Experimental and numerical study of the hydroforming process of copper-aluminum double layered tube

Tube hydroforming is a forming process in which the hydraulic pressure is used to change the shape of material. In this research, the formability of copper-aluminum double-layered tube in the hydroforming process has been investigated by experimental and simulation methods. First, the double-layered tube with the outer layer of aluminum has been examined, which was burst due to the low plasticity of the aluminum tube. Then, a two-layered tube with the outer layer of copper has been examined, and the inner aluminum tube was wrinkled. To prevent the inner aluminum layer from wrinkling, an internal mechanical restraint made of copper has been used, and the experiment in this case has led to the formation of the double-layered tube without bursting and wrinkling. Response surface method has been used to study the effect of parameters. These parameters included axial punch displacement, first pressure, final pressure, aluminum tube thickness and the counterpunch. The objective functions were the thinning of copper layer, the thinning of aluminum layer and the height of the protrusion. The results showed that the axial displacement has the greatest effect on the height of the protrusion and the thickness of the inner aluminum layer has the greatest effect on the thinning of the layers. In order to achieve the maximum height of the protrusion and the minimum thinning for both layers, the optimal parameters have been extracted in the two cases of the presence and absence of the counterpunch, and the results were compared with the finite element simulation.