Adhesive Layer Effects on PZT-induced Lamb Waves at Elevated Temperatures

The role of the adhesive layer on PZT-induced Lamb wave propagation in structures exposed to elevated temperatures is presented in this article. Both experiments and numerical simulations were performed to study the effects of the adhesive layer on sensor signal at elevated temperatures. Experimentally, signals from PZT transducers with different adhesive thicknesses (40 and 120 μm) were investigated up to 500 kHz. In model simulations, the spectral element package (PESEA), which was developed previously, was adopted to simulate the test results. The simulations agreed with the experimental data quite well. Parametric studies were was then performed using PESEA to evaluate the effect of adhesive layer on PZT-induced Lamb wave propagation at elevated temperatures as compared to other mechanical properties of the host structure and PZT materials; these studies revealed that the stiffness change of adhesive layer due to temperature is the most influential parameter for the change in sensor signals as compared to other mechanical properties, and that the thickness of the adhesive layer can affect a sensor signal in a different manner at elevated temperatures. This study shows PESEA can reasonably simulate the adhesive layer effect at elevated temperatures and hence can be a useful tool for understanding the behavior of Lamb wave propagation generated by adhesively bonded PZTs on structures.