Local surface stability of multi layer viscoelastic half-spaces

New materials are required, instead of conventional materials, in order to ensure that scientific developments are carried to technological field and put at the disposal of humanity. Materials science researchers performed their studies in the direction of this objective and developed new materials. In this context, one of the most critical materials, which are put at the disposal of technology, is composites. As composite materials began to be used in technological field, problems that source from its structural characteristics began to occur. One of the critical problems that source from structural characteristics of these materials is the stability loss of the material with the impact of external force. Stability loss of composite materials is divided into two categories as near-surface and internal loss. It is known that surface stability loss occurs at the surface and near-surface region. Occurrence of surface stability loss decreases from surface to the internal areas of the material. Therefore, it is very important to estimate the limit value of the near-surface stability loss of the composite materials, which are subjected to load. In this study, surface stability loss problems that are faced by composite structures comprised of elastic and viscoelastic materials are solved by using three dimensional- linearized stability theory (TLTS) equations within the scope of piecewise homogeneous body model. The TLTS equations are obtained from the three dimensional geometrical nonlinear exact equations of the theory of viscoelasticity by using boundary form perturbation technique. A method is developed for solving problems by applying Laplace transform. It is considered that the beginning has initial infinitesimal imperfection at the near-surface region of material. The fact that enlargement and reaching of this imperfection to eternity with the impact of external force is considered as near-surface stability loss criteria. Developed method is applied on two-dimensional and three-dimensional problems, and impact that the rheological parameters of the materials, which form the examined composite structures, make on critical time and critical force values are studied. Viscoelastic materials inside of composite structures are defined by Rabotnow operator. Programs are written with Mathematica programming language by using formed algorithms. Numerical results related to the examined composite structures are obtained by using these programs.