Stress Measurement Using Pulsed Eddy Current （使用脉冲涡流压力测量）.pdfVIP

Stress Measurement Using Pulsed Eddy Current Thermography Libing Bai1,2 and Gui Yun Tian1, 2 1School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu, 611731, China 2 School of Electrical and Electronic Engineering, Newcastle University, NE1 7RU, UK Abstract This paper reports a noncontact inspection method, using Pulsed Eddy Current (PEC) stimulated thermography, for the evaluation of the anisotropic dependency of electrical conductivity of steel exposed to tensile stress. This method combines microscope lens based thermography with PEC using a rectangular excitation coil, giving directional excitation, to infer the electromagnetic properties variation in the longitudinal and transverse directions to a static uniaxially applied tensile stress. Theoretical analysis and details of the experimental set-up are presented. The relationship between excitation coil layout and applied stress, and the measured transient thermal images are discussed. Comparison of the results with previous work on PEC techniques for stress measurement is also discussed. 1. Introduction Residual Stress (RS) measurement and characterisation are important for early warning of failure and lifetime extension (1-2). However, RS prediction is still a big challenge (3) . At present, the most common methods of RS evaluation are X-ray diffraction and hole drilling. However, the penetration of laboratory X-rays in most engineering metals is typically of the order of tens of microns at most. Consequently, the technique must be combined with destructive layer removal to extend it to depths of around 1-2 mm (4) . Hole drilling typically has similar depth capability (5) . For magnetic materials, Magnetic Memory Method