Effect of engagement force on vibration characteristics and frictional heating in sonic IR imaging

• We design an experiment setup to quantify engagement force between in sonic IR imaging.
• The engagement force affects test plate vibration characteristics and crack heating.
• We employ force excitation to simulate inverse pizoelectric effect in the FEM model.
• The engagement force alters the plate’s vibration intensity and spatial distribution.
• The crack closure and differential velocity of crack surfaces dominate crack heating.

In sonic infrared imaging, the engagement force strongly affects the plate׳s vibration characteristics and frictional heating at the crack, which have been proved by experimental results. We developed a FEM model in which piezoelectric-force analogy was employed to simulate inverse piezoelectric effect. Simulation results revealed that an increase in the engagement force not only enhances the vibration intensity of the test plate but also causes a sharp change in its spatial distribution. However, when the increase exceeds a certain level, the enhanced crack closure and weakened crack differential velocity will lead to a lower heat dissipating at the crack.