Wir benötigen Ihre Einwilligung zur Verwendung der einzelnen Daten, damit Sie unter anderem Informationen zu Ihren Interessen einsehen können. Klicken Sie auf "OK", um Ihre Zustimmung zu erteilen.
Standard Practice for Size Scaling of Tensile Strengths Using Weibull Statistics for Advanced Ceramics
Name übersetzen
NORM herausgegeben am 1.7.2019
Bezeichnung normen: ASTM C1683-10(2019)
Anmerkung: UNGÜLTIG
Ausgabedatum normen: 1.7.2019
SKU: NS-953877
Zahl der Seiten: 18
Gewicht ca.: 54 g (0.12 Pfund)
Land: Amerikanische technische Norm
Kategorie: Technische Normen ASTM
Keywords:
advanced ceramics, censored data, effective area, effective volume, fractography, fracture origin, size scaling, strength, Weibull characteristic strength, Weibull modulus, Weibull scale parameter, Weibull statistics,, ICS Number Code 81.060.30 (Advanced ceramics)
Significance and Use | ||||||||||||||||||||||
5.1 Advanced ceramics usually display a linear stress-strain behavior to failure. Lack of ductility combined with flaws that have various sizes and orientations typically leads to large scatter in failure strength. Strength is not a deterministic property, but instead reflects the intrinsic fracture toughness and a distribution (size and orientation) of flaws present in the material. This standard is applicable to brittle monolithic ceramics which fail as a result of catastrophic propagation of flaws. Possible rising R-curve effects are also not considered, but are inherently incorporated into the strength measurements. 5.2 Two- and three-parameter formulations exist for the Weibull distribution. This standard is restricted to the two-parameter formulation. 5.3 Tensile and flexural test specimens are the most commonly used test configurations for advanced ceramics. Ring-on-ring and pressure-on-ring test specimens which have multi-axial states of stress are also included. Closed-form solutions for the effective volume and effective surfaces and the Weibull material scale factor are included for these configurations. This practice also incorporates size-scaling methods for C-ring test specimens for which numerical approaches are necessary. A generic approach for arbitrary shaped test specimens or components that utilizes finite element analyses is presented in Annex A3. 5.4 The fracture origins of failed test specimens can be determined using fractographic analysis. The spatial distribution of these strength-controlling flaws can be over a volume or an area (as in the case of surface flaws). This standard allows for the conversion of strength parameters associated with either type of spatial distribution. Length scaling for strength-controlling flaws located along edges of a test specimen is not covered in this practice. 5.5 The scaling of strength with size in accordance with the Weibull model is based on several key assumptions 5.6 Even if test data has been accurately and precisely measured, it should be recognized that the Weibull parameters determined from test data are in fact estimates. The estimates can vary from the actual (population) material strength parameters. Consult Practice C1239 for further guidance on the confidence bounds of Weibull parameter estimates based on test data for a finite sample size of test fractures. 5.7 When correlating strength parameters from test data from one specimen geometry to a second, the accuracy of the correlation depends upon whether the assumptions listed in 5.5 are met. In addition, statistical sampling effects as discussed in 5.6 may also contribute to variations between computed and observed strength-size scaling trends. 5.8 There are practical limits to Weibull strength scaling that should be considered. For example, it is implicitly assumed in the Weibull model that flaws are small relative to the specimen size. Pores that are 50 μm (0.050 mm) in diameter are volume-distributed flaws in tension or flexural strength specimens with 5 mm or greater cross section sizes. The same may not be true if the cross section size is only 100 μm. |
||||||||||||||||||||||
1. Scope | ||||||||||||||||||||||
1.1 This standard practice provides methodology to convert fracture strength parameters (primarily the mean strength and the Weibull characteristic strength) estimated from data obtained with one test geometry to strength parameters representing other test geometries. This practice addresses uniaxial strength data as well as some biaxial strength data. It may also be used for more complex geometries proved that the effective areas and effective volumes can be estimated. It is for the evaluation of Weibull probability distribution parameters for advanced ceramics that fail in a brittle fashion. Fig. 1 shows the typical variation of strength with size. The larger the specimen or component, the weaker it is likely to be. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5.1 The values stated in SI units are in accordance with IEEE/ASTM SI 10. 1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. |
||||||||||||||||||||||
2. Referenced Documents | ||||||||||||||||||||||
|
Bereitstellung von aktuellen Informationen über legislative Vorschriften in der Sammlung der Gesetze bis zum Jahr 1945.
Aktualisierung 2x pro Monat!
Brauchen Sie mehr Informationen? Sehen Sie sich diese Seite an.
Letzte Aktualisierung: 2024-12-23 (Zahl der Positionen: 2 217 157)
© Copyright 2024 NORMSERVIS s.r.o.