Image-based Simulation of Wave Propagation and its Application to UT Modelings

Time domain simulation tools for ultrasonic wave propagation in materials with a complex outer surface or various inclusions are developed by combining the elastodynamic finite integration technique (EFIT) and the finite element method (FEM) with an imagebased modeling approach. The EFIT is a grid-based spatial discretization method that works in conjunction with a leap-frog time marching scheme. On the other hand, the FEM adopts a voxel-shaped spatial element and the calculation is updated by an explicit scheme without solving system equations. In our simulation, geometries of targets are determined by scanned digital images and the processed bitmap images are directly fed into the wave simulation by the image-based EFIT and FEM. First, formulations of the image-based EFIT and FEM are described and the accuracy of the two methods is discussed by comparison with the boundary element method (BEM). Then, the modeling and simulation of contact ultrasonic testing for concrete is shown using the image-based EFIT.