Stress wave propagation due to a moving force: comparison of fem and bem solutions

摘要

In this paper the perfomrance of two numerical methods of solving the problem of a time dependent moving force on the surface of an elastic continuum will be evalauted. One method is the finite element mehtod (FEM) formualted in convected coordinates coupled with an absorbing boundary condition of the impedance type. The other method to be considered is the boundary element method (BEM), where a new formualtion using Green's functions transformed to a moving coordinate system is introudced. The methods are tested by the classic wave propagation problem of a Ricker pulse propagating from the surface of an elastic halfspace. The time integral net impulse of the considered loading must be null for the considered FEM to work. Further, the FEM is unable to absorb Rayleigh waves, since the considered impedance condition has been tuned to P- and S-waves. By contrast the BEM is able to handle also these case.s The disadvantage of the BEM is the increased calcualtion time.