Experimental research on laser shock forming metal foils with femtosecond laser

Mold-free fs laser shock micro forming and its plastic deformation mechanism

“…The main component of the gum water is polyvinyl alcohol, and its acoustic impedance is 0.16 Â 10 6 gcm À 2 s À 1 [23]. This kind of confining layer has been used in Ref [10]. Adhesive tape, the main component of which is polypropylene, was another new confining layer used in our experiments [15], because of its higher acoustic impedance (0.19 Â 10 6 gcm À 2 s À 1 ) [24].…”

“…Laser shock forming-a non-thermal laser forming method that has the advantages of non-contact, tool-free, high efficiency, and high precision-has been successfully introduced into micro manufacturing and has been reported as having great importance [5][6][7][8][9][10]. Generally, there are two categories of laser shock forming: with mold [5][6][7][8] and without mold [4,[9][10].…”

“…All these properties make fs lasers very suitable for microforming. In our previous work [10,15], we conducted experiments involving fs laser shock forming. A new confining layer has been used in the fs laser shock process and three-dimensional (3D) microstructures have been produced successfully on metal foil.…”

“…Generally, there are two categories of laser shock forming: with mold [5][6][7][8] and without mold [4,[9][10]. For the former, the maximal horizontal size of the formed microstructure is determined by the mold, and the laser parameters are the main influence on the vertical size.…”

“…We also quantitatively evaluated the peak pressure of a fs laserinduced shock wave when it was used for confined ablation (where a transparent confining layer is used to confine the expansion of the ablated plasma) and we found that, even with a very low laser fluence, the peak pressure could reach several tens of GPa [15], which is much higher than the dynamic yield strengths of most metals. So, fs laser-induced shock waves have been used in processing materials and fabricating parts [10,[15][16][17][18][19][20]. Compared to a ns laser, a fs laser has unique advantages when performing micromachining and micro manufacturing, including higher precision and the lack of a heat-affected zone [21,22].…”