Path planning the processing of titanium matrix composites

The high temperature consolidation of fiber reinforced titanium matrix composites (TMCs) seeks to reduce the concentration of matrix pores (i.e. increase relative density) while simultaneously minimizing fiber microbending/fracture and the growth of reaction product layers at the fiber-matrix interface. These three goals have conflicting dependencies upon the consolidation processes variables (temperature and pressure), and "trial and error" has had difficulty in identifying optimal process pathways that lead to composites with the least fiber damage, reaction layer thickness and matrix porosity. Here, model predictive control (MPC) concepts have been combined with dynamic consolidation models to investigate the design of locally optimal process cycles that minimize fiber damage, reaction product layer thickness and pore concentration. The approach is used to path plan the input process schedules for a Ti-6Al-4V/SCS-6 TMC system. We then show how useful process windows (i.e. an approximation to the domain of the reachable goals) can be computed by varying the goal and repeating the path planning procedure.