Fatigue Behavior of Natural Fiber Reinforced Thermoplastic Composites in Dry and Wet Environments

Over the past decade, there has been an increased demand for products manufactured using sustainable materials. Natural fiber composites are seen as an excellent replacement for synthetic fiber composites due to their low density, good mechanical properties (stiffness), good thermal/acoustic insulation properties and environmental benefits (waste stream utilization and low carbon footprint). While there has been a considerable number of studies examining the short-term behavior of natural fiber composites, very limited work has been done to characterize their long-term durability under cyclic loading. In this study, the fatigue behavior of a natural fiber reinforced thermoplastic composite material was investigated. Cyclic fatigue experiments were conducted on hemp fiber reinforced high density polyethylene (HDPE) at various fiber volume fractions, and under both dry and wet ambient conditions. Using a stress level concept, a generalized model was developed to predict the fatigue life of the various composite formulations tested. The concept of pseudo-plastic flow was incorporated in the fatigue model to form a new model, which is capable of simulating fatigue behavior at different frequencies, fatigue stress ratios and volume fractions.Copyright © 2011 by ASME