State-of-the-art and annual progress of bridge engineering in 2020

Bridge construction is one of the cores of traffic infrastructure construction. To better develop relevant bridge science, this paper introduces the main research progress in China and abroad in 2020 from 16 aspects. The content consists of four major categories in 16 aspects. The first part is about the bridge structure, including concrete bridge and high-performance materials, steel bridges, composite girders. The second part is about the bridge disaster prevention and mitigation, including bridge seismic resistance, wind resistance of bridge, train-bridge coupling vibration research, bridge hydrodynamics, the durability of the concrete bridges, fatigue of steel bridge, temperature field and temperature effect of bridge; The third part is about the bridge analyses, including numerical simulation of bridge structure, box girder and cable-stayed bridge analysis theories. The last part is concerning the bridge emerging technologies, including bridge informatization and intelligent bridge, the technology in bridge structure test, bridge assessment and reinforcement, prefabricated concrete bridge structure.

Mistuning parameter identification and vibration localization analysis of the integration rotor

This paper deals with the coupling vibration characteristic of the disk-blade-shaft integration rotor. First, a reduced-order model (ROM) based on an improved hybrid interface component mode synthesis method (IHISCMSM) is carried out, which takes the prestress effect into account. The frequency of the disk-blade-shaft integration rotor at different rotating speeds are calculated and the influence of selecting different mode truncation numbers is investigated. In order to quantitatively evaluate the coupling degree of blade and disk, the coupling factor is defined from the perspective of strain energy, and the influence of prestress on system’s dynamic is discussed. Then, an experimental modal analysis is performed on blades to identify the mistuning parameters, and the mode localization of the disk-blade-shaft integration rotor is analyzed with and without blade mistuning. The results indicate that there are several types of coupling modes among blade, disk and shaft of the integration rotor. After considering the prestress, the frequency increases, and the axial coupling vibration degree and radial coupling vibration degree of the integration rotor change. The mode localization of mistuned rotor is more likely to occur in the modes dominated by mistuning stage blades. There also exists a subtle mode localization phenomenon for tuned integration rotor.

Vehicle-Bridge Coupling Vibration Analysis for Simply Supported Girders of High-Speed Railway Bridges Based on the Cross-Sectional Decentralized Centre of Mass and Shear

Taking the simply supported box girder bridge of high-speed railway as an example, the effect of cross-sectional decentralized centre of mass and shear on the spatial beam element stiffness matrix was theoretically derived. Based on the vehicle-bridge coupling vibration analysis method of the railway bridge, an analysis program of vehicle-bridge coupling vibration for the high-speed railway was compiled, and its reliability was verified through an example analysis. On this basis, considering the cross-sectional decentralized centre of mass and shear, the influence factors of vehicle-bridge coupling vibration response were studied, which included the offset distance of the beam section’s mass and shear centre, offset distance of track centreline, vehicle weight, and vehicle speed. The results show that the additional items of the spatial beam element stiffness matrix are generated by the torsion effect when the cross-sectional decentralized centre of mass and shear is considered, and it will affect the lateral and vertical stiffness of the element. The cross-sectional decentralized centre of mass and shear has a significant effect on the lateral dynamic response of the bridge’s mid-span, but the influence on the vertical response of the bridge and the dynamic response of the car body is small. The main influence factors of the lateral dynamic response of the bridge are the vertical offset distance of the beam section’s centre of mass and shear, the lateral offset distance of the track centreline, and the vehicle weight.

Vibration Analysis of Hub Motor Based on ANSYS

The hub motor is designed with multidirectional excitation and Halbach Array, which includes inner rotor, left and right stator, outer stator, encoder and rotary transformer. The rotor consists of an axial disk and a top ring. The rotor’s permanent magnets are affixed to the left and right sides of the disk and to the outside of the top ring. The permanent magnets on the rotor adopt a Halbach Array. The three stators have not the iron core and they are arranged outside the rotor to form a three-way closed loop. The motor has high power density, high torque density, low heating, strong adaptability and no cogging effect. It is suitable for electric car control. On this basis, the dynamic equation of the hub motor is established, the vibration mode of the rotor system is analysed, when the inner rotor’s speed is 18000rpm. By use of the solid model, the hub-rotor’s accurate dynamics solution can be obtained. In the future, the effect of vertical coupling vibration will be investigated for its ride comfort and safety.

Propagation Characteristics of Pressure Pulsation in Hydraulic Hose

Most modern aircraft hydraulic systems use variable plunger pumps. The pulsating flow output is its inherent characteristic. The resulting pressure pulsation often causes serious damage to the energy pipeline system and endangers the lives of the occupants. This paper studies the propagation law of hydraulic oil in hydraulic hoses, fully considers the coupling vibration of hydraulic oil high-pressure fluid and flexible solids of the hose, establishes a fluid-solid coupling vibration model of hydraulic hoses, and uses ANSYS for numerical simulation to study different frequencies and pipe bending. Using ANSYS for numerical simulation to study the influence of different frequencies and pipe bending radii on the amplitude of fluid pressure pulsation, after comparative analysis, the law of fluid pressure pulsation propagation in hydraulic hoses is obtained.

Characteristics Analysis of Fluid-Structure Coupling Vibration of spray bar for High gap sprayer

With the progressive improvement of the level of mechanization of agricultural production, the high-gap rod sprayer has gradually become an important component of agricultural production equipment. The stability of spray rod has an important influence on the life and operation quality of spray rod. Therefore, considering the stability of the spray rod of high gap sprayer, a fluid-solid coupling vibration simulation model of the spray rod of high gap sprayer is established in this paper. The influence of inlet velocity, inlet pressure, fluid density and fluid viscosity on the flow rate and dynamic pressure in the pipe was analyzed by fluent. The results show that the exit velocity increases with the increase of the inlet velocity, but when the velocity reaches a certain value, backflow occurs. With the increase of inlet pressure, the dynamic pressure increases, and the local energy loss and the energy loss along the path also increase. The velocity and dynamic pressure decrease with increasing density.