On The Scattering Of SH-Wave By Interface Crack And Circular Cavity Near The Interface

The present thesis investigates the scattering problems of SH-waves by interface circular lining as well as interface cracks originating diametrically at the lining edge or the collinear cracks originating diametrically lining, the Green' Function method is used here. First thing is to use a suitable Green' Function, which is a essential solution of displacement field for the elastic half space with a half circular lining, which impacted by out-plane harmonic line source loading at horizontal surface. The model of the problem is composed of two half spaces with half circular lining inclusion. Horizontal surfaces of the half spaces are loaded with undetermined anti-plane force in order to satisfy continuity conditions at linking section, or with some certain forces to appear cracks. A series of Fredholm integral equations of the first kind for determining the unknown forces can be set up through continuity conditions that expressed by using of the Green' Function. For the model of interface cracks originating at lining edge, the added force at crack tip can be replaced by expression including dynamic stress intensity factor. The integral equations for determining the unknown forces can be transformed into algebraic equations and solved numerically. Our analytic works in concrete are mainly as follows:Scattering of SH-wave by interface circular lining are investigated by combining tow half spaces with unknown loading at interface into on finite elastic body, the interface circular lining can be formed. Integral equations to determine the unknown are established by use of Green's Function. Given dynamic stress concentration factor around the interface circular lining. Some examples and numerical results and illustrated, the influence of wave number, incident wave angle and combination of different medium parameters upon dynamic stress concentration factor are discussed.Scattering of SH-wave by collinear cracks of any limited length originating diametrecally at the boundary of circular lining which has cracks in homogeneous medium is investigated, and solution of dynamic stress intensity factors in mode at crack tip are obtained. The cracks are made out by means of crack-division technique. Integral equations for determine the dynamic stress intensity factors established by use of the Green's Function. The influence of circular lining with crack tip is discussed though graphical results.