Reliability of Innovative Designs: A Numerical Approach Applied to Exhaust Manifolds 2006-01-0110

Car manufacturers have to introduce innovative designs during new products development. It is a way of increasing the attractiveness of new models and gaining a competitive edge over competitors. It is also necessary for new engine development in order to meet increasingly stringent emission standards. On the other hand, field reliability of these new products must be achieved and demonstrated before the start of production. As the design is innovative, this demonstration cannot be based on field and warranty results of existing engines. Specific methods must be developed to reach this goal.

This paper presents such a method based on numerical simulations. Two aspects are studied. Loadings applied by customers are evaluated according to typical car usage and the specificities of engine behavior generated by the new concept. Reliability of mechanical components is assessed, taking into account the manufacturing processes dispersion. This is performed with numerical reliability based design (RBD) methods such as FORM / SORM. The combination of these two types of information provides an evaluation of the future field reliability of the new concept. Results such as parameter sensitivities also help to improve reliability during development by optimizing the design or the manufacturing process. This numerical approach is illustrated with the example of a manufactured steel exhaust manifold.