Specimen size effects on the determination of KIc-values in the range of elastic-plastic material behavior
✍ Scribed by W. Seidl
- Publisher
- Elsevier Science
- Year
- 1979
- Tongue
- English
- Weight
- 1000 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0013-7944
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✦ Synopsis
A new fracture mechanics evaluation method, (method of specific potential energy) is introduced, which enables one to predict the fracture load of large specimens in the range of elastic-plastic material behavior. This method is discussed using test results obtained from CT-specimens of the steels 22 Ni MO Cr 37 and A 533 BI. Also, fracture mechanics data published in the literature were evaluated using the above method. These measurements had been performed on several titanium and aluminum alloys using CT-specimens, SENB-specimens, and CCT-specimens. In all cases a relation between the potential energy at the point of fracture and the net cross sectional area is found. The analytical form of this relation permits the derivation of relationships for evaluating maximum stress intensity factors or fracture loads for arbitrary specimen sizes. The results show that a maximum stress intensity factor can be derived which is dependent on the specimen dimensions. This method is recommended in the case of elastic-plastic material behavior for the evaluation of critical stress intensity factors K,,, which fulfils the requirements of ASTM E 3%74; moreover, the method seems to be useful for the evaluation of fracture loads of thin-walled sheets containing cracks.
NOTATION
crack length, mm specimen thickness, mm required minimum thickness to performe valid K,,-test, mm constant constant deflection (SENB-specimen), mm modulus of elasticity, Nrn-' net cross-sectional area, mm' correction factor critical stress intensity factor, Nnun"' maximum stress intensity factor at fracture. Nmm-"'r specimen length, mm load, N fracture load or maximum load, N constant ultimate tensile strength, Nmm-' tensile yield strength, Nmm-* elastic or potential energy at fracture, Nmm load point displacement, mm v, at fracture or maximum load, mm v, when specimen unloaded after deformation, mm geometric correction function critical nominal stress. Nmme2