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Standard Test Method for KR Curve Determination (Includes all amendments And changes 7/31/2019).
Automatische name übersetzung:
Standard Test Method for Curve KR Bestimmung
NORM herausgegeben am 1.12.2015
Bezeichnung normen: ASTM E561-15a
Anmerkung: UNGÜLTIG
Ausgabedatum normen: 1.12.2015
SKU: NS-623626
Zahl der Seiten: 16
Gewicht ca.: 48 g (0.11 Pfund)
Land: Amerikanische technische Norm
Kategorie: Technische Normen ASTM
Keywords:
effective crack extension, fracture mechanics, fracture resistance, fracture toughness, KR , KR curve, linear elastic, plane stress, plastic zone, standard test method, stress intensity factor,, ICS Number Code 77.040.10 (Mechanical testing of metals)
Significance and Use | ||||||||
5.1 The KR curve characterizes the resistance to fracture of materials during slow, stable crack extension and results from the growth of the plastic zone ahead of the crack as it extends from a fatigue precrack or sharp notch. It provides a record of the toughness development as a crack is driven stably under increasing applied stress intensity factor 5.2 For an untested geometry, the 5.2.1 To predict crack behavior and instability in a component, a family of crack driving curves is generated by calculating K as a function of crack size for the component using a series of force, displacement, or combined loading conditions. The KR curve may be superimposed on the family of crack driving curves as shown in Fig. 1, with the origin of the 5.2.2 Conversely, the KR curve can be shifted left or right in Fig. 1 to bring it into tangency with a crack driving curve to determine the initial crack size that would cause crack instability under that loading condition. 5.3 If the K-gradient (slope of the crack driving curve) of the specimen chosen to develop the KR curve has negative characteristics (see Note 1), as in a displacement-controlled test condition, it may be possible to drive the crack until a maximum or plateau toughness level is reached Note 1: Fixed displacement in crack-line-loaded specimens results in a decrease of K with crack extension. Note 2: With force control, K usually increases with crack extension,
and instability will occur at maximum force.
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1. Scope | ||||||||
1.1 This test method covers the determination of the resistance to fracture of metallic materials under Mode I loading at static rates using either of the following notched and precracked specimens: the middle-cracked tension M(T) specimen or the compact tension C(T) specimen. A 1.2 Materials that can be tested for 1.3 Specimens of standard proportions are required, but size is variable, to be adjusted for yield strength and toughness of the materials. 1.4 Only two of the many possible specimen types that could be used to develop KR curves are covered in this method. 1.5 The test is applicable to conditions where a material exhibits slow, stable crack extension under increasing crack driving force, which may exist in relatively tough materials under plane stress crack tip conditions. 1.6 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. |
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2. Referenced Documents | ||||||||
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