METHOD FOR DECELERATING FATIGUE CRACK PROPAGATION IN PARTS Russian patent published in 1994 - IPC

FIELD: aircraft repairs. SUBSTANCE: method involves drilling holes in apices of cracks, placing fasteners in these holes and their tightening. Drilling is started from front surface of part; then additional holes are drilled in middle portion of crack symmetrically to its plane and in apex of crack. Outlet of each hole on other side of part shall be located opposite to place of starting the drilling of next hole. Axes of holes are positioned in different planes and fasteners are tightened in pairs in two parallel planes passing in front surface of part through inlets of hole at crack apex and hole in its middle portion and on opposite side of part through outlets of the same holes. Such sequence of operations makes it possible to make use of compressing forces within entire volume of metal adjacent to crack plane as well as dynamic compression in volume of metal adjoining crack plane and to create bending and torsional moments and consequently to change the kind of metal stress state. EFFECT: creation of conditions for crack growth deceleration and for its further low-speed propagation. 5 dwg