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Characterization of the Compressive and Fracture Behavior, as Well as the Residual Tensile Strength of a Polyurethane Foam

Zhang, Yanli
Experiments were conducted on polyurethane foam to determine its compressive strength/modulus, relaxation behavior, fracture toughness, as well as residual tensile strength after repetitive compression at room temperatures and ?170 C. Results indicate that, in general, both the Young's modulus and collapse strength increase with the increase of the strain rate at both room temperature and -170 C. The relationship between Young's modulus and strain rate, between collapse strength and strain rate were fitted into equations. A Prony series was constructed for the average modulus at different strain rates. Young's relaxation master curve was constructed based on time-temperature superposition principle to show property change as a function of time. The critical stress intensity factor and critical energy release rates are determined to be 110.25 KPa.m1/2 and 22.25 J/m2, respectively. Residual tensile strength has been determined to reduce by 40% after 100 cycles of compression at the amplitude about 55% of the collapse compressive strength.