Numerical and experimental investigation of fiber drawing process

The manufacturing process of glass fibers used for the reinforcement of composite material consists in drawing liquid glass at high temperature into fibers. This process is very complex and sensitive to numerous disturbances that can cause the breaking of the forming fibers. Breaks have a strong negative impact on the process efficiency. It is thus very important to understand the mechanisms of fiber breaking in order to optimize the manufacturing process. As a first step towards elucidating the causes of these failures, we investigate here the underlying physics of the forming of a single fiber through numerical simulations. In particular, we focus on the region from the hole tips at the bushing plate to the glass transition point. The influence of key parameters (e.g., glass flow rate, drawing velocity, external environment, glass properties) on the fiber radius attenuation and the internal stresses is investigated through a sensitivity analysis. Finally, these numerical studies are compared with experimental data measurements obtained from a dedicated fiberization unit for a single fiber. These experimental results also serve as additional insight into the forming process and as validation of the physical models, such as glass rheology or heat transfers. Comparisons between numerical and experimental results show a good agreement and demonstrate that simulations can provide a useful tool to gain insight into the underlying physics and to devise new strategies for adjusting the process operating window.