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零件、构件产生疲劳破坏时、其断裂点几乎都集中在焊缝边缘一类形状不连续的部位上。这些部位由于应力集中,一般都存在初始裂纹,零件、构件寿命则取决于裂纹扩展速度的大小。为了精确地评价机器的寿命,必须明确裂纹发生条件和扩展速度。长期处于高温和腐蚀环境下的裂纹特点至今尚存在一系列未弄清的问题,同时也很难正确予测机器的实际载荷谱。因此,为了保证零件、构件安全,对可能产生损伤的危险部位,采取连续监测裂纹扩展是行之有效的手段。无损检测裂纹的方法有(1)光学显
Parts, components fatigue damage occurs, the fracture point almost all concentrated in the weld edge of a discontinuous shape of the site. Due to stress concentration in these parts, there are usually initial cracks, parts, component life depends on the size of the crack propagation speed. In order to accurately evaluate the life of the machine, it is necessary to clarify the crack occurrence conditions and the expansion speed. There are still a series of problems that have not yet been solved so far in the long-term high temperature and corrosion environment. At the same time, it is difficult to correctly determine the actual load spectrum of the machine. Therefore, in order to ensure the safety of parts and components, it is an effective measure to continuously monitor the crack growth for the dangerous parts that may be damaged. Methods of non-destructive testing of cracks are (1) optically significant