Analysis of transient elastic wave scattering by cavity in micropolar elastic solids using 2-D M-EFIT

This paper presents an M-EFIT (Micropolar Elastodynamic Finite Integration Technique) formulation for 2-D micropolar elastodynamics. The micropolar elastic solids are known as the microscopic inhomogeneous materials, such as concretes, bedrocks, and bones that composed the human body. In the micropolar elastodynamic theory developed by Eringen [1], the couple stress cannot be ignored unlike the classical one. According to the micropolar elastodynamic theory, three kind of waves (P, S and M-waves) having different wave velocities exist in micropolar elastic solids, and two of them (S and M-waves) have the dispersibility for 2-D formulation. This fact makes difficult to formulate the wave propagation theory and its simulation for micropolar elastodynamics. Fukui et al. [2] achieved a boundary element method (BEM) in 2-D frequency-domain. Mirzajani et al. [3] implemented a wave propagation analysis of micropolar elastic beams using a finite element method (FEM). In this research, an EFIT which was developed in the field of the ultrasonic nondestructive testing [4] is extended to the micropolar elastodynamic wave propagation, which is called M-EFIT in this research. The M-EFIT is a grid-based numerical method based on the finite difference time-domain (FDTD), and can easily treat the boundary conditions on the interface between different materials. As numerical examples, elastic wave scattering by a cavity in micropolar elastic solids is demonstrated to validate the proposed method.