Lifetime Prediction of Polymeric Composites Subjected to Spectrum Loading Conditions

摘要

This work describes our efforts to develop a lifetime prediction method for [(+-45)_2/0_2/0]_s laminates fabricated using T700 and T600 fibers. This lifetime prediction method involves characterizing the fatigue lifetimes at four different R-ratios (0.1, -0.37, -1, and 7). These results are then used to generate a constant lifetime plot. This constant lifetime plot, as well as the residual strength-based lifetime prediction philosophy form the basis for the analysis. A key feature of the analysis is that it enables us to predict changes in the residual strength of the composite (both in tension and compression) as a function of applied fatigue cycles, rather than just calculating a "damage sum" as one might do in a Miner's rule approach. Predicted lifetimes agree well with the experimental determined ones for a spectrum loading. Comparisons are also made between predicted and measured residual strength values.