Prediction of stress-rupture life of glass/epoxy laminates

This paper reports an effort to predict the life of quasi-isotropic E-glass/epoxy composite laminates under constant load and in an acid environment. An experimental program involving stress-rupture tests of unidirectional coupons immersed in a weak hydrochloric acid solution was conducted to determine their stress-life response. Creep tests were conducted on unidirectional coupons parallel and transverse to the fibers, and on ±45° lay-ups to characterize the lamina stress- and time-dependent compliances. Lamina data were used in a composite stress-rupture life model, based on the critical element modeling approach, to predict the life of quasi-isotropic laminates. Predictions compare favorably with experimental data. Discrepancies underscore the need for detailed materials characterization in the actual service environment.