Effect of residual stresses on ductile crack growth resistance

• Published in: Engineering fracture mechanics Vol. 77; no. 8; pp. 1325 - 1337
• Main Authors: Ren, X.B., Zhang, Z.L., Nyhus, B.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-05-2010; Elsevier
• Subjects: Complete Gurson model; Computer simulation; Crack propagation; Ductile crack growth resistance; Ductile fracture; Eigenstrain method; Exact sciences and technology; Fracture mechanics; Fracture mechanics (crack, fatigue, damage...); Fundamental areas of phenomenology (including applications); Inelasticity (thermoplasticity, viscoplasticity...); Mathematical models; Nucleation; Physics; Residual stress; Residual stresses; Solid mechanics; Structural and continuum mechanics; Welded joints; Ductile crack growth resistance; Eigenstrain method; Residual stresses; Complete Gurson model; Nucleation; Volume fraction; Layer model; Metal; Modeling; Crack propagation resistance; Finite element method; Inelasticity; Welded joint; Ductile material; Boundary layer; Internal crack; Stress analysis; Void fraction; Steel; Gurson model; Cavitation; Pipeline; Plane strain; Ductile fracture; Principal stress; Residual stress
• ISSN: 0013-7944; 1873-7315
• DOI: 10.1016/j.engfracmech.2010.03.007

It is well known that residual stresses influence the ductile fracture behaviour. In this paper, a numerical study was performed to assess the effect of residual stresses on ductile crack growth resistance of a typical pipeline steel. A modified boundary layer model was employed for the analysis under plane strain, Mode I loading condition. The residual stress fields were introduced into the finite element model by the eigenstrain method. A sharp crack was embedded in the center of the weld region. The complete Gurson model has been applied to simulate the ductile fracture by microvoid nucleation, growth and coalescence. Results show that tensile residual stresses can significantly reduce the crack growth resistance when the crack growth is small compared with the length scale of the tensile residual stress field. With the crack growth, the effect of residual stresses on the crack growth resistance tends to diminish. The effect of residual stress on ductile crack growth resistance seems independent of the size of geometrically similar welds. When normalized by the weld zone size, the ductile crack growth resistance collapses into one curve, which can be used to assess the structural integrity and evaluate the effect of residual stresses. It has also been found that the effect of residual stresses on crack growth resistance depends on the initial void volume fraction
f
0, hardening exponent
n and
T-stress.