Induction heating model for high-frequency induction joining and repair of complex-shape graphite fiber/polymer matrix composites

An induction heating model has been developed to predict heating patterns and behavior in complex-shape graphite fiber/polymer matrix composites under arbitrary induction coil shapes. The heating is assumed to be caused primarily by resistive losses in the fibers due to eddy currents generated by an alternating magnetic field. The model predicts the eddy current patterns in the material as a function of coil and material geometry, allowing the user to predict heating effects due to factors such as edges and anisotropy. Heat generation rates and heat transfer are then calculated to find the full transient temperature distribution throughout the composite. Additional capabilities of this program include the ability to deal with multiple coils and workpieces and moving coils. The model uses finite difference methods in two dimensions for these calculations. Basic electromagnetic and heat transfer laws are used to calculate the magnetic fields, eddy currents and temperatures. The predicted heating patterns correspond well with experimental data. The ultimate purpose of this model is to enhance the users' understanding and control of the induction heating process under various conditions and thereby make this a more viable method for joining and repair of composite materials.