Multiphysics modeling and analysis of the photoinductive imaging effect for crack detection

Numerical multiphysics modeling of the photoinductive imaging (PI) effect was performed with a 2-D transient to characterize corner cracks at the edge of a specimen with a bolt hole. We present how the finite-element method (FEM) can be utilized to model the PI effect and observe the influence of critical factors on the coil probe impedance for a rectangular crack in the Ti-6Al-4V specimen. As anticipated, the proposed model can show that the PI method has a higher spatial resolution in the defect in 2-D models compared to the conventional eddy current testing method. The FEM simulation results for 0.25-, 0.50-, and 0.75-mm rectangular notches are shown and discussed. The effects of coil current frequency, laser-point temperature, and lift-off distance on the PI signal are also examined and analyzed. We demonstrate that the PI effect is a novel sensing method for characterizing the geometric shape of cracks and that the enhanced output signals of the coil probe can also be obtained given an appropriate quantity of factors.