Simulation of Non-isothermal Crystallization Kinetics of Thermoplastics during Fiber Placement Process

Currently more and more thermoplastic composites are applied in aircraft structures. During automated fiber placement process, thermoplastic composites, which adopted “ in-situ consolidation” technology, can be formed and consolidated in several minutes. Therefore, using “ in-situ consolidation” technology instead of autoclave technology is more economically. However, some technical indicators of laminates using “in site consolidation” technology are below the autoclave laminates. In order to eliminate the most significant barriers, the automated fiber placement process should be studied. The crystallization rate of thermoplastic in the cooling stage of automated fiber placement is one of the most important factors. In order to obtain the special crystallization, the cooling temperature and cooling time should be strict controlled. According to the coupling phenomena between the non-isothermal crystallization kinetics and the heat transfer in thermoplastic during the cooling stage, a mathematical model has been established. By solving above model, the relationship among cooling temperature, cooling time and relative crystallization rate has been obtained. Above simulated data can guide the cooling stage of automated fiber placement process.