Repeatability of Incremental Hole Drilling and Slitting Method Residual Stress Measurements

Author(s):  
Adrian T. DeWald ◽  
Michael R. Hill
2013 ◽  
Vol 772 ◽  
pp. 167-172 ◽  
Author(s):  
M. Burak Toparli ◽  
Michael E. Fitzpatrick

Residual stress measurements are very challenging in thin aluminium plates. Rolling-induced crystallographic texture can lead to an S-shape fit when using the sin2ψ method for surface X-ray diffraction. Peak broadening and missing peaks can also be observed for synchrotron X-ray diffraction with conventional θ/2θ scanning due to texture. In addition, when measuring near the plate surfaces, partially-filled gauge volumes in diffraction experiments will lead to “pseudo-strains”, an apparent shift between measured and actual positions for the diffraction peak. Obtaining a meaningful value of d0 for strain calculations is another issue for diffraction experiments in thin plates. The low thickness also offers challenges for destructive methods including incremental hole drilling, i.e. there is no defined ASTM standard for measuring non-uniform residual stress profile for thin plates. In this work, 2-mm-thick Al2024-T351 plate was investigated for residual stress fields due to laser peening. Neutron diffraction measurements were carried out at POLDI (Pulse Overlap time-of-flight Diffractometer) in PSI, Switzerland and the results are compared with incremental hole drilling.


2014 ◽  
Vol 996 ◽  
pp. 283-288 ◽  
Author(s):  
Esther Held ◽  
Simone Schuster ◽  
Jens Gibmeier

The incremental hole-drilling method is a widely used technique to determine residual stress depth profiles in technical components. Its application is limited in respect to the components geometry, for instance the components thickness. In this paper, a direct correction of the measured strain relaxations is proposed to consider the impact of deviant geometries, here the component thickness, on the residual stress evaluation that moreover, allows the application of commercially available evaluation software. The herein proposed approach is based on finite element simulation of the incremental hole drilling. The simulated strain relaxations for thin metal sheets are evaluated with an algorithm as used in commercially available evaluation software (i) for uncorrected data as well as (ii) for strain data corrected by the proposed correction procedure. It is shown that the correction approach leads to a significant improvement of the measurement accuracy. Further, by means of the approach residual stress depth profiles in thin metal sheets can be as usual determined using commercial evaluation software for the incremental hole-drilling method regardless of the algorithm used, i.e. differential or integral.


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