钢材压应力与感应电动势实验效应

Experimental Investigation on Relationship Between Steel Bar's Compressive Stress and Induction EMF

通过力学与电磁学相结合,进行HPB235和HRB335钢材的压缩实验,研究用感应电动势变量ε测试应力σ的方法·将直径25mm的钢棒放入感应线圈,然后由液压式压力机对试件施加压力,同时在线圈中接通交流电流,产生一个沿钢棒轴向的微小感应电动势·试验结果表明:感应电动势ε随压应力σ增大而减小,压应力σ则随感应电动势增量Δε上升而增大,两个变量之间的关系能够用线性拟合公式表达·将分别由感应电动势增量和应变测试得到的应力数据进行比较,平均相对误差为2·94%·运用毕奥-萨伐尔定律,分析了由导线倾斜缠绕的线圈其轴向电流分量Ih产生横向磁场Bx的原理·

A compression test was done in combination with induction EMF（electromotive force） to investigate the relation＇ship between the EMF variable ε and compressive stress σ, taking the D25 mm HPB 235 and HRB 335 steel bars as specimens. The specimens were passing through an AC induction coil and a tiny EMF was produced axially in the steel bar. Then the specimens were compressed by a hydraulic press. Testing results showed that the EMF ε decreases with the increasing stress σ, but σ inereases with the increasing EMF increment △ε, and the relationship between the two variables, i.e., ε and σ, or σ and △ε, can be expressed respectively by a linear fitting equation. The stress obtained from the induction EMF measured was compared to that obtained from the strain measured one by one, from which the relative mean error was 2.94%. According to the Biot and Savart Law, the reason why the axial current current lh in the induction coil winding obliquely around a specimen forms a traverse magnetic field Bx was explored.