Development of the crack detection system of the steel structures by using magnetic properties

为了保证钢结构物品的安全使用，需要对其进行可靠性检测。探讨了利用磁性无损检测开发“裂纹检测系统”的目的，该系统可用于无损检测，得到了以下结果：1)为考虑构件退化，开发了基于landau - lifshz - gilbert方程的磁性能计算程序。2)在综合考虑所开发程序的基础上，提出了基于磁性能的无损检测疲劳损伤评价方法，并研制了磁性能测量装置。3)利用研制的磁性能测量装置，对构件进行了静态拉伸载荷和按载荷反复进行构件损伤程度的测量检测，验证了构件损伤检测的可行性，并找出了可用于损伤评价的磁性能参数。4)在为“探伤系统”开发磁性能测量小传感器的同时，针对信号处理，新开发了程序，建成了“探伤系统”。5)利用研制的“裂纹检测系统”，对平焊、对接焊和角焊接头试件进行了裂纹检测，找出了有效的磁性能参数。有了这个参数，它不关心油漆的存在，也不关心板的前后，而是检查是否有可能检测到裂缝。6)阐明了利用商用磁场分析程序对裂纹损伤分析开发的测量装置的有效性进行检验，以及建立裂纹形态评价所需数据库的方法。利用本研究开发的“裂纹检测系统”对钢结构焊缝中存在的裂纹进行检测。

For safe use of a steel structure thing, soundness inspection is required. It inquired for the purpose of development of the "crack detection system" by the non-destructive test using magnetic property which can be used for soundness inspection, and the following results were obtained.1) In order to consider component degradation, the magnetic property calculation program based on a Landau-Lifshiz-Gilbert equation was developed.2) While proposing the fatigue damage appraisal method by the non-destructive test which used magnetic property based on the consideration using the developed program, the magnetic property measuring device was developed.3) Using the developed magnetic property measuring device, static tensile load and the measurement examination of the degree of component damage according to load repeatedly were done, it checked that detection of component damage was possible, and the magnetic property parameter which can be used for damage evaluation was found out.4) While developing the small sensor for magnetic property measurement for the "crack detection system", for signal processing, the program was newly developed and it built as a "crack detection system".5) Using the developed "crack detection system", for the plain, butt welded joint and fillet welding joint specimens, the crack detection examination was carried out and the effective magnetic property parameter was found out. With this parameter, it was not concerned with the existence of paint, and the back and front of the plate, but checked that detection of a crack was possible.6) The check of the usefulness of the measuring device analyzed and developed about crack damage using the commercial magnetic field analysis program and the method of building a database required for crack form evaluation were clarified.The existence of the crack which exists in the weld joints of the steel structure is detectable by the "crack detection system" developed by this research.