Enhancing ultrasonic thermal excitation performance through adaptive loading device for excitation morphology

In ultrasonic excitation infrared thermography, coupling pressure is a critical factor affecting detection performance. The coupling pressure loading device plays a pivotal role in the ultrasonic excitation process, as it indirectly influences the ultrasonic thermal excitation effect by regulating the coupling pressure. This study performed ultrasonic thermal excitation tests on concrete microcracks under varying coupling pressures. By optimising the material of the loading device, disturbance forces exerted by the device on the transducer during excitation were attenuated. A comparative analysis of the ultrasonic thermal excitation effect was then conducted before and after loading device optimisation. Using two distinct loading methods, the temperature distribution within microcracks under different coupling pressures was analysed to evaluate the thermal excitation temperature-rise effect. Additionally, a finite-element simulation model was developed for quantitative assessment of the coupling pressure excitation. The results demonstrated that the application of coupling pressure to the piezoelectric transducer via an optimized loading device effectively mitigated the disturbance and fluctuation amplitudes of the coupling pressure during excitation, thereby enhancing the overall thermal excitation performance.