Abstract
The present work investigates the fatigue performance of fibre-reinforced injection-moulded leaf springs. Twenty per cent discontinuous long, short glass fibre-reinforced polypropylene (SFPP) and unreinforced polypropylene (UFPP) materials are used for manufacturing constant-thickness, varying-width, mono leaf spring. Fatigue tests are performed on moulded leaf springs at various alternating loads under the pulsating compression mode at 0.5Hz frequency with the aid of in-house developed fixtures integrated with the servo-hydraulic fatigue machine. During fatigue testing, cyclic load—deflection of the test leaf spring of each and every cycle is measured; the energy dissipation ratio and spring rate of the test leaf springs are reported as an index for the accumulated damage at various stages of its life. Test leaf springs are subjected to fatigue load up to 2×105 cycles or failure, whichever is earlier. SFPP and UFPP leaf springs exhibited drops in the spring rate, whereas long glass fibre-reinforced polypropylene exhibited fracture as leaf spring failure. Fatigue performance as well as failure morphology of the leaf springs confirmed the role of reinforced fibre length in the thermoplastic composite leaf spring.
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