Fatigue Property and Mechanism of Unidirectional Jute Spun Yarn Reinforced PLA

Natural fiber reinforced plastics have been expected as alternative materials of glass fiber reinforced composites. The fatigue properties of natural fiber reinforced plastics are, however, not always well known. In this study, uniaxial tensile fatigue tests of unidirectional jute spun yarn reinforced polylactic acid (PLA) were conducted in order to clarify the fatigue strength and its mechanism. The fatigue strength decreased with increasing the number of cycles. The fatigue strength at 106 cycles was 55% of the ultimate strength. The fatigue failure of composite specimens was probably caused by the breakage of the jute filaments of spun yarn at the tips of fatigue cracks in PLA. This implies that the fatigue strength of the composite was strongly affected by the fatigue property of PLA.