Research On The Stress-testing Technique In Steel Structure Based On Magnetomechanical Coupling Effect

Human beings have become more and more strict in serviceability and safety of the complex engineering structures with a long span or defect sensitive structures, however, under the action of design loads and other sudden factors, the damage will occur unavoidably in above structures within the service, which will lead to the frequent deterioration in health conditions of structures and thus will threaten the serviceability and safety of the whole structure. Therefore, in order to ensure the serviceability and safety of the engineering structures, it is necessary to perform an on-line testing or monitoring, so as to find out the flaws or damages which are latent in the structure and then adopt necessary preventive and repairable measures, otherwise, which will bring about catastrophic results. How to carry out direct and testing and monitoring precisely on real-time load bearing conditions of structures becomes an important basis to judge whether structure design is reasonable and safe. Meanwhile this also poses an urgent and front line problem. Based on this background, Ferromagnetic materials, in this paper the main research contents are following:Magnetic domain structure of ferromagnetic materials is systemically analyzed basing on the theory of ferromagnetics. And we analyze the microscopic mechanism of magnetic domain structure. According to the minimum principle in energy, we analyze the microcosmic mechanism of magnetic domain construction and the main factors that affect the shape, size and connecting of the magnetic domain etc.From the microscopic mechanism of ferromagnetic materials, we analyze how stress influence the domain and domain wall, and discover the increase of stress energy and magnetism elasticity energy which destroy the balance of system energy make up the influence of magnetic domain structure, and set up basic disciplinarian between stress and characteristic of magnetism.On the basis of domain theory and energy, the stress sensitivity of magnetization is explainedmacroscopically and symmetrically. Then a mathematical model of relationship between permeability and stress is established, and also according to the thermal mechanical laws, the analogous relevant relationship between permeability and stress is deduced. This work form a theoretical foundation for further research and engineering application.