Finite Element Modeling of Tow-Placed Variable-Stiffness Composite Laminates

Abstract

Tow-placement machines have made it possible to manufacture curved-fiber composite tow paths. A composite structure with curved-fiber tow paths can be formed in a manner similar to filament winding. The result is a laminate with spatially varying stiffness and response. This manufacturing method can also result in overlap regions between adjacent tow paths. In previous research, a closed-form solution was developed to determine the response of these variable-stiffness laminates, but the overlap regions were not included in this model. Additionally, the fiber-orientation angle throughout the panel was based on individual fiber path definitions and not tow path definitions. In this thesis, a method of creating a finite element model of tow-placed variable-stiffness composite panels is presented. This method provides a representation of the overlap regions and an accurate model of the fiber-orientation angle change throughout the laminate. The GENESIS finite element analysis and design package is used to solve for the static response of the models created. The results of these analyses compare favorably with the results of the previous research and give some insight into the interaction of the thickness and fiber-orientation variation. Additionally, some of the advanced design capabilities of the finite element modeling method, and some results of those designs are demonstrated.