Papers by Keyword: Magnetic Methods

Abstract: The complexity and diversity of civil engineering structures impose requirements on the monitoring systems, which are difficult to be satisfied. In the paper the concept of the distributed diagnostic system capable of monitoring the technical state of critical elements of large infrastructure objects like steel trusses, supermarket buildings, exposition halls, bridges etc. is discussed. Adaptation of such systems is essential for online assessment of technical state of the infrastructure objects and could limit the possibility of catastrophic disasters with loss of people. As a source of information data from strain gauges, passive magnetic field sensors and acceleration sensors applied to the construction are considered. For the process of selection of sensors and diagnostic methods the mathematical model of the construction and the physical test stand were used.

Abstract: Ferrogarnets of the system {Y3}[Fe2-xScx](Fe3)O12 were investigated by neutron diffraction and magnetic methods. Parameters of crystal structure were refined. It was found that deviations from a collinear ferrimagnetic structure emerged at x ~ 0.7. At high concentrations of Sc a growth of the high-field magnetic susceptibility and an abnormal temperature dependences of dynamic susceptibility typical of local angular spin structures were revealed. The fracture temperatures for the local angular structures were determined.

Abstract: An attempt has been made to measure existing steel stress using magnetoelasticity. A device has been developed and used for the measurement of magnetism in response to the deformation of a steel bar. The proposed technique can be used for the assessment of existing reinforced concrete structures by the measurements of steel stress embedded inside concrete. A traditional technique requires to break the existing steel bar to measure existing strain. However, the proposed technique is developed to measure the stress without damaging the steel bar. A successful application of magnetoelasticity depends on the establishment of relationship between elastic and magnetic response due to loading. To investigate the correlation between the two, steel bars are loaded in tension under uniaxial loading while the magnetic reading is recorded. Based on the test results, equations are suggested to predict stress for steel bars with different diameters.