Product Code: ICA12_M1204

Heat Accumulation in Short-Pulse Laser Processing of CFRP
Authors:
Rudolf Weber, Institut für Strahlwerkzeuge (IFSW),; Stuttgart Germany
Christian Freitag, Institut für Strahlwerkzeuge (IFSW),; Stuttgart
Margit Hafner, Institut für Strahlwerkzeuge (IFSW),; Stuttgart
Volkher Onuseit, Institut für Strahlwerkzeuge (IFSW),; -
Peter Berger, Institut für Strahlwerkzeuge (IFSW),; Stuttgart
Thomas Graf, Institut für Strahlwerkzeuge (IFSW),; Stuttgart
Presented at ICALEO 2012

Short-pulse laser processing is usually referred to as cold" due to the very high intensities causing a large fraction of the processed material to evaporate. This minimizes the thermal interaction with the remaining material. However, very often recast layers and rims of molten material are observed in metal processing. In the case of CFRP processing much larger heat affected zones are observed than expected from pure heat conduction. Besides plasma energy redistribution and scattering the so-called heat accumulation is very often made responsible for such thermal effects.
An analytical model was used to describe the process of heat accumulation. It allows estimating the amount of energy which does not contribute to the process itself and remains as heat in the material contributing to a time-averaged temperature increase. The model takes 3-D heat flow into account for different pulse repetition rates and beam profiles.