A two-parameter framework to describe effects of constraint loss on cleavage fracture and implications for failure assessments of cracked components

Cravero, Sebastian; Ruggieri, Cláudio

doi:10.1590/s1678-58782003000400013

Cited by 19 publications

(12 citation statements)

References 21 publications

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“…6 and 7, lower a/W ratios corresponding to higher J values exhibit a trend observed by other authors (Cravero and Ruggieri, 2003). Also, the J-integral differs greatly for a/W = 0.75 if matched with a/W = 0.25 and 0.5, then they tend to be close in values.…”

Section: Discussionsupporting

confidence: 77%

Numerically predicted J-integral as a measure of crack driving force for steels 1.7147 and 1.4762

Vukelić

Brnić

2017

jtam

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Fracture behavior of two types of steel (1.4762 and 1.7147) is compared based on their numerically obtained J-integral values. The J-integral are chosen to quantify the crack driving force using the finite element (FE) stress analysis applied to single-edge notched bend (SENB) and compact tensile (CT) type fracture specimens. The resulting J-values are plotted for growing crack length (∆a -crack length extension) at different a/W ratios (a/W -relative crack length; 0.25, 0.5, 0.75). Slightly higher resulting values of the J-integral for 1.4762 than 1.7147 can be noticed. Also, higher a/W ratios correspond to lower J-integral values of the materials and vice versa. J-integral values obtained by using the FE model of the CT specimen give somewhat conservative results when compared with those obtained by the FE model of the SENB specimen.

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Section: Discussionsupporting

confidence: 77%

Numerically predicted J-integral as a measure of crack driving force for steels 1.7147 and 1.4762

Vukelić

Brnić

2017

jtam

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“…Consequently, an initially blunted crack is modelled with a notch tip radius (r 0 ) of 2.5 µm. This radius can be assumed to represent an infinitely sharp crack [10,11]. Furthermore, the outer radius is 10 6 times the notch tip radius, which is in good correspondence with reported MBL models [10,12,13].…”

Section: Finite Element Model a Parametric Pythonsupporting

confidence: 68%

“…This radius can be assumed to represent an infinitely sharp crack [10,11]. Furthermore, the outer radius is 10 6 times the notch tip radius, which is in good correspondence with reported MBL models [10,12,13]. This large outer radius prevents the interaction of plasticity effects with the applied linear elastic boundary conditions.…”

Section: Finite Element Model a Parametric Pythonsupporting

confidence: 60%

Development and validation of a high constraint modified boundary layer finite element model

Verstraete¹,

Waele²,

Hertelé³

2011

IJSMED

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When a notched structure is loaded, its behaviour is not only affected by the material propertiesbut also by the geometry (of both the structure and the defect) and loading condition, alternatively termedas constraint condition. Therefore, the relation between the failure behaviour of a small scale fracturemechanics test and a full scale structure needs to be elucidated.In an attempt to understand and describe such relationships, the crack tip stress fields are analysed bymeans of finite element simulations and compared for several test specimen geometries. A reference forcomparison is the crack tip stress field obtained from a high constraint reference geometry, further called amodified boundary layer model.First, this article provides some theoretical background on the modified boundary layer model. Second, thedevelopment of a 2D model is outlined in detail, focussing on the mesh design in the vicinity of the crack tipand the applied boundary conditions. Afterwards, an analytical and numerical validation is provided, basedon the level of the applied load and, on the other hand, on the magnitude of the crack tip stress fields.Finally, this validated model is used for the comparison of several constraint parameters. This comparisonindicates a weak influence of the T-stress on the Q-parameter for positive T-stresses. In contrast, negativeT-stresses result in more pronounced negative Q-values.

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“…In elastic–plastic fracture mechanics, the Q ‐stress is commonly used as the measure of in‐plane constraint 36 . The Q ‐stress is the difference between the opening stress ahead of the crack tip obtained for example from FE analysis and the opening stress calculated by the Hutchinson Rice Rosenberg (HRR) formula 37,38 for the same value of the J ‐integral.…”

Section: Measures Of Constraintmentioning

confidence: 99%

Reduction of measured toughness due to out‐of‐plane constraint in ductile fracture of aluminium alloy specimens

Mostafavi

Smith

Pavier

2010

Fatigue Fract Eng Mat Struct

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A B S T R A C T It is generally believed that a lower bound on the fracture toughness of a material is obtained from a standard test, particularly in metals where yielding occurs prior to fracture. The understanding is that in such a test the material around the crack tip is highly constrained hence reducing the extent of yielding. In this paper, we report the results of fracture tests where a tensile load is applied to a biaxial aluminium alloy specimen in the direction parallel to the crack front in addition to the fracturing load normal to the crack surface. We show that in this case a lower fracture toughness is measured than that obtained from a standard test. Indeed, for the highest value of tensile load used in our tests the J-integral at fracture was half the value measured in a standard test. It is also shown that the volume of the plastic region can be used to measure the effect of constraint, irrespective of the manner in which the constraint arises. This approach suggests an even lower fracture toughness may be obtained than that measured here in certain loading conditions. a = crack length A = area of the plastic region A c = area of the plastic region at fracture A ref = area of the plastic region at fracture measured in a standard test A 2 = parameter quantifying second and third term of stress relative to the first term in a cracked elastic-plastic body B = biaxiality ratio (dimensionless T-stress) E = elastic modulus F c = corrected fracture load F c = fracture load F T = transverse load (side load)i = the number of tested specimen J = J-integral J c = J-integral at fracture J ref = J-integral at fracture measured in a standard test K I = mode I stress-intensity factors K Ic = mode I fracture toughness measured from a standard test N = total number of specimens tested P f = fracture probability Q = parameter quantifying the deviation of opening stress in a non-standard specimen from a standard specimen Correspondence: M. J. Pavier.

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A two-parameter framework to describe effects of constraint loss on cleavage fracture and implications for failure assessments of cracked components

Cited by 19 publications

References 21 publications

Numerically predicted J-integral as a measure of crack driving force for steels 1.7147 and 1.4762

Numerically predicted J-integral as a measure of crack driving force for steels 1.7147 and 1.4762

Development and validation of a high constraint modified boundary layer finite element model

Reduction of measured toughness due to out‐of‐plane constraint in ductile fracture of aluminium alloy specimens

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