Technical Paper
Improvements in Empirical Representation of A356-T6 Cast Aluminum Alloy Round-Robin Low Cycle Fatigue Data
1988-08-01
881702
The results of the SAEFDE Committee's round robin low cycle fatigue test program with A356-T6 cast aluminum alloy indicated that the conventional low cycle fatigue model was not a satisfactory representation of the data. This occurred because the elastic strain amplitude-life curve was not log-log linear and this yielded a non-conservative fatigue life representation at both extremes of long and short lives. This paper involves a reanalysis of the A356-T6 composite all-laboratory data using two additional empirical models. These models are: 1. linear log-log total strain amplitude-life 2. bilinear log-log elastic strain amplitude-life Both proposed empirical models improve the representation of the data compared to the conventional low cycle fatigue model. The bi-linear log-log elastic equation, however, when added to the plastic equation, yields a discontinuous curve with non-conservatism in the region of the discontinuity.