电子剪切散斑技术在木材无损检测中的应用

Application of electronic shearography speckle pattern interferomety to nondestructive testing of wood material

复合板材及木制品等表面或内部的缺陷对材料性能有很大影响,如何快速准确地对其进行无损检测,并判断缺陷的位置大小是很有意义的.针对松木板试件,通过预置表面和内部隐藏缺陷来近似模拟实际缺陷情况,提出一种基于剪切散斑干涉技术的木材无损检测技术新方法,实现了对松木试件的无损检测.在表面缺陷的检测中讨论了剪切量对结果的影响,利用像素标定的方法,得到直径为6、5、3 mm的缺陷信息;在内部隐藏缺陷检测中,借助热加载技术同时引入相移技术使剪切散斑检测技术不仅具有非接触、全场实时检测等特点,而且完成对内部隐藏近表面缺陷的定量无损检测.整个检测过程光路简单,实时快速,实验结果与实际情况符合较好.

Material properties of composite panels and woodwork are greatly influenced by surface or inner defects. It is necessary to use nondestructive testing methods during the detection process. Artificial defects were made on surfaces and inside panels to simulate real defects. The electronic shearography speckle pattern interferometry method was used for nondestructive testing of pine wood samples. Different shearing values were evaluated during the process. When detecting surface defects, the pixel calibration method was used to get defect information for defects of 6mm, 5ram, and 3mm diameters. Also the thermal loading method and the phase shifting technique were adopted to provide a detection process for inner, invisible defects. The defects which were close to the surface could be quickly and easily quantitatively detected. The whole detection set-up was easy and ran in real time. The results agreed well with actual defects. Therefore the proposed method is feasible.