Fatigue-Life Prediction of SiC Particulate Reinforced Aluminum Alloy 6061 Matrix Composite Using a Weibull Distribution Model

This paper presents the feasibility of acoustic emission technique in predicting the residual fatigue life prediction of 6061-T6 aluminum matrix composite reinforced with 15 vol. % SiC particulates (SiCp). Fatigue damages corresponding to 40%, 60% and 80% of total fatigue life were stimulated at a cyclic stress amplitude. The specimens with and without fatigue damage were subjected to tensile tests. The acoustic emission activities were monitored during tensile tests. The number of the cumulative AE events increased exponentially with the increase of strain during tensile tests. This exponential increase occurred when the material was in the plastic regime and was attributed mainly to SiC particulate/matrix interface decohesion. The cumulative events during post fatigue tensile tests reduced with the decrease of the fatigue residual life. Based on the high cycle fatigue damage accumulation model, a Weibull probability distribution model is developed to explain the post fatigue AE activity of specimens during tensile test. Using the model, the residual fatigue life can be predicted by testing the specimen in tension and monitoring the AE events. In high cycle fatigue, it was observed that the residual tensile strengths of the material did not change significantly with prior cyclic loading damages since the high cycle fatigue life was dominated by the crack initiation phase.