Rationale

E08.02 is working to update the definition for “specimen width, W” in ASTM E1823. ASTM E561 uses specimen width, W for a C(T) specimen geometry and a M(T) specimen geometry and subsequent equations. ASTM E561 has Fig. 8 with a recommended C(T) specimen geometry, where W is defined within the figure. However, there is no figure for an M(T) specimen geometry within this standard. There is a separate work item (WK88301) to add a recommended M(T) specimen drawing to ASTM E561 and explicitly define W within this figure. This figure could have two potential drawings, one for specimens using single-pin grip and one for specimens using multiple-bolt grips or wedge grips. During the May 2024 task group meeting, the history of ASTM E561 for the use of Single Pin Grips, Multiple-Bolt or Wedge Grips in terms of the specimen width and free length (distance between loading pin holes, distance between inner most gripping points) was reviewed. There was discussion around modifying the Single Pin Grips for W = 305 mm (12 in.) to W = 75 mm (3 in.), similar to ASTM E647 Fig. A2.1. There were concerns raised that there should be some investigation to ensure the free length (distance between loading pin holes, distance between inner most gripping points) requirements of 1.5W for Single-Pin Grips and 3W for Multiple-Bolt or Wedge Grips were ensuring a uniform stress state at the crack tip before changing the width limit for the Single-Pin Grips. There was also discussion and consensus to ballot to remove the Single Pin Grips option from E561, since the industry practice is to use Multiple-Bolt or Wedge Grips. This work item is to remove the single-pin grip option in ASTM E561.