A study on the influence of excitation parameters and sensor configuration on the performance of ultrasonic longitudinal and transverse wave bolt preload detection

Abstract

Accurate measurement of bolt preload is crucial for the safe service life of engineering structures. Addressing issues such as the lack of theoretical basis for parameter selection, insufficient signal stability, and limited measurement accuracy in traditional longitudinal and transverse wave bolt preload testing, this study focuses on M36 × 3-350 high-strength bolts to a force–electric–acoustic multiphysics coupling model was established to investigate the mechanisms by which key parameters—such as excitation frequency, modulation period, piezoelectric transducer material, and excitation position—influence ultrasonic propagation characteristics and testing performance, and a parameter optimization method was proposed. Based on this, a combination of experimental and simulation methods was used to compare and validate the testing performance under optimized and non-optimized parameter configurations. The study indicates that the optimal excitation frequencies for longitudinal and transverse waves are 2 MHz and 1 MHz, respectively. When using a Hanning window modulation with a period of 5, an optimal balance between ultrasonic signal energy and the accuracy of first-arrival time identification is achieved; the transducer combination of PZT-4 for excitation and PZT-5 H for reception significantly improves the signal-to-noise ratio, while axial excitation helps suppress modal transition and enhance beam directivity; Under optimized parameter conditions, the measurement error for preload was controlled within 3%, whereas under non-optimized conditions, the error could reach 8%. The experimental results were in good agreement with numerical simulations. The proposed parameter optimization strategy can significantly improve the accuracy and stability of bolt preload detection using the longitudinal and transverse wave methods, providing a theoretical basis and technical support for engineering applications.