scholarly journals SENSITIVITY OF STRENGTH, RIGID AND DYNAMIC CHARACTERISTICS OF THE CONSOLE ROTOR TO VARIATION OF DESIGN PARAMETERS

2021 ◽  
pp. 104-113
Author(s):  
Mykola А. Tkachuk ◽  
Andrey Grabovskiy ◽  
Nickolay Prokopenko ◽  
Mykola M. Tkachuk ◽  
Oleksandr Shut ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Modulus Of Elasticity ◽  
Natural Vibration ◽  
Rotation Speed ◽  
Design Parameters ◽  
Natural Vibration Frequency ◽  
Radial And Axial Displacements ◽  
Angular Velocities ◽  
Air Blower ◽  
Critical Rotation Speed

The analysis sensitivity of strength, rigid and dynamic characteristics of the console rotor to variation of design parameters in paper describes The speed of rotation of the shaft, the material of the impeller vary. The dependences of radial and axial displacements on the angular velocities of rotation and the modulus of elasticity of the impeller material are established. For objects of the type of rotary systems with a cantilever arrangement of the impeller, not one, but a set of criteria has been introduced into consideration, which should be taken into account in the research of this type of objects. The tendencies of change of the first and second critical rotational speeds from the modulus of elasticity, rotor rotational frequencies and density of the impeller material are also determined. On this basis, recommendations have been developed for determining the design parameters of the rotor part of the air blower with a cantilevered impeller. Keywords: air blower; critical rotation speed; natural vibration frequency; rotary system; stress-strain state

scholarly journals Analysis of the natural oscillation frequency of the long-span trusses with flanged connections

2021 ◽  
pp. 76-85
Author(s):  
Татьяна Георгиевна Рытова ◽  
Людмила Анатольевна Максимова ◽  
Анастасия Георгиевна Николаева ◽  
Татьяна Михайловна Макарова ◽  
Надежда Георгиевна Пфаненштиль
Keyword(s):  
Dynamic Characteristics ◽  
Vibration Frequency ◽  
Natural Vibration ◽  
Natural Oscillation ◽  
Natural Vibration Frequency ◽  
Building Structures ◽  
Long Span ◽  
Local Areas ◽  
Calculation Results ◽  
Natural Oscillation Frequency

Приводится анализ частоты собственных колебаний большепролетной фермы с фланцевыми соединениями. Выполнен расчет фланцевого соединения с различными случаями исключения болтов из работы соединения. Анализ результата расчета показал, что возникновение повреждений и дефектов конструкций здания в локальных зонах, величина которых несущественно снижает общую жесткость каркаса, практически не влияет на динамические характеристики каркаса. The analysis of the natural vibration frequency of a large-span truss with flanged connections is given. The calculation of the flange connection with various cases of exclusion of bolts from the connection operation is performed. Analysis of the calculation results showed that the occurrence of damage and defects in the building structures in local areas, the value of which significantly reduces the overall rigidity of the frame, practically does not affect the dynamic characteristics of the frame.

scholarly journals Static and Dynamic Mechanical Properties of Long-Span Cable-Stayed Bridges Using CFRP Cables

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Mei Kuihua ◽  
Sun Shengjiang ◽  
Jin Guoqing ◽  
Sun Yamin
Keyword(s):  
Vibration Frequency ◽  
Temperature Effects ◽  
Natural Vibration ◽  
Dynamic Performance ◽  
Design Parameters ◽  
Natural Vibration Frequency ◽  
Steel Cable ◽  
Cable Stayed Bridge ◽  
Steel Cables ◽  
Cable Stayed Bridges

The elastic modulus and deadweight of carbon fiber-reinforced polymer (CFRP) cables are different from those of steel cables. Thus, the static and dynamic behaviors of cable-stayed bridges using CFRP cables are different from those of cable-stayed bridges using steel cables. The static and dynamic performances of the two kinds of bridges with a span of 1000 m were studied using the numerical method. The effects of geometric nonlinear factors on static performance of the two kinds of cable-stayed bridges were analyzed. The live load effects and temperature effects of the two cable-stayed bridges were also analyzed. The influences of design parameters, including different structural systems, the numbers of auxiliary piers, and the space arrangement types of cable, on the dynamic performance of the cable-stayed bridge using CFRP cables were also studied. Results demonstrate that sag effect of the CFRP cable is much smaller than that of steel cable. The temperature effects of CFRP cable-stayed bridge are less than those of steel cable-stayed bridge. The vertical bending natural vibration frequency of the CFRP cable-stayed bridge is generally lower than that of steel cable-stayed bridge, whereas the torsional natural vibration frequency of the former is higher than that of the latter.

Experimental Research on the Dynamic Young’s Modulus of Specified Density Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 164-167
Author(s):  
Xiao Er Zhou ◽  
Yan Kun Zhang ◽  
De Min Jiang
Keyword(s):  
Young’S Modulus ◽  
Experimental Research ◽  
Vibration Frequency ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Natural Vibration ◽  
Young's Modulus ◽  
Natural Vibration Frequency ◽  
Dynamic Modulus Of Elasticity ◽  
Static Young’S Modulus

From the experimental research, the relations between the dynamic modulus of elasticity and natural vibration frequency of specified density concrete are studied, the static Young’s modulus and dynamic modulus are compared. Based on regression analysis, the influence of different Substitution ratio of lightweight aggregate, age of concrete and cement water ratio is studied. According to the test results, the formula of natural vibration frequency and the dynamic modulus of elasticity of Specified density concrete is given, which provide theory basis for the nondestructive detector of the specified density concrete.

scholarly journals Dynamic Characteristics Analysis and Experimental Verification of Long Span Suspension Bridge

2021 ◽  
Vol 272 ◽  
pp. 01019
Author(s):  
Guojun Yang ◽  
Qiwei Tian ◽  
Guangwu Tang ◽  
Longlong Li ◽  
Su Ye ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Vibration Frequency ◽  
Natural Vibration ◽  
Structural Parameters ◽  
Great Influence ◽  
Suspension Bridge ◽  
Natural Vibration Frequency ◽  
Vibration Modes ◽  
Dead Load ◽  
Long Span

The dynamic characteristics of long-span suspension bridges are complex. The natural vibration frequency is changed with different structural parameters, and the sensitivity to different parameters is different. In order to solve this problem, the spatial model of a long-span suspension bridge was established by using finite element software, and the first 20 natural vibration periods, natural vibration frequencies and vibration modes were analyzed and calculated. The accuracy of the obtained natural vibration frequency data was verified through field tests. Finally, based on the model, the stiffness of structural components is studied by one -factor-at-one-time, and the influence of various variables on the frequency and mode of a certain mode is studied by one-factor-at-one-time method. The results show that different structural parameters have different effects on the vibration frequency. When the stiffness of stiffening girder and main tower is changed, with the increase of stiffness, the variation of frequency mostly presents an upward trend, and the range is large. With the change of the secondary dead load, most of the frequencies decrease first and then tend to be stable. It can be seen from the field test results that the vibration shapes and frequencies measured by numerical simulation and test are close to each other, which can meet the requirements of engineering precision. The stiffness of the main cable and the main tower has a great influence on the modes and periods corresponding to them. The increase of the secondary dead load can reduce the natural vibration frequency of the suspension bridge, but it is not unlimited to increase the secondary dead load to reduce the frequency. The stiffness of the stiffening girder has a great influence on the frequency of the suspension bridge. When the bending stiffness of the stiffening girder increases to 3 times of the original one, the order of vibration modes of the structure will change. The research results can provide references for structural design and dynamic parameter adjustment of long-span suspension bridge.

Study on Fluid-Solid Coupling Analysis Method of Bridge Pier

2012 ◽  
Vol 594-597 ◽  
pp. 1504-1508
Author(s):  
Ji Xin Yang ◽  
Sheng Rong Zuo ◽  
Yi Feng Huang
Keyword(s):  
Numerical Analysis ◽  
Water Level ◽  
Dynamic Characteristics ◽  
Vibration Frequency ◽  
Natural Vibration ◽  
Frequency Effect ◽  
Natural Vibration Frequency ◽  
Strong Impact ◽  
Analysis Method ◽  
Coupling Analysis

This paper introduces the numerical analysis method to analyze the dynamic characteristics of pier in water. The method comes to realize by the software ANSYS. By the calculating of ANSYS, the 1~3 order frequency can be found regular when the pier in full of water and anhydrous conditions. Water has a strong impact on natural vibration frequency of structures, as the water level rises, the natural vibration frequency decreases gradually, the value of the reducing is about 13%. At the same time, the frequency decreases as an increasing rate. So the natural frequency effect which the water acting on the structure can not be ignored.

The Simplified Analytical Method for Computing Dynamic Characteristics of Transmission Steel Towers

2011 ◽  
Vol 105-107 ◽  
pp. 303-306
Author(s):  
Jing Bo Yang ◽  
Jin Fei Zhao ◽  
Jun Jiang
Keyword(s):  
Dynamic Characteristics ◽  
Analytical Methods ◽  
Natural Vibration ◽  
Head Width ◽  
Natural Vibration Frequency ◽  
The Finite Element Method ◽  
Root Space ◽  
Lumped Mass ◽  
Mode Of Transmission ◽  
Tower Height

Based on vibration theory, simplified analytical methods for computing the first natural vibration frequency and mode of transmission steel tower are investigated, which has improved the currently applied method. The method for frequency includes parameters of lumped mass such as tower head or cross arm, and can show the influence of section of tower main leg. The method for mode considers tower height, root space and head width. Examples of some typical transmission steel towers show that the dynamic characteristics computed with the simplified analytical methods are close to those of the Finite Element Method. Then the methods given in this paper are superior to the present methods used in engineering and have a better generality, which are suitable to different tower type structures.

Stationary Rotation of the Partially Liquid-Filled Unbalanced Rotor under External Friction Force Action

2014 ◽  
Vol 1040 ◽  
pp. 903-906 ◽  
Author(s):  
E.N. Pashkov ◽  
Nikita Martyushev ◽  
Pavel G. Yurovsky
Keyword(s):  
Rotation Speed ◽  
External Friction ◽  
Design Parameters ◽  
Mathematical Research ◽  
Rotating Shaft ◽  
Critical Rotation ◽  
Unbalanced Rotor ◽  
Liquid Type ◽  
Critical Rotation Speed ◽  
Automatic Balancing

Rotor rotation with liquid layer on the chamber wall under viscoelastic action of the shaft within a planar model is examined in the article. The solution to the problem of determining the deflection of a rotating shaft with liquid filled chamber is given, which is important when designing an automatic balancing device. The issue of the cooperative motion of a solid body and liquid is considered in mathematical research. The set task is performed by applying D'Alembert's principle. The modeling results indicate that an increase in liquid’s mass in a rotor decreases its critical rotation speed; at the same time, the external friction accelerates the system’s self-centering. The developed mathematical models enable us to select the design parameters of a liquid-type autobalancer which operates within the set range of rotor’s angular velocity.

scholarly journals Analysis of the dynamic characteristics of downsized aerostatic thrust bearings with different pressure equalizing grooves at high or ultra-high speed

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110180
Author(s):  
Ruzhong Yan ◽  
Haojie Zhang
Keyword(s):  
Dynamic Characteristics ◽  
High Speed ◽  
Rotation Speed ◽  
Dynamic Stiffness ◽  
Simulation Method ◽  
Perturbation Amplitude ◽  
Thrust Bearings ◽  
Supply Pressure ◽  
Ultra High Speed ◽  
Air Film

This study adopts the DMT(dynamic mesh technology) and UDF(user defined functions) co-simulation method to study the dynamic characteristics of aerostatic thrust bearings with equalizing grooves and compare with the bearing without equalizing groove under high speed or ultra high speed for the first time. The effects of air film thicness, supply pressure, rotation speed, perturbation amplitude, perturbation frequency, and cross section of the groove on performance characteristics of aerostatic thrust bearing are thoroughly investigated. The results show that the dynamic stiffiness and damping coefficient of the bearing with triangular or trapezoidal groove have obvious advantages by comparing with that of the bearing without groove or with rectangular groove for the most range of air film thickness, supply pressure, rotation speed, perturbation amplitude, especially in the case of high frequency, which may be due to the superposition of secondary throttling effect and air compressible effect. While the growth range of dynamic stiffness decreases in the case of high or ultra-high rotation speed, which may be because the Bernoulli effect started to appear. The perturbation amplitude only has little influence on the dynamic characteristic when it is small, but with the increase of perturbation amplitude, the influence becomes more obvious and complex, especially for downsized aerostatic bearing.

Development of High-Speed Response Electromagnetic Linear Actuator Using for Pneumatic Control Valve

2014 ◽  
Vol 532 ◽  
pp. 41-45 ◽  
Author(s):  
Myung Jin Chung
Keyword(s):  
Optimal Design ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Design Method ◽  
Control Valve ◽  
Design Parameters ◽  
Linear Actuator ◽  
Analytic Model ◽  
Electromagnetic Linear Actuator ◽  
Quadratic Programming Method

Analytic model of electromagnetic linear actuator in the function of electric and geometric parameters is proposed and the effects of the design parameters on the dynamic characteristics are analyzed. To improve the dynamic characteristics, optimal design is conducted by applying sequential quadratic programming method to the analytic model. This optimal design method aims to minimize the response time and maximize force efficiency. By this procedure, electromagnetic linear actuator having high-speed characteristics is developed.

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