Stress singularities and transverse stresses near edges of doubly curved laminated shells using TSNDT and stress recovery scheme

A third order shear and normal deformable plate/shell theory (TSNDT) and a stress recovery scheme (SRS) are used to predict stress singularities near edges of doubly curved composite laminated shells deformed statically with tangential and normal tractions applied on the shell major surfaces. In fluid-structure interaction problems both tangential and normal tractions may simultaneously act on the fluid-structure interface. The accurate computation of all six stress components is important for ascertaining a structure's load carrying capacity. In the TSNDT the three displacement components at a point are expressed as complete polynomials of degree three in the thickness coordinate. The boundary-value problems are numerically solved by using an in-house developed finite element code. Results for six problems involving different boundary conditions at the edges and different surface tractions on the two major surfaces are presented. For each problem studied, the computed stresses at interior points located at a distance greater than 0.1% of the span from an edge are found to at most differ by 5% from those obtained by either analytical or numerical (with a commercial software) solutions of the 3-D linear elasticity theory equations. The order of the stress singularity near an edge and boundary layers close to bounding surfaces are well captured; the region of stress singularity extends from the edge only till 0.4% of the edge length. Advantages of using the TSNDT include considering general tractions on bounding surfaces and finding a reasonably accurate solution, including singular stresses near the edges, with considerably fewer degrees of freedom than those needed to analyze the corresponding 3-D problem.