Year-end Sale % OFF 
Abstract
Under cyclic loading in combination with high local stress levels a change in stiffness of connection points, e.g. spot welds, self-piercing rivets or flow drill screws can be observed. This paper introduces a numerical approach for the simulation of stiffness changes in vehicle structures under multiaxial cyclic loading as a result of the stiffness degradation of individual spot welds. The basic approach is based on a conventional damage accumulation combined with a power law representing the change in the spot weld’s stiffness. Instead of an accumulated damage value D a residual stiffness is set as failure criterion. Extensions to the approach are presented for its application to multiaxial loading with variable amplitudes. A conventional multiaxial fatigue test of a complete vehicle, focusing on its rear end including global stiffness and local strain measurements at the beginning, median and at the end of the test are presented and compared to the simulated results. This computation approach allows a more reliable fatigue assessment in comparison to a fatigue analysis which does not consider stiffness changes. The damage propagation after the crack initiation at an individual spot weld is represented more accurately as subsequent changes in the load paths are considered.
Highlights
Strength and stiffness requirements highly influence the dimensions and the weight of components and structures
This paper introduces a numerical approach for the simulation of stiffness changes in vehicle structures under multiaxial cyclic loading as a result of the stiffness degradation of individual spot welds
The results show the feasibility and basic simulation capabilities of the extended DegraRP approach
Summary
Strength and stiffness requirements highly influence the dimensions and the weight of components and structures. To achieve a lightweight construction a diversity of materials and joining techniques, are applied. Resistance spot welding is one of the most commonly used joining techniques in conventional vehicles. E.g. ALIVE (Advanced High Volume Affordable Lightweighting for Future Electric Vehicles) show a high potential for resistance spot welding or similar techniques (e.g. resistance element welding) to be applied in future vehicle projects [1]. For a consequent light weight construction, novel methodologies are needed to predict the material’s fatigue behaviour as stiffness changes are not taken into account in currently used fatigue analysis tools yet. In this paper the basic approach DegraRP [2], which showed promising results for the stiffness degradation simulation under single channel torsional loading, is extended and applied to a complete vehicle simulation in order to take into account multiaxial loading
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
