🔧 Researchers from the Laboratory of Hierarchically Structured Materials at Skoltech have developed an approach based on rational experimental-computational correlation (RECC) that makes residual stress estimation more stable against measurement noise. With an experimental error of up to 10 percent, the error in stress determination was reduced from 40 to 6 MPa. The results are published in Measurement. Residual stress arises after manufacturing, processing, or loading and affects durability, fatigue resistance, and crack propagation — especially near fastener holes in aviation and transport structures. One way to determine its distribution is the contour method: a specimen is cut, displacements on the cut surface are measured, and the stress field is reconstructed numerically. Because it solves an inverse problem, even small errors in the initial data can be amplified. What did the results show? 🔹 For a noise level of 10%, the reconstruction error was about 40 megapascals for aluminum alloy 2024-T4. 🔹 The Sur-RECC approach describes the displacement profile with a smooth analytical function — a Gaussian curve with a quadratic background — suppressing high-frequency deviations and reducing the effective error to approximately 5–6 MPa. "Traditionally, the accuracy of experimental data in the contour method is accepted as sufficient based on comparison with other approaches (for example, diffraction-based), but the stability and reliability of the solution are rarely assessed quantitatively. We created an experimental-computational scheme that allows us to quantitatively trace how the error in displacement measurement affects the determination of stress fields. For the representative noise level of 10% that we selected, the reconstruction error was about 40 megapascals for aluminum alloy 2024-T4. The proposed approach (Sur-RECC) describes the displacement profile with a smooth analytical function — a Gaussian curve with a quadratic background. This allows suppressing high-frequency deviations and, in the case considered, reduces the effective error to approximately 5–6 MPa", — explains the first author, Igor Zorin, a PhD student in the Engineering Systems program. "Sur-RECC effectively regularizes the solution of the inverse problem: it preserves the smooth component of deformation, which is essential for determining the macroscopic stress field, and suppresses high-frequency deviations. At the same time, we don’t claim that all local fluctuations are related to measurement error — some of them may be related to material, cutting, or data processing features. The article compares direct modeling and inverse problem approaches for determining residual stresses by specimen sectioning methods, which are extremely important for assessing the distribution of internal stresses through thickness. The proposed data processing makes these approaches more reliable and resistant to noise", — noted co-author, Professor Alexander Korsunsky, head of the Laboratory of Hierarchically Structured Materials. The approach was tested on 2024-T4 aluminum alloy specimens: double-sided dimpling, wire EDM cutting with special clamping, confocal laser profilometry, and independent verification by X-ray diffraction and focused-ion-beam digital image correlation. In parallel, the process was modeled by finite elements. The study was carried out with the participation of the Moscow Aviation Institute and the Central Institute of Aviation Motors, supported by the Ministry of Science and Higher Education of the Russian Federation. Skoltech is part of the VEB.RF group.