A point and line source model of laser keyhole welding

The keyhole formed during penetration welding with a laser is modelled so far as its thermal absorption characteristics are concerned by the combination of a point and a line source. In this way a representation of the broader surface section of the weld is obtained in addition to the lower section. A simple analytical form for the temperature distribution is obtained and possible weld profiles are found numerically from this. These are compared with examples of actual welds; it is possible in this way to estimate the proportion of the laser power absorbed in each section of the weld. Graphs and some simple approximations are given which allow it to be done easily for a given weld.