Significance and Use
5.1 Summary:
5.1.1 Residual stresses are present in almost all materials. They can be created during the manufacture or during the life of the material. Residual stresses can be a major factor in the failure of a material, particularly one subjected to alternating service loads or corrosive environments. Residual stress may also be beneficial, for example, the compressive stresses produced by shot peening. The hole-drilling strain-gage technique is a practical general-purpose method for determining residual stresses.
Scope
1.1 Residual Stress Determination:
1.1.1 This test method specifies a hole-drilling procedure for determining in-plane residual stresses near the surface of an isotropic linearly elastic material. It is applicable to residual stress determinations where the stresses do not vary significantly across the diameter of the drilled hole. The measured stresses are the in-plane residual stresses that exist within the depth of the drilled hole. Stress sensitivity rapidly decreases with depth from the measured surface and deep interior stresses cannot be evaluated. The measured residual stresses are described as “uniform” if they remain approximately constant within the hole depth, “non-unifom” if they vary significantly.
1.1.2 In general, “blind” holes are used, where the depth of the drilled hole and therefore the depth of the residual stress evaluation is less than the workpiece thickness. However, for a thin workpiece, it is also possible to do through-thickness measurements of uniform (membrane) stresses using a through-hole.
1.2 Stress Measurement Range:
1.2.1 This test method applies in cases where material behavior is linear-elastic. When near-yeild residual stresses are present, it is possible for local yielding to occur due to the stress concentration around the drilled hole. Satisfactory measurement results can be achieved providing the residual stresses do not exceed about 80 % of the material yield stress for blind-hole drilling and about 50 % of the material yield stress for through-hole drilling.
1.3 Workpiece Damage:
1.3.1 The hole-drilling method is often described as “semi-destructive” because the damage that it causes is localized and often does not significantly affect the usefulness of the workpiece. In contrast, most other mechanical methods for measuring residual stresses substantially destroy the workpiece. Since hole drilling does cause some damage, this test method should be applied only in those cases either where the workpiece is expendable, or where the introduction of a small shallow hole will not significantly affect the usefulness of the workpiece.
1.4 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.
1.5 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.
