Papers by Keyword: Rayleigh Law

Abstract: Vertical prestressing tendons finishing twisted steel is widely used in the concrete box girder, but ,it is hard to effectively control the loss of anchor stress. Based on the dynamic, the three-parameter model was built which include the frequency of the exposed segmentthe segment length of the exposed steel reinforcements and effective tensile force. The vertical tensioning force of the box girder webs model was designed at laboratory .The natural frequency was obtained through test. Relying on experimental test data ,the model of the nonlinear relationship between fine bundle the rebar tensile force and the exposed segment frequency was established. Here in NDT methods to be able to quickly and effectively measured vertical prestressing tension.

Abstract: Based on the dynamic, selecting the vibration shape functions for obtaining the structural frequency, without using the differential operation of the conventional Rayleigh law which improved the calculation accuracy, the three-parameter model was built which include the frequency of the exposed segment, the segment length of the exposed steel reinforcements and anchorage segment increased stiffness coefficient. Meanwhile the validity of the three-parameter model was verified using finite element numerical simulation. The vertical pretensioning force of the box girder webs model was designed at laboratory. The natural frequency of vertical prestressing tendons exposed section was obtained through the high-frequency acceleration sensor which was set up at the top of the exposed section. Relying on experimental test data, the model which had the nonlinear relationship between the effective tensile force and anchorage segment increased stiffness coefficient was established.

Abstract: Industrial alloys are generally multi-component systems with volatile and highly reactive components. Consequently, their processing in the liquid state requires special precautions. Therefore, an existing electromagnetic-levitation device with a high-vacuum chamber, designed for surface tension measurements, was modified and improved. For the measurements of the surface tensions with the help of the oscillating drop technique the temperatures and the video sequences of the levitated, molten alloy were recorded without contact by pyrometer and by high-speed camera, respectively. This method yields the frequencies of the surface oscillations of the sample around the equilibrium shape and - using the modified Rayleigh law - eventually the values of the surface tension. With the help of this method two commercial industrial steels were processed in the new EML-apparatus for ESA`s Thermolab project [1]. The results of these measurements are presented and discussed