Stress Concentration Factors for ASTM E8/E8M-16a Standard Round Specimens for Tension Testing

Occasionally, round specimens for tension testing that comply with ASTM standards fail in one of the transition regions between gage and grip sections. This occurs because of the stress concentration present in transition regions. When this happens, it is possible to seek stress relief by increasing fillet radii in these regions. The objective of this note is to quantify the relief afforded by increasing radii. The approach adopted to this end is finite element analysis that is carefully verified. Stress concentration factors are thus accurately determined to three figures for all of the various types of standard round specimens in ASTM E8/E8M-16a, Standard Test Methods for Tension Testing of Metallic Materials.