基于磁记忆的受弯钢梁力-磁效应试验

Experimental Research on Magnetic-mechanical Effectiveness of Bending Steel Beam Based on Metal Magnetic Memory

建筑钢结构磁记忆检测技术的关键问题是确定磁记忆信号与内应力之间的关系。由于应力与应变是一一对应关系,故本文通过研究磁记忆信号与应变的关系,得到其与应力之间的关系。分析表明:钢梁下翼缘表面法向漏磁场强度与拉应变有着一定的关系,不论是处于弹性阶段,还是塑性阶段,磁记忆信号曲线变化与其应变变化趋势表现一致,磁记忆信号曲线可以反映应变的变化状态。钢梁腹板表面磁记忆信号与其水平压应力之间呈线性关系,无明显的拐点;但不同钢梁试件在相同应变下磁记忆信号强度存在差值,目前仅能作出定性评判。

A key issue of magnetic memory testing technique for steel structure of building is to determine the relationship between the magnetic memory signals and the stress within the steel structure. As one-to-one correspondence between stress and strain, the relationship curve between the normal component of the surface magnetic fields and the strain of the steel beam was first obtained, and the relation law between the strain and signal was analyzed. Testing results show that there is some certain law between the magnetic memory signal and tensile stress. In whichever elastic and plastic deformations, the strain change of the flange of the beam and the magnetic memory signal of the steel surface exhibits a corresponding relation, and the curve changes of the two have some similar trend~ The magnetic memory signal value of the web surface of the beam has a linear relationship with stress showing no significant inflection point. However, there is a difference of magnetic memory signal strength for different span steel beam even if at the same strain of flange or web. Therefore,the above relation can just be used to do some qualitative judgment.