EXPERIMENTAL SETUP FOR MODELING AND STUDY OF COMPLEX STRESS STATE IN FERROMAGNETIC MATERIALS

Abstract

Most of the load experiencing parts operate in a complex state of stress (СSS). The article describes the device layout diagram for modeling a СSS in a ferromagnetic material and the development of monitoring methods. The principle of operation of the device is based on the joint action at a sample of longitudinal extension and lateral bending. The article describes the methods of creating a СSS and materials research using the method of the Barkhausen effect in static and dynamic loading conditions. The article presents the functioning of the algorithm and device operating principle. The article also shows the diagram for modeling a СSS in a steel sample. In this work, are the construction and operation of the device described in detail. This device differs from simple industrial test equipment by small weight, size and cost. The paper presents experimental examples of the influence of the simple forms of the state of stress (longitudinal stretching or lateral bending) and a CSS on the intensity of the magnetic noise in two samples of structural steel. The study established that the total value of the magnetic noise in complex stress state of the sample caused by the forces of simultaneously stretching and bending load, is approximately equal to the algebraic sum of magnetic noise values for each simple type of stress. The linearity of the intensity of the magnetic noise versus axial tensile stress is observed in a range of 0 to ≈ +300 MPa, flexural tensile stresses – of 0 to ≈ +500 MPa, the total stresses – to ≈ 100–110 MPa. The obtained results confirmed the efficiency and effectiveness of the device. The article shows that the magnetic noise is affected not only by the magnitude of the tensile stress of the axial force or tensile stresses in bending or full stresses, but also by the steel grade, the physical and mechanical properties of the material under test. The sensitivity of the magnetic noise to the combined action of the two types of state of stress was higher than for any separate type. The results may be useful in the evaluation of a CSS in ferromagnetic products and the various elements of steel structures. The paper presents the main technical characteristics of the device (weight 18 kg, dimensions 600 × 200 × 170 mm).

Keywords

• stress
• strain
• tension
• bending
• method barkhausen effect