Crack shielding and amplification due to multiple microcracks interacting with a macrocrack

Abstract

We investigate the effect of crack shielding and amplification of various arrangements of microcracks on the stress intensity factors of a macrocrack, including large numbers of arbitrarily aligned microcracks. The extended finite element method is used for these studies. In some cases the numerical XFEM simulation provides results that are more accurate than currently available analytical approximations because the assumptions are less restrictive than those made in obtaining analytical approximations. Stress intensity factors for the tip of a macrocrack under the influence of nearby microcracks are calculated under far field mode 1 boundary conditions. For a microcrack aligned with the macrocrack the numerical results agree quite well with the analytically exact stress intensity factors. The influence of the distance to the macrocrack tip and the rotation angle is investigated for unaligned microcracks, and it is shown in several examples with many randomly distributed microcracks that the influence of those microcracks which are not in close proximity to the macrocrack tip is on the order of 5%.

Effect of crack orientation statistics on effective stiffness of mircocracked solid

“…For a solid containing a periodic array of rectilinear or penny-shaped cracks, the solutions were obtained by Fil'shtinskii (1974), Nemat-Nasser and Yu (1993), and Wang (2004, among others. The representative unit cell containing several cracks, in conjunction with the numerical method, has been applied to evaluate the elastic constants (e.g., Huang et al, 1996;Greengard and Helsing, 1998;Helsing and Peters, 1999;Orlowsky et al, 2003) and stress intensity factors (Binienda et al, 1993;Loehnert and Belychko, 2007) of 2D solids with randomly oriented rectilinear cracks. Kushch and Sangani (2000a,b) have developed the multipole expansion method to solve for the local stress and effective moduli of a 3D solid containing randomly placed parallel penny-shaped cracks; a similar problem was studied by Grechka (2007) who applied the numerical, finite-element method.…”

The effect of pit size and density on the fatigue behaviour of a pre‐corroded martensitic stainless steel

“…[62][63][64][65]71,72 As such, a square grid with sides on order of 1700 μm was chosen to accommodate the interaction of 5 pits on order 300 μm. MountainsMap software (by Digital Surf) was used to perform automatic pit detection and characterization (depth, surface width/area, volume, density, etc.).…”

3D corrected XFEM approach and extension to finite deformation theory

“…in [7][8][9]. A multiscale approach is presented in [10] to efficiently consider the influence of microcracks [11] for the 2D and in [12] for the 3D case. A new development is to combine cracks and material inhomogeneities for the 3D case by Huynh and Belytschko [13].…”