The degradation of mechanical properties for a glass/polyurethane automotive composite due to exposure to various environments while under stress is reported. Two types of loading were compared: constant strain and nearly constant stress. Loads varied from 0 to 50% of the average tensile strength. The composite studied was a polyurethane resin reinforced with continuous strand E-glass mat, manufactured by the SRIM process. Novel fixtures applied tensile loads to dogbone specimens while exposed to automotive fluids. After 300 hours, the specimens were tensile tested to failure in air. Degradation in mechanical properties typically increased with stress level but was independent of the type of loading. This result is explained in terms of damage and deformation mechanisms in the material.
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