Evaluation of fatigue life of fiberglass reinforced polyester composite materials using Weibull analysis methods

A composite material based on a polyester resin and fiberglass reinforcement was fabricated by the contact molding process with a fiber percentage of 40%. This material underwent a cyclic fatigue loading and 3-point bending at slow speed. The experimental results were used to plot the S–N curve based on a linear function, Hwang & Han’s relation and Basquin’s hypothesis. A probabilistic analysis based on the Weibull distribution with two and three parameters was used in order to adjust and predict the fatigue behavior of the material used in the study. This analysis made it possible to plot the fatigue curve for different levels of reliability (Ps = 99%, Ps = 90%, Ps = 50%, Ps = 36.8% and Ps = 10%), in order to identify first time to failure for material reliability and safety limits.