Prediction of Long Term Flexural Fatigue Strength of Honeycomb Sandwich Composites

A prediction method for the fatigue life of polymer composites under arbitrary frequency, load ratio and temperature was extended to that of polymer composite structures. The three-point bending tests for honeycomb cored sandwich (SW) panels with GFRP skin plates and Nomex honeycomb core under constant strain rates (CSR) and fatigue loading at various strain rates and temperatures were conducted. The maximum bending moments for CSR and fatigue loadings strongly depend on time and temperature, and the time-temperature superposition principle for the storage modulus of matrix resin holds for the maximum bending moments for fatigue loading as well as CSR loading. The long term fatigue strength at any time, temperature and number of cycles to failure can be predicted using the master curves of the bending moment by fatigue loading based on the accelerated testing methodology.