Залежність поздовжньої магнітної проникності і поперечної електропровідності від механічних навантажень на валу

This research deals with transformer type eddy-current transducer connected in differential circuit and it also proposes method for real-time evaluating mechanical tension in metal cylindrical products. The authors have proposed contactless method for estimating product mechanical deformation which is based on utilizing correlation connections between metals’ electromagnetic properties and their structural condition. The authors have introduced a generalized normalized informative magnetic parameter and on its basis obtain basic transform functions aided for determining increments of relative magnetic permeability and specific electric conductivity of product under load comparatively to standard sample. The article shows the possibility of using the differential method to increase the sensitivity of the evaluation of cylindrical products mechanical parameters. The authors have developed a physical model of an electromagnetic transducer with a product that is subjected to torsion, a theoretical justification is given at the level of the domain structure of the material under study and electromagnetic phenomena. The authors have created an experimental setup, the results of experimental studies of the influence of the mechanical moment caused by the torsion of an object on its electromagnetic properties were obtained. The research has proposed amplitude and phase methods for evaluating mechanical stresses. The results of the research allow to conclude, that there is an efficient transducer operating mode in the range 1 ≤ х ≤ 3, in which for η = 0,38 errors of mr and  estimation are less than 1% and 3% correspondingly. It is also noticeable, that in this range of x relative sensitivity of transducer is maximal. This allows us to create industrial devices for contactless multi-parameter evaluation of physical and mechanical parameters of metal products and structures. The obtained results of theoretical and experimental studies do not contradict the previously known laws of theoretical mechanics, which allows them to be widely used in the practice of nondestructive testing.