Elastic displacement of the surface due to a laser heating pulse

When the surface of a substrate material is heated by a laser pulse, the surface initially expands and then contracts after the laser heating pulse ends. This may allow the surface temperature to be measured by monitoring the surface displacement. In the present study, the elastic displacement of the surface due to the temperature field generated during a laser heating pulse is examined. Three-dimensional laser gas-assisted heating is considered and the governing equations of flow and energy are solved numerically using a control volume approach, while the elastic displacement of the surface due to the temperature field is modelled through the finite element method. The relationship between the temperature rise and the elastic thermal displacement is discussed in detail. It is found that the rate of thermal expansion of the surface in the heating cycle is not the same as the rate of thermal contraction in the cooling cycle. Moreover, in the heating cycle, the rate of temperature rise and the rate of thermal expansion are similar.