Residual Stress Measurement by the Hole-Drilling Method Residual Stress Measurement by the Hole-Drilling Method | HBM

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Integral Method

This method, proposed by G. S. Schajer, provides a separate residual stress analysis at every hole-drilling depth increment. In this method, the contributions to the total measured strain relaxations of the stresses at all depths are considered simultaneously giving a higher spatial resolution than the other methods.

To simplify the problem of residual stress evaluation, Schajer proposed that the stress field could be described by means of step-wise functions whose value is constant through the partial hole depths. Using this hypothesis, Schajer established the numerical coefficients that are used for the calculation. The maximum depth that the method can be used for is 0.5 times the mean radius of the strain rosette used for the test.

The integral method should be chosen when residual stresses are expected to vary significantly with depth; however, it also has the highest sensitivity to test errors.

Flyer Residual Stress Measurements