METHOD FOR DETERMINING RESIDUAL STRESS IN PARTS Russian patent published in 2016 - IPC G01L1/06 

FIELD: aviation.

SUBSTANCE: invention relates to aircraft engineering, and is intended for determination of residual stresses in surface layers of parts with radial transitions of greater curvatures, for example in area of rounded edge of turbine blade and compressor. Subject: flat billet is cut out, curvilinear specimen of rectangular section is produced, surface layers of material with residual stresses are successively removed, alternating with determination of geometrical parameters of specimen, calculations are executed using formulas and experimentally obtained geometrical parameters. In order to determine residual stress, V-shape specimen is employed with curvilinear part rounding radius R = 1…3 and more mm, with arc ABC with central angle φ≈126°±5°, with two extender ends, opened at angle α to make≈ βdesign angle 126°±5°. Layers of material with residual tangential stresses are removed at area of convex surface of curvilinear part with arc ABC, after each removed layer, thickness t is measured of curvilinear part, height H of specimen, width A at base of sample, angle α of extenders separation. When performing calculations, first, additional parameters of curvilinear part of sample are determined: design angle β of extenders separation, chord a, boom h, and radius R of arc ABC, radius r of neutral flexure line, and radius of ρ axis, displacement e between r and ρ, distance y from arc of radius r to convex surface, using formulas. Then residual tangential stresses σ_i in surface layers of material are calculated, starting from first layer, by formula.

EFFECT: technical result is possibility of determining tangential residual stress in area of blade feather edge with radius of rounding 1…3 mm and more.

1 cl, 2 dwg