Thin-plate stress monitoring using S1-ZGV mode based on a PVDF comb transducer

This Letter proposes an ultrasonic stress monitoring method utilizing the S1 zero group velocity (S1-ZGV) mode based on a PVDF comb transducer. Experimental investigations have revealed that under varying uniaxial stress conditions, both the measured S1-ZGV frequency and its corresponding amplitude exhibit appreciable variations. By adopting the relative change rate of the amplitude corresponding to the S1-ZGV frequency (denoted by RCA) as the characteristic parameter, it is evident that RCA demonstrates a monotonic and highly sensitive response to the applied uniaxial stress. Notably, RCA exhibits a significant increase as the applied uniaxial stress rises. This characteristic enables the use of RCA to predict the stress state, facilitating real-time stress monitoring. Experimental validation indicates that the predicted stress values align closely with the actual applied stress values, demonstrating a high level of accuracy in stress prediction. This method enables real-time and in situ monitoring of the stress state in thin plates subjected to uniaxial stresses, which holds paramount importance for a wide array of industrial applications in structural health monitoring.