Abstract: A weight-reduction design method is presented, which can make auto components and parts with finite life. The method is technically based on the strengthening and degenerating properties of the structure strength meanwhile combining dynamic strength equation (i.e., calculating model) with strength test results of auto parts. In order to realize the given critical load or the design goal, finite element method is used in getting a rational increase of design stress. As an application of this method, a truck front axle was re-designed. By designing the critical section and reducing the figuration dimensions, a lower critical load of the front axle is obtained. Consequently the test stress is increased to an area of causing the strength of axle not to be strengthened under repeated stresses. As a result, the mass of front axle was reduced with 5.5 kg. The new axles were verified to fulfill the strength standards on test rig, and no obvious change was observed for static strengths after fatigue tests. The tests results show that the strength potential of components and parts of automobile could be exerted more fully than that designed with the method of using finite element analysis adding to the allowed stress, which can only make the design of infinite life for auto parts. The light weight design for components and parts of automobiles can be realized in a deeper extent with this new method. This new method is of important science value and guidance meaning for now a day’s development in auto light weighting. engineering value in many industrial fields other than in auto industry.

Key words: Auto structures, Finite life, Strength features, Weight-reduction design