EFFECT OF BOUNDARY CONDITIONS ON STRESS STATE OF COMPOSITE CYLINDRICAL SHELLS UNDER EXTERNAL PRESSURE

Abstract

Composite materials are often used in the construction industry nowadays. Including such industries as construction of bridges and other transport structures. Today it is possible to produce from FRP not only separate bridge parts and single structural elements, but also entire span and basement structures made as a shell. Composite shells have a number of features that must be taken into account in the calculation and design.

Analyzing the latest achievements in mechanics of thin-walled structures, we can assert, that there is a large number of directions to study the stress state of composite shell structures. However, there are a lot of unsolved problems regarding the stress state of thick-walled anisotropic shells. It is generally well known that refined higher-order theories to calculate the stability of thick-walled anisotropic shells should be applied. The paper presents an approach to calculate the stress state of thick-walled anisotropic cylindrical shells using the refined Timoshenko beam theory. The above-mentioned constructions are made of materials having one plane of elastic symmetry. Parameters for a nonlinear stress-strain state of the shell are established by using a system of ordinary non-uniform differential equations, taking into account the conditions of its fixation. The Newton-Kantorovich method is used to linearize nonlinear equations. The methods of the considered problems solutions are based on a numerical discrete orthogonalization by the Kutt-Merson method implemented in a software packages for PC.

The problem of calculating the stress state of composit cylindrical shell made of Carbon Fiber Reinforced Polymer (CFRP) under external pressure is analyzed in order to present the possibilities of the proposed method. Influences of fibrous composite stacking on magnitude of internal forces and moments for different boundary conditions of the shell are investigated.