The inspection of thickness thinning defects and corrosion defects is greatly significant for the health prediction of plate structures. The main aim of this research is to propose a novel and effective approach to achieve the accurate and rapid detection of arbitrary defects using shear horizontal (SH) guided waves, particularly for large-depth and complex defects. The proposed approach combines the quantitative detection of Fourier transform with a reference model-based strategy to improve the accuracy of large-depth defect detection. Since the shallow defect profile is theoretically constructed by inverse Fourier transform of the product of reflection coefficients and integral coefficients of reference models, the unknown large-depth defect can be initially assessed using the relevant information from a predefined reference model. By iteratively updating the integral coefficients of reference models, the accuracy of reconstruction of large-depth defects is much improved. To achieve the converged defect profile, a termination criterion, the root mean square error, is applied to guarantee the construction of defects with a high level of accuracy. Moreover, the hybrid finite element method is used to simulate the propagation of SH guided waves in plates for calculating the reflection coefficients of plates with defects. Finally, to demonstrate the capability of the developed reconstruction method for defect detection in terms of accuracy and efficiency, three types of large-depth defect profiles, i.e., a rectangular flaw, a double-rectangular flaw and a complex flaw, are examined. Results show that the discrepancy between the predicted defect profile and the real one is quite small, even in the largest-depth defect case where the defect depth is equal to 0.733 times the plate thickness, the minimal difference is observed. It is noted that the fast convergence of the proposed approach can be achieved by no more than ten updates for the worst case.

厚度减薄缺陷和腐蚀缺陷的检查对于板结构的健康预测非常重要。这项研究的主要目的是提出一种新颖而有效的方法，以使用剪切水平（SH）导波，特别是对于大深度和复杂缺陷，来实现准确，快速地检测任意缺陷。所提出的方法将傅里叶变换的定量检测与基于参考模型的策略相结合，以提高大深度缺陷检测的准确性。由于理论上是通过反射系数和参考模型积分系数乘积的傅立叶逆变换来构造浅缺陷轮廓的，因此可以使用来自预定义参考模型的相关信息初步评估未知的大深度缺陷。通过迭代更新参考模型的积分系数，可以大大提高大深度缺陷的重建精度。为了获得收敛的缺陷轮廓，采用终止标准，即均方根误差，以确保高精度地构造缺陷。此外，采用混合有限元方法模拟了SH导波在板中的传播，从而计算出有缺陷的板的反射系数。最后，为了证明所开发的缺陷检测方法在准确性和效率上的能力，对三种大深度缺陷轮廓进行了检验，即矩形缺陷，双矩形缺陷和复杂缺陷。结果表明，即使在缺陷深度等于板厚的0.733倍的最大深度缺陷情况下，预测缺陷轮廓与真实缺陷之间的差异也很小。应当指出，对于最坏的情况，可以通过不超过十次的更新来实现所提出方法的快速收敛。