3-D Analysis of Composite Structures

Dr. Sergei Yushanov
3TEX
North Carolina State Centennial Campus
Raleigh, NC  27606

Sponsored by: The Center for Materials Research and Analysis and the Department of Engineering Mechanics

Date:  Friday, March 5, 1999
Time:  3:30 p.m.
Place:  W128 Nebraska Hall


A novel 3-D variational structural analysis approach is introduced in this presentation. The approach is aimed at the development of a unified 3-D stress-strain, fracture, and damage prediction tool applicable to a variety of composite structures. The approach is based on the 3-D mosaic model, proposed earlier, and the associated variational principle of minimum total potential energy (in the case of static analysis) or the Hamilton variational principle (in the case of dynamic analysis). The displacement field in a composite structure is approximated by triple series with Bernstein basis functions. The advantages of the proposed method compared to conventional finite element analysis are illustrated by numerical examples. The accuracy of the method is validated on several exact solutions of classical composite bending problems.

Several applications of the developed method are considered. A 3-D progressive failure analysis of bonded composite joints is performed. The adhesive, cohesive, and interlaminar failure modes are taken into account. It is shown that, at the initial stage of loading, the adhesive crack would develop, while the interlaminar crack would likely become the dominating failure mechanism at the advanced stage. These theoretical predictions are in good agreement with experimental observations. 3-D dynamic response of laminated composite bars is also analyzed. All inertia terms are included in the analysis that allows one to study various types of stress wave phenomena in composite structures, including wave propagation and reflection from interfaces and exterior surfaces in a 3-D laminated composite body. Other possible applications are discussed.