Stress Measurement Using Pulsed Eddy Current Thermography

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.

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