Introduction: Composite structures have been used many engineering applications, such as aircrafts, space vehicles, automotive industries, defence industries and civil engineering applications because these structures have higher strength-weight ratios, more lightweight and ductile properties than classical materials. With the great advances in technology, the using of the composite structures is growing in applications. With the increased use of composite structures, understanding the mechanical behavior of composites is very important for their design. Structural elements may be subjected to destructive effects in the form of initial defects within the material or caused by fatigue or stress concentration. As a result of destructive effects, cracks may occur in structural elements. It is known that the occurrence of a crack in a structure introduces a local flexibility, which may result in the reduction of stiffness and change of the buckling, dynamic and static behavior of the structure. Therefore, an understanding of the mechanical behavior and safe performance of edge-cracked structures is important to structural designs. With the increased use of composite structures, an understanding the mechanical behavior and safe performance of cracked composite structures is important to the structural designers. Aim: In this study, the static bending analysis of a cracked fiber reinforced composite cantilever beam resting on Winkler-Pasternal elastic foundation is investigated under distributed loads. The Euler- Bernoulli beam theory is used in the kinematic model of the beam. In the study, the effects of the crack location, the crack depth ratio, foundation parameters and composite material parameters on the static bending deflections of the fiber reinforced composite beam are investigated and disused. Also, the difference between the cracked and the intact beams is investigated and compared for different foundation and composite material parameters. Content: In accordance with this purpose, a fiber reinforced composite beam is modelled by using the Euler- Bernoulli beam theory. The boundary condition of the fiber reinforced composite beam is selected as cantilever. In the selection of the composite materials, fibre-reinforced polyamide composite is considered in the numerical results. In the elastic foundation model, the Winkler-Pasternak elastic foundation model is used in the considered problem. In crack effect, the crack is considered on the edges of the fiber reinforced composite beam. It is assumed that the crack is perpendicular to beam surface and always remains open. The cracked beam is modeled as an assembly of two sub-beams connected through a massless elastic rotational spring. The constitute model of the fiber reinforced composite beam is considered as orthotropic material model. Constraints: In this paper, the constitute model of material is considered as a orthotropic material model. The kinematic model of the fiber reinforced composite beam is used the Euler- Bernoulli beam theory. So, the shear stress and strains are neglected. Method: The governing equations of the problem are obtained by using virtual work principle. The Euler- Bernoulli beam theory is considered in the solution of the problem. In the solution method of the considered problem, the finite element method is used. In obtaining the numerical results and graphs, MATLAB program is used. Findings: The numerical results shows that that composite material, fondation and crack parameters have very important role on the bending behavior of the fiber reinforced composite rectangular beams. Choosing the suitable composite material parameters, the effects of the cracks can be diminished. Conclusion: In this paper, the bending deflections of the fiber reinforced composite cantilever beam are investigated by using finite element method based on the Euler- Bernoulli beam theory. The effects of the crack location, the crack depth ratio, foundation parameters and composite material parameters on the static bending deflections of the fiber reinforced composite beam are investigated.
Anahtar Kelimeler: Composite Beams, Crack, Finite Element Method, Elastic Foundation
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