Applying thermoelasticity to impact-damaged structural components

An experimental method is presented for quantifying impact damage in composite materials using specimens of glass fiber reinforced polyurethane and epoxy. Thermoelastic stress analysis (TSA) was used to quantify the stress concentration associated with impact-damage. Following impact and TSA imaging, the samples were fatigued to failure over a range of stress amplitudes. The stress concentration factors acquired from TSA were used to determine a modified stress for each sample that collapsed the impact, then fatigue data onto a master curve on stress-life axes. This approach provides a quantitative measure of impact damage and a rational estimate of the expected residual fatigue lifetime of impact damaged composites.