Electrothermics

4.7. Conclusion and general instructions

The results obtained from simulations and experiments in the previous sections show that the flaw detection quality is strongly influenced by the inductor’s shape, the physical characteristics of the inspected component and the inspected flaws, the electromagnetic frequency, and the heating and acquisition times. This is why certain precautions must be taken into account during a thermo-inductive inspection. These precautions are summarized in this section in the form of general guidelines. They include rules on the choice of an induction generator, the position and design of the inductor, the frequency of electromagnetic heating, and the position and geometry of the inspected components.

4.7.1. Discussion on the choice of induction generator and inductor

In the industry, critical flaws generally depend on constraints put on the components. These constraints are linked to the nature of the environment to which the components are submitted. The potential flaw types and positions are then known beforehand. However, their sizes remain a critical unknown that must be defined in order to evaluate their threat on operating safety. This knowledge of the flaw type, combined with that of the materials’ physical properties, allows us to make a good choice regarding an induction generator and inductor design.

Indeed, a flaw must generally produce a thermal signal greater than that obtained from noise. Furthermore, to detect the temperature rise due ...