RESIDUAL STRESS MEASURING METHOD Russian patent published in 1995 - IPC

FIELD: mechanical tests of coatings. SUBSTANCE: method involves static indentation of pyramidal indentor until dent is formed with brittle cracks developing from its top to sectional area of coating at orthogonal orientation of dent diagonals relative to direction in which residual stresses act. Upon removing load geometric parameters of dent are measured; those of cracks are metered separately in two relatively perpendicular directions, their pattern is evaluated, equilibrium value K_1C and effective value Kef1C

^f of fracture viscosity is determined, respectively, parallel and perpendicular to action of residual stresses, and σ value is calculated including linear dimensions of actual grain of coating. For constructing curve, residual stress is determined at several points of sectional area of coating spaced at different distances from its outer boundary and residual stress at point determined from y = 0 equation is found including Kef1C^f obtained during indentation into coating surface. EFFECT: improved reliability of test results. 2 tbl