Reliability assessment of innovative designs in automotive industry

Car manufacturers have to introduce innovative designs during new product development. 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. To overcome this difficulty, the present paper presents a method based on numerical simulations, and two aspects are studied. The reliability of mechanical components is assessed, taking into account the manufacturing processes variability. This is performed with numerical reliability based design (RBD) methods such as the first or second order reliability methods (FORM/SORM). Loads applied by customers are also evaluated according to typical car usage and the specificities of engine behaviour generated by the new concept. 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 in an example of a manufactured steel exhaust manifold.