Ultrasonic Attenuation Results Of Thermoplastic Resin Composites Undergoing Thermal And Fatigue Loading

This report highlights our initial ultrasonic attenuation results from thermoplastic composite samples that have undergone over 4000 flight cycles to date. Ultrasonic attenuation measurements are a standard method used to assess the effects of material 2 degradation [1]. Recently, researchers have shown that they could obtain adequate contrast in the evaluation of thermal degradation in thermoplastic composites by using frequencies of ultrasound on the order of 24 MHz [2]. In this study, we address the relationship of attenuation measured at lower frequencies in thermoplastic composites undergoing both thermal and mechanical loading. We also compare these thermoplastic results with some data from thermoset composites undergoing similar protocols. The composite's attenuation is reported as the slope of attenuation with respect to frequency, defined as b = Da(f)/Df