This paper develops a reliability-based methodology for the evaluation of stiffness degradation of spot-welded joints under high mileage in automotive structures. A global-local finite element analysis is used, with the loads on the detailed threedimensional joint model coming from finite element analysis of the entire car model with proving ground loads. Probabilistic fatigue crack propagation analysis is developed for multi-axial variable amplitude loading history on the joint. Multiple spot welds contribute to the stiffness of the joint. Hence the problem is addressed through system reliability techniques. The effect of spotweld separation on joint stiffness, and on global vehicle stiffness, is incorporated. This results in the computation of the statistics of vehicle stiffness degradation with mileage. The overall methodology for progressive analysis is sound, however, more modifications need to be made to ensure accurate results. First, a more realistic pillar-to roof joint finite element model needs to be developed. Also, the methodology to compute the global frequency distribution needs to include the case of multiple significant weld failure sequences instead of a single dominant sequence. Finally, the stiffness degradation calculations should be performed for each of the six directions, instead of the approximation used in this study. Other longterm needs include considering the effects of the heat affected zone and residual stress around the weld.
Spot-weld joint stiffness degradation under high mileage: probabilistic analysis
2003
8 Seiten, 7 Bilder, 4 Tabellen, 25 Quellen
Aufsatz (Konferenz)
Englisch
Spot-Weld Joint Stiffness Degradation Under High Mileage: Probabilistic Analysis
SAE Technical Papers | 2003
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