基于磁记忆的建筑钢结构焊接试件拉伸试验研究

发布时间：2018-10-31 17:05

【摘要】：日前,我国钢结构建筑蓬勃发展,钢结构建筑越来越多,而钢结构之间的连接有很大一部分采用的是焊接连接方式,在焊缝施工中和结构使用过程中难免会出现缺陷和损伤,这都会使结构的安全性和耐久性大大降低,因此,如何识别这些缺陷和损伤,在整个钢结构建筑中就显得尤为重要。金属磁记忆检测技术至今发展了二三十年,对结构是否存在缺陷能够做出有效判断,研究表明其对焊缝的质量检测也是适用的。目前金属磁记忆检测技术对焊缝缺陷的判断还处在初级阶段。本文通过Q345钢材拉伸试验,利用金属磁记忆检测仪EMS-2003进行检测,分析比较有缺陷试件和无缺陷试件在各级荷载下漏磁场信号的变化规律,结合金属磁记忆检测原理,分析应力和漏磁场信号之间的关系,找出可以判断试件有无缺陷的依据,试验结果表明,在试件拉伸过程中,磁信号随着荷载的增大而增大,信号梯度值也随着增大,无缺陷试件没有“峰-峰值”,而有缺陷试件出现“峰-峰值”,且“峰-峰值”随荷载呈线性变化,在弹性阶段和塑性阶段之间出现“拐点”,可以作为确定试件是否有缺陷的依据,以及是否从弹性阶段进入到塑性阶段。有缺陷试件的“峰值宽度”在整个加载的过程中都保持很好的稳定性,“峰值宽度”在20~30mm之间,可用来确定缺陷的位置。通过对比有缺陷试件和无缺陷试件表面磁场信号,分析焊缝缺陷与磁信号之间的关系,都有过零点现象,但是位置不固定。断裂后,试件的磁信号呈现出相同的变化规律,在裂缝处两边的信号幅值增大符号相反,可以用来确定试件裂缝位置。另外,本文还利用信息熵的理论对试验结果进行了分析,得出有缺陷试件和无缺陷试件的相对谱熵带和奇异谱熵带都能有效的区分,可以用来判断试件是否存在缺陷。通过以上试验结果,可以得出金属磁记忆检测方法可以有效识别焊缝的缺陷,是一种切实可行的方法。
[Abstract]:A few days ago, the steel structure building developed vigorously in our country, the steel structure building more and more, but the connection between the steel structure has adopted the welding connection way, will inevitably appear the flaw and the damage in the weld seam construction and the structure use process. This will greatly reduce the safety and durability of the structure, therefore, how to identify these defects and damage, in the whole steel structure is particularly important. The technique of metal magnetic memory testing has been developed for 20 to 30 years, and it can be used to judge the defect of the structure. The research shows that it is also applicable to the quality test of weld. At present, metal magnetic memory detection technology for weld defect judgment is still in the primary stage. In this paper, through the tensile test of Q345 steel, the metal magnetic memory detector (EMS-2003) is used to detect and compare the variation of magnetic field leakage signals between defective and non-defective specimens under various loads, combining with the principle of metal magnetic memory detection. The relationship between stress and magnetic field leakage signal is analyzed, and the basis for judging whether the specimen is defective or not is found. The test results show that the magnetic signal increases with the increase of load, and the signal gradient increases with the increase of load. There is no "peak-peak" in non-defect specimens, while "peak-peak" appears in defective specimens, and "peak-peak" varies linearly with load, and "inflection point" occurs between elastic stage and plastic stage. It can be used as the basis for determining whether the specimen has defects and whether to move from elastic stage to plastic stage. The "peak width" of the defective specimen remains stable throughout the loading process, and the "peak width" between the 20~30mm can be used to determine the location of the defect. The relationship between weld defect and magnetic signal is analyzed by comparing the surface magnetic field signals of defective and non-defective specimens. The phenomenon of crossing zero is found, but the position is not fixed. After fracture, the magnetic signal of the specimen shows the same change law, the amplitude of the signal on both sides of the crack increases the sign is opposite, it can be used to determine the crack position of the specimen. In addition, the information entropy theory is used to analyze the experimental results. It is concluded that the relative spectral entropy band and the singular spectral entropy band can be effectively distinguished between the defective specimen and the non-defective specimen, which can be used to judge whether the specimen has defects or not. According to the above experimental results, it can be concluded that the metal magnetic memory detection method can effectively identify the weld defects, which is a feasible method.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU391

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