Journal Published Online: 24 January 2024
Volume 13, Issue 2

Analysis of ASTM E647 Compliance Equation for the M(T) Specimen



The existing compliance equations in ASTM E647-23a, Standard Test Method for Measurement of Fatigue Crack Growth Rates, for the M(T) specimen include coefficients for (i) a long specimen with L/W = 2 to approximate pure uniform stress loading, and (ii) a much shorter specimen with L/W = 0.72 that has rigid grips for uniform displacement. The standard does not provide guidance for what compliance coefficients should be used with intermediate length specimens using rigid grips. This article uses as its starting point the original ASTM Committee E24 research report that presented the compliance equation as a function of gauge length and crack length. An analysis shows that the compliance equation could underestimate crack length by nearly 10 % for certain combinations of crack length and gauge length, especially short crack lengths and large gauge lengths. This article investigates the relationships for the normalized specimen length and existing coefficients for intermediate values 0.72 < L/W < 2 to provide guidance to practitioners that may observe inaccuracies in the current compliance solution.

Author Information

James, Mark A.
Howmet Aerospace, New Product Introduction, Cleveland, OH, USA
Fulton, Erin
Icon Information Consultants LP, Houston, TX, USA
Maciejewski, Kimberly
Arconic Technology Center, Aerospace and Extrusions, New Kensington, PA, USA
Pages: 11
Price: $25.00
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Stock #: MPC20230089
ISSN: 2379-1365
DOI: 10.1520/MPC20230089