Modelling of Induction Heating for the Press Consolidation Process

Abstract

The increasing use of composite materials in aerospace is driven by their high strength-to-weight ratio, but manufacturing these structures represents a large energy footprint and consumption of auxiliary materials. Thermoplastic composites consolidated with Induction heating offers a sustainable alternative to autoclave produced thermosetting composites, eliminating the need for prepreg refrigeration along with most auxiliary materials and a reduction in cycle time and energy consumption. Induction heating, however, is difficult and expensive to test and prototype and therefore there is a need for a way to predict tool behavior.

This thesis develops and builds on a finite element simulation framework in COMSOL Multiphysics to model induction heating of a tool for a C cross-section composite spar, using both, stationary and transient simulations- the latter of which incorporate temperature-dependent material properties - to analyze heating behavior in the tool and the effect of various parameters on the temperature distribution. The simulation model is validated through coil inductance measurements as well as heat surveys on an existing subscale tool.

Design guidelines for tool dimensions, coil placement are derived from simulations and tested virtually on a hypothetical tool geometry. A parametric modeling framework is created in the simulation software package itself, enabling rapid iterations of tool designs, streamlining development. Results demonstrate strong agreement between simulations and experiments with the stationary models predicting the variation in temperatures over the tool better while the transient model calculating the absolute temperatures more accurately. A combination of both these models in conjunction with tool design guidelines presented in this thesis can be potentially used for efficient, first-time-right tooling design for induction heated press consolidation tools.