Efficacy of drilling degrees of freedom in the finite element modeling of P- and SV-wave scattering problems

This paper deals with a hybrid finite element method for wave scattering pr oblems in infinite domains. Scattering of waves involving complex geometrie s, in conjunction with infinite domains is modeled by introducing a mathema tical boundary within which a finite element representation is employed. On the mathematical boundary, the finite element representation is matched wi th a known analytical solution in the infinite domain in terms of fields an d their derivatives. The derivative continuity is implemented by using a sl ope constraint. Drilling degrees of freedom at each node of the finite clem ent model are introduced to make the numerical model more sensitive to the transverse component of the elastodynamic field. To verify the effects of d rilling degrees freedom and slope constraints individually, reflection of n ormally incident P and SV waves on a traction free half space is considered . For P-wave incidence, the results indicate that the use of a slope constr aint is more effective because it suppresses artificial reflection at the m athematical boundary. For the SV-wave case, the use of drilling degrees of freedom is effective in reducing numerical error at the irregular frequenci es.