SOME SPECIAL FEATURES OF FRACTURE IN LARGE SEMIFINISHED PRODUCTS MADEOF ALUMINUM-ALLOYS

The load-bearing structure of modern airframes requires monolithic mem bers that are produced from large forged and rolled aluminum-alloy sem ifinished products. These members are designed in accordance with the principle of ''safe service life,'' and critical parts are designed in accordance with the principle of ''safe vulnerability to damage.'' Fo r this reason, the characteristics of static and cyclic crack resistan ce (K-lc, RGFC, sigma(cr)(net), and others) have become very important and some of them are used as control parameters in standard documenta tion. These parameters characterize the operating capacity of the mate rial of a structure with a crack and take into account the magnitude a nd direction of the applied load. If the crack front deviates from the given direction to another plane (for example, from a transverse plan e to a heightwise plane), the process of crack propagation becomes unp redictable and uncontrollable. The present paper is devoted to the spe cial features of fracture in large semifinished products made of alumi num alloys.