ASTM E837 test method defines a standard to determine the usefulness of a workpiece by measuring residual stress through the hole-drilling strain-gage method. It helps in the design process, choosing failure risks, corrosion possibilities, and service loads. It contributes to the reliability and acceptance of material by calculating its residual stress through residual strain. The examination of the hole depth also determines the toughness and thickness of the material.
A work piece is taken for its flat surface area where the holes are drilled to measure the residual stress. The choice of workpiece depends upon the hole and strain gage circle diameter. The depths of the holes are determined, and the variation in pressure concerning the depth direction is studied. A strain gage rosette is attached to the workpiece, and a hole is drilled at its geometric center. The relieved strain values are determined, which contribute to the calculation of residual stress. The residual stress should not exceed the 80% yield stress for hole drilling in thick material and 50% yield stress in thin material.
Specimen size should be as per the requirements. In this case, it is ±1 µm, and its resistance to ground should be at least 20,000 MΩ.
The residual stresses within each hole depth are calculated using the strain calculations data where p, q, and t are the combination strains. A matrix equation needs to be solved for this purpose.