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

为了钢结构物的安全使用，必须进行完好性检查。1)为了考虑构件的退化，开发了基于Landau-Lifshiz-Gilbert方程的磁性计算程序；2)在提出基于磁性无损检测的疲劳损伤评估方法的同时，基于所开发的程序开发了磁性测量装置。3)利用研制的磁性测量装置，反复进行了静态拉伸载荷和构件损伤程度随载荷的测量检验，验证了构件损伤检测的可行性，找出了可用于损伤评估的磁性能参数。4)在为“裂纹检测系统”研制磁性能测量小型传感器的同时，针对信号处理，新开发了程序，将其构建为“裂纹检测系统”。5)利用研制的“裂纹检测系统”，对平焊、对接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。6)阐述了利用商用磁场分析程序分析研制的裂纹损伤测量仪的实用性检验，以及建立裂纹形态评估所需的数据库的方法。

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.