| Buckling and postbuckling analysis of composite laminated structures having delaminations were studied numerically. The analyses were performed using the differential quadrature method of Bellman et al (1972).; Prediction of the buckling strength of the delaminated composite beams and the examination of the influencing factors were carried out by employing several models. The effects of the shear deformation and the bending-stretching coupling were added by incorporating a shear deformation beam theory. In addition to the effect of shear deformation, bending-stretching coupling, the influence of material properties, lamination sequence and fiber-orientation, through-the-thickness and through-the-length locations of delaminations on buckling and postbuckling responses were investigated.; The buckling response of composite laminated plates having a thin elliptical delamination was also studied by employing two-dimensional models. Employing the serendipity shape functions, the elliptical delaminated region was transformed into a rectangular computational domain with clamped boundaries, Subsequently, the differential equilibrium equations of the sublaminate were solved based on classical plate theory. In order to reduce the computational efforts include the effect of the bending stretching coupling, the reduced bending stiffness of the plates was employed. The integrity of the current methodology was compared with other numerical methods, and found to be computationally less complex, and numerically more accurate.; For the postbuckling analysis, the differential quadrature method combined with an arc-length strategy was used to model the postbuckling analysis of composite beams having single or multiple delaminations. Several case studies were presented and the effects of parameters such as the number of delaminations, the imperfection amplitudes and the delamination length were investigated.; Throughout the course of the research, the differential quadrature results were compared with those of published analytical and numerical investigations or with those obtained by analyzing problems with the use of the commercial finite element packages. The results show that the differential quadrature technique can be used as a powerful, reliable, accurate and efficient numerical tool in assessing the buckling and postbuckling responses of delaminated composite structures. Throughout the thesis, we will demonstrate several advantages of the method in comparison to the other popular numerical methods such as the finite difference, finite element and boundary element methods. (Abstract shortened by UMI.)... |
