Flexural fatigue and reliability analysis of wood flour/high-density polyethylene composites

In this study, the flexural fatigue behavior of wood flour/high-density polyethylene composites is characterized. A non-dimensional analysis is adopted to establish a prediction equation for the fatigue life of the composites, and S-N curves and survivability diagrams are then constructed to show the fatigue life prediction of the wood/plastic composites (WPCs). Small coupon samples of the composites are tested in flexural fatigue. The predicted results in the non-dimensional (non-linear) fatigue model are better related to the testing data than the classical S-N curve (linear experimental data) fitting, and they could be used as the predicting model for fatigue life analysis of the WPCs. The best-fit S-N curve and its corresponding bounds based on 95% confidence are provided for the composites, and the fatigue data are well distributed within 95% confidence range. Fatigue life distribution diagrams are produced for the WPCs using a two-parameter Weibull cumulative density function based on the probability of survival concept, and this concept is then used to predict the fatigue life of the composites under an applied load. From these diagrams, the fatigue life can be easily determined at any given reliability index. The S-N plots under different reliability index present considerable value to the designer if the structure contains a critical component where any failure is catastrophic. The proposed experimental fatigue study and related analyses verify the applicability of non-dimensional fatigue model and theory of two-parameter Weibull distribution to fatigue life prediction and reliability analysis of WPCs, and they can be used to predict fatigue behavior of similar materials.