MECHANICAL ENGINEERING SEMINAR SERIES 2008MS Thesis PresentationMonday, May 5, 2008 10:00 amCVRC Conference Room“UNIT CELL ANALYSIS OF COMPOSITE MICROSTRUCTURES” ByShawn Christopher KlannAdvisor: Dr. Dahsin Liu Composite materials are replacing traditional metals in many applications due to their superior stiffness and strength to weight ratios. However, one problem with composites is the tendency of successive layers in a structure to delaminate in the thickness direction. This problem has been addressed in many ways such as z-pinning, stitching, and woven fabrics that help to maintain the structural integrity of a composite. Fiber weaving does not introduce the stress concentration present in the other two cases. A new type of composite, the Quasi-Three Dimensional (Q3D) weave, has shown great promise in combating delamination. Unlike the popular 2D Plain Weave, this weave holds successive layers together in order to increase the delamination resistance. There are not fibers aligned in the thickness direction but the tight weave creates a 3D network. An analytical technique is needed to predict the properties of the weave. This thesis presents an analytical method based on Classical Laminate Theory, using unit cell analysis, to predict the mechanical properties of weaving patterns. It is derived on the 2D Plain Weave and compared to other composite microstructures, such as laminates and the Q3D Weave. It was found that the Q3D weave has very similar properties to the 2D Plain Weave while having increased delamination resistance. Several case studies involving the material and geometric parameters of the composite weave are also presented. The undulation zones in the weave are found to be the most critical for the weave properties.Persons with disabilities please contact Aida Montalvo montalai@egr.msu.edu to request accommodations.