Abstract:

In order to investigate the method of electromagnetic measurement of stress, an experimental research of the relation between stress and induction EMF (electromotive force) was performed for Q235A parallelchord steel truss. Two types of magnetic core sensors, planar or arc, was put respectively in the surface of chord and vertical web member flange, Ishaped steel of 12#, or in the surface of diagonal in diameter 25 mm. The magnetic line of force was made to penetrate the partial area of member and EMF was induced at the point of measurement. When the load was acted on the truss, the data of induction EMF and strain were measured at the same time. The experiment indicates that the change law of stress and induction EMF hold unanimity, within the range of loading. With the compressive stress increasing, EMF of upper chord and vertical web member decreases. With the tensile stress increasing, EMF of bottom chord increases, and the algebraic value of negative EMF of diagonal rises. The experimental datafitting result accords with the relation between load and EMF from the analysis of stressmagnetic moment deflection.

Key words: engineering mechanics, steel truss, load, stress, electromotive force, measurement