Reinforcement of perforated metal sheets by thermal shock with laser beams

A quantitative study was conducted on the improvement of load-bearing capacity and fatigue life of a thin aluminum sheet containing a small hole by means of thermal shock generated by a pulsed laser. A finite-element computer code based on the thermoelastic-plasticity theory was used to assess the distributions of temperature and residual stresses in the affected region. Analytical results were verified by the measured values from various techniques including the X-ray diffraction method for the residual-stress measurements. The improvement of fatigue life of the sheet metals resulting from this thermal shock process has been demonstrated by tests and correlates well with a postulated empirical model with the calculated induced residual stress.