Investigation of novel laser shock hydroforming method on micro tube bulging

Tubular components are indispensable in manufacturing industry, but when its size decreases to micro level, the formability of micro tube will become undesirable. To improve the formability of micro tube, this study suggested a novel laser shock hydroforming method. This method used laser-induced shock wave as energy source and liquid as medium to transmit pressure wave. It was the pressure wave that forced the material of micro tube to flow into the die cavity and replicated the shape of that. The dynamic forming process of micro tube was first studied by numerical means, and the numerical results agreed with experimental ones. Then, the middle section thickness of formed micro tube was researched experimentally. The results shown that the uniformity of thickness distribution was improved compared to that in quasi-static condition, and the improvement of that was analyzed by numerical means. In addition, the reason for the increase of formability was investigated in the aspect of contact stress, and numerical results confirmed that the impact of the material of micro tube on the die caused the increase in compressive stress, a phenomenon beneficial to the formability enhancement. Finally, the paper compared the deformation behaviors-deformation velocity and strain rate-with and without a die, proving that the die was one factor that contributed to the formability improvement.