Abstract

The buckling of a structure may have an adverse effect on the structural performance and may cause instability of the structure or even failure of a structure, especially in structures with thin elements. Single layered tri-axial woven fabric composite structures belong to this type of thin structures. The load at which buckling will occur has to be determined. It is the purpose of the present dissertation to perform this task. The study of the dissertation covers the following aspects: (1) The buckling analyses of several simple tri-axial composite structures, such as straight composite beam and curved composite beam subjected to different boundary conditions, simply-supported composite structure with two intersected curved tows and simply-supported tri-axial woven composite structure with three intersected curved tows, that are a part of tri-axial woven fabric composite tow structures are performed. (2) The buckling behavior of more complicated tri-axial woven fabric composite structures is studied. These more complicated structures include basic tri-axial structure, modified basic tri-axial structure and enlarged basic tri-axial structure where additional weavings are added to make the sample longer and wider. The basic tri-axial structure is subjected to uni-directional or bi-directional loading. The sensitivity of the buckling behavior of the basic tri-axial structure to the change in the boundary conditions and to the imperfection due to initial configuration is investigated. The sensitivity analysis of buckling behavior to the in-plane aspect ratio of the structure is also conducted. Their numerical results and corresponding physical explanations are given. In order to gain some insight into the buckling behavior of more complicated tri-axial woven fabric composite structures, the buckling analysis of the modified and enlarged basic tri-axial composite structures subjected to uni-directional loading is also conducted. (3) The value of the buckling load is normalized. Extension to the buckling of real life large tri-axial structures is discussed. Buckling load of a real life large tri-axial structure can be obtained approximately by subtracting from the value of the approximate analytical solution by 8%. Thus determined value of buckling load for a real life larger sized tri-axial structure is on the safe side. (Abstract shortened by UMI.)