Leaf
springs are a part of the suspension system attached between the axle and the
chassis of the vehicle to support weight and provide shock absorbing capacity
of the vehicle. For more than half a century the leaf springs are being made of
steel which increases the weight of the vehicle and is prone to rusting and
failure. The current study explores the feasibility of composite leaf spring to
reduce weight by designing, manufacturing and testing the leaf spring for the
required load cases. An off the shelf leaf spring of Ford F-150 is chosen for making
of composite hybrid spring prototype. The composite hybrid prototype was made
by replacing all the leaves with glass fiber unidirectional laminate except the
first leaf. Fatigue tests are then done on steel and composite hybrid leaf
spring to observe the failure locations and mechanism if any. High frequency
fatigue tests were then done on composite beams with varying aspect ratio in a displacement-controlled
mode to observe fatigue location and mechanism of just glass fiber composite
laminate. It was observed that specimens with low aspect ratio failed from
crack propagation initiated from stress concentrations at the loading tip in
3-point cyclic flexure test and shear forces played a dominant role in
propagation of crack. Specimens with high aspect ratio under the same loading did
not fail in cyclic loading and preserved the same stiffness as before the
cyclic loading. The preliminary fatigue results for high aspect ratio composite
beams predict a promising future for multi-leaf composite springs.