Effect of elasto-plastic material behaviour on determination of residual stress profiles using the hole drilling method

Abstract

The hole drilling method is a well-known technique for the determination of non-uniform residual stress profiles by measuring relaxation distortions caused by the presence of the hole. The integral method, an inverse calculation technique on which the hole drilling method is based, assumes linear elastic material behaviour and is therefore limited to the measurement of residual stresses below 60% of the yield strength. The aim of this study is to investigate the effects of elastic-plastic material behaviour on the determined non-uniform residual stress profile when the residual stresses exceed the given 60% limit. To this end, compressive residual stress profiles, as they are typically induced by laser shock peening, are investigated using finite element simulations followed by an analysis with the integral method. The obtained results from the analysis are compared to the applied residual stress profiles. An evaluation of the deviation between these two profiles provides detailed insight into the expected error as a function of hole drilling depth and the ratio of residual stress magnitude to yield strength. As an additional benefit of the presented approach, it also provides an indication of the range of depth at which the non-uniform residual stress profile should be corrected to reduce measurement error.

Effects of laser shock peening on the microstructure and fatigue crack propagation behaviour of thin AA2024 specimens

“…This residual stress state can be caused by the rolling process of the sheet material. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 overestimates the residual stress values when they are close to the yield strength of the material, as investigated by Chupakhin et al (2015) [2], the actual residual stress values should be lower. Nevertheless, the hole drilling technique provides a useable qualitative result.…”

Fatigue Life Extension of AA2024 Specimens and Integral Structures by Laser Shock Peening

“…500 MPa are significantly higher than the yield strength of the material investigated (370 MPa). As the used hole drilling technique overestimates residual stress values close or above the yield strength of the material, as investigated in [13], the real residual stress values should be lower. In case of equibiaxial residual stress profiles a correction methodology based on artificial neural network can be applied [14].…”

A procedure for high residual stresses measurement using the ring‐core method

“…Beghini et al, with consideration to the local plasticity induced by the introduction of the hole, showed plasticity‐induced errors of around 40% and proposed a procedure to take into account its effects on the residual stress evaluation. Lately, Chupakhin et al showed significant overestimated plasticity‐induced errors in the case where the residual stresses exceeded from 60% of the yield strength. They also provided an indication of the range of depth, at which the residual stress profile should be corrected.…”

“…Thus, in view of this, an incremental milling of a circular groove on a stressed plate was simulated using the killing element technique. Residual stresses were simulated by applying mechanical uniform preloading on a plate before the ring‐core milling, as in the past researches on the hole‐drilling and ring‐core techniques . Strain due to preloading and ring milling was sensed by the three resistance strain gauges located in the principal directions on the specimen.…”

“…Residual stresses were simulated by applying mechanical uniform preloading on a plate before the ring-core milling, as in the past researches on the hole-drilling and ring-core techniques. [10][11][12][13][14][15][16] Strain due to preloading and ring milling was sensed by the three resistance strain gauges located in the principal directions on the specimen. For the actual strain results, the FEM strain gauge responses were evaluated by averaging the strains in all the nodes locating in each of the strain gauge area.…”