**5. The main sources of errors and limits of applicability in the hole drilling method**

The hole-drilling method has some typical sources of error that can influence the accuracy of the measurements. The ASTM E837 standard identifies the maximum values of these errors for the validity of the test (limits of applicability) without providing recommendations on how to correct them, as reported in **Table 2**.

Some of these errors, for example, eccentricity and hole bottom chamfer, can be generated by external sources such as the operator, testing condition or the drilling process. In other cases, the limits of applicability are directly connected with the test method, as in the case of intermediate thickness of the specimen or the local plasticity effect.

**Table 2** also shows the bibliographic sources dealing with possible methods of error correction. The cases of uniform and non-uniform stress distribution are analyzed. In the case of uniform stress distribution, both the thin workpiece and the thick workpiece are considered.


The following sections examine the errors mentioned above in more detail and consider possible corrections.

#### **Table 2.**

*Typical sources of errors, ASTM E837 limit of applicability and current state-of-the-art of correction methodologies.*

*Recent Advancements in the Hole-Drilling Strain-Gage Method for Determining Residual Stresses DOI: http://dx.doi.org/10.5772/intechopen.90392*
