Application of Fatigue Damage Criteria to CAE-Based Fatigue Life Prediction of a Welded Chassis Component

In recent years, computer-aided engineering (CAE) has become an essential practice in design and durability analysis of industrial components such as weldments. The current analytical trend for CAE-based fatigue life prediction of weldments includes procedures based on design guidelines, mesh-sensitive methods (e.g., local strain-life approach) and mesh insensitive methods (e.g., Volvo and Verity methods). As an inherent characteristic of weldments, the geometry of the weld is often simplified in failure analysis and important hotspots such as start/stop of the weld beads are not considered in designing process. However, such critical locations cannot be avoided in complex welded structures. Therefore, incorporating main geometrical details of the weld can improve the accuracy of critical regions identification and damage calculation using mesh-sensitive CAE-based methodologies. Herein, a framework for life prediction of welded components including the weld geometry is discussed and evaluated by its application to a coupled torsion beam axle. The weldment was simulated in finite element (FE) environment as a shell model with local mesh refinement and improved weld geometry. The FE model was validated by strain gage measurements of the actual component under single-channel constant amplitude load and critical locations in the component were accurately identified. Local stress-life and critical plane approaches were employed to predict fatigue life to failure resulting in reasonable accuracy within a factor of two. Despite the close results by the uniaxial and multiaxial fatigue damage criterion in this work, multiaxial life prediction approaches such as the critical plane concept are recommended due to their robustness for more complex and realistic loading conditions during service.