Sensor placement study for online flow monitoring in liquid composite molding

On-line sensing can play an important part in controlling the quality of the final product in any manufacturing environment, including liquid composite molding (LCM). Having a sensor embedded within the part itself is often the most effective means of monitoring its condition at various stages of manufacturing and even throughout its useful life. However, given their intrusive nature, there are practical Limitations imposed upon their size, quantity and trajectory within the part. This study explores the possibility of using a single Lineal sensor to monitor the resin now front during the mold filling stage of LCM, and to detect the onset of void formation and the presence of dry spots within the mold, Experiments were conducted to characterize the response of a fiber optic system previously developed for cure monitoring. Simulations were then performed to determine the optimal placement of just one such sensor in a mold to demonstrate that sufficient information on the mold filling process could be obtained. The purpose of the simulation work was to learn how to interpret the sensor response and, subsequently, use it to control the LCM process.