Brittle fracture assessment of engineering components in the presence of notches: a review

An in‐house finite element code was used to analyse a diametrically compressed isotropic homogeneous Brazilian disc having a central inclined crack with frictional surfaces for the evaluation of its corresponding modes I and II stress intensity factor (SIF). One‐half of the disc was successfully idealized. The coefficient of friction between the crack surfaces ranged from 0 to 1 in steps of 0.1. Relative crack length ratios of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7 were analysed with crack angles up to 90° in steps of 5°. The crack angle corresponding to the transition from a mixed mode I/II to a pure mode II decreases with increasing the relative crack length ratio. An increase in the relative crack length ratio leads to an increase in the range of crack angles corresponding to a partially closed crack. The crack angle at which fully closed sliding crack surfaces commences is 30° independent of the relative crack length ratio and the friction coefficient. With the same relative crack length ratio and increasing the friction coefficient, there is a corresponding decrease in the crack angle for the maximum mode II SIF. With a decrease in the relative crack length ratio or the friction coefficient, the crack angle beyond which the crack surfaces become in a fully sticking mode decreases resulting in zero mode II SIF. Generally, mode II SIF decreases with increasing the friction coefficient between the crack surfaces. Good agreement has been generally obtained with relevant results found in the literature.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modes I/II SIF of a diametrically compressed Brazilian disc having a central inclined crack with frictional surfaces

Hammouda

Fayed

2017

“…To overcome the disadvantage, Lazzarin and co‐authors proposed the strain energy density (SED) range as a means of representing weld fatigue life based on the NSIF methods. This approach has been widely applied to brittle fracture and fatigue failure focusing on different fracture modes based on notch theory . The SED can be calculated over a control volume of radius R c surrounding the weld toe or the weld root, which depended on the material's properties.…”

Section: Introductionmentioning

confidence: 99%

Fatigue failure transition analysis in load‐carrying cruciform welded joints based on strain energy density approach

Song

Liu

Berto

et al. 2017

This paper details a study of the application of notch stress intensity theory to the fatigue failure mode analysis of the transition in load‐carrying cruciform welded joints. The weldment fatigue crack initiation point is difficult to predict precisely because it usually occurs in the vicinity of the weld toe or weld root. To investigate the relationship between fatigue failure location and the geometry of the weldments, we analysed the weld toe and root asymptotic notch stress fields were analysed using the notch stress intensity factors on the basis of the Williams' solution in Linear Elastic Fracture Mechanics (LEFM). Numerous configurations of cruciform joints of various plate thicknesses, transverse plate thickness, weld sizes and incomplete penetration size were used to investigate the location of the fatigue failure. The strain energy density (SED) surrounding the notch tip was introduced to unify the scalar quantity and preclude the inconsistency of the dimensionality of the notch stress intensity factors for various notch opening angles. The results of the investigation showed that the SED approach can be used to determine the transition zone for a variety of joint geometries. The validity of the SED criteria was verified by comparing the experimental results of this study with the complied results for load‐carrying cruciform welded joints reported in literature.

“…Williams introduced the eigenfunction expansion method to solve the stress singularity orders in a notched plate subject to inplane loadings. 9,10 Similar to the plane problem, bending singularities can occur in a notched plate under bending. 6,7 In Williams-type singularities, the near-field stresses are assumed to be f (θ)r −s , where the exponent is the stress singularity order and f (θ) is the corner function.…”

Section: Introductionmentioning

confidence: 99%

Investigation of thickness effects on the bending singularities of a notched plate

Chen¹

2017

In this paper, the bending singularities of a notched plate are investigated through the finite element method. The computed singular parameters, including the singularity orders and associated corner functions, are compared with those of classical plate theory and first‐order shear deformation plate theory (FSDPT); the comparisons demonstrate the inaccuracy of the boundary conditions in classical plate theory. The thickness effects are then investigated through the finite element method. The results show that although the singularity parameters computed by finite element agree with those of the FSDPT in the interior of the plate, the FSDPT is not applicable at the notch tip on the top or bottom surface because of substantial free surface effects. For a very thin plate, the inconsistence in the comparison slightly increases because of the free surface effects.