FEA-based prediction and experimental validation of clutch transient temperature in automatic transmission

Multiple-disk clutch packs are commonly used in automotive automatic transmissions to transfer power and to change gears. Owing to packaging-space restrictions and performance requests, many clutch packs have non-uniform loading characteristics, resulting in local stress and temperatures much higher than bulk targets. Extremely high local temperatures or temperature gradients in clutch packs can cause frictional material carbonisation, debonding, coning or many other failure modes. This paper describes the development of a Finite Element Analysis (FEA) model that is capable of predicting transient temperature in the multiple-disk clutch packs. The FEA predictions are correlated with experimental data. A good agreement, with 5% discrepancy in the clutch pack temperature rise during the first engagement is obtained. The developed method improves the understanding of the heat transfer characteristics during the clutch operating conditions, and reduces product development time and cost.