ASTM E837 Determining Residual Stresses by the Hole Drilling Strain-Gage Method

Scope:

ASTM E837 test method defines a standard to determine the usefulness of a workpiece by measuring the 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 the material by calculating its residual stress through residual strain. The examination of the hole depth also determines the toughness and thickness of the material.

Procedure:

In ASTM E837, a workpiece is taken on 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 materials and 50% yield stress in thin materials.

Specimen size

In ASTM E837 testing, the 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. 

Data:

The residual stresses within each hole depth are calculated for ASTM E837 using the strain calculations data where p, q, and t are the combination strains. A matrix equation needs to be solved for this purpose.

Conclusion:

ASTM E837 test method defines a standard to determine the usefulness of a workpiece by measuring the residual stress through the hole-drilling strain-gage method.