采用磁记忆方法对铁磁材料进行缺陷检测时，为降低环境噪声及应力集中对检测的影响，提出一种基于S变换的缺陷定位方法。该方法首先将负熵作为评价指标，确定S变换矩阵中由噪声产生的行向量，而后通过将噪声行向量元素置零后经S逆变换得到降噪后的信号；其次定义瞬时能量函数，并通过分析信号的瞬时能量分布特征，实现铁磁材料缺陷的准确定位；最后通过对瞬时能量函数进行加窗处理，进一步抑制应力集中对检测的影响。将该方法应用于磁记忆信号降噪及缺陷定位实验，结果表明：该方法不仅可以有效降低噪声的干扰，而且可以抑制应力集中的影响，从而实现缺陷的准确定位。%To reduce noise interference and inhibit the influence of stress concentration when the metal magnetic memory (MMM) was utilized to test defects of ferromagnetic material, the paper proposed an approach of defect location based on S-transform. Firstly,the negentropy was treated as the estimate criterion,and the rows of S-transform matrix generated by noise were confirmed, then the rows produced by noise were set to zeroes, and the denoised signal was obtained by S inverse transform. Then the transient energy function was defined,and the precise location of the defect was obtained by analyzing the transient energy of the signal. Finally, to inhibit the influence of stress concentration, the window function was proposed and it was used to produce the energy function. Experiment was performed to verify the feasibility of the proposed approach. The results indicate that the proposed approach not only can reduce the noise effectively but also inhibit the influence of stress concentration and locate defect accurately.
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