Influence of material properties and friction in dual tube hydroforming process

The tube hydroforming process has become an indispensable manufacturing technique in recent years. With tube hydroforming, manufacturers can realise substantial cost savings as it provides reduced part count, increased part strength and stiffness and reduced weight. A dual hydroforming process was introduced to achieve a favourable tri-axial stress state during the deformation process. For materials with less formability, excessive thinning could be prevented. The tube material properties - such as yield strength, anisotropic values, hardening exponent - and process conditions such as friction - affect the tube deformation process. Hence, a parametric study has been conducted to investigate the effectiveness of dual hydroforming based on the various material properties and process conditions. It is concluded that dual tube hydroforming can significantly improve the strain distribution and reduce thickness variation. The advantages of dual tube hydroforming are best shown in materials with a low anisotropy value and which are in a high friction condition.