A cumulative damage model was verified for predicting the fatigue life of woodflour-filled polypropylene (PP) composites and a general fatigue model was modified to describe the influences of environmental temperature on fatigue life. The model incorporated applied maximum stress, stress amplitude, environmental temperature, residual static modulus, and material constants as parameters. Residual modulus and partial damage were measured at a certain number of loading cycles under a given maximum load by intermittent static test to calculate damage growth. Wood-flour-PP composite samples were tested in flexural fatigue, and the model was verified using damage assessment. Both the residual static modulus at predetermined loading cycles and the number of cycles at which the samples fail were measured. Under the same applied stress level, the fatigue life of the composite in the lower temperature range is shorter than that at room temperature, due to the brittle and glassy properties of the matrix polymer. The fatigue life of the composite in the higher temperature range is longer than that at room temperature, due to the ductile property of the matrix polymer. Damage growth in the higher temperature range was slowed due to the ductile property of the matrix polymer. The experimental data generated from the intermittent static modulus test is in good agreement with the calculated model.
展开▼
