The impact tensile fatigue tests were conducted on alumina and silica filler reinforced epoxy resin castings. From the experiments, the properties of these resin castings under repeated impact tensile loads were clarified and the scatter properties of their strength were statistically analyzed. Safety factors and allowable stresses for resin castings under service impact tensile loading were studied on the basis of failure probability theory. The results were as follows:
(1) The fatigue tensile strength σt of resin castings subjected to repeated impact tensile loading shows a scatter of logarithmic normal distribution and can be estimated statistically by the following formula.
σtNfmt=ξDtμtStu
where mt and Dt are the parameters of impact fatigue properties, Nf is the life to failure, μt and St are statistical values and u is the parameter of probability.
(2) The strength constant Dt is closely related to the static tensile strength σB, and it can be estimated from the latter.
(3) The safety factor and the allowable stress of these resin castings under service impact loads can be determined according to the expectative failure probability. It is useful for the most suitable structural design.