In-situ strength degradation of glass fibers in a pultruded composite by environmental aging

The long-term performance of the glass-fiber reinforced composites can be studied by establishing the relationship between aging process and the statistical fiber-strength distribution. Using a sub-critical crack growth model, the rate of crack growth on glass fibers is described as da/dt = [AK_Iⁿ+C]exp(-G/RT), where a is crack size, t is time, A and n are constants, C is the corrosion rate at zero stress, G is activation energy, T is absolute temperature and R is the gas content. The critical stress intensity factors, failure probability, and strength distribution are derived from the equation.