Accounting for driver variability in vehicle powertrain durability testing

Fundamental technical information and analytical methodology useful in vehicle powertrain durability testing are discussed. The durability testing in a laboratory is designed to correlate to vehicle proving grounds (PG) in terms of fatigue damage. A PG loading history is often acquired by running an instrumented vehicle in one of the repeated PG events with various drivers. The statistical technique to identify a median or an extreme loading profile from a given set of PG loading histories and the algorithm to extrapolate one short-term measured load data to the expected long-term loads are reviewed. The measured load time history is converted to either a rainflow cycle counting histogram for use of a component bench test development or a rotating moment histogram for use of a powertrain gear set durability testing. Damage analysis is then performed in the histogram domain for the durability of a powertrain component and system.