Advanced accelerated testing methodology for long-term life prediction of CFRP laminates

An advanced accelerated testing methodology (ATM-2) for long-term life prediction of CFRP laminates exposed to actual loading with a general stress and temperature history is proposed based on the conventional accelerated testing methodology (ATM-1) established for the long-term life prediction of CFRP laminates exposed to stress and temperature. The most important condition for ATM-1 is that the time-temperature superposition principle held for the viscoelastic behavior of matrix resin holds also for the static, creep, and fatigue strengths of CFRP laminates. Furthermore, three conditions that form the basis of ATM-2 are introduced along with their scientific bases. The long-term fatigue strength of CFRP laminates under an actual loading is formulated based on the three conditions. The viscoelastic coefficients of matrix resin, which perform an important role for the time and temperature dependence of long-term life of CFRP laminates, are also formulated based on the time-temperature superposition principle. The applicability of ATM-2 is demonstrated by predicting the long-term fatigue strengths of four typical directions of unidirectional CFRP laminates.