4-Post durability test simulations using a nonlinear FEA model have been executed by engineers responsible for structural durability performance and validation. An integrated Body and Chassis, full FEA model has been used. All components of the test load input were screened and only the most damaging events were incorporated in the simulation. These events included the Potholes, Belgian Block Tracks, Chatter Bump Stops, Twist Ditches, and Driveway Ramps.
The CAE technology Virtual Proving Ground (eta/VPG®*) was used to model the full system and the 4-Post test fixtures. The nonlinear dynamic FE solver LS-DYNA** was used in this analysis.
The fatigue damage of each selected event was calculated separately and then added together according to the test schedule. Due to the lack of stress/strain information from hardware test, only the analyzed fatigue damage results of the baseline model were scaled to correlate with physical test data. As designs matured, the analyses conducted on the later design iterations were compared with the baseline results to show if desired fatigue life improvement of the analyzed structure had been achieved.
The presented CAE analysis method would provide the best analysis results if the VPG FEA vehicle baseline model could be correlated with hardware in loads/stress/strain, maybe just for one event (pothole, for example) or a few. Even after baseline hardware correlation, it is still best to use the analysis results in A-to-B comparison for later design iterations, mainly due to uncertain nature for fatigue and the limitations in fatigue damage calculation.