Investigation of the stability behavior of sandwich rectangular plates consisting of layers of nanocomposites under the uniaxial and biaxial compressive loads

In structural engineering, determining the structural behavior of nanocomposite sandwich rectangular plates, which possess high strength, light weight, corrosion resistance, and insulation properties in terms of material characteristics, under external effects is of great importance for structural safety. In the thesis, stability behavior of polymer-based sandwich rectangular plates with uniform and heterogeneous reinforced layers subjected to uniaxial and biaxial compressive loads is investigated within the framework of classical plate theory. First, properties, advantages and application areas of carbon nanotube and polymer-based nanocomposites forming the layers are defined. Following the basic information, mechanical properties of each layer of sandwich rectangular plates consisting of polymer nanocomposites are modeled according to the extended mixture rule. After the basic relations of sandwich plates consisting of polymer-based nanocomposite layers are constructed, stability and deformation compatibility equations are derived based on the assumptions of classical plate theory. The stability and deformation compatibility equations system of sandwich plates with polymer-based nanocomposite layers under simply supported boundary conditions are solved together and analytical expression will be found for critical biaxial compressive load. Based on the obtained closed solution, the minimum value of critical biaxial compressive load for sandwich plates consisting of heterogeneous nanocomposite layers are found numerically depending on wave numbers. Also, the expressions for the critical uniaxial compressive loads are obtained from the analytical expression for the critical biaxial compressive load in special cases. Detailed numerical calculations are made for the minimum values of uniaxial and biaxial buckling loads for different volume fraction ratios in the layers, five different carbon nanotube patterns in the layers, layer alignment and various plate sizes, and these calculations are interpreted.