Prediction of plasticity-controlled failure in polyamide 6:influence of temperature and relative humidity

In this study, the influence of temperature and relative humidity on the plasticity controlled failure of polyamide 6 was investigated. Uniaxial tensile tests were performed at several temperatures, strain rates, and relative humidity; creep tests were performed at different relative humidity and applied load. In order to describe and predict the yield kinetics, the Ree–Eyring equation was employed and modified to include the effect of relative humidity. Subsequently, by the introduction of the concept of critical amount of accumulated plastic strain, the yield kinetics were successfully translated to predictions of time-to-failure. A good agreement between predictions and experimental results is obtained, showing that the model is a suitable and versatile tool to evaluate mechanical performance of a temperature and moisture sensitive material such as polyamide 6.