Laser shock incremental forming by employing high repetition rate laser pulses with pulse duration in the scale of 100 ns

Laser shock forming is an advanced method with characteristics of ultra-high strain rates up to 106-107 s-1 for deformation of micro/nanostructures on foils. However, the former related studies mainly focused on the laser shock forming with large laser spots, short pulse duration, and low repetition rate, which has many limitations in deformation homogeneity and processing efficiency. In this study, a laser shock incremental forming with small laser spot, long pulse duration, and high repetition rate is investigated. To demonstrate the feasibility of this method, a rectangular bulge on an aluminum foil is fabricated. By analyzing the cross-section profiles and average heights at eight different locations in the bulge and comparing them with the reference, the uniformity of the present laser shock incremental forming is investigated. The heat accumulation effect under the action of laser with high repetition rate was analyzed by means of theoretical calculation and analytical comparison. And the deformation behavior of the foil in laser shock incremental forming was simulated by using Abaqus software. Results show that the laser shock incremental forming with small laser spot, long pulse duration, and high repetition rate can be used to deform aluminum foil in thickness of 10 mu m. The height of the micro bulge deformed by a laser with a pulse duration of 100 ns and a lower pulse energy can reach a scale similar to that deformed through a larger laser spot with pulse duration of 10 ns. And heat accumulation effect may exist in high repetition rate laser, but it is not the main factor affecting the forming depth.