IRJET- Design, Analysis and Comparison between the Conventional Materials with Composite Material of the Leaf Springs

IRJET- Design, Analysis and Comparison between the Conventional Materials with Composite Material of the Leaf Springs

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  International Research Journalof Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 09 | Sep 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 1696 Design, Analysis and Comparison between the Conventional Materials with Composite Material of the Leaf Springs Girish h c 1 Dr K M Purushotama2 1Student, Master of Technology, Dr. Ambedkar Institute of Technology Bangalore, Karnataka, India 2Professor, Dept. of Mechanical Engineering Dr. Ambedkar Institute of Technology Bangalore, Karnataka, India ----------------------------------------------------------------------***--------------------------------------------------------------------- Abstract – Currently automobile suspension systems use a special kind of springs, which is Leaf spring. The added advantage of leaf spring over conventional springs is that the end of the spring can be guided along a definite path as it deflects0to act as a structural member0in addition to energy absorbing0device.Reducing weight while increasing or0maintaining strength of products is getting0to be highly important research issue0in this modern world. Composite materials are one0of the material families which are attracting researchers0and being solutions of such issue. In this paper0we describe design and analysis of composite0leaf spring. Further to reduce weight of structural steel leaf0spring by using different materials and also to improve the deflection attributes of leaf spring. Finally compare the stresses, deformations and weight saving of composite leaf spring with that of steel leaf spring. The main function of leaf spring is not only to support vertical load but also to isolate road induced vibrations. It is subjected to millions of load cycles leading to fatigue failure. The Automobile Industry has great interest for replacement of steel leaf spring with that of composite leaf spring, since the composite materials has high strength to weight ratio, good corrosion resistance. The material selected was glass fiber reinforced polymer (E-glass/epoxy) and Kevlar 149. The design parameters were selected and analyzed with the objective of selecting the best material for leaf spring. Result shows that, the E – glass composite leaf spring has maximum strength to weight ratio and can undergo about more deflection than Kevlar 149 and conventional steel leaf spring. The leaf spring was modeled in ANSYS Design Molder and the analysis was done using ANSYS 14.0 software. Key Words: leaf spring, ANSYS design of leaf spring, structural analysis, E-glass ANSYS workbench, 1. INTRODUCTION The system which reduces the road shock and vibrations of the vehicles are termed as suspension system. Some of the basic components of suspension system are shock absorber, Torsion bar and springs. Uneven surfaces of the roads cause lot of vibrations during the vehicle run. Engine when it is running also contributes to the vibration. Hence in the absence of suspension system, these vibrations are transferred to the entire body of the car, which may lead to uncomfortable ride and can result in failure of some car body parts. Suspension system separates the vehicle body and wheel, so that when the wheels feel the vibration, they are absorbed by the springs of suspension system instead of being transferred to the vehicle body. Present day different types of suspension systems and springs are being used based on the load capacity and the comfort level. A multi-leaf spring or laminated spring is a very important component in automobile suspension system, it is essential elements in suspension system of vehicle including sport utility vehicles, trucks, and rail road vehicles. Semi-elliptical leaf springs are almost universally used for suspension. The laminated spring consists of number of leaves called blades. The blades are varying in length curvature so that they will tend to straighten under the load. The leaf spring is design is based upon the theory of beams of uniforms strength. The accurate modelling of leaf spring is evaluated by performing static structural analysis using ANSYS software and to compare the stress induced and deformation for different load 1.1 Suspension leaf spring The leaf spring main purpose is to filter out the axle excitation before these disturbances reach the chassis. There are a variety of different suspensions used on vehicles. However, some types of suspensions have grown more popular than others. In the truck /car industry the overwhelming majority are leaf springs. Leaf springs are less expensive, simpler and more reliable than any other common suspension. In addition, they act as both spring and damper simultaneously, thus, reducing or eliminating the need for independent shock absorbers 1.2 Leaf Spring Figure 1: Leaf Spring 2D diagram The leaf spring consists of a series of flat plates or leaves, usually of semi-elliptic shape, which are held together with the help of U-bolts and centre clip. Generally, two types of leaves may be observed in a multi-leaf spring i.e.
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  International Research Journalof Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 09 | Sep 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 1697 some graduated -length leaves and a few extra full-length leaves. The length of the leaves gradually decreases from top to bottom. The longest leaf in the top is known as master leaf which is bent at both the ends to form spring eyes. The extra full-length leaves are inserted between the master leaf and the graduated-length leaves to support the transverse shear force. In order to maintain proper alignment and to restrict the lateral shifting of leaves, rebound clips are used in practice, these springs rest on the axle of an automobile. Its front end is connected with the frame by means of a simple pin joint and the rear end is connected with the frame through a flexible link known as shackle 1.3 PARTS OF LEAF SPRING Master leaf Top side of the leaf is called a master leaf for this leaf eye is provided for linking the spring with the other mechanical member Camber The certain amount of bend is given to the spring from the central line, passing through the eyes, is known as camber The camber is provided so that even at the maximum load the deflected spring should not touch the machine member to which it is attached. Central clamp The central clamp is required to hold the leaves of the spring. Rebound clips Rebound clips are used to hold the leaves together and to keep the leaf in aligned and avoid lateral shifting Graduated leaves Smaller leaves are called graduated leaves extra full-length leaf is provided to increase strength against shear force 2. LITERATURE REVIEW Mahmood M. Shokrieh et. al [1], have replaced a steel leaf spring by a composite one. Primary aim of their study was to design a leaf spring that possess minimum weight and is capable of taking a given external static force without any undergoing failure. Numerical analysis was carried using ANSYS V5.4. The obtained deflection and stress results were compared with analytical results Using the results obtained for steel leaf spring they designed a composite leaf spring made of fibreglass with epoxy resin. Further numerical analysis was carried out for the composite leaf spring using ANSYS V5.4 with displacement and stress as design constraints. Composite leaf spring weighed about 80% less and comparatively less stress as compared to steel springs. Pozhilarasu V. [3] carried out the comparative analysis of conventional steel and composite leaf spring. The composite material chosen was GFRP – Glass Fibre Reinforced Plastic. Numerical analysis was carried out using ANSYS software and the experimental analysis was carried out in Universal Testing Machine. Both methods of analysis showed large differences in results for conventional leaf spring and composite leaf spring. Aishwarya A.L [4] in their study carried out free vibration analysis of composite leaf springs. Modelling and analysis were done using ANSYS. Effect of relative movements of the leaves, variation of width and friction between the leaf spring was studied. They found that friction co efficient had no effect on the results. 3.1 PROBLEM IDENTIFICATION  Weight of the structural steel leaf spring is comparably high.  Deflection attributes are poor in case of structural steel.  Poor ride properties due to the noise and friction 3.2 OBJECTIVES  To find the replacement of the structure  To analyze the behavior of springs under varying loads.  To reduce weight of structural steel leaf spring by using other materials.  To improve the deflection attributes of leaf spring  To reduce the failure of leaf spring under various loading 3.3 METHODOLOGY A structural analysis is used to calculate deformations stress and strain on model in response to specified conditions  A static analysis gives certain information about model i.e. Stress analysis: tells us amount of stress that material can withstand  Strain analysis: tells us amount of strain that material can withstand i.e. part will break  Deformation analysis: tells us how much the shape of the model changes  The leaf spring is designed by using ANSYS 14.0 software with specified dimension  The 3D leaf spring model is imported to the ANSYS work bench  The analysis is carried out by specifying material properties and meshing  Application of boundary conditions for static structural model  Interpretation of solution and results
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  International Research Journalof Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 09 | Sep 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 1698 3.4 MATHEMATICAL ANALYSIS For the purpose of analysis, the leaves are divided in two groups as master leaf along with graduated length leaves forming one group and the extra full-length leaves forming the other group. 3.5 DIMENSION OF EACH LEAF Table 1: length of each leaf spring 3.6 DESIGN SPECIFICATION Table 2: design specification Geometric variable Design implications Leaf length 2L=1250mm Number of leaves (n) n=5 Leaf thick ness (t) t=12mm Leaf width (b) b=80mm Load acting at the centre of the spring 20000 N,15000 N,10000 N, 5000 N, Table 3: variation of maximum bending stress and deformation 4. LEAF SPRING CAD MODEL Leaf spring for the current analysis was created using ANSYS Design Modeller software. Figure 2: Leaf Spring Isometric view Leaf spring is modelled in ANSYS design modeller software by taking dimension of each leaf spring first master leaf is designed, next graduated leaf spring is designed All the model is assembled is as shown in fig with all dimension are in mm 4.1 LEAF SPRING MESH DETAILS Mesh generation process is important process in finite element analysis. Meshing discretise entire model into very small elements. In this work “fine mesh” is selected for meshing the 3D model of the leaf spring. Meshing of the leaf spring CAD model was carried out using ANSYS meshing platform. Care was taken to see that the meshing error is as minimal as possible Figure 3: Meshed Leaf Spring Grid independency test was carried out to make sure that the results do not vary with the mesh size. In total there are 16240 and 2502 nodes and elements respectively. Length of smallest leaf 275 mm Length of 2nd leaf 550 mm Length of 3rd leaf 775 mm Length of 4th leaf 1050 mm Length of 5th leaf 1250 mm Load in N Stress in Pa Deformation in m 5000 2.0304 1008 0.02047 10000 3.997 1008 0.037941 15000 6.581 1008 0.05541 20000 8.8215 1008 0.071852
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  International Research Journalof Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 09 | Sep 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 1699 4.2 PROPERTIES OF THE MATERIAL CHOSEN FOR ANALYSIS 1. E Glass Table 4: Mechanical Properties of E Glass Mechanical Symbols Units Values Young’s modulus E Pa 8.5x1010 Shear modulus G Pa 3.4553x1010 Bulk modulus K pa 5.2469x1010 Poisson’s ratio µ - 0.23 Density p Kg/m3 2600 Tensile Yield strength Sy Pa 1.95x1010 Compressive yield strength Scy Pa 4x1009 Compressive ultimate Scy Pa 5x1009 2. Kevlar 149 Table 5: Mechanical Properties of Kevlar 149 Mechanical Symbols Units Values Young’s modulus E Pa 1.86x1005 Shear modulus G Pa 6.8889x1010 Bulk modulus K Pa 2.0667x1011 Poisson’s ratio µ - 0.35 Density p g cm/m3 1.45 Tensile Yield strength Sy MPa 3440 3. Structural steel Table 6: Mechanical Properties of Structural Steel Mechanical symbols units values Young’s modulus E Pa 2x1005 Shear modulus G Pa 7.6923x1010 Bulk modulus K Pa 7.6923x1010 Poisson’s ratio µ 0.3 Density p Kg/m3 7850 4.3 BOUNDARY CONDITIONS X, Y and Z component of remote displacement is set to zero for one end, indicating that there is no displacement on that end. For the other end the X component is assigned free type boundary condition while the other two components are set to zero. For both the ends the X and Y component of rotation are set to zero, while Z component is allowed to rotate freely. Different loads are applied in the positive Y direction at the bottom of the leaf spring. RESULTS AND DISCUSSION 5.1 LEAF SPRING ANALYSIS Leaf spring analysis was carried out at 5000 N, 10000 N, 15000 N and 20000 N. Below figures shows the analysis carried out at 20000 N for E Glass, Kevlar 149 and Structural Steel. 5.2 ANALYSIS OF E-GLASS LEAF SPRING AT 20000N Figure 4: Equivalent Stress for E Glass at 20000 N Figure 4 shows the stress acting on the leaf spring at a load of 20000 N. The maximum value of the stress is found to be occurring near to eye region Maximum stress is 8.5391 x108 Minimum stress is 5.3794 x105 Figure 5: Total Deformation for E Glass at 20000 N
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  International Research Journalof Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 09 | Sep 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 1700 Figure 5 shows the total deformation of the leaf spring during application of load, the deformation is progressing from centre at a maximum value Maximum deformation: 0.16497 Minimum deformation: 0.10443 5.3 ANALYSIS OF KEVLAR LEAF SPRING AT 20000 N Figure 6: Equivalent Stress for Kevlar 149 at 20000 N Values of stress Maximum stress: 8.4982 x108 Minimum stress: 2.7512 x105 Figure 7: Total Deformation for Kevlar 149 at 20000 N Values of deformation Maximum deformation: 0.074922 Minimum deformation: 0.047347 5.4 ANALYSIS OF STRUCTURAL STEEL LEAF SPRING AT 20000N Figure 8: Total Deformation for Structural Steel Leaf spring at 20000 N Values of stress Maximum stress: 8.5215x108 Minimum stress: 3.4148 x105 Figure 9: Total Deformation for Structural Steel Leaf spring at 20000 N Values of deformation Maximum deformation: 0.069882 Minimum deformation: 0.044198 Table 7: Comparison of deformation between theoretical and ANSYS based results Load in N Maximum deformation Maximum deformation Theoretical ANSYS based 5000 0.0247 0.01747 10000 0.037941 0.034941 15000 0.05541 0.05241 20000 0.071852 0.069882 It is seen that the software-based results almost match with the theoretical solutions and hence, it validates the
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  International Research Journalof Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 09 | Sep 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 1701 concept of mathematical formulations for maximum deformation and bending stress in different leaves. Figure 10: variation of max. deformation v/s load The results obtained by the analysis of E – Glass, Structural Steel and Kevlar 149 respectively at loads of 5000 N, 10000 N, 15000 N, and 20000 N. From the above analysis figures, it is clear that in all the cases the maximum stress appears to be near the eye region. The value of stress increases with increase in loading for all the cases. E – Glass leaf spring undergo more deformation than other two materials at all the loading condition. In the figure 10, it is observed that when varying load the maximum deformation of the leaf spring for the steel material and the composite material are compared. E- Glass material shows more deflection then structural steel 7. CONCLUSIONS The material selected as a replacement for conventional structural steel was glass fiber reinforced polymer0(E-glass/epoxy) and Kevlar0149. The leaf spring0was modeled in ANSYS Design Molder and the analysis0was done using ANSYS014.0 software. The design parameters were0selected and analyzed with the objective of0selecting the best material for leaf spring. Result shows that. E – glass composite0leaf spring has maximum strength to0weight ratio and can undergo about more deflection than Kevlar 149 and conventional steel leaf spring. Hence E – glass0can be preferred as0the material for the fabrication of leaf spring over Kevlar 149 and conventional structural steel. 8. REFERENCES [1] Mahmood M. Shokrieh , Davood Rezaei “ Analysis and optimization of a composite leaf spring ” Composite Structures, 60 (2003) pp- 317–325, Vol.2. [2] A Skrtz, T.Paszek,(1992) “Three dimensional contact analysis of the car leaf spring”, Numerical methods in continuum mechanics, 2003, Zilina, Skrtz republic, pp- 234-256, Vol.4. [3] Cheng Wang, (1999) “Design and Synthesis of Active and Passive vehicle suspensions, pp-137-207, Vol.2. [4] I Rajendran, S. Vijayarangan, “Design and Analysis of a Composite Leaf spring”, Journal of Institute of Engineers India, 82, 2002, pp-180-187, Vol.2 [5] M. Venkatesan , D. helmen devaraj (2012) , Design And Analysis Of Composite Leaf Spring In Light Vehicle int. jr. of modern engineering research, pp-213-218, Vol.2. [6] H.S. Manjunath, Maqsood Ali, Dr. L. Chandra sager “Computational fluid dynamic analysis and structural analysis of ribbed panel structure using FEA International Research Journal of Engineering and Technology (IRJET) oct 2017, pp-975-981, Vol.4, [7] S. Venkatesh, Dr. S. S. Mohamed Nazirudeen, Dr. A. K. Shaik Dawood, R. Karthikeyan IRACST – Engineering Science and Technology: An International Journal (ESTIJ), ISSN: No. 4 August 2012, pp-2250-3498, Vol.2, [8] G. Harinath Gowda & E Venugopal Goud “Static Analysis Of Leaf Spring” International Journal of Engineering Science and Technology (IJEST), ISSN: 0975- 5462, No.08 August 2012, pp-, Vol. 4.