STATIC AND DYNAMIC FEA ANALYSIS OF A COMPOSITE LEAF SPRING by HIMANSHU ARUN

66 Pages·2017·1.88 MB·English

by  Raut, Himanshu Arun

STATIC AND DYNAMIC FEA ANALYSIS OF
A COMPOSITE LEAF SPRING
by

HIMANSHU ARUN RAUT

Presented to the Faculty of the Graduate School of
The University of Texas at Arlington in Partial Fulfillment
of the Requirements
for the Degree of

MASTER OF SCIENCE IN MECHANICAL ENGINEERING

THE UNIVERSITY OF TEXAS AT ARLINGTON
Fall 2016
Copyright © by HIMANSHU ARUN RAUT 2016
All Rights Reserved

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Acknowledgements

I would like to express my gratitude to Dr. Andrey Beyle for his inspiring
guidance, encouragement and for investing his valuable time in mentoring me. It has
been a journey filled with learning experience. I thank Dr. Andrey Beyle for being on the
thesis defense committee chair.
I would also like to extend my sincere thanks and appreciation to Dr. Wen Chan
and Dr. Kent Lawrence for serving on the thesis defense committee and providing me
with several learning opportunities.
I am grateful to my parents and my sister, friends and all those who helped and
supported me to achieve my goal.

December 1, 2016
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Abstract

STATIC AND DYNAMIC FEA ANALYSIS OF
A COMPOSITE LEAF SPRING

HIMANSHU ARUN RAUT, MS MECHANICAL ENGINEERING

The University of Texas at Arlington, 2016

Supervising Professor: ANDREY BEYLE

Composite materials are widely used in aeronautical, marine and automotive industries,
because of their excellent mechanical properties, low density and ease of manufacture.
Due to this increasing trend to utilize composite materials, it has become necessary to
investigate the pros and cons of composites. This research investigated the static and
dynamic behaviors for a composite leaf spring that are used in Chevrolet Corvette Grand
and light tractor-trailers.

The objective of this study was to find the cause of de-lamination/ failure of the
unidirectional composite layers in varying cross sections of the leaf spring. Finite element
method is used to calculate Static and dynamic behavior using ANSYS V17 software to
simulate real time operating conditions. Anisotropic material properties are taken into
account to observe resultant behavior. The leaf spring is modeled using SOLIDWORKS
2016 for the three materials, reinforced fiberglass epoxy, Kevlar epoxy and Carbon epoxy
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which are of great interest to the transportation industry. Vibration analysis is carried out
using same FEA software. This study depicts and explains the causes of de-lamination.
Suitable design changes are suggested to mitigate the defects sustained during operation
for the preceding model.

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Table of Contents
Acknowledgements ............................................................................................................ iii
Abstract .............................................................................................................................. iv
List of Tables ...................................................................................................................... x
Chapter 1 Introduction and Background ............................................................................. 1
1.1. Leaf springs .................................................................................................................. 2
1.2. Composites ................................................................................................................... 3
1.3 Motivation and Objective ........................................................................................... 11
Chapter 2 Literature Review ............................................................................................. 12
Chapter 3 CAD Model and Boundary Conditions ............................................................ 13
3.1. CAD Model ................................................................................................................ 13
3.2. Material Properties ..................................................................................................... 17
3.3 Meshing ...................................................................................................................... 18
3.4. Theoretical Model and Assumptions ......................................................................... 21
Chapter 4 Results .............................................................................................................. 22
4.1. Analytical and Computational Results Comparison for Theoretical
Model ................................................................................................................................ 22
4.2. Static Model Results .................................................................................................. 29
4.2.1 Reinforced fiberglass epoxy ............................................................................ 29
4.2.3. Kevlar epoxy and Carbon epoxy .................................................................... 31
4.3.1. Dynamic calculations ..................................................................................... 35
4.3.2. Models with varying thickness ....................................................................... 36
Chapter 5 Conclusion ........................................................................................................ 39
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Chapter 6 Future Work ..................................................................................................... 40
Appendix A Calculation of Anisotropy of Composite material ........................................ 41
Chapter 7 ........................................................................................................................... 52
Chapter 8 Block 6 ............................................................................................................. 52
References ......................................................................................................................... 54
Biographical Information .................................................................................................. 56

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List of Illustrations
Figure 1-1 Laminate composites ......................................................................................... 5
Figure 1-2 Unbonded views of anti-symmetric and symmetric cross-ply laminates ......... 6
Figure 1-3 Representation of an angle lamina with the local and principal directions .........
............................................................................................................................................ 7
Figure 1-4 Orientation of the fibers of a unidirectional composite along x1 direction .........
............................................................................................................................................ 8
Figure 3-1Leaf spring assembly parts ............................................................................... 11
Figure 3-2 3D CAD model made in SOLIDWORKS ....................................................... 14
Figure 3-3 Alternate design for leaf spring ....................................................................... 15
Figure 3-4 SOLID 186 mesh element ............................................................................... 16
Figure 3-5 Meshed CAD Model ....................................................................................... 19
Figure3-6 Lekhnitskii’s Model for a curved composite beam .......................................... 20
Figure 4-1 Radial stress results based on the theoretical models ..................................... 21
Figure 4-2 Radial stresses in (a) transverse and (b) longitudinal sections ...................... 22
Figure 4-3 Graph of the comparative study ...................................................................... 23
Figure 4-4 (a) Position of maximum radial stress and (b) Equations to calculate radial,
normal and shear stresses .................................................................................................. 24
Figure 4-5 Radial stress values distributed over the radius to the composite leaf spring . 25
Figure 4-6 Its shows (a) Deflection, (b)Radial stresses in the longitudinal section, (c)
Radial stresses in the mid plane and (d) Transverse shear stresses in x-y plane............... 28
Figure 4-7 Comparison for various glass epoxy, carbon epoxy and Kevlar epoxy showing
(a) Deflections and (b) Radial Stresses ............................................................................. 30
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Figure 4-8 Deflection for the transient case ...................................................................... 31
Figure 4-9 The maximum deflection for the dynamic case is 88.59 mm ......................... 33
Figure 4-10 Radial stresses for transient case ................................................................... 33
Figure 4-11 radial stresses are offset from the center, as the leaf spring is not rigidly
bonded ............................................................................................................................... 34
Figure 4-12 (a)Original model top and (b) reduced thickness bottom .............................. 34
Figure 4-13 (a)Original model top and (b) increased thickness bottom ........................... 36
Figure 4-14 Delamination stresses (σr) max as a function of b/a for β=3.568 ................. 37
Figure 6-1 Eye end design ................................................................................................ 39

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List of Tables
Table 3-1 Anisotropic material properties calculated from fiber and matrix (calculated for
70% fiber) ......................................................................................................................... 17
Table 3-2 Fiber and matrix material properties ................................................................ 17
Table 3-3 Mesh Data ......................................................................................................... 20
Table 4-1 Computational and Analytical results comparison ........................................... 24
Table 4 2 Radial stresses in various sections of leaf spring .............................................. 27

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