Cylinder Head Reliability Assessment: From Numerical Method Development to Validation Based on High Mileage Field Data

Car manufacturers are selling more and more different vehicles with closer and closer renewals. To achieve this, they must reduce time of development for their vehicles and powertrains. Nevertheless, this is not sufficient and it pushes into doing the race for the best quality products. Thus, longer warranty periods and lower objectives of failure rate are required for automotive components. Renault Powertrain Engineering division has developed a numerical methodology allowing to estimate this reliability, particularly for Diesel cylinder heads.

This paper describes an original approach designed to validate this numerical method and based on data obtained from the field. About thirty vehicles with high mileage have been bought from private users and analyzed. The failure rate has been consequently estimated independently of any physical model. It has then been compared with assessment issued from numerical method and. This comparison has allowed validating numerical estimation of reliability.