Laser induced flexural wave analysis: an aluminum element in steel substrate

Laser non-conduction limited heating is involved with evaporation at the surface, which in turn results in a recoil pressure generated at the vapor liquid interface. Depending on the magnitude of interface pressure, a pressure force acting normal to the workpiece surface occurs. This generates flexural waves propagating in the substrate material. When the material contains some impurities or defects, the flexural wave characteristic changes. On the detection of the wave characteristics, it becomes possible to identify the location and size of the impurities and defects in the substrate material. In the present study, laser induced evaporation of the steel substrate is considered. The interface pressure and normal pressure force acting at the workpiece surface is determined. Three-dimensional flexural wave analyses is carried out. An aluminum element is considered as impurity in the steel substrate. The effect of location of an element aluminum on the flexural wave motion is investigated. It is found that the flexural wave amplitude is influenced considerably by the presence of aluminum element. Temporal behavior of aluminum element changes the displacement characteristics considerably in the axial direction while characteristics of displacement difference do not alter considerably.