Dynamics of a system comprising a pre-stressed orthotropic layer and pre-stressed orthotropic half-plane under the action of an oscillating moving load

This thesis investigates the dynamic response to a time-harmonic oscillating moving load of a system comprising an initially stressed covering layer and initially stressed half-plane, within the scope of the piecewise-homogeneous body model utilizing Three-Dimensional Linearized Theory of Elastic Waves in Initially Stressed Body (TLTEWISB). It is assumed that the materials of the layer and half-plane are anisotropic (orthotropic), and that the velocity of the line-located time-harmonic oscillating moving load is constant as it acts on the free face of the covering layer. Our investigations were carried out for a two-dimensional problem (plane-strain state) under subsonic velocity for a moving load in complete and incomplete contact conditions.The corresponding numerical results were obtained for the stiffer layer and soft half-plane system in which the modulus of elasticity of the covering layer material (for the moving direction of the load) is greater than that of the half-plane material. The effects of the oscillating frequency of the moving load, initial stress and mechanical properties of the materials on the critical velocity and stress distribution are investigated.In particular, it was established that the critical velocity of the moving load is controlled mainly with a Rayleigh wave speed of a half-plane material and the initial stretching of the covering layer causes these values to increase. Moreover, it was established that with the oscillating frequency of the moving load, the values of the critical velocity decrease.