Validation of an Accelerated Test on a 4-Post Road Simulator

The 4-post simulator has been used for many years in the automotive industry to validate vehicle durability. The test vehicle's vertical wheel accelerations and the wheel-to-body displacements that are measured on the proving ground are reproduced accurately on the simulator using commercially available iterative-control software. It is often assumed that the remainder of the vehicle responds as it does on the road. This, of course, applies only to components influenced by vertical loading. However, even within this restricted set of components, questions often arise over failures that occur on the proving ground test, that are not reproduced on the simulator and vice-versa.

This paper defines the process used to derive an accurate laboratory simulation where both accuracy and test time are important; proposes an analysis methodology to pre-define those components where the majority of damage is caused by only vertical loading and explains why some failures are not observed in both tests.