Optimal cure cycles for the fabrication of thermosetting-matrix composites

Abstract

Polymer-matrix composites using thermosetting resins as the matrix are increasingly finding use. However, a major impediment to their widespread commercial use is the high cost associated with their manufacture, arising from the long processing cycle times. This paper addresses the problem of determining cure temperature and pressure variations with time for a time-optimal manufacture of thermosetting-matrix composites subject to practical constraints. The optimal cure cycles are determined using the nonlinear programming scheme of sequential quadratic programming combined with a physical model base to simulate the process phenomena. The optimized cycles are shown to Improve upon the manufacturer-recommended cycles as well as the improved cycles reported in the literature. The optimization results are reported for a wide range of resin materials, product specifications, and process constraints to illustrate their effects on the optimal cure cycles. Parametric studies are presented in terms of dimensionless groups to assess the combined effects of the product and process variables on the optimal cycles in a generalized manner.