DFD Stratagem Investigation on Suspension Subframe Durability Test with Spindle Coupled Road Test Simulator

In order to replicate the vehicle chassis proving ground (PG) durability test on the laboratory half vehicle spindle coupled Road Test Simulator (RTS), a drive file which can excite the actuators of the RTS to duplicate the chassis component strain state need to be developed. Traditionally the Drive File Development (DFD) aims to match the spindle forces and moments in addition with some supplemental channels such as the suspension link axial forces and the suspension travels. However the suspension subframe which is connected to the vehicle body achieves the equilibrium state with the inertia force applied on the vehicle body at arbitrary time when the vehicle is running on the PG. Suspension subframes mounted on the fixture of the RTS experience reaction forces from a fixed static boundary. This boundary condition discrepancy between the vehicle PG test and the laboratory RTS test may particularly lead to a different strain state on the suspension subframe. In this paper, the impact of the different boundary conditions on the chassis structures’ strain state is investigated both physically and virtually. It’s proved that the subframe strain state has a significant difference from full vehicle PG test to the half vehicle spindle coupled RTS test using the conventional DFD stratagem. Thus, a special DFD stratagem which employs the subframe strain road load data is then established and validated on the 2 corner MTS 329 RTS system with a front suspension assembly. It’s concluded that the suspension subframe strain state can be well retained on the RTS compared to the PG test by using this special DFD stratagem. In other words, the durability validation of the suspension subframe can be implemented much more accurately on the laboratory RTS system with this special DFD stratagem.