Work Item
ASTM WK83266
Revision of E1820-21 Standard Test Method for Measurement of Fracture Toughness
Rationale
Justification: “Crack extension” is used extensively in E647, but it is not defined. The definition will be added to E647. E2472 defines the term but E1823 does not include the E2472 discussion. The discussion will be added to E1823 referencing E2472. If the term is defined in a standard, E1823 needs to reference that standard so E647, E1820 and E2472 will be added to E1823. E561 no longer defines this term so the reference will be removed. E1823 discussion specific to E561 will remove the E561 reference. This ballot is to change E1823 and E647. The other standards identified are shown for reference. These changes have been coordinated with E08.06.01, E08.07.05, and E08.07.07.
E1823
crack extension, ?a [L]—an increase in crack size. E561, E647, E1820, E2472
DISCUSSION—For example, in Practice E561, ?ap or ?ae is the difference between the crack size, either ap (physical crack size) or ae (effective crack size), and ao (original crack size).
DISCUSSION— In E2472, it should be noted that in thin-sheet and thick-plate materials under low constraint conditions, the crack extension observed on the surface of the specimen may be significantly less than that in the interior of the specimen due to the effects of crack tunneling. This must be considered if direct optical techniques are used to monitor and measure free-surface crack extension. Indirect crack extension measurement techniques such as unloading compliance and electric potential drop method may be used in place of (or to complement)
the direct optical techniques to provide a measure of average crack extension. (See Test Method E647 for compliance methods for C(T) and M(T) specimens; and ISO 12135 and Test Method E647 for electric potential-drop methods for C(T) specimens.)
Work Item Status
Date Initiated: 08-26-2022
Technical Contact: Charlotte Belsick
Item: 011
Ballot: E08 (22-03)
Status: Negative Votes Need Resolution