Impact Fatigue Strength and Reliability for Filler Reinforced Epoxy Resin Castings under the Condition of High Temperatures

Abstract

The impact fatigue tests were performed on alumina-filler reinforced epoxy castings at room and various high temperatures below the glass-transition point. From the experiments, the temperature-dependence of impact fatigue strength was clarified. The scatter property of this strength at each temperature was statistically analyzed and its temperature-dependence was also clarified. The safety factor and the allowable stress for the epoxy castings were studied with regard to the influence of circum-temperature used, on the basis of failure probability theory. The main results obtained were as follows:
(1) The impact fatigue strength σ_t of the epoxy castings shows a scatter of logarithmic distribution at high temperatures below the glass-transition point as well as at room temperature and can be estimated failure-probabilistically by the formula of σ_tN_f^mt=D_tμ_tS_t^μ.
(2) The parameters of impact fatigue property, m_t and D_t, and their scatter S_t are dependent on temperature and increase with rise of temperature.
(3) The safety factor and the allowable stress of epoxy castings under service impact loads can be determined according to the allowable failure probability with regard to the circum-temperatures practically used. It is very useful for the optimum structural design.