金属磁记忆检测方法在钢结构静载与疲劳试验中的应用研究

Metal Magnetic Memory Testing Method and Its Application for Static Load and Fatigue Test in Steel Structure

结构裂纹无损检测是钢结构性能评价的基础。介绍了一种基于金属磁记忆的无损检测方法。为验证该方法对于钢结构性能检测和评价的适用性,首先开展了全母材和带焊缝的钢材标准试件的静力拉伸试验研究,获取了矫顽力随荷载和应变的变化规律。然后,通过开展钢桥面板疲劳试验,对矫顽力与裂纹萌生扩展之间的相关性进行了研究。相关成果可为该方法推广应用提供参考。研究表明:内力水平越高,矫顽力值越高;相比于弹性应变,矫顽力值对塑性应变更为敏感。当宏观疲劳裂纹出现时,矫顽力值出现10%的下降,而在出现前矫顽力值仅发生2.5%左右的波动,因此该方法对宏观裂纹的检测较为适用,而对于微观裂纹的检测效果较差。

Crack detection is the basis of performance evaluation for steel structure. Metal magnetic memory testing method is introduced and investigations are conducted to verify its feasibility for detection and evaluation for steel structure. Firstly,static tensile experiment is conducted for two standard specimens to obtain the regulation between the coercivity and tensile force or strain. One of the specimens is base metal and the other one is with weld. In addition,the correlation between coercivity and state of fatigue cracking is obtained by conducting fatigue experiment of orthotropic steel deck. The investigation indicates that the value of coercivity is increased with the development of stress. And,the value of coercivity is more sensitive with the plastic strain. When visible fatigue cracks appears,the value of coercivity decreases with ratio of 10%. However,the value of it fluctuates for only about 2. 5% before the appearance of visible fatigue cracks. The method is much more applicable for detection of visible fatigue cracks.