Experimental and Finite Element Investigation of Composite Mono-Leaf Springs for Lightweight Automotive Suspension

An experimental and finite element comparison of EN45 steel, carbon/epoxy, E-glass/epoxy and Kevlar/epoxy mono-leaf springs has been consolidated from the dissertation data. The CAD–ANSYS–UTM workflow successfully reproduced the global bending response and provided exact agreement between numerical and test reaction forces for the reported load cases. For the common 1000–5400 N static comparison, carbon/epoxy maintained lower equivalent stress than steel at every load. At 5400 N, the carbon model reached 380.15 MPa compared with 417.83 MPa for steel, while deformation was 128.5 mm compared with 119.12 mm. Thus, carbon/epoxy improved stress performance but was approximately 7.9% more compliant at the maximum load, indicating that its laminate architecture or thickness should be optimized rather than assuming direct geometric substitution. The strongest evidence in favour of composites is the combined mass and fatigue response. Carbon/epoxy weighed 0.635 kg and reached approximately 1,000,000 cycles, while the 15 kg steel spring reached 100,000 cycles. Kevlar/epoxy also performed well, with 0.614 kg mass, 5280 N reaction force and 652,000 cycles. E-glass/epoxy showed stable low-load numerical behaviour but lower cycle endurance. Overall, carbon/epoxy is identified as the most technically promising replacement because it combines full target load, the highest reported fatigue life, lower equivalent stress and very large mass reduction. Future work should standardize the load spectrum across materials, document ply sequence and fibre volume fraction, conduct mesh-convergence and composite failure-index studies, incorporate eye-end inserts and environmental ageing, and validate the optimized spring under full vehicle road-load histories.    

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