Finite Element Analysis of Glass/Epoxy Composite Laminates with Different Types of Circular Cutouts

This paper is focused on the analysis of stress-strain and displacement for compressive load on the fiberreinforced composite laminates. Three different orientations of fibers are analyzed with and without the circular cut-outs. Also different dimensions of circular cut-outs are applied on the laminates at different compressive loading conditions. This analysis is carried out using the finite element software ANSYS. From the result, it is identified that cross-ply composite laminates possess the highest strength as compared to other types of angle orientations. Also it is concluded that the maximum load bearing capacity decreases as the cut-out size increases.


INTRODUCTION
In recent years, it would appear that progress has been in the development of engineering advanced materials, especially composite laminated materials. Composite laminates are composed of thin layers (plies) consisting of reinforcement and a matrix. The reinforcement is typically a strong, stiff material, in the form of long fibers. The matrix is typically a material that is applied in a liquid form and then cured and hardened. The matrix is applied to support the reinforcement, and to distribute the load through the reinforcement and plies. It is common to have plies with fibers at one direction or several directions in a weave. The orientation of the fibers and stacking sequence has a large effect on the deformation and stress throughout the laminate. Composite laminates have been used increasingly in a variety of industrial areas due to their high stifness and strength-to-weight ratios, long fatigue life, resistance to electro chemical corrosion, and other superior material properties of composites. A true understanding of their structural behavior is required, such as the deflections, buckling loads and modal characteristics, the through-thickness distributions of stresses and strains, the large deflection behavior and, of extreme importance for obtaining strong, reliable multi-layered structures, the failure characteristics. Finite element method is especially versatile and efcient for the analysis of complex structural behavior of the composite laminates.
The largest damage future is usually delamination, which may cause significant reductions in flexural stiffness and buckling loads. The effect of delamination has been a subject of extensive research, and fairly reliable methods are now available for prediction of growth of artificial single delamination [1]. Cut-outs commonly appear in the structures due to the requirement of stability maneuverability, low weight optimization and accessibility of other systems. During operation, these structural elements may experience compressive loads and thus lead to buckling and post buckling. Their buckling and post buckling behaviors play an important role in determining safe operating conditions and effective designs for these structures [2].

Figure.1: Composite laminate with different stacking sequence
An experimental study of the behavior of woven glass fiber/epoxy composite laminated plates under compression is explained by Hakim S. Sultan Aljibori and W.P. Chon [2]. Compression tests were performed on to 16 fiber-glass laminated plates with and without circular cut-outs using the compressed machine. The maximum load of failure for each of the glass-fiber/epoxy laminated plates under compression has been determined experimentally. According to M. de Freitas and L. Reis [3], impact loading in composite plates lead to damage with matrix cracking, inter-laminar failure and eventually fiber breakage for higher impact energies. Even when no visible impact damage is observed at the surface on the point of impact, matrix cracking and inter-laminar failure can occur, and the carrying load of the composite laminates is considerably reduced.

OBJECTIVES
Composites are found to have great strength to weight ratio. It can be further increased by making use of perforated plate in case of complete composite sheet. This results in the loss of strength but increase in strength to weight ratio. A study of the stress-strain and displacement of woven glass fiber/ epoxy composite laminated plates under compression load is presented. The maximum load of failure for each of the glass fiber/epoxy laminated plates under compression load has been determined through simulation software (ANSYS). The effects of varying the centrally located circular cut out sizes and fiber angle ply orientations under the ultimate load has been simulated. The crack propagation in the drilled laminate sheets is focused. The study of stress-strain development and displacement on composite plate with circular hole of three different diameters and three different orientations ReseaRch PaPeR under varying compression load is per  . Orthotropic material has been chosen for the analysis as their property varies in different direction which is true for fiber reinforced composites. Two plates of different orientation with same dimension but varying dimensions of the cut hole located centrally in the plate are designed.

RESULTS
The results obtained from the ANSYS analysis are presented in the following Tables. The compressive load is increased gradually in steps of 500N starting from zero. Thus the values of the displacement, stress and strain are noted for the load of 500N, 1000N, 1500N and so on till the maximum load is achieved.