Stress Wave Propagation Due to A Moving Force: Comparison of Fem and Bem Solutions

In this paper the performance of two numerical methods of solving the problem of a time dependent moving force on the surface of an elastic continuum will be evaluated. One method is the finite element method (FEM) formulated 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 formulation using Green’s functions transformed to a moving coordinate system is introduced. 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 cases. The disadvantage of the BEM is the increased calculation time.