DEFLECTION ANALYSIS OF STEEL LEAF SPRING VS COMPOSITE LEAF SPRING THROUGH FEA SOFTWARE Ashvini P.lad 1, Prof.B.S.gandhare 2, Prof.A.S.Aradhye 3, Prof.N.V.Hargude 4 1 PG student, Sinhgad college of Engineering, Korti, Pandharpur 2 &3 Assistant professor, Sinhgad college of Engineering, Korti, Pandharpur 4 Associate professor. PVPIT Budhagaon, Sangli ABSTRACT In Automobile sector leaf spring of steel material which is used in suspension system The current leaf spring is multiple leaf spring types with a steel material. Current issue in Automobile is to reduce the weight of product by maintaining its strength[8]. Therefore it can be replaceable by composite material due to its high strength to weight ratio. The objective of this paper is to present analysis of deflection of composite leaf spring (epoxy carbon fiber) to the conventional steel leaf spring through FEA software ie in Ansys. Keywords:-Composite Leaf spring, FEA analysis, Deflection. 1.INTRODUCTION A composite material is defined as a material composed of two or more constituents combined on a macroscopic scale by mechanical and chemical bonds. Many composite materials offer a combination of strength and modulus that are either comparable to or better than any traditional metallic metals. Because of their low specific gravities, the strength to weight-ratio and modulus to weight-ratios of these composite materials are markedly superior to those of metallic materials. The fatigue strength weight ratios as well as fatigue damage tolerances of many composite materials are excellent. For these reasons, fiber composite have emerged as a major class of structural material and are either used or being considered as substitutions for metal in many weight-critical components in aerospace, automotive and other industries. High damping capacity of composite materials can be beneficial in many automotive applications in which noise, vibration, and hardness is a critical issue for passenger comfort [5]. 2.LEAF SPRING Leaf springs also known as flat spring are made up of flat plates. Leaf springs are designed in two ways: 1. Multi leaf 2. Mono leaf. The importance of leaf spring is to carry bump loads (i.e due to road irregularities), brake torque, driving torque, etc.. in addition to shocks.[7] The multi-leaf spring is made up of several steel plates of different length stacked together, while mono-leaf spring is made up of single steel plate. During normal operation, the spring compresses to absorb road shock. The leaf springs bend and slide on each other allowing suspension movement. 3.LITERATURE REVIEW An advanced book on mechanics of composite material by R. Jones covers applications of composite materials and micro mechanical and macro mechanical behavior of lamina and laminates as well as design of composite structure. E. Mahdi [1] has tested three types of composites, namely, carbon/epoxy, glass/epoxy and glass/carbon/epoxy. A comprehensive experimental investigation of composite semi-elliptical suspension springs has been carried out. Typical behaviors of their compression, tension, torsion and cyclic tests are presented and discussed. The carbon-glass/epoxy elliptical springs exhibited higher spring rate but poor ride quality compared with the non hybrid one. Adding four layers of carbon fiber control the load carrying capacity of hybrid composite elliptical spring. Mahmood M. Shokrieh [2] has presented that the optimum spring width decreases hyperbolically and the thickness increases linearly from spring eye towards the axle seat. The stresses in the composite leaf spring are much lower than that of the steel spring. Compared to the steel leaf spring (9.2 kg) the optimized composite leaf spring without eye units weights nearly 80% less than the steel spring. The natural frequency of composite leaf spring is higher than that of the steel leaf spring and is far enough from the road frequency to avoid the resonance. Ranjit Mithari [3] has prepared Glass Epoxy leaf spring which has high natural frequency, low weight etc. He concluded that under the dynamic load conditions natural frequency and stresses of steel leaf spring and composite leaf Volume 4, Issue 4, April 2015 Page 1
spring are found with the great difference. The natural frequency of composite material is high than the steel leaf spring. Conventional steel leaf spring has more weight as compared with E-Glass/Epoxy mono leaf spring. Pankaj Saini [4] has carried out the research on design and analysis of composite leaf spring. He concluded that the static analysis results that there is a more displacement in the steel leaf spring and the corresponding displacements in E glass / epoxy, graphite/epoxy, and carbon/epoxy are more. And all the values are below the camber length for a given uniformly distributed load. They have used three composites E glass / epoxy, graphite/epoxy, and carbon/epoxy and found that among the three composite leaf springs, only graphite/epoxy composite leaf spring has higher stresses than the steel leaf spring. M. Raghavedra [5] has described design and analysis of laminated composite mono leaf spring. In the present work, the dimensions of an existing mono steel leaf spring of a Maruti 800 passenger vehicle is taken for modeling and analysis of a laminated composite mono leaf spring with three different composite materials namely, E-glass/Epoxy, S- glass/epoxy and Carbon/Epoxy subjected to the same load as that of a steel spring. Compared to mono steel leaf spring the laminated composite mono leaf spring is found to have 47% lesser stresses, 25%~65% higher stiffness, 27%~67% higher frequency and weight reduction of 73%~80% is achieved. Vijaya [6] has conducted the static and dynamic analysis of composite leaf spring for heavy vehicles. They have carried out modal and harmonic analysis experimentally and in ANSYS software. They concluded that S-glass epoxy is the best material to manufacture leaf spring because of good structural stability low production cost and good efficiency From above literature review it is clear that main requirement in the automobile industry is to reduce the weight of product by maintaining its strength. It also achieves material saving and space accommodation. 4.METHODOLOGY To carry out FEA analysis of any component, the solid model of the same is essential. It is also called body in white. So the solid model of Leaf Spring is require and this can be done in special CAD package like CATIA. 4.1 Solid Modeling Following are the solid models of leaf spring prepared using CATIA. 4.1.1 Mounting positions. In this view we can clearly visualize various mounting locations on the main body structure. Fig.1 leaf Mounting Positions Fig.2 Solid Model of leaf springs in CATIA After solid modeling of leaf spring then give the actual boundary conditions. Through Software analysis max deflection in horizontal and vertical direction are determined by giving up to 150 kg vertical load in steps of 50 kg rise, at centre of each leaf spring as recommended by manufacturer of Maruti 800 car. 4.2 RESULTS OF ANSYS Volume 4, Issue 4, April 2015 Page 2
4.2.1 Loading on steel leaf 4.2.1.1 Stress Distribution for load of 50kg. Fig 3. Deflection In y Direction Fig 4 Horizontal deflection 4.2.1.2 Stress Distribution for load of 100Kg Fig 5 Deflection In y Direction Volume 4, Issue 4, April 2015 Page 3
Fig 6 horrizontal deflection 4.2.1.3 Stress Distribution for load of 150kg. Fig 7. Deflection In y Direction Fig 8. horrizontal deflection Volume 4, Issue 4, April 2015 Page 4
4.3 Loading on composite epoxy carbon fiber leaf spring For deformation analysis of Composite Leaf Spring Modulus of Elasticity= 231000 MPa Poission ratio=0.3 Density = 1464.9kg/m3 Software analysis is done as follows to find max deflection in horizontal and vertical direction by giving up to 150 kg vertical load in steps of 50 kg rise, at centre of each leaf spring as recommended by manufacturer of maruti 800 car. Fig.9 Deflection in y direction Fig. 10 Horizontal deflection Fig.11 Deflection in y direction Volume 4, Issue 4, April 2015 Page 5
Fig.12 Horizontal deflection Fig 13 Deflection in y direction Fig 14 In Horizontal direction Volume 4, Issue 4, April 2015 Page 6
5.COMPARISON OF HORIZONTAL DEFLECTION DUE TO LOADING ON EPOXY CARBON FIBER COMPOSITE MATERIAL LEAF PRING WITH STEEL LEAF SPRING THROUGH ANSYS Table No.1 Sr No Load in Kg Maximum displacement (Ux) in mm Maximum displacement (Ux) in mm % Difference 1 50 1.734 1.576 0.158 2 100 3.469 3.153 0.316 3 150 5.203 4.730 0.473 6.COMPARISON OF VERTICAL DEFLECTION DUE TO LOADING ON EPOXY CARBON FIBER COMPOSITE MATERIAL LEAF SPRING WITH STEEL LEAF SPRING THROUGH ANSYS Table No.2 Sr.No Vertical Vertical Deflection In Vertical Deflection In %Difference. Load By Steel Leaf Spring In Carbon Epoxy Deflection Utm In Kg Mm Composite Leaf Spring In Mm 1 50 10.57 9.62 0.95 2 100 21.15 19.23 10 3 150 31.7 28.84 9 In 7.CONCLUSION ON RESULTS Graph 1. Steel leaf spring vs. composite leaf spring Through Software analysis max deflection in horizontal and vertical direction are determined by giving up to 150 kg vertical load in steps of 50 kg rise, at centre of each leaf spring as recommended by manufacturer of Maruti 800 car. Volume 4, Issue 4, April 2015 Page 7
This deflection is found satisfactory when compared with regular steel leaf analysis. That found with 7 % avg difference which is acceptable.loading deflection - ANSYS results of steel leaf & epoxy carbon fiber leaf are compared and found similar with acceptable range of difference. REFERENCES [1] E.Mahdi, A.M.S.Hamouda, An experimental investigation into mechanical behavior of hybrid and nonhybrid composite semi-elliptical springs Elsevier Science Ltd. 2013. [2] Mahmood M. Shokrieh, Davood Rezaei,; Analysis and optimization of a composite leaf spring, Composite Structures pp. 317 325 2003. [3] Ranjeet Mithari, Amar Patil, & Prof. E. N. Aitavade Analysis of Composite Leaf Spring By Using Analytical & FEA International Journal of Engineering Science and Technology Vol. 4 No.12 December 2012. [4] Pankaj Saini, Ashish Goel, Dushyant Kumar Design and Analysis of Composite Leaf Spring For Light Vehicles International Journal of Innovative Research in Science, Engineering and Technology Vol. 2, Issue May 2013. [5] M. Raghavedra, Syed Altaf Hussain, V. Pandurangadu, K. PalaniKumar Modeling and Analysis of Laminated Composite Leaf Spring under the Static Load Condition by using FEA International Journal of Modern Engineering Research (IJMER) Vol.2, Issue.4, pp-1875-1879 ISSN: 2249-6645, July-Aug. 2012 [6] B.Vijaya Lakshmi, I. Satyanarayana Static and Dynamic Analysis on Composite Leaf Spring in Heavy Vehicle International Journal of Advanced Engineering Research and Studies, Vol. II/80-84/ Issue I/ 2012. [7] P.Moulali1,N.Upendra, D.Siva Kumar Fatigue Analysis of Leaf Spring by Using ANSYS Workbench International Journal of Engineering Research Volume No.3 Issue No: Special 1, pp: 97-100 ISSN:2319-6890 March 2014 [8] Anandkumar Satpute, Mono Composite Leaf Spring Design and Testing Indian journal of applied research Volume : 3 ISSN - 2249-555X July 2013 [9] Tirupati R.Chandrupatla and Ashok D.Belegundu, Introduction to Finite Elements in Engineering, Third edition 2002. [10] Robert M.Jones, Mechanics of Composite Material 1998. Volume 4, Issue 4, April 2015 Page 8