The hole drilling method is a mechanical technique that can determine residual stresses as a function of depth. Hole drilling involves introducing a small hole at the center of a specially designed strain gage and measuring the resulting strain relaxation. Residual stress is determined from the relaxed strain and calibration coefficients for each specific strain gage geometry and hole size. Hole drilling is conducted per the ASTM E837 specification.
The Center Hole Drilling Method:
- On-site determination of subsurface principal residual stress in components that are not readily measured using x-ray diffraction.
- Measurements are made per ASTM specification E837.
- Measurements can be made in all types of metals and non-metals. A polycrystalline material is not necessary for the hole drilling method.
- Offers high spatial resolution
How does the hole drilling process work?
The hole drilling method relies on stress relaxation when a hole is drilled into the center of a rosette strain gage. When the material is removed by drilling, the extent of the strain relief is monitored by the gages and the direction and magnitude of the principal stresses can be calculated.
The accuracy of the hole drilling method is directly related to the ability of locating the hole accurately in the center of the rosette. Lambda employs the use of specially designed fixturing and precision optics with high magnification to ensure the proper location of the hole.
To discuss your residual stress measurement needs, just contact us by phone at (800) 883-0851 or by email here.