Application of electrodynamic treatment with amplitude-frequency control of current pulses for life extension of aircraft structures of light alloys

Abstract

The pulsed electric current (PEC) generator of a new generation with the controlled amplitude-frequency characteristics of PEC for electrodynamic treatment (EDT) of thin-sheet metal structures was designed and manufactured. The use of a new class of equipment allows a significant extension of capabilities of electrodynamic effects due to the controlled synchronization of the EDT dynamic and electric pulse components. The effect of EDT on reducing the level of residual welding stresses in magnesium alloy ML10 joints was investigated. As the investigated specimens the fragments of the shell of the intermediate body of the aircraft engine D-36 containing repair welds were used. It was found that EDT allows reducing the level of residual welding stresses from 120 to-40 MPa, providing their transition from tensile to compressive ones. It is shown that the local plastic deformation applying EDT of specimens of an aircraft wing stringer of aluminum alloy D16 in the area of technological holes 1.6-2.5 times increases the resistance to a delayed fracture. 9 Ref., 2 Tables, 14 Figures. K e y w o r d s : electrodynamic treatment, electric current pulse, aircraft structures, residual stresses, repair welding, body of aircraft engine, stringer, technological hole * According to the materials of the work performed within the frames of the target integrated program of the NAS of Ukraine «Problems of Life and Safe Operation of Structures, Constructions and Machines» (2013-2015).

Application of Electro-Plasticity Effect and Shearography Method for Non-Destructive Determination of Residual Stresses

“…The paper proposes replacing the hole-drilling process for stress relaxation, which compromises the integrity of the surface of structures, with a non-destructive method of local stress relief using high-density current pulses. This approach aims to combine the benefits of mechanical relaxation methods with the possibility of non-destructive study of the stressed state of structural elements [1][2]. The proposed method relies on the electroplasticity effect, which occurs when introducing HDCP into the material under investigation, leading to stress relaxation in the local zone.…”