Combining the crack compliance method and speckle interferometry data for determination of stress intensity factors and T-stresses

•Crack modeling by a sequence of narrow notches.•Recording strain-induced interference fringe patterns.•Displacement measurements on crack borders immediately including CMOD and COD.•Determination of the first four coefficients of Williams’ series.•Calculations of SIF and T-stress.•Cracks in actual and residual stress fields.