泡沫金属直流电位法检测技术

Direct Current Potential Drop Inspection Technique for Metallic Foam

为验证直流电位法检测泡沫金属缺陷孔洞及大小的有效性,对实物泡沫金属进行了直流电位法无损检测试验。设计制作了具有不同大小缺陷的五个试件,对各试件进行了恒流加载和表面电位分布测量,并对所测结果进行了相应的差分及滤波处理,以提高信噪比。同时,为确定有效的试验条件,运用有限元分析程序对电位检测信号进行了数值模拟。试验和数值结果表明,对泡沫金属可以利用直流电位方法检出缺陷,且缺陷大小和检测电位信号的大小有一定对应关系。这为泡沫金属缺陷的定量无损检测打下了基础。

In order to verify the validity of direct current potential drop （DCPD） inspection technique for inspecting the defects and its size in metallic foam, the real metallic foam inspection experiment by DCPD was conducted. Five specimens with defects of different sizes were fabricated. Direct current was loaded to the specimens respectively and the potentials on the middle line of the top surface of the specimens were measured. By making difference and filtering operation, the S/N ratio of the measured signals was improved. In addition, a numerical model was built to simulate the DCPD signals by using an FEM numerical code. Based on the experimental and the numerical results, it showed that the defect in the actual metallic foam could be detected by using I）CPD technique, and the size of the defects depended on the amplitude of the potential signal, which laid a foundation for the quantitative NDT of the metallic foam.