Optimum Filter Based Techniques for Data Fusion

Abstract

In our previous studies the ultrasonic measurements have been done in the dif- ferent stages of fatigue life by stopping the mechanical test and performing the ul- trasonic measurement on a sample removed from the fatigue motion. In this paper we report the results of ongoing research and development of an ultrasonic method for in-situ fatigue damage characterization. A [0/90] SiC/Ti-15V-3Cr-3Al-3Sn metal matrix composite is considered as a model system. Cyclic loading at 50 and 70% of the ultimate sample strength were used until failure. The ultrasonic goniometer mod- ule was integrated with an MTS machine which allowed performing real-time velocity measurements during the fatigue test. Also off-line ultrasonic velocity measurements were performed. The fatigue-induced changes in elastic constants were calculated from the measured ultrasonic velocity data. For damage characterization from the experi- mentally determined reduction in effective composite moduli we developed a damage model based on the Generalized Method of Cells [10, 11]. For detailed description of our model the reader is referred to the accompanying paper [12].