The Detection of Internal Defects of Concrete Based on the Imaginary Part of the Frequency Response Function and Singular Value Entropy
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摘要: 根据相干函数和力锤激励的有效频段来确定频响函数的研究频段，再将频响函数虚部与信息熵理论相结合，计算频响函数虚部构造的Hankel矩阵的奇异值熵，最后通过概率法计算出异常情况的判断值来实现对混凝土内部缺陷的检测。在此基础上提出了一种简单实用的混凝土缺陷成像的定性分析方法，首先利用各扫射射线的奇异谱熵值将试件分为最有可能产生缺陷与最不可能产生缺陷的区域，再计算各缺陷单元格的投影函数值，非缺陷单元格的投影函数值置0，最后用各单元格的投影函数值的等高线来反应混凝土内部情况，并通过试验验证了该方法的有效性。Abstract: Based on the coherence function and effective frequency band of hammer excitation,the frequency band of the frequency response function was determined. Then the imaginary part of frequency-response function and the information entropy theory were combined to calculate the singular value entropy of Hankel-matrix which was constructured by the imaginary part of the frequency-response function. Finally, probabilistic method was used to calculate the abnormal condition and examine the internal defects of concrete. Based on these, the paper offers a simple and practical method of qualitative analysis to image the concrete defect. Firstly, the specimen was divided into two zones to differ in degree of defect.Then the projection function value of the defect cell was calculated and the non-defect cell was set to zero.Lastly, the inside situation of concrete was reacted by the contour of the projection function,and the test was performed to assess availability of the method.
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Keywords:
- Singular value entropy /
- Frequency response function /
- Coherence function /
- Defect
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