基于熵带与DS理论的焊缝等级磁记忆量化评价

Quantitative MMM evaluation of weld levels based on information entropy and DS evidence theory

针对焊缝不同等级的磁记忆特征提取及定量评价难题,提出信息熵带与D-S理论联合的磁记忆定量评价模型。以Q235B焊接试件为实验材料,通过焊缝疲劳损伤试验,对照X射线定量评价标准,引入能够反映焊缝损伤程度的奇异谱熵、功率谱熵和小波空间能谱熵,分别提取不同损伤等级对应的这3种信息熵及其熵带的特征值,构建基于信息熵带数学期望的各等级贴近度公式,以信息熵贴近度作为证据体,建立基本可信度分配函数,通过D-S理论的证据组合原理将基本可信度进行信息融合,依据D-S诊断规则输出焊缝缺陷等级的定量识别结果,建立基于信息熵带和D-S证据理论联合的焊缝等级磁记忆评价模型。结果表明焊缝等级识别的不确定度为0.008,为实际工程中焊缝缺陷等级磁记忆定量化评定提供新的思路和方法依据。

In order to extract metal magnetic memory（ MMM） feature and quantify defect levels of welded joints,information entropy and D-S theory combination model is presented. Q235 B experimental materials are used as welded plate specimens. By comparing the X ray detection national standard,the singular spectrum entropy,power spectrum entropy and wavelet space spectrum entropy are introduced from the time domain,frequency domain and time-frequency domain,respectively. MMM characteristic values of the above information entropies and their entropy zones are extracted from different weld defect levels. Then the neartude formula is established based on the mathematical expectation of the entropy zones. By using entropy neartude as the evidence body,the function of the basic credibility distribution is built for different weld levels. On the basis of D-S evidence combination theory,the information fusion of the basic credibility is made in order to obtain quantitative MMM evaluation of weld levels. The result shows the uncertainty is as low as 0. 008,which provides a new method in practical engineering.