H型钢梁翼缘感应电动势随应力变化实验研究

Experimental Investigation of Induction EMF Changing with Stress for H-Section Steel Beam Flanges

目的探索钢梁在役应力的电磁学测试方法及原理.方法将带有交流线圈的磁芯传感器置于翼缘表面,形成闭合磁路.在钢梁跨中施加集中力的同时,测量1/2和1/3跨径位置感应电动势E和应变ε.结果实验表明:钢梁上翼缘感应电动势随压应力增大而减小,并服从线性规律;下翼缘感应电动势随拉应力增大呈现增幅递减的上升趋势,由二次幂函数表达其变化特征;上下翼缘应力与应变关系均为直线.结论钢梁铁磁材料在翼缘拉伸与压缩两种不同状态下,磁矩偏转对感应电动势变化的影响具有不对称性.

For exploring the electromagnetic method of measuring the in-service stress of steel beams, an experiment of the relation between induction EMF E and tensile or compressive stress a from bending was conducted for Q235B hot rolling H-section steel beam. An open-ended magnetic core with alternating current coils was laid on the flange surface to come a closed magnetic circuit. While exerting a vertical concentrative load on the middle of the steel beam, the data variation of induction EMF E and strain ε at half span or one-thirds span was measured. The experimental results indicate that induction EMF E of the upper flange of the steel beam decreases with the compressive stress a increasing and the descending change complies with a linear law;induction EMF E of the lower flange rises with the tensile stress a increasing at a rate of progressive decrease and the ascending change can be expressed in the second power function. The relation between stress and strain of upper or lower flange is linear. As for the ferromagnetic material of the steel beam, under two different states of tension and compression of flanges, the unsymmetrical principle of magnetic moment deflection was analyzed, which influences the change of induction EMF.