Optimization of course locations in fiber-placed panels for general fiber angle distributions

Fiber-reinforced composites are usually designed using constant fiber orientation in each ply. In certain cases, however, a varying fiber angle might be favorable for structural performance. This possibility can be fully utilized using tow placement technology. Because of the fiber angle variation, tow-placed courses may overlap and ply thickness will build-up on the surface. This thickness buildup affects manufacturing time, structural response, and surface quality of the finished product. This paper will present a method for designing composite plies with varying fiber angles with composite plates or panels. The thickness build-up within a ply is predicted as function of ply angle variation using a streamline analogy. It is found that the thickness build-up is not unique and depends on the chosen start locations of fiber courses. Optimal fiber courses are formulated in terms of minimizing the maximum ply thickness, maximizing surface smoothness or combining these objectives with and without periodic boundary conditions.