Finite elements for laminated composite plates | |
| Author | Chowdhury, Saiful Haider |
| Call Number | AIT Thesis no.ST-91-2 |
| Subject(s) | Plates (Engineering) Laminated materials |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Abstract | The increased use of laminated composites as structural plates has generated considerable interest in the analysis and design of laminated composite plates. Earlier analyses of composite plates, were based on classical laminated plate theory, and they ignored the effects of transverse shear deformations. The transverse shear deformations are significant in composite plates due to their low transverse shear modulus relative to the in-plane moduli. In addition, interlaminar normal stresses may be of importance in some class of problems. Recently many different theories have been proposed which account for transverse shear deformations and interlaminar normal stresses. These higher-order theories do not in general lend themselves for easy closed-form classical solutions. Thus, they have been used in displacement based finite element formulations. The accuracy of solutions, computer storage demand, computing time and the cost varies depending on the displacement model assumed in the finite element formulations. The present study, primarily, concerns with the establishment of the above indicated variables for three different finite elements based on three different displacement models. Then these models have been applied to study the influence of transverse shear deformation and inter laminar stresses for plates having different width to thickness ratios and material properties. The study also includes the effects of boundary conditions, material anisotropy and number of layers on the static elastic response of such plates. In Displacement Model: 1 the transverse shear strains are considered to be constant over the thickness of the plate. In Displacement Model: 2, a higher-order variation is adopted, which leads to parabolic distribution of the transverse shear strains. In Displacement Model: 3 which a development over the preceding one, incorporates parabolic distribution of transverse shear strains and also a linear variation of transverse normal strain through the plate thickness. Following the standard displacement based finite element formulations three finite elements have been obtained corresponding to the three displacement models. Based on the displacement models and the respective FEM formulations computer codes have been developed to obtain solutions for different class of problems. The finite elements developed in this study were employed in the analysis of variety of laminated composite plates composed of symmetric layers. In order to validate the finite element formulation, a convergence and accuracy study has been performed. In addition, the performance of the present finite elements has been assessed through the application of the three elements to -iii- different benchmark problems. In most of the cases solutions are compared to the existing three-dimensional elasticity, closed-form, and finite element solutions. The response quantities that have been presented, include deflections, in-plane stresses, transverse shear stresses and normal stresses. In further applications this elements have been employed to study the influence of certain parameters such as, plate width to thickness ratio, material anisotropy, boundary conditions, number of layers in the laminate, layer orientation, bidirectional layer thickness ratio etc. on the behavior of laminated composite plates. In the concluding remarks, the performance of the present finite elements has been summarized based on the results of convergence and comparison study. Further comments on the influence of various parameters on the behavior of laminated composite plates have also been noted. However, the numerical results presented, both in tabular and graphical form, are useful for practical engineers in making an informed choice of an appropriate finite element for the analysis of laminated composite plates. |
| Year | 1991 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Worsak Kanok-Nukulchai ;Sivakumaran, K.S. |
| Scholarship Donor(s) | Government of Switzerland |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1991 |