Measurement of residual stresses in slender support plates in aeroengine inlet case based on the sampling Moiré method

This paper proposes a residual stress testing method for slender support plates based on 2D moiré phase analysis, which can non-destructively detect the residual strain field generated on the surface of a specimen. A model of the aeroengine inlet case is used as the experimental object. By fabricating ±45° gratings on the support plate, the issue that traditional gratings cannot be used for deformation calculation in the width direction of the slender support plate was resolved. In the experiments, grating images of the support plate surface under different installation states were recorded, and the Moiré phase difference and displacement distributions in the x and y directions in the Cartesian coordinate system were calculated. A local phase unwrapping algorithm was used to analyse the normal and shear strain distributions on the surface of the support plate under different installation states. Based on the material's elastic properties, the normal and shear residual stress distributions on the surface of the support plate were also calculated. The experimental results show that after the installation of the plate with actual dimensions larger than the design, the measured plate exhibits tensile residual stress in the radial direction, and the circumferential residual stress is tensile on the outer ring side, while it undergoes a reversal from positive to negative near the inner ring. Additionally, based on the analysis of the displacement distribution, it was found that the support plate underwent bending after the installation of the larger-sized support plate.