Finite element based evaluation of stress intensity factors for interactive semi-elliptic surface cracks

Abstract A finite thickness plate with two coplanar self-same shallow and deep semi-elliptical surface cracks subjected to remote tensile surface traction is considered for fracture analysis. Based on three-dimensional (3D) finite element solutions, stress intensity factors (SIFs) are evaluated along the entire crack front using a force method. The line spring model has also been used to evaluate crack depth point SIFs using shell finite element analysis. A wide range of geometric dimensions and crack configurations viz. crack shape aspect ratio (0.3≤ a / c ≤1.2), crack depth ratio (1.25≤ t / a ≤6), relative crack location (0.33≤2 c / d ≤0.9) and normalized location on the crack front (0≤2 φ /π≤2) are considered for numerical estimation of crack interaction factors. SIFs evaluated at the depth point using the force method from the 3D finite element results are compared with SIFs evaluated using the line spring model. Finally, using finite element results, an empirical relation is proposed for the evaluation of crack interaction factors. For the ranges considered, the proposed empirical relation predicts crack interaction factors at critical locations within ±2% of the 3D finite element solutions.

[1]  Raju Sethuraman,et al.  Computational simulation of fatigue crack growth and demonstration of leak before break criterion , 1999 .

[2]  Wole Soboyejo,et al.  Fatigue crack propagation of coplanar semi-elliptical cracks in pure bending , 1990 .

[3]  Sia Nemat-Nasser,et al.  Interacting dissimilar semi-elliptical surface flaws under tension and bending , 1982 .

[4]  James C. Newman,et al.  An empirical stress-intensity factor equation for the surface crack , 1981 .

[5]  Satya N. Atluri,et al.  Further Studies into Interacting 3D Cracks , 1999 .

[6]  Walied A. Moussa,et al.  The Interaction of Two Parallel Semi-Elliptical Surface Cracks Under Tension and Bending , 1999 .

[7]  J. J. Golecki,et al.  Extension fracture due to collinear cracks , 1996 .

[8]  R. Bell,et al.  The interaction of two parallel non-coplanar identical surface cracks under tension and bending , 1999 .

[9]  Erasmo Viola,et al.  Non-singular stresses effects on two interacting equal collinear cracks , 1983 .

[10]  J. Rice,et al.  The Part-Through Surface Crack in an Elastic Plate , 1972 .

[11]  Xin Wang,et al.  Stress intensity factors and weight functions for high aspect ratio semi-elliptical surface cracks in finite-thickness plates , 1997 .

[12]  X. Wang,et al.  On the general treatment of interacting cracks near an interfacial crack , 1996 .

[13]  Y. Murakami.  Stress Intensity Factors Handbook , 2006 .

[14]  Hiroshi Noguchi,et al.  Parallel array of semi-elliptical surface cracks in semi-infinite solid under tension , 1991 .

[15]  A. F. Grandt,et al.  Stress intensity factors for coalescing and single corner flaws along a hole bore in a plate , 1984 .

[17]  T. Fett.  Estimation of stress intensity factors for semi-elliptical surface cracks , 2000 .

[18]  W. Binienda,et al.  Theory of cohesive crack model with interactive cracks , 1998 .

[19]  I. C. Howard,et al.  An examination of methods of assessing interacting surface cracks by comparison with experimental data , 1996 .