The linear process of design-engineeringmanufacturing is nowadays obsolete. Even DFX (Design For X) methodologies are often replaced by Simulation for XFD (X being also Design) approaches. Optimization is also often applied before design. For instance, engineering design optimization of mechanical structures is nowadays essential in the mechanical industry (automotive, aeronautics ...). But optimizing mechanical structures cannot be efficient without taking in account other phases of the design-manufacturing process. In some cases, optimization is only based on trade kwnowledge. Engineers must then design parts or assemblies that are a better compromise, between mechanical and functional performance, weight, manufacturing costs etc. In this paper, after giving an overview on the different disciplines in design optimization of mechanical structures, we propose some trends to take into account the trade knowledge in the optimization/design phases. We propose an integrated approach to optimization in a functional design process with a methodological point of view. We present three different industrial cases of optimization on three examples : one in mechanical structures optimization, on based only on trade knowledge and the third mixing calculus and knowledge
Tolerance Optimization Design Based on the Manufacturing-costs of Assembly Quality