Torsion beam suspensions are lightweight and low in cost, and they are therefore frequently used as the rear suspensions of small front-wheel drive vehicles. However, it is difficult to predict their characteristics and to satisfy performance targets in the early stages of development in particular, because the various aspects of performance required of a suspension must be achieved by a single structure. A great deal of research has been conducted into the cross-sectional shape of the beam section; however, this paper focuses on the effect of the properties of the trailing arms on suspension characteristics.
Two similar test torsion beam suspensions differing only in the rigidity of the trailing arms were fabricated, and kinematics and compliance (K&C) tests were conducted using a 3D measurement system.
The lateral compliance test showed the anticipated result that change in toe and camber is greater in the suspension with lower rigidity trailing arms. On the other hand, the roll motion test indicated that the lower rigidity arms had substantially greater toe change as well. Analysis of displacement at each measurement point showed that lateral movement becomes larger toward the ends of the trailing arms in a linear manner. This result indicates that the difference in toe change originates from the restraint of the trailing arms by the torsion beam, and not from the deflection of the trailing arms themselves. This mechanism was verified via FEM simulations.