Fatigue in Sisal Fiber Reinforced Polyester Composites: Hysteresis and Energy Dissipation

Natural fibre reinforced polymer biocomposites (NFPBCs) constitute an important branch in the field of green composite materials. The work describes the fatigue behaviour of polyester biocomposites reinforced with natural sisal fibres and stacked as cross laminates with [0/90]s sequence Three-point bending static and cyclic tests have been used to investigate the fatigue behaviour of these particular bio-reinforced composites. The cyclic tests have been carried out at 1.5 Hz of frequency using a sinusoidal waveform and loading levels varying between rd = 0.55 to 0.95 and the curves of stiffness degradation (F/F0) has been plotted. Failure is reached after the first few cycles for high loading levels, whereas for low values of rd (0.55) fracture is only partial, even after reaching one million of cycles.