Computational modelling of laser treatment of plates for increased buckling loads and natural frequencies

摘要

As a special measure in lightweight design, residual stresses can be used for improving the stability and vibration behaviour of thin-walled structures. In contrast to the common practice of inducing proper residual stresses by mechanically caused local plastic deformation, in the present paper it is shown by numerical procedures as well as by experiments how such beneficial residual stresses can be produced by a proper heat treatment using laser. This is shown by simple plate examples, for proof of concept. A finite element approach is combined with algorithms simulating the heat input from laser beams. The analyses comprise investigations of a single laser dot for studying the fundamental behaviour of laser treatment according to the abovementioned aspects, and - for practical applications - continuously moving and intermittently acting beams are considered. Unwanted effects, such as distortions and possible instabilities appearing during the laser treatment, are considered as well, and methods are presented for avoiding them. A number of generic laser tracks as well as patterns of laser dots of different configurations are investigated. Experiments were performed which confirm the potential of laser treatment of plates for improving stability and dynamic behaviour.