A Ghaznavi - Niroo Research Institute (NRI), Tehran, Iran
S Mirzaei - Faculty of Physics and Energy Engineering, Amirkabir University of Technology (Tehran Polytechnic),Tehran, Iran

The suspension system, one of the essential parts of any vehicle which has a significant role in vehicle steering, accelerating, and braking. One of the suspension system's main components is the trailing arm, which is exposed to frequent loadings and is made by welding method. Due to the use and nature of this piece, its fatigue analysis is crucial. Since this part is made by welding process, its fatigue analysis is much more complicated than other parts. In this paper, fatigue life of the trailing arm is investigated by using different numerical method. At first, safety factor of the component is calculated using dang van criteria. Dang van is one of the most famous and appropriated method for multi axial non proportional loads. However it is not a good criterion in order to calculate the damage of the weld line. So Volvo method that developed base on the weld process and properties is consider for fatigue analysis of the weld line. The obtained results improve the necessity of using this kind of method for welding process.  Finally, it could be concluded that for fatigue analysis of a welded component such as trailing arm, using both method are necessary. Considering two different criteria for a component and comparing the obtained results of the trailing arm under non proportional applied load is one of the achievement of this paper. Of course by using this method, the calculated fatigue life of the trailing arm is accurate. At the end, it should be noted that the both applied methods, Dang Van and Volvo, are completely verified by the available experimental result in the reliable references.

Fatigue analysis, Dang van theory, Non-proportional loads, Seam weld analysis, Volvo method, Trailing arm