Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Mechanical Engineering

First Advisor

Su-Seng Pang


The objective of this study is to develop a method of analysis for fiber glass composite skew plates subjected to static and dynamic loading. An investigation has been carried out on the stress and deflection characteristics of stiffened parallelogramic plates with different skew angles. The numerical solution with assumed displacement function was developed using finite element analysis. Experiments using aluminum and Scotchply composite laminated plates were conducted to verify the results. Cantilever and simply supported boundary conditions were included in the analysis and an optimized angular stiffener for a particular swept back panel was achieved. A finite element model for these types of composite stiffened plates has been formulated by combining the nine-node plate element with the three noded beam element. The effect of the stiffener orientation and eccentricity has been taken into account by proper transformation matrix. The analysis has been carried out using this finite element model for plates of rectangular and skew plan form. Three different boundary conditions have been considered in the analysis: only one side clamped, two opposite edges clamped, and all sides free. Fundamental frequencies and the mode shapes for these plates with no stiffener, single stiffener and two stiffeners parallel to one boundary have been obtained. For validation of these results, experiments were conducted on Scotchply glass-fiber composite plates with all the above mentioned boundary conditions. The modal analysis software STAR has been used to analyze the experimental data and to prepare the mode shapes. The results are found to be in good agreement with the finite element results. A finite element analysis for a three dimensional composite aircraft wing consisting of skin, stiffener and ribs was carried out and the mode shapes were obtained.