Overload analysis and fatigue life prediction of spot-welded specimens using an effective J-integral

• Published in: Mechanics of materials Vol. 37; no. 1; pp. 19 - 32
• Main Authors: Lee, Hyungyil, Choi, Jinyoung
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier Ltd 2005; Amsterdam Elsevier Science; New York, NY
• Subjects: Applied sciences; Effective crack driving parameter Je; Exact sciences and technology; Fatigue; Fatigue analysis; Fatigue life; Finite element model; Fracture mechanics (crack, fatigue, damage...); Fundamental areas of phenomenology (including applications); J-integral; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Overload analysis; Physics; Solid mechanics; Spot-welded specimen; Structural and continuum mechanics; Fatigue life; Finite element model; J-integral; Effective crack driving parameter J e; Spot-welded specimen; Fatigue analysis; Overload analysis; J integral; Mode coupling; Surface crack; Rupture; Fatigue; Experimental study; Test bar; Modeling; Effective crack driving parameter Je; Finite element method; Spot weld; Overload; First integral; Size effect; Fracture mode; Structural analysis
• ISSN: 0167-6636; 1872-7743
• DOI: 10.1016/j.mechmat.2003.12.006

This paper proposes an integrated approach for predicting the fatigue life of spot-weld specimens. The approach is independent of specimen geometry and loading type. We establish finite element (FE) models reflecting the actual specimen behavior observed from the experimental load-deflection curves of four types of single spot-welded specimen. Using established FE models, we first evaluate J-integral as a fracture parameter for describing the effects of specimen geometry and loading type on the fatigue life. It is confirmed, however, that J-integral concept alone is insufficient to produce the generalized relationship between load and fatigue life of spot-welded specimens. On this ground, we introduce another effective parameter J e composed of J I, J II, J III. The mechanism of the mixed mode fracture, which incites the use of J e, is discussed. The parameter J e is demonstrated to more sharply define the relation between load and fatigue life of spot-welded specimens. The crack surface displacement method is adopted for decomposition of J.