NUMERICAL ANALYSIS OF MECHANICAL BEHAVIOR AND OPTIMIZATION OF FIBER-REINFORCED THERMOPLASTIC COMPOSITES USING THERMO-HYDROFORMING PROCESS

摘要

The thermo-hydroforming process is a complex molding process developed and patented by Pourboghrat et al. Due to the use of heated and pressurized fluid to form the part, no additional heating is required to mold the composite. The application of uniform force and pressure applied by the fluid to the composite sheet significantly reduces the out-of-plane distortion, therefore allowing deeply drawn parts to be formed. However, wrinkles could still occur in thermo-hydroforming process. To solve this problem, a numerical study was initiated to minimize wrinkles. The mechanical behavior of the fiber-reinforced polymer composites was modeled using the preferred fiber orientation (PFO) model, which was implemented into ABAQUS as a User Material Subroutine (VUMAT). To simulate the thermo-hydroforming of multi-layer composite laminates with the PFO model, the cohesive zone model was used to represent the interfacial properties between each composite layer. This model is suitable for the simulation of forming of multilayer composite laminates. In this study, the goal was to minimize the number of wrinkles occurring in the forming process, by optimizing parameters such as the fluid pressure, boundary conditions, and the initial blank shape in the molding process.