Stress Online Monitoring Method Based on Multifrequency SH0 Guided Wave Information Fusion

Abstract

This article proposes a stress monitoring technique based on multifrequency SH0 guided wave information fusion. Its nondispersive acoustoelastic characteristic facilitates joint analysis in the whole frequency band. Moreover, the typical representation of broadband multifrequency signal is equivalent to realizing multiple measurements simultaneously, effectively improving the measurement efficiency and reliability. First, a generalized multifrequency comprehensive measurement model is established, which combines with specific data analysis and postprocessing criteria to construct a new stress characterization method. Then, the acoustoelastic effect of SH0 guided wave is investigated. Next, the wideband shear piezoelectric transducer based on the out-of-plane d15 mode is designed. The frequency-domain finite-element method (FDFEM) is applied to optimize the SH0 guided wave excitation and reception interval. Finally, the laboratory experiments of 6061-T6 aluminum plates with a thickness of 1 mm are conducted to verify the proposed strategy. The fitting result of multifrequency component fusion is better than that of any single-frequency algorithm. The actual measurements from the same batch are carried out through the calibration results. The maximum error does not exceed 2.5 MPa and the maximum relative standard deviation (RSD) is 7% in the range of 15–85 MPa, demonstrating good measurement accuracy and consistency.