METHOD FOR DETERMINING THE STRESS INTENSITY FACTOR FOR A FRACTURE IN A STRUCTURE Russian patent published in 2022 - IPC G01L1/24 G01N3/08 

FIELD: measuring.

SUBSTANCE: invention relates to the field of experimental mechanics and is intended for determining the stress intensity factor (SIF) for fatigue fractures occurring in full-size thin-walled aircraft structures in the process of cyclic loading thereof during operation. The method consists in measuring the displacement of fracture edges, calculating the intensity factor from displacement-approximating functions, the parameters whereof are determined by the least squares method. To implement the method, a contrasting speckle structure is applied to the surface of the structure in the area of the fracture tip by means of a dye. A stereo system consisting of two video cameras is calibrated by means of a calibration grid installed in the same position and at the same distance from the cameras as the area under study. The stereo system is used to record a digital image of the initial state of the surface speckle structure. The structure is loaded, and the speckle structure of the deformed state of the structure surface is recorded by the stereo system. The displacement of points on the structure surface is determined by the method for numerical correlation of digital images.

EFFECT: increase in the accuracy of determining the SIF for large-sized fractures in full-scale thin-walled structures.

2 cl, 4 dwg