Hole-drilling technique: Modifications in the analysis of residual stresses

Conclusions

It is known that the hole-drilling technique to determine the surface residual stresses is a very useful tool. It has been shown in this work that without having found the correct angle γ, the values of stresses obtained were such that ε_max was less than ε_min for some strain relaxations. This point was not considered in the previous work. The present work points out this anomaly, gives a set of equations for a rosette of general configuration, reduces these equations for a rectangular rosette and gives a method to yield correct principal stresses and their directions. It is thus concluded here that the determination of the correct angle γ is very necessary to evaluate the stresses correctly; without doing so, the results are suspect and, thus, are of no use.

It must be mentioned here that the method of determining the correct angle as described in this article is useful not only in the hole-drilling technique but also in any analysis where the angle is to be computed by taking the inverse of a trigonometric function. This method has been used by the author in the determination of the directions of the resultant bearing loads in a crankshaft.