Analytical and experimental study on wave propagation problems in orthotropic media

Wave propagation problems in orthotropic media are studied jointly by analytical and experimental methods in this paper. Dynamic orthotropic photoelasticity, which studies experimentally the dynamic behavior of orthotropic materials on a macroscopic scale by employing orthotropic birefringent materials, is established. A dynamic stress-optic law for orthotropic birefringent materials is postulated and practical methods of calibrating dynamic mechanical constants and dynamic stress-fringe values are proposed. Meanwhile, time domain boundary element method (BEM) for wave propagation in orthotropic media, is also presented based on the theory of elastodynamics. A scheme of stress calculations that is necessary for strength analysis is established. The paper stresses on the applications in wave propagation problems in orthotropic media by demonstrating three examples. The semi-infinite orthotropic plates with and without a circular hole modeled by a unidirectional fiber-reinforced composite under impact loading are analyzed. Time histories of birefringent fringe orders or stresses for specific points of the plates are obtained respectively from the two methods and compared with each other. Based on the above comparative study, the dynamic response of an underground workshop under seismic waves is studied by time domain BEM. The responses of displacements and stresses are solved. The effects of angle and frequency of incident waves and the degree of media anisotropy on dynamic response of the underground workshop are investigated.