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目前国内测量裂纹深度及裂纹扩展速率所使用的方法较费事,精度也不理想。而且在疲劳试验机上用显微镜从两边目测裂纹扩展速率时,操作者必须长期经受疲劳机噪音的折磨。这就促使我们去寻求一种新的测量方法。本文介绍我们在利用高音频电流的集肤效应测量裂纹深度及裂纹扩展方面所设计、制造的仪器装置、测量方法、取得的经验及获得的实验数据。文中还介绍了用本仪器在10吨疲劳试验机上对三点弯曲试样进行电测的情况,同时还列出了用显微镜目测的结果以求对比。结果表明:显微镜目测裂纹开裂时滞后现象严重,电测能及时发现开裂,并且精度较显微镜目测要高,还易实现遥测遥控。这些特点无疑是极有吸引力的。
At present, the methods used to measure crack depth and crack propagation rate in China are more complicated and less accurate. And in the fatigue testing machine with a microscope on both sides of the crack growth rate from the visual inspection, the operator must withstand long-term fatigue machine noise. This prompted us to seek a new measurement method. This article presents the instrumentation, measurements, experience and experimental data we have designed and manufactured to measure crack depth and crack propagation using the skin effect of high-frequency currents. The article also introduced the instrument in 10 tons of fatigue testing machine for three-point bending test specimens for electrical measurements, but also lists the results with a microscope for comparison purposes. The results show that: the microscope has a serious lag after the visual crack cracking, the electrical crack can be found in time, and the precision is higher than that of the microscope. It is also easy to realize the telemetering and remote control. These features are undoubtedly very attractive.