On the transferability of fracture mechanics parameters from specimens to structures using fem

Brocks, W.; Künecke, Georgia; Noack, H.-D.; Veith, H.

doi:10.1016/0029-5493(89)90140-4

Cited by 37 publications

(10 citation statements)

References 6 publications

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“…The grown crack has a shape close to a semi-ellipse, quite similar to the original notch, though the crack growth is greater at the deepest point. This conflicts with earlier observations that the semi-elliptical crack growth tends to form a canoe-shape [5].…”

Section: Methodscontrasting

confidence: 99%

Using 3D Digital Image Correlation (3D-DIC) to Measure CTOD in a Semi-Elliptical Surface Crack

Samadian

Hertelé

Waele

2018

The 18th International Conference on Experimental Mechanics

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The subsurface nature of Crack Tip Opening Displacement (CTOD) makes its direct measurement very difficult, if not impossible. During fracture toughness testing, CTOD is commonly calculated by applying a plastic hinge model using externally applied clip gauges. However, clip gauge CTOD calculations merely provide information relating to the center of the defect (which is typically the most critical point, but not always). For the case of a finite-length surface defect, CTOD will be variable over the defect front. Exact knowledge of CTOD over the entire front is useful for detailed calculations, such as crack profile evolution due to ductile tearing or calculations involving interacting defects. To experimentally measure the CTOD at locations other than the center of the crack, the authors propose a technique based on full field threedimensional profile measurement of the notched surface by means of stereoscopic Digital Image Correlation (3D-DIC). The method is based on the plastic hinge model assuming that the crack flanks rotate in a rigid manner around a plastic hinge point in the un-cracked ligament. Having measured full-field out-of-plane displacement at the surface of the specimen around the crack using the 3D-DIC method, CTOD can be inferred over the entire crack front. Results show that, due to the acceptable agreement between the DIC based calculation and CTOD measured from cast replicas, the proposed technique has a sufficient accuracy to measure CTOD on the entire crack front in plastically deforming specimens.

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Section: Methodscontrasting

confidence: 99%

Using 3D Digital Image Correlation (3D-DIC) to Measure CTOD in a Semi-Elliptical Surface Crack

Samadian

Hertelé

Waele

2018

The 18th International Conference on Experimental Mechanics

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“…For the dw=0.3 crack, the amount of crack growth along the crack front is almost constant except point A. A significant "canoeing" effect [13,14] can be seen for the a/w=0.7 crack. The "canoeing" becomes less significant in the a/w=0.5 crack.…”

Section: Crack Growth -Surface Cracksmentioning

confidence: 80%

“…For surface cracks, the "canoeing" behaviour [13,14] has been predicted for both the a/w=0.5 and 0.7 cracks, especially when the total amount of crack growth is small. In general, the crack growth behaviour of the surface cracks depends on crack size.…”

Section: Discussion and Concluding Remarksmentioning

confidence: 99%

Ductile Damage and Constraint in Components with Embedded and Surface Semi-Circular Cracks

Zhang

Skallerud

1996

J. Phys. IV France

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Abstract. Semi-elliptical surface cracks are among the most common defects in welded components subject to fatigue loading. Embedded cracks are also an important type of defects to be considered in welded structures. Control of the static capacity of structures with such defects is important in order to determine load levels corresponding to crack growth initiation and tearing. In the present investigation, the Gurson model based approach has been applied in studying the ductile crack initiation and constraint effect in tension components with semi-circular surface cracks and embedded circular cracks. 3D models of 3 different crack sizes but with exactly the same crack tip element arrangement have been analyzed using the micromechanical parameters established in an earlier study. The results show that for a relatively large embedded crack, the initiation of crack growth will start at the point with the smallest ligament, however, the largest amount of crack growth will occur at the point with the largest ligament. The initiation and growth of surface cracks are rather consistent, with a distinct "canoeing" effect. The influence of crack size and growth on the ductile fracture behaviour is explained by means of constraint.

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“…Therefore, they do not cover problems with loss of constraint and hence deformation in the thickness direction. Detailed information on determining constraint parameters and their role in fracture can be obtained in Refs [ 12–17].…”

Section: Crack Growth Resistancementioning

confidence: 99%

R‐CURVE TESTING AND ITS RELEVANCE TO STRUCTURAL ASSESSMENT

Schwalbe

Heerens

1998

Fatigue Fract Eng Mat Struct

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Crack growth resistance can be substantially affected by the constraint conditions of a structural member which in turn are mainly a function of geometrical variables and the degree of plasticity. Standardized test methods are restricted to high constraint conditions as represented by deeply cracked bend‐type specimens and may hence lead to conservative structural assessments. It is demonstrated that adjusted testing can be used to reduce the degree of conservatism. Due to rapidly increasing computer capabilities, a combination of conventional R‐curve testing with micromechanical models emerges as an accurate tool which may permit routine evaluations of practical situations in the near future.

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On the transferability of fracture mechanics parameters from specimens to structures using fem

Cited by 37 publications

References 6 publications

Using 3D Digital Image Correlation (3D-DIC) to Measure CTOD in a Semi-Elliptical Surface Crack

Using 3D Digital Image Correlation (3D-DIC) to Measure CTOD in a Semi-Elliptical Surface Crack

Ductile Damage and Constraint in Components with Embedded and Surface Semi-Circular Cracks

R‐CURVE TESTING AND ITS RELEVANCE TO STRUCTURAL ASSESSMENT

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