Method for measuring two-dimensional stress at weld joint by using Barkhausen effect and detection instrument

Abstract

The invention discloses a method for measuring two-dimensional stress at a weld joint by using a Barkhausen effect and a detection instrument. A ferrite magnetic core and a magnetic core of a Barkhausen measuring probe are directly contacted with the surface of the weld joint of the test piece, so that the X-direction tangential stress and the Y-direction axial stress of the weld joint of the test piece are calibrated; the Barkhausen measuring probe is used for collecting excitation signals and detecting Barkhausen signals, stress signal amplitude waveforms are obtained, and signal amplitude noise is obtained according to the waveforms; a Barkhausen noise signal amplitude is extracted from a signal detected by the Barkhausen measuring probe, the Barkhausen noise signal amplitude continuously changes along with the tension and pressure stress values to form a tension and pressure fitting curve, and the tension and pressure fitting curve serves as a calibration result of the relation between the Barkhausen noise signal amplitude and the continuous tension and pressure stress; and finally, a Barkhausen noise signal, the residual stress sigma1 in the vertical direction, the residual stress sigma2 in the parallel direction and the quantitative relation of the included angle theta between the main stress direction and the magnetic field direction are obtained, and the two-dimensional residual stress of the welding area is directly detected.

Description

technical field [0001] The invention relates to the technical field of stress detection, in particular to a method and a detection instrument for measuring two-dimensional stress at welds by using the Barkhausen effect. Background technique [0002] During the magnetization process of the ferromagnetic material specimen in the alternating external magnetic field, when the strength of the external magnetic field reaches a certain strength, the magnetic domain wall interface begins to move, which occurs most significantly in the steepest region of the magnetization curve. At this time, the magnetization process is discontinuous, but is carried out in the form of a jump. This phenomenon is the jump magnetization. Professor first discovered it in 1919, hence the name). A noise pulse signal is generated in the form of voltage by the detection coil placed on the surface of the test piece, so this signal is called Barkhausen noise signal (referred to as Barkhausen signal). [000...

AI Technical Summary

Problems solved by technology

Since the change and movement of the magnetic domain structure are closely related to the microstructure and stress state of the material, it can be used for the detection and evaluation of the internal stress and mechanical properties of the material; however, the traditional stress detectors using the Barkhausen effect are all The detection is based on the magnetoelastic model, but this method cannot directly realize the two-dimensional residual stress at the weld after welding various materials, resulting in

Images