous bucket wheel or segmented shovel (Fig.10) like teeth profile then it will help for separation of soil while digging only. By combining different ways of processing, few designs are made and discussed next.

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2.2 Updated designs: 2.2.1 Groundnut Harvester 1 (GH1):

Fig. 13 Groundnut harvester 1

This design is combination of A2, B1, B2 (refer Fig. 13). Different components and their functions are described in Table 4. Components Rotor 1

Table 4 Components and their functions of GH1 Functions 1. Short teeth soften upper layer of soil. 2. Long teeth will dig out groundnuts.

Rotor 2

Support and ensure the motion of the segmented conveyor belt.

Chain drive

Supply power from engine to Rotor 1 and Rotor 2.

Engine

Acts as prime mover.

Conveyor belt

1. Collecting pods from teeth. 2. Transfer pods from rotor 1 to box.

Box

1. Collecting pods. 2. Separating soil from pod.

Drawbacks: a) To avoid falling back of groundnuts, segmented belt should be provided which will increase cost of product. b) Though in collecting it is more efficient than TWGH, assembly of many parts included makes design bulky. 14

2.2.2 Groundnut Harvester 2 (GH2):

Fig. 14 Groundnut Harvester 2

This design (Fig. 14) is inspired by old watermill (Rahat) which was pulled by bulls. This design is a combination A2, A3, B2 and B3. Different components and their functions are given in Table 5. Components

Table 5 Components and their functions of GH2 Functions

Cylindrical rotor with blades

Box

Bearings

Wheels

Main frame

1. Digging of groundnuts. 2. Transfer groundnuts from ground to box. 3. Separate soil cloud from pod. 1. Collecting pods. 2. Separating soil from pod. 1. To ensure smooth motion of shaft. 2. Support rotating shaft. 1. Provide mobility to design. 2. Support the main frame. 1. Acts as hub for all attachments. 2. Provide rigidity to harvester.

Drawback: Certainly it is more efficient and reliable in digging/collecting than GH1, but it will collect plant with soil cloud and would ultimately increase undesirable weight of groundnut harvester.

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2.2.3 Groundnut Harvester 3 (GH3):

Fig. 15 Groundnut Harvester 3

This design (Fig. 15) is next version of GH without conveyor (GH3). To avoid carrying undesirable weight of soil, horizontal conveyor belt is incorporated in between cylindrical rotor and box. Different components and their respective functions are given in Table 6. Components

Cylindrical rotor with blades

Conveyor belt

Bearings

Wheels

Main frame

Box

Table 6 Components and their functions of GH3 Functions 1. Digging of groundnuts. 2. Transfer groundnuts from ground to conveyor belt. 3. Separate soil cloud from pod. 1. Transfer groundnut plant from rotor to box. 2. Separation of soil and pod. 1. To ensure smooth motion of shaft. 2. Support rotating shaft. 1. Provide mobility to design. 2. Support the main frame. 1. Acts as hub for all attachments. 2. Provide rigidity to harvester. 1. Collecting pods. 2. Separating soil from pod. 16

GH1

Table 7 Comparative study of proposed designs GH2

Inefficient in separation of soil Bulky structure.

Least power requirement

Efficiently separate soil

GH3

Less efficient in separation

Long frame required to accommodate conveyor Highest power requirement

of soil Simple design

High power requirement

From the comparison given in Table 7, it is concluded that GH3 is most appropriate solution to the problem.

2.3 Material selection & torque calculations: While selecting the material, initially we need to find out what type of stresses will be acting on the rotating blade. Soil is extremely weak in tension, very strong in compression and in practice fails mainly in shear [14]. While digging, blades are going to interact with layers of soil which clearly indicates that shear stress would be the most significant stress component. Table 8 shows shear stress values for different types of soil. Table 8 Shear strengths of different soil types [15] Granite 14-50 MPa Diabase

25-60 MPa

Basalt

20-60 MPa

Slate

15-30 MPa

Quartzite

20-60 MPa

Sandstone

8-40 MPa

Shale

3-30 MPa

Limestone

10-50 MPa

Gravel

200-600 kPa

Sand

100-300 kPa

Very soft clay

0-25 kPa

Soft clay

25-50 kPa

Medium clay

50-100 kPa

Stiff clay

100-200 kPa

Very Stiff clay

200-400 kPa

Hard clay

> 400 kPa

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Usually groundnut crop is taken in Medium or Soft soil [15], so considering factor of safety , maximum shear stress (τ) experianced by bucket wheel excavater will be 100 kPa. From the design GH3 made in Catia V5, Frontal area of bucket wheel= 0.052 m2………………………………refer Fig. 16 Side area= 0.004 m2 …………………….……………………………refer Fig. 16

Fig. 16 Close View of GH3 rotor

Maximum force required for digging(Fmax) = τ x Frontal Area =>

Fmax = 100 x 103x 0.0052

=>

Fmax = 5.2 kN

Maximum torque required (Tmax) = Fmax x radius Tmax = 5.2 x 103x 0.3

=> =>

Tmax = 1560 Nm…………………………………...(2.1)

Bajaj M80 engine power= 3.5 kW P= =>

Nmin= 20 RPM

So the RPM to dig out typical groundnut farm field is 20 and mild steel is opted for GH3 design because it is easily available and satisfies all desired constraints. 18

Chapter 3 Analysis of GH3 3.1 Kinematic analysis: The kinematic analysis is carried out to find out the trajectory of the groundnut pod for different angular velocities of rotor. The analytical calculations are validated using ADAMS. By using simple formulae of projectile motion based on model designed in Catia V5, feasible range of rpm is calculated. Using ADAMS software, maximum distance travelled by groundnut pod is calculated for different speeds and compared with analytical solution. 3.1.1 Analytical calculations: Range is calculated by considering the size of conveyor belt. The groundnut pod must fall on conveyor belt. From model drawn in Catia V5,  Radius of rotor= 200 mm,  Blade length=100mm,  Pulley radius= 160mm,  Length of rotating platform =290mm.  Distance that should be travelled by groundnut pod ≥ 360mm So the desired minimum velocity can be calculated as follows, 0.36 = => => =>

v 2 sin 2 g

v=1.777 m/s



……………(Formula for max. range of the projectile) ……………(  =450)

= 8.885 rad/sec. .....……….. (Radius of rotor = 0.2 m)

N = 80.56 rpm

Similarly the distance that should be travelled by groundnut pod ≤ 590 mm To travel this distance, angular velocity needed can be calculated as follows, 0.59 = =>

v 2 sin 2 g

v= 2.048 m/s

=>

 = 11.45 rad/sec

=>

N= 109.39 rpm

19

So according to the designed size of conveyer, feasible range of angular velocity is 80.56rpm < N < 109.39 rpm Or 8.4 rad/sec <  < 11.45 rad/sec 3.1.2 Modelling in ADAMS: As model actual groundnut pod is difficult in ADAMS, it is idealized as cube of edge 5cm length. Following inputs are given to ADAMS, 

Weight of box = 0.5 kg………(assumed weight of groundnut pod+ soil cloud 500gm )



Coefficient of restitution= 1



Coefficient of dynamic friction= 0.9

For different angular velocities of rotor, results are discussed next. a) For 8.4 rad/sec: Model developed in ADAMS software is shown in Fig. 17, Rotor rotating in clockwise direction

Idealized Groundnut Pod Fig. 17 Model for kinematic analysis in ADAMS

Variation of position of pod (X coordinate) with respect to time is shown in Fig 18. According to simulation done, pod lose contact with rotor after 0.15 sec. One can see from the graph that after 0.15 sec, pod has travelled substantial distance and has settled down after 0.38 sec.

Fig. 18 'X' coordinate of trajectory versus Time

20

Variation of position of pod (Y coordinate) with respect to time is shown in Fig. 19. According to simulation done, pod loses contact with rotor after 0.15 sec. One can see from the graph that at 0.15 sec Y is maximum and it is least settled down after 0.38 sec. in Fig 19.

Fig. 19 ‘Y’ coordinate of trajectory versus Time

Variation of Y coordinate with respect to X coordinate of pod is shown in Fig. 20. From the graph shown in Fig 20, one can see X coordinate at Y maximum (Point A) is 537 mm, landing X coordinate (Point B) is 891 mm. So the distance travelled by pod is given by,

Fig. 20 ‘Y’ coordinate of trajectory versus ‘X’ coordinate of trajectory

Distance travelled by box = Maximum height (X coordinate) – landing X coordinate =537.0068 - 891.0005= 353.9337 mm b) For 11.45 rad/sec: Variation of position of pod (X coordinate) with respect to time is shown in Fig. 21. According to simulation done, pod loses contact with rotor after 0.1 sec. One can see from graph, after 0.1 sec, pod has travelled substantial distance. And it has settled down after 0.28 sec.

21

Fig. 21 ‘X’ coordinates of trajectory versus Time

Variation of position of pod (Y coordinate) with respect to time is shown in Fig. 22. According to simulation done, pod loses contact with rotor after 0.1 sec., one can see from the graph that at 0.12 sec Y is maximum and it is least settled down after 0.28 sec. in Fig. 22.

Fig. 22 ‘Y’ coordinates of trajectory versus Time

Variation of Y coordinate with respect to X coordinate of pod is shown in Fig. 23. From the graph shown in Fig. 23, one can see X coordinate at Y maximum (point A) is 1147.21 mm, landing X coordinate (point B) is 604.72 mm. So the distance travelled by pod is given by,

Fig. 23 ‘Y’ coordinates of trajectory versus ‘X’ coordinates of trajectory

Maximum height (X coordinate)–landing X coordinate =1147.2118- 542.4907= 604.7211mm 22

3.1.3 Validation: The maximum distance travelled by the pod, calculated analytically and in ADAMS is compared in Table 9. Table 9 Comparison of analytical and ADAMS results Angular velocity of rotor 8.4rad /sec 11.45 rad/sec Max. Distance travelled by pod analytically

0.36 m

0.59 m

Max. Distance travelled by pod in ADAMS

0.353 m

0.60 m

As it can be seen that the results in both the cases compared in Table 9 are very close.

3.2 Static analysis of GH3 rotor assembly: In static analysis, only cylindrical rotor is considered as it is most crucial part of the harvester. Analysis is done by using ABAQUS software package. Two different cases have been taken into consideration. 3.2.1 Twisting case for GH3 rotor assembly: In this case it is assumed that the blade has got stuck in soil and shaft is exerting torque trying to push it out. Following inputs are fed in ABAQUS,  Young’s modulus (E)= 210GPa  Density=7850 kg/m3  Element used: C3D4 ( A 4-node linear tetrahedron)  Calculation to find exerted force: Max. torque required for digging= 1560 Nm………………………….. from eq. (2.1) Hence for the shaft of 25mm diameter equivalent force is 124800 N.  Loading condition: Concentrated force of 62.4 kN is applied on both sides of the shaft at opposite nodes so as to create desired torque. Loading conditions are shown in Fig. 24.

Fig. 24 Loading and boundary conditions on GH3 rotor assembly

23

 Boundary conditions: Two separate boundary conditions are considered, in the first case only blade edge is fixed and in the second case whole blade surface is fixed. i) Edge of blade fixed: In this boundary condition, only edge of blade is fixed as shown in Fig. 25.

Fig. 25 Fixed edge boundary condition

Sectional view of shaft showing von Mises stress distribution is shown in Fig. 26. The maximum von Mises stress induced in the shaft region is 977.5MPa.

Fig. 26 von Mises stress distribution in shaft region

The induced stresses around blade surface are shown in Fig. 27. The maximum von Mises stress induced in blade surface is 226 MPa.

24

Fig. 27 von Mises stress distribution in the blade region

ii) Blade surface fixed: Fixed blade boundary condition is shown in Fig. 28.

Fig. 28 Fixed blade surface boundary condition

Sectional view of shaft is shown in Fig. 29. The maximum von Mises stress induced in shaft is 974MPa.

Fig. 29 von Mises stress distribution in sectional view of shaft and ribs

25

The von Mises stress distribution around the blade is shown in Fig. 30. The maximum von Mises stress induced in near the blade surface around the ribs is 221MPa.

Fig. 30 von Mises stress distribution around blade surface

3.2.2 Reconsiderations of design: As stresses induced in the shaft region (refer Fig. 27) of GH3 rotor assembly are quite high (like 977MPa), analysis is done again by changing the dia. of shaft from 25mm to 32mm, and using ribs of 20mm X 20mm (width X thickness). New rotor assembly is nomenclated as NGH3 rotor assembly. Both designs are shown in Fig. 31.

Fig. 31 NGH3 and GH3 rotor assembly

26

3.2.3 Twisting case for NGH3 rotor assembly All other inputs like material properties, boundary conditions are same as those of previous analysis. But there is change in loading conditions because of change in diameter.  Equivalent force calculations: Max. torque required for digging = 1560 Nm.........................................(refer eq. 2.1) =>

Equivalent force required = 97.5 kN …………….………… (Radius =16 mm)

Concentrated force of 48.75 kN is applied at the position shown in Fig. 24. From the results shown in Fig. 26 and Fig. 29, one can easily conclude that boundary condition blade edge fixed is more severe (max. von Mises stress = 977 MPa ) than that of blade surface fixed (max. von Mises stress = 974 MPa). So while analysing NGH3 rotor assembly only ‘blade edge fixed’ boundary condition is taken into consideration.  Boundary condition blade edge fixed: Stress distribution around the shaft is shown in Fig. 32. The maximum von Mises stress induced in the shaft region is 752 MPa.

A

Fig. 32 von Mises stress distribution around shaft

27

The von Mises stress distribution around the blade surface is shown in Fig. 33. The maximum von Mises stress induced in the blade region is 236 MPa.

Fig. 33 von Mises stress distribution around blade surface

As average von Mises stresses induced in NGH3 rotor assembly are not that severe (σeqv < 250 MPa), NGH3 rotor assembly is considered for further analysis. 3.2.3 Convergence study for twisting case NGH3 rotor assembly: The convergence study is carried out by refining the mesh. The stress values are compared for different meshes at 13 points along a circular path in the shaft from region A marked in Fig. 32. The number of elements in each mesh is given in Table 10. The stress values at three different conditions are plotted in Fig. 34. Table 10 No. of elements used in different meshes (NGH3 twist) Mesh No. of elements Coarse

129170

Fine

233536

Finer

353846

28

Stresses for different meshes ( NGH3 Twist) 3.50E+08

A

von Mises stress

3.00E+08 2.50E+08 2.00E+08

Coarse mesh Stress 1.50E+08

Fine mesh

1.00E+08

Finer

5.00E+07 0.00E+00 1

2

3

4

5

6

7

8

9

10 11 12 13 14

Point number Fig. 34 Graph of von Mises stress versus Point number marked in region A (Fig. 32)

3.2.4 Shear case for NGH3 rotor assembly: In this case shear force required for digging the soil has been taken into consideration. According to the literature survey, maximum shear strength of groundnut soil is 100 kPa. So, by applying surface traction of 0.1 MPa magnitude and considering shaft as fixed static analysis is carried out. Following inputs are fed in ABAQUS  Young’s modulus (E) = 210 GPa  Density=7850 kg/m3  Element used: C3D4 ( A 4-node linear tetrahedron)  Loading and boundary conditions: Surface traction of magnitude 0.1 MPa is applied on blade surface and shaft is fixed at both ends as shown in Fig. 35.

Fig. 35 Surface traction applied on blade surface and fixed shaft boundary condition

29

The von Mises stress distribution observed in sectional view of shaft is shown in Fig. 36. The maximum stress induced is 98.77 MPa.

A

Fig. 36 von Mises stress distribution around the shaft

3.2.5 Convergence study for shear case NGH3 rotor assembly: In convergence study by making mesh more fine convergence is verified. Circular path of 13 points is considered from region A marked in Fig. 36. The stress values at three different conditions are plotted in Fig. 37. The number of elements in each mesh is given in Table 11. Table 11 No. of elements used in different meshes (NGH3 Shear) Mesh No. of elements Coarse

132347

Moderate

226848

Fine

336475

Stresses for different meshes (NGH3 Shear) 8.00E+07

A

von Mises Stress

7.00E+07 6.00E+07 5.00E+07 4.00E+07

Coarse mesh

3.00E+07

Moderate mesh

2.00E+07

Finer Mesh

1.00E+07 0.00E+00 1

2

3

4

5

6

7

8

9

10

11

12

13

Point number Fig. 37 Graph of von Mises stress versus Point number marked in region A (Fig. 36)

30

Chapter 4 Fabrication, Assembly and Testing Out of all parts of the groundnut harvester, rotor was the only part which could not be fabricated in our workshop because of complexity involved in the fabrication of the proposed model of rotor.

4.1 Casting of blade-hand: 4.1.1 Pattern making: Wooden pattern of exact dimensions (110mm X 400mm) of blade-hand is made with the help of ‘Ravindra Engg. Works’. The designed and fabricated wooden pattern is shown in Fig. 38.

Fig. 38 Designed and fabricated wooden pattern

4.1.2 Casting and drilling: With the help of wooden pattern, sand mould is prepared and mild steel casting of desired shape and size has been produced. After casting, 32 holes of 10mm diameter have been drilled in the casting. Designed and fabricated blade-hand is shown in Fig. 39.

Fig. 39 Designed blade-hand and casted blade-hand

4.1.3 Drum assembly: Two pipes, one of OD (outer diameter) 405 mm, 400 mm length and 10 mm thickness and second of OD 35 mm, 720 mm long & 8 mm thick were taken. For rib plates of dimensions 400 mm X 40 mm X 20 mm are taken and by using welding, assembly has been done as shown in Fig. 40.

31

Fig. 40 Total assembled NGH3 rotor design and actual fabricated NGH3 rotor assembly

To minimize the eccentricity introduced due to welding, middle shaft OD has been reduced to 32 mm from 35 mm using lathe machine and proper rotation of drum has been ensured. Casted blade-hands are welded to the drum as shown in Fig. 40.

4.2 Trial 1: Fabricated rotor is designed to fit in the old frame made in the course of AML777. So, by fitting the rotor in the old frame, testing was carried out. Rotor fitted in frame is shown in Fig. 41.

Fig. 41 Arrangements for Trial 1

32

4.2.1 Observations: When machine was without load, engine was capable of rotating the rotor. But when it came in contact with the field soil wooden platform below the engine could not sustain the thrust produced due to actuation of rotor and cracks on the wooden platform were observed which made power transmission chain incapable of transmitting power to the rotor. 4.2.2 Causes of failure:  The plywood plate was underdesigned to hold engine while actuating rotor.  Old frame was not able to hold too heavy rotor (80 kg). Large wheels need to be considered.  Rotor started to rotate at very high RPM and thus sudden acceleration could not be sustained by plate and engine was also stopping. Cracked plywood plate is shown in Fig. 42.

Fig. 42 Photograph of failed plywood plate

33

Chapter 5 Design Modifications, Analysis and Testing Based on observations made while testing NGH3 rotor assembly following three major modifications are made: 1. Weight reduction of rotor assembly 2. Static analysis of new rotor assembly 3. Frame analysis 4. RPM reduction

5.1 Weight reduction of rotor: The weight reduction is based on the static analysis results of NGH3 rotor assembly. The material is removed from locations/sections where negligible stresses (σeqv < 100 MPa) were induced. The resulting skeleton rotor design is shown in Fig. 43.

Fig. 43 von Mises stress distribution in NGH3 rotor assembly

Fig. 44 Skeleton rotor design

34

The redesigned assembly (refer Fig. 44) is analysed under static twisting case as explained in section 3.2.1. From the analysis it is observed that the maximum deflection of the teeth tip after loading is 2 mm. The results are shown in Fig. 45.

Fig. 45 Deflection distribution in rotor teeth without ribs under twisting case

To reduce the deflection, ribs are introduced in the curvature region of teeth. The maximum deflection is reduced to 0.2 mm after introducing ribs as shown in Fig. 46.

Fig. 46 Deflection distribution in rotor teeth with ribs under twisting case

Step-wise design modifications in the rotor assembly are shown in Fig. 47.

35

Removal of unnecessary material

Removal of unnecessary material

Without ribs (deflection 2 mm)

With ribs (deflection 0.2 mm)

Modified teeth

Fig. 47 Flow chart for design, modifications done in the rotor assembly

36

While analysing the rotor assembly significantly greater stresses (≈ 1225 MPa) are also observed in shaft region as shown in Fig. 48.

Fig. 48 von Mises stress distribution in shaft region

To reduce the stress concentration, either shaft OD should be increased or supports should be provided to sprockets from rib region. If shaft OD is increased, it will lead to alteration of bearing and weight of rotor will increase. So, we are left only with the second option left. According to GH3 design length of rotor is 400 mm.

Fig. 49 Problem in sprocket support

From Fig. 49 one can clearly observe that supports provided to the sprockets from rib region will obstruct the motion of rotor itself. To avoid this problem, the length of rotor is

37

reduced to 300 mm and instead of outside chain drive, it is taken in between the bearings. The new proposed design (GH4 rotor assembly) is shown in Fig. 50.

Fig. 50 GH4 rotor assembly

Basic difference between GH4 and NGH3 is sprocket position. In the NGH3 design, sprockets were supposed to fit outside the bearings but in the GH4 they are fitted with drum ribs with four supports as shown in Fig. 51. Weight of proposed model of rotor assembly is now reduced to half of the previous i.e. 40 kg.

Fig. 51 Difference between rotor assembly of NGH3 and GH4

38

5.2 Static analysis of modified rotor assembly: Static analysis of the GH4 rotor assembly has been carried out for two different loading conditions, 1. Twisting case 2. Shear case 5.2.1 Twisting case for GH4 rotor assembly: In this case it is assumed that the blade has got stuck in soil and shaft is exerting torque trying to push it out. Following inputs are fed in ABAQUS,  Young’s modulus (E) = 210GPa  Density=7850 kg/m3  Element used: C3D10 ( A 10-node quadratic tetrahedron)  Calculation to find exerted force: Maximum force required for digging (Fmax)= τ x Frontal Area........( τ = soil shear strength) Surface area of each blade (shown in Fig. 52) is 0.005 m2

Fig. 52 Close view of blade surface

Fmax = 100 x 103x 0.005 x 6................( τ for soil =100 kPa) =>

Fmax =3 kN

Maximum torque required(Tmax) = Fmax x radius =>

Tmax = 3 x 103x 0.308

=>

Tmax =924 Nm

So, for sprocket of 170 mm diameter, equivalent force of 5435 N should be applied on both sides.  Loading condition: Concentrated force of 2.718 kN is applied on two nodes of both sides of the sprocket so as to simulate the induced torque. Loading conditions are shown in Fig. 53. 39

Fig. 53 Loading and boundary conditions

 Boundary Conditions: 1. Shaft rotation about X-axis is allowed for the region shown in Fig. 53. 2. Partial blade edge fixed as shown in Fig. 54.

Fig. 54 Partial edge of blade tooth fixed

The von Mises stress distribution observed in sectional view of blade-hand is shown in Fig. 55. The maximum von Mises stress induced is 113.9 MPa.

A

Fig. 55 von Mises stress distribution in blade region

40

5.2.2 Convergence study of GH4 rotor assembly for twist case: In convergence study by refining the mesh convergence is verified. Four node points are considered around the point of maximum stress (refer region A in Fig. 55). The stress values at three different conditions are plotted in Fig. 56. The number of elements in each mesh is given in Table 12. Table 12 No. of elements used in different meshes twisting case for GH4 rotor assembly Mesh No. of elements Coarse

14535

Finer

135318

Finest

1059525

Stresses for differnet meshes (GH4 twist) 1.20E+08

A

von Mises stress

1.00E+08 8.00E+07

Coarse

6.00E+07

Finer

4.00E+07

Finest 2.00E+07 0.00E+00 1

2

3

4

Nodes

Fig. 56 Graph of ‘von Mises stress’ versus ‘Point number marked in region A (Fig. 55) ’

5.2.3 Shear Case for GH4 rotor assembly: In this case shear force required for digging the soil has been taken into consideration. According to literature survey, maximum shear strength of groundnut soil is 100 kPa. So, by applying surface traction of 0.1 MPa magnitude and considering shaft as fixed static analysis has been done. Following inputs are fed in ABAQUS  Young’s modulus (E) = 210 GPa  Density=7850 kg/m3  Element used: C3D10 ( A 10-node quadratic tetrahedron)

41

 Loading and boundary conditions: Surface traction of magnitude 0.1 MPa is applied on blade surface and rotation of shaft along X-axis is enabled and both sprockets are fixed. Both conditions are shown in Fig. 57.

Fig. 57 Boundary and loading conditions

The von Mises stress distribution observed in sectional view of blade-hand shown is in Fig. 58. The maximum von Mises stress induced is 296 MPa.

A

Fig. 58 von Mises stresses observed in sectional view of blade

42

5.2.4 Convergence study of GH4 rotor assembly for shear case: In convergence study by refining the mesh convergence is verified. Four node points from the region A marked in Fig. 58 are considered for study. The stress values at three different conditions are plotted in Fig. 59. The number of elements in each mesh is given in Table 13. Table 13 No. of elements for different meshes shear case for GH4 rotor assembly Mesh

No. of elements

Coarse

14535

Finer

135318

Finest

1059525

Stresses for different meshes (GH4 shear) 2.50E+09

A von Mises stress

2.00E+09

1.50E+09 Finest Finer

1.00E+09

Coarse 5.00E+08

0.00E+00 1

2

3

4

Nodes

Fig. 59 Graph of von Mises stress versus Point number marked in region A (Fig. 58)

5.3 Frame analysis: As discussed in section 5.2.1 (Twisting case), maximum torque needed for digging is 924 Nm. So for the sprocket of diameter 17cm, equivalent force would be 10.87 kN.  Element used: C3D10 ( A 10-node quadratic tetrahedron)  Loading and boundary conditions are shown in Fig. 60.

43

Fig. 60 Loading and boundary conditions for frame

The deflection distribution is shown in Fig. 61. The maximum deflection of about 7 mm is observed below engine block. This means that after each digging impact, engine block will get displaced by 7 mm. This excessive deflection lead to the reduction of tension in power transmitting chains, this was the reason for failure of first trial.

Fig. 61 Deflection distribution in frame

To provide stiff support to the engine block, static analysis is carried out for different support plate thicknesses. For plate of 10mm thickness, the deflection below engine block is

44

observed to be 0.9 mm as shown in Fig. 62. This support is stiff enough for the engine to transmit power to the GH4 rotor assembly.

Fig. 62 Deflection observed in frame with 10 mm plate

5.4 RPM reduction: Rotational speed of ouput shaft of the engine was measured using rotameter. After starting the engine, output shaft was rotating in the range of 92 RPM to 100 RPM in first gear whereas the desired speed for the rotor is 20 RPM (section 2.4). Conceptual gear train for RPM reduction is shown in Fig. 63.

Fig. 63 Conceptual gear train

By using sprocket combination as shown in Fig. 63, RPM can be reduced to 15 from 100.

5.5 Trial 2: All discussed modifications are incorporated in the NGH3 rotor assembly. The fabrication procedure discussed in Chapter 4 is followed. Only difference is that teeth were 45

welded to the cylindrical rotor in NGH3 whereas in GH4 rotor assembly, the teeth are fitted to the cylindrical rotor with fasteners. Testing of new rotor assembly (GH4 rotor assembly) is carried out. Setup for trial is shown in Fig. 64. It has been observed that all previous errors are minimized. The GH4 rotor assembly is working perfectly fine.

Support Plate of t= 10mm Fig. 64 Arrangements for Trial 2

The teeth of GH4 rotor assembly are going 8 cm deep into the soil for digging. The conveyer belt is shown only for conceptual visualisation of overall working. The GH4 rotor assembly digs out the groundnut pod from soil and throws it on the conveyer belt. Or conveyer belt will comb stuck groundnut pod in between teeth and transfer it to the collector box. Scope for improvement is discussed in the next chapter.

46

Chapter 6 Costing, Features and Scope for Improvement Final design of groundnut harvester’s model (GH4) is shown in Fig. 65 and the photograph of fabricated prototype is given in Fig. 66.

Collector Conveyor Digger

Fig. 65 GH4 model

Fig. 66 Photograph of actual developed groundnut harvester

47

6.1 Cost estimation: After fabrication of groundnut harvester, estimated approximate cost of the developed product is given in the Table 14. Table 14 Cost estimation for GH Sr. Items no. 1. L- angle frame

Price (in Rs.)

2.

M-80 Bajaj Engine (second hand)

4000

3.

Bearings (6 nos. X 280 Rs.)

1680

4.

Casting of teeth (100 Rs/kg X 20 kg)

2000

5.

Rotor (20kg)

1000

6.

Sprockets (4X 300 Rs)

1200

7.

Engine support plate(50 Rs/kg X 20 kg)

1000

8.

Other (Shaft, belt, wheels, labour etc.)

3000

Total

15880/-

2000

While surveying typical groundnut farm fields it was observed that 35-40 labours are necessary to harvest 1 acre of groundnut farm field in a day which will cost around Rs. 6000 (considering daily wedge rate of Rs.150 per person and 40 labours). Now, let us see running cost of developed groundnut harvester: Consumption of fuel (oil mix petrol) = 1 lit. per hour* Approximately 2 hours* are sufficient for farmer to harvest 1 acre of typical groundnut farm field. That means only 2 litre of fuel and 2 labours are enough to harvest 1 acre of field in 2 hours. So, it can be seen that the developed groundnut harvester is very much cost effective.

6.2 Features: As discussed in section 6.1, developed GH4 is affordable multifunctional tool for farmers. Few functional features are discussed below. It can be used to harvest groundnuts as well as for operations like tilling/cultivating. As teeth of the rotor are detachable, by altering teeth we can use this machine for harvesting other underground crops like onion, potato etc.

*Judgments are based on Trial 2, vary according to working conditions and skill of farmer.

48

6.3 Scope for improvement: There is still scope for the optimization of rotor, weight of the rotor can be reduced to about 25-30 kg. Engine should be positioned outside the frame so that single conveyer belt can be used which will collect groundnut pod efficiently. Frame should be long enough to accommodate horizontal conveyer belt. The mobility of the GH can be improved for different field soil conditions. Since one has to push the machine all the time, power drive can be provided to the wheels to reduce the efforts required for pushing. After above modifications, improved model can be commercialised. This machine is certainly going to ease life of small scale farmers. It will convert costly and lengthy endeavour of harvesting into cheap and simple harvesting process.

49

References: [1] http://www.soyatech.com [2] World Peanut Production (http://www.CNAGRI.com).

2012,

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and

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Market,

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[3] S. Talwar, Peanut In India , History, Production & Utilization, Peanut in Local and Global Food System Series Report No. 5, Department of Anthropology , University of Georgia 2004. (http://www.worldpeanutinfo.com). [4] www.peanutsusa.com [5] www.ikisan.com [6] C. F. Tseng, W.S. Lin, The Processing and Fracture Analysis on Transmission Shafts of a Peanut Harvester, Journal of Materials Processing Technology 201 (2008) 374– 379.

[7] R. Singhal, Case Study on Groundnut Digger Cum Separator developed by Y. Khan, Grassroots Innovations Augmentation Network, North (GIAN - North) (http://www.gian.org). [8] United States Patent Documents, Crop Harvesting & Separating (1,260 patents) (http://www.ostc.thaiembdc.org). [9] S. S. Kumar, Land Accounting in India: Issues and Concerns, Government of India, 2005, National Bureau of Soil Survey and Land Use Planning (http://unstats.un.org). [10] S. Pawar, Union Agriculture Minister of India, The Indian Express, Mon, 16 Sep 2013. [11] A. K. Y. N. Aiyer, Mixed cropping in India, Indian Journal of Agricultural Science 19 (1949) 439-543. [12] M. S. Reddy, C. N. Floyd, and R. W. Willey. Groundnut in Intercropping Systems (1980): 133-142. [13] A. Gulati, S. Jain, N. Satija, Rising Farm Wages In India, Discussion Paper no. 5, Commission For Agricultural Costs and Prices, Department of Agriculture & Cooperation, Ministry of Agriculture, Government of India, April 2013. [14] E. McKyes, and J. Maswaure, Effect of Design Parameters of Flat Tillage Tools on Loosening of a Clay Soil. Soil and Tillage Research 43.3 (1997) 195-204. [15] Soil Testing Report, South Australian Water Corporation, 10 January 2007. [http://www.sawater.com]

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