A hybrid LSM-SA algorithm for locating simulated weld crack acoustic emission sources in plates

Abstract Accurate localization of simulated acoustic emission (AE) sources representing weld cracks is critical for ensuring the structural integrity and operational safety of welded components. Traditional methods such as the Least Squares Method (LSM) often yield significant positioning errors, while the Simplex Algorithm (SA) is highly sensitive to initial values and converges slowly. This paper proposes a hybrid LSM-SA algorithm that leverages the analytical initial estimate provided by LSM and the local refinement capability of SA. The method employs an autoregressive (AR) model for AE signals from simulated crack sources, using the Akaike Information Criterion (AIC) to pick arrival times at each sensor, from which time differences across sensors are computed. An initial source location estimate from LSM serves as the starting point for SA, enabling refined optimization and accurate crack source coordinates. Lead-break experiments conducted on an aluminum alloy plate at a single simulated crack location demonstrate that the proposed LSM-SA hybrid algorithm achieves a 42.2% reduction in localization error (from 11.22 mm to 6.48 mm) compared to the standalone LSM, while exhibiting a 55.6% decrease in the number of required optimization iterations (from 9 to 4) relative to the SA alone. By improving both accuracy and computational efficiency, this method can support online weld crack monitoring via acoustic emission.