WAVE MOTION AND ITS DISPERSIVE PROPERTIES IN A FINITE-ELEMENT MODEL WITH DISTORTIONAL ELEMENTS

Solutions are obtained for wave motion in a hybrid-mass distortional f inite element model by employing the extended method of lattice dynami cs. The dispersion equations of wave motion are also given through the solutions. The dispersive properties of a plane wave and the existent ial condition of an inhomogeneous wave are studied. The results show t hat the ability of the hybrid-mass model to resist the distortion of e lement shape is greater than that of the consistent-mass model but low er than that of the lumped-mass model. The velocities of wave propagat ion in the lumped-mass model are not always lower than that in the cor responding continuum. When the element shape is highly distorted, the velocities in the lumped-mass model may exceed those in the continuum. The effects of discretization in time domain on wave propagation are also discussed.