Assessment of residual stresses and mechanical characterization of materials by "hole drilling" and indentation tests combined and by inverse analysis

Hole Drilling (HD) tests are frequently employed as “quasi-non-destructive” experiments, for assessments of residual stresses in metallic components of power plants and of other industrial structures. With respect to the present broadly standardized HD method, the following methodological developments are proposed and computationally validated in this paper: assessments of elastic and plastic parameters by indentation exploiting the hole generated by HD tests; employment of “Digital Image Correlation” (DIC) for full-field displacement measurements, instead of the strain measurements by gauge “rosettes” usually adopted so far; transitions from experimental data to sought parameters by inverse analyses based on computer simulations of both tests and on minimizations of a “discrepancy function”. Interactions between the two experiments are here investigated, besides the elastic parameters transition from indentation (IND) to HD test interpretation. The main advantage achievable by the procedure proposed herein is reduction of additional “damage” and cost due to usual experimental procedures for diagnosis of structural components (e.g. frequently adopted “small punch” experiments or laboratory tension tests).