Transmission Durability Objective Assessment: A Method to Estimate Durability Requirement

Abstract

The transmission application process is more than ever characterized by a shorter and shorter development time and an increasing number of vehicle variants with different engines/weight.

These vehicles are often developed targeting several markets with different requirements in terms of final in vehicle validation (required by a specific brand) or a different final customer mission profile due to driving style and/or road condition.

Furthermore, in recent years, one of the major challenges has been the advent of hybrid and electric powertrains. The new load cases, typical of these new architectures (e.g. regenerative braking), have introduced new critical issues and drastically modified the hardware validation procedures.

The purpose of this methodology (Transmission Durability Objective Assessment) is to establish, with reference to a defined failure modes, an objective criteria to “measure” the level of damage generated on the transmission components by different vehicle/engine variants, vehicle test validation procedure or final customer mission profile.

The procedure consists in two phases: a sample data collection on a vehicle equipped with an instrumented transmission, and the data post processing with the in house developed Software TDOA to obtain an estimate of the damage that the transmission would suffer if it was subjected to the entire test.

This estimate of the damage makes it possible, beside the vehicle test comparison, to set up a representative bench procedure, tuned on the customer’s operation, or to set (with an already established test procedure) a target according to the vehicle requirements for each failure mode considered (wear, power, fatigue).