Test methodInfluence of loading frequency on the fatigue behaviour of coir fibre reinforced PP composite

The influence of loading frequency on the fatigue behaviour of a coir fibre reinforced polypropylene (PP) composite was studied. The mechanical behaviour was assessed through monotonic tensile and flexural tests, followed by cyclic bending fatigue tests employing a new specimen geometry, with loading frequencies ranging from 5 to 35 Hz. Results revealed that higher strain rates during monotonic loading lead to higher flexural strength, and higher loading frequencies in cyclic tests promote reduction in fatigue life. Fractographic examination showed that one of the reasons for reduced fatigue life under higher loading frequencies might be related to increased heat generation by hysteresis, leading to a fatigue damage mechanism governed by temperature effects. The results, thus, encourage the development of good practices regarding test frequencies in order to be able to uncouple thermal and mechanical effects and provide relevant data for structural integrity assessments.