MATEC Web Conf.
Volume 165, 201812th International Fatigue Congress (FATIGUE 2018)
|Number of page(s)||7|
|Section||New Trends for Fatigue Design of Structures (SF2M)|
|Published online||25 May 2018|
A novel approach to simulate the stiffness behaviour of spot welded vehicle structures under multi axial variable amplitude loading
BMW AG, Knorrstr. 147, 80807 Munich, Germany
* Corresponding author: firstname.lastname@example.org
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.
© The Authors, published by EDP Sciences, 2018
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (http://creativecommons.org/licenses/by/4.0/).
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