Surface crack imaging based on delayed temperature difference at symmetric points by laser spot thermography  

作　　者：WANG Xiaona WANG Xiaoning HOU Dexin YE Shuliang 

机构地区：[1]Institute of Industry and Trade Measurement Technique in China Jiliang University,Hangzhou 310018,China

出　　处：《Instrumentation》2014年第2期30-37,共8页仪器仪表学报（英文版）

基　　金：supported by the National Key Scientific Instrument and Equipment Development Projects,China(Grant No.2013YQ470767)。

摘　　要：Laser spot thermography is a novel technique for the detection of surface cracks with a laser to heat sample locally and with an IR camera to record the surface temperature distribution. Common methods to characterize cracks are only suitable for the situation that the laser scanning path is vertical to the crack. But due to the randomness of cracks,when the scanning path is parallel to the crack,surface cracks cannot be detected by these methods. To tackle this problem,a method is presented which is suitable for the situation that the scanning path is parallel to crack. The main idea is to evaluate the crack-caused asymmetries of the surface temperature distribution. The effect of temperature gradient and the maximum scanning interval are analyzed by a 2D simulation. A new crack imaging technique is presented that is based on delayed temperature difference at symmetric points to characterize the crack in the thermal image. Compared well with those obtained by the spatial first derivative method,experimental results are shown to efficiently prove this method.

关 键 词：Laser spot thermography Scanning path parallel to crack Delayed temperature difference at symmetric points Surface crack 

分 类 号：TP391.41[自动化与计算机技术—计算机应用技术]