Dynamic Characteristics Analysis of Cylinders Bundle Coupling System Under Axial Flow

Nuclear reactor fuel assemblies are mainly composed of cylinders bundle(CB), calculating the dynamics characteristics of CB under axial flow can lay a foundation for predicting fretting wear and vibration fatigue. In the paper, the CB coupling dynamic model of forced vibration under pulsating flow is established. And the stability analysis and natural frequency calculation of the CB system under steady flow are compared with the existing results to verify the model. Finally, the Runge-Kutta method is applied to solve the forced vibration equation of the CB under pulsating flow. The influence of the pulsating parameters m, w0, on the amplitude-frequency characteristics and the motion trajectory of the midspan cross section of the CB under forced vibration are analyzed and discussed. The results show that the pulsating parameters have an important influence on the vibration of the CB system.

JuliaFEM beam element implementation

This article describes implementations of beam elements to JuliaFEM. The theory is briefly introduced, and the usage of beam elements is introduced with a usage example that involves a natural frequency calculation of a formula race car frame. The calculation results were compared to results from a commercial program, and their consistency is excellent.

Method for determining the rational parameters of dynamic dampers of low-frequency vibrations

The problems have been considered of natural nonlinear vibrations of an absolutely rigid semiball and a semicylinder on a horizontal plane, assuming that there is no energy dissipation, sliding and tipping on foundation. To adjust the damper to a frequency close to the fundamental tone of vibrations, it is necessary to assess the natural frequency of the damper, which is determined under the assumption on smallness of the vibrations amplitude. This paper represents the comparison of the natural frequency of linearized and nonlinear system. The relative error has been estimated of the natural frequency calculation, which is caused by linearization. It is shown that the ratio of the natural frequency of the linearized system to the natural frequency of the nonlinear system does not depend on the mass and radius. This conclusion made it possible to generalize the results of particular computational solutions and to obtain a formula which takes into account the amplitude influence on the natural vibrations frequency and helps to determine the natural frequency for the initial angles to ninety degrees.

Dynamic Analysis on PCI Girder Bridge

To produce a quality bridge then it should be taken into account with the correct parameters and the condition of the bridge. One of the parameters is an important bridge natural frequency incurred due to dynamic loads. The purpose of this study was to conduct a comparative analysis of the natural frequency of bridge girder value measurement results in the field of natural frequency calculation results using Midas Civil programs and manuals, as well as knowing the value of the condition value of natural frequency of bridge between the actual value of natural frequency measurement results on the field and the value of natural frequency calculation program results Midas Civil. In the analysis, use design bridge gelagar PCI with a span of 21,95 meters. And bridge specifications will be made from the analysis of the natural frequency of the load calculation of structures with Midas program manual and Civil that would then be compared with the results of field measurements to find out the condition of the bridge. The natural frequency obtained from calculation manual for a bridge girder single of 5,95 Hz, and multi girder of 5,72 Hz.While value natural frequency of program midas civil for singles girder of 6,16 Hz, and for multi girder of 5,93Hz.