Structural durability of a product is achieved only by careful design, taking into account the different aspects of the required mission profile with regard to component strength. In order to include all effects on component strength (like material, manufacturing, local geometry, scatter) on one hand, and to meet competition requirements on the other hand, the design engineer has to apply efficient methods for guaranteeing service durability. A brief overview over these methods is presented.Today's developments are focusing on the reduction of time-tomarket periods. This fact is putting more emphasis on numerical methods (simulations of dynamic system behaviour, of component properties and local stresses) in order to reduce experimental procedures of optimizing and proof.The mechanical components of future mechanical engineering constructions are increasingly being replaced by electric and even multifunctional components. Electronics are gaining influence which is reflected by current keywords like brake or steer-by-wire technology. Knowledge of the system behaviour as well as all interactions between electronical control and mechanical behaviour are absolutely imperative to assess the reliability of such approaches.