Prediction of void growth and fiber volume fraction based on filament winding process mechanics

Abstract

The void growth and fiber volume fraction in filament winding composites are critical to the mechanical performance of composite structures. In this paper, a comprehensive prediction model for void growth and fiber volume fraction is developed based on various time-dependent manufacturing characteristics in the filament winding process. This prediction model is basically decoupled into three sub-models: a diffusion-controlled void growth sub-model, a thermo-chemical sub-model and a resin flow sub-model for fiber volume fraction modeling. The relationships between manufacturing parameters and void size, fiber volume fraction are investigated by employing this new model. The results show that, in conventional models, the predicted size of voids was underestimated without considering the change of resin pressure and processing temperature. Strict control of the initial void size has limited benefits on reducing the final size of voids after winding process. However, the ambient humidity is critical to the control of the final void size in the composite products. Moreover, a higher winding tension will result in a smaller size of voids and a higher volume fraction of fibers, benefiting the improvement of product quality.