The Lightweight Chassis Sub-frame Design by Applying Hydroforming Technology

The twist beam type design on the rear sub-frame is widely used in both the sedan and MPV/SUV models. One of the conventional designs of the twist axle is combined with one torsion bar and another stamping part in order to meet the torsion stiffness requirement. However, in many cases, the torsion stiffness of the prototype does not match the CAE simulation results. In order to change the design, it is necessary to develop a new die to make the prototype; this will substantially increase the cost. We also propose an innovative concept called an adjustable die, in order to save die cost during prototype conceptualization. In this paper, a redesigning process for a hydroformed twist beam is presented, including model redesign, prototype manufacture, die design and performance test. The research results of this paper could serve as reference material when engineers want to apply hydroforming technology to achieve lightweight chassis sub-frame design.