Electrothermics

5.4. Induction and the lifecycle of composite materials

In most phases of the lifecycle of composite materials, a supply of heat is often necessary. It is currently carried out by thermal transfer from the material’s outer surface (heating pads, heat transfer, autoclave, etc.). Generally speaking, these processes have high cycle times, since heat needs time to diffuse in the volume. Furthermore, the cycle time is a function of the material’s physical properties and geometry only, and is not controllable by the heating process. These constraints result in productivity losses.

Induction is an alternative technique to supply heat in the composite material. We can thus heat metallic molds for a shorter time, but we can also heat the material directly if the reinforce is an electrical conductor.

The main advantages of induction are [DUP 52, DEV 00a, DEV 00b] the following:

– Core or surface heating, based on the generator’s frequency;

– Lack of contact allowing dynamic elaboration;

– Global or localized heating;

– High transmitted power density;

– Adaptation of the inductor’s shape to the charge.

5.4.1. Mastery of induction heating of composite materials

Mastering the process of heating by induction depends essentially on:

– an efficient simulation tool for electromagnetic and thermal phenomena suited to the special structure of these materials;

– adapting the inductor’s frequency and form to the geometry, material, and heating type;

– precise knowledge of their physical properties. ...