scholarly journals Effect of Boundary Conditions on Fluid–Structure Coupled Modal Analysis of Runners

2021 ◽  
Vol 9 (4) ◽  
pp. 434
Author(s):  
Dianhai Liu ◽  
Xiang Xia ◽  
Jing Yang ◽  
Zhengwei Wang
Keyword(s):  
Energy Loss ◽  
Boundary Conditions ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Rotating Shaft ◽  
Torsional Mode ◽  
Hydraulic Machinery ◽  
Natural Modes ◽  
Turbine Runner ◽  
Characteristics Analysis

To predict the resonance characteristics of hydraulic machinery, it is necessary to accurately calculate the natural modes of the runners in the operating environment. However, in the existing research, the boundary conditions of the numerical modal analysis of the runner were not unified. In this paper, numerical modal analysis of a prototype Francis pump turbine runner was carried out using the acoustic–structure coupling method. The results of three different constraints were compared. The influence of the energy loss on the chamber wall on the natural modes of the runner was studied by the absorption boundary. The results show that the constraint condition (especially the rotating shaft) has significant impacts on the torsional mode, the radial mode, the 1 nodal-diameter mode, and the 0 nodal-circle mode, and the maximum differences in the natural frequencies under different conditions are 69.3%, 56.4%, 35.1%, and 9.4%, respectively. The change of the natural frequencies is closely related to the modal shapes. On the other hand, the energy loss on the wall mainly affects the nodal-circle modes, and the influence on other modes is negligible. The results can provide references for the design and resonance characteristics analysis of hydraulic machinery runners.

scholarly journals The modal analysis of cylindrical steel tank with selfsupported roof filled with different level of liquid

2013 ◽  
Vol 12 (2) ◽  
pp. 205-212
Author(s):  
Daniel Burkacki ◽  
Michał Wójcik ◽  
Robert Jankowski
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Environmental Disaster ◽  
Natural Modes ◽  
Liquid Products ◽  
Safety And Reliability ◽  
Steel Tank ◽  
Steel Tanks ◽  
Cylindrical Steel Tanks ◽  
Cylindrical Steel

In technical branches, such as chemical or petroleum industries, cylindrical steel tanks are essential structures used for storage of liquid products. Therefore, their safety and reliability is essential, because any failure might have dangerous consequences, in extreme cases may even lead to an environmental disaster. The aim of the presented paper is to show the results of the modal analysis concerning the cylindrical steel tank with self-supported roof which has been constructed in northern Poland. The investigation was carried out with the use of the FEM commercial computer program Abaqus. The values of natural frequencies, as well as the natural modes, for different levels of liquid filling (empty tank, partly filled and tank fully filled) were determined in the study. The results of the study clearly indicate that the increase in the liquid level leads to the substantial decrease in the natural frequencies of the structure.

Node Control of Uniform Beams Subject to Various Boundary Conditions

1992 ◽  
Vol 59 (4) ◽  
pp. 983-990 ◽  
Author(s):  
L. Weaver ◽  
L. Silverberg
Keyword(s):  
Free Boundary ◽  
Boundary Conditions ◽  
Natural Frequencies ◽  
Controlled System ◽  
Free Boundary Conditions ◽  
Various Boundary Conditions ◽  
Natural Modes ◽  
Modes Of Vibration ◽  
Control Forces ◽  
Direct Feedback

This paper introduces node control, whereby discrete direct feedback control forces are placed at the nodes of the N+1th mode (the lowest N modes participate in the response). Node control is motivated by the node control theorem which states, under certain conditions, that node control preserves the natural frequencies and natural modes of vibration of the controlled system while achieving uniform damping. The node control theorem is verified for uniform beams with pinned-pinned, cantilevered, and free-free boundary conditions, and two cases of beams with springs on the boundaries. A general proof of the node control theorem remains elusive.

FEA on Vibration Characteristics of a Shrouded Turbine Blade

2012 ◽  
Vol 189 ◽  
pp. 443-447
Author(s):  
Wei Qiang Zhao ◽  
Yong Xian Liu ◽  
Mo Wu Lu
Keyword(s):  
Optimal Design ◽  
Modal Analysis ◽  
Turbine Blade ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Vibration Characteristics ◽  
Mode Shapes ◽  
Software Environment ◽  
Aero Engine ◽  
Characteristics Analysis

This paper introduces a FEA method for vibration characteristics analysis of an aero-engine shrouded turbine blade and makes an actual modal analysis of this shrouded blade based on this method in UG software environment. The first six natural frequencies and mode shapes of this shrouded blade are calculated. And also, the dynamic characteristics of the shrouded turbine blade are discussed in detail according to the analysis results. The FEA method and the vibration characteristics analysis results in the paper can be used for optimal design and vibration safety verification of this aero-engine shrouded turbine blade.

FEA on Vibration Characteristics of a Gas Turbine Blade-Disc

2012 ◽  
Vol 516-517 ◽  
pp. 731-734 ◽  
Author(s):  
Wei Qiang Zhao ◽  
Yong Xian Liu ◽  
Mo Wu Lu
Keyword(s):  
Optimal Design ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Natural Frequencies ◽  
Vibration Characteristics ◽  
Natural Mode ◽  
Analysis Method ◽  
Gas Turbine Blade ◽  
Natural Modes ◽  
Characteristics Analysis

This paper introduces a FEA method for vibration characteristics analysis of blade-disc structure and makes a modal analysis of a certain gas turbine blade-disc based on this method. The natural frequencies and natural modes of this blade-disc are obtained and also vibration characteristics of each natural mode and corresponding influence on gas turbine blade-disc and other components are discussed in detail. The analysis method and analysis results presented in this paper are helpful for further research on optimal design and vibration safety verification for this gas turbine blade-disc.

scholarly journals Effect of the Weight reduction of a Gear Wheel on Modal Characteristics

2019 ◽  
Vol 299 ◽  
pp. 03002
Author(s):  
Katarina Monkova ◽  
Peter Monka ◽  
Jozef Tkac ◽  
Romana Hricova ◽  
Dusan Mandulak
Keyword(s):  
Numerical Analysis ◽  
Boundary Conditions ◽  
Modal Analysis ◽  
Experimental Method ◽  
Measurement System ◽  
Weight Reduction ◽  
Natural Frequencies ◽  
Gear Wheel ◽  
Modal Parameter ◽  
Simulation Tools

The paper deals with the influence of gear weight reduction on its modal properties. The aim of thepaper is to use the simulation tools to introduce the dependence of natural frequencies on the change in the shape of the gear, which is reflected in the change in weight. At the beginning of the paper, the theory and experimental bases of vibration testing and analysis are introduced to understand the principles of modal parameter specification. Verification of the boundary conditions used in the simulation was performed using the experimental method and it is described in the next part of the article. Tests confirmed the consistency of the values achieved by both approaches. Thus, the same boundary conditions could be used to specify the dependence of natural frequencies on the change in the geometry ofthe gear (which is associated with weight reduction). Numerical analysis was performed by FEM analysisusing PTC Creo software. Experimental modal analysis was performed using a PULSE measurement system.

Dynamic Characteristics Analysis of the Mud Transfer Pump Rotor

2013 ◽  
Vol 455 ◽  
pp. 248-252
Author(s):  
Jun Yuan Sun ◽  
Ji Ming Xiao
Keyword(s):  
Dynamic Analysis ◽  
Modal Analysis ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Dam Construction ◽  
Pump Rotor ◽  
Characteristics Analysis ◽  
Rotor Dynamic ◽  
Dynamic Characteristics Analysis

The mud pump damming technology is a new idea put forward for realization of mechanization and automation of warping dam construction. A mud pump damming machine is studied, the FEM of the mud transfer pump rotor is built, modal analysis and rotor-dynamic analysis are carried out, natural frequencies and mode shapes under different constraints are obtained and the critical speeds of the pump rotor are determined, which will provide reference to improve the running reliability of the mud transfer pump rotor.

Analysis of Structure Dynamic Characteristics of a Metal Plate

2012 ◽  
Vol 268-270 ◽  
pp. 1075-1079
Author(s):  
Chen Zhang ◽  
Zhi Gang Yang ◽  
Yin Zhi He
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Modal Analysis ◽  
Dynamic Characteristics ◽  
Natural Frequencies ◽  
Modern Method ◽  
Metal Plate ◽  
Mode Shapes ◽  
Structure Dynamic ◽  
Fixed Boundary Condition

Modal analysis is a modern method to study structure dynamic characteristics. In this paper, computational modal analysis with Finite Element Method is applied to simulate an aluminum plate with the dimension of 160mm*240mm*1.5mm under different boundary conditions (Including free boundary condition and fixed boundary condition). The results of structure natural frequencies and mode shapes of this plate show obvious difference between the two boundary conditions.

Stress and Modal Analysis Assessment of Race Cars Chassis Structure

2014 ◽  
Vol 663 ◽  
pp. 103-107
Author(s):  
S. Fazidah ◽  
N.A. Nor Azrin ◽  
A.L. Zulkarnain
Keyword(s):  
Modal Analysis ◽  
Natural Frequencies ◽  
Material Selection ◽  
Frame Structure ◽  
Maximum Displacement ◽  
Torsional Mode ◽  
Race Car ◽  
Bending Mode ◽  
Bending Loads ◽  
Race Cars

A simulation investigation was conducted to compare and validate results for using bended and non-bended chassis structure for race cars. In this study, the basic engineering design criteria which are material selection, type of material used and production processes were presented. Modal analysis was used to validate the effect of chassis stiffness between the two different frames which is bended and non-bended frame using torsional and bending loads. The results reveals that the maximum displacement and Von Misses stress of the frame occur at the non-bended frame, instead of the bended frame with the value of 539.93 mm and 4.67 x 1010 Nm2 respectively. However, the critical area occurs on the main roll bar instead of on the frame structure itself. It was found that in the bended frame, the maximum Von Misses stress occurs at the rear section of the frame structure, which indicates possible chassis failure at given frequency of 62.16 Hz. The results indicate that there is only slight difference in the natural frequencies for both frames and the modeshape of both frames starts with torsional mode. For the second modeshape of the frames, the non-bended frame still remain having the torsional mode while the bended frame start to have the bending mode. The results presented here may facilitate improvements in the race car frame where the non-bended frame is having better structural frame than the bended frame. This was proved by the bended frame had a changed of modeshape from torsional mode to bending mode. The significance of the results indicates that the bended frame has less stiffness than the non-bended frame and it is not permittable for a race car frame.

Identification of the string boundary conditions using natural frequencies

2016 ◽  
Vol 11 (1) ◽  
pp. 38-52
Author(s):  
I.M. Utyashev ◽  
A.M. Akhtyamov
Keyword(s):  
Inverse Problems ◽  
Power Series ◽  
Boundary Value Problem ◽  
Boundary Conditions ◽  
Natural Frequencies ◽  
Boundary Value ◽  
External Environment ◽  
Direct And Inverse Problems ◽  
Symmetric Potential ◽  
Modified Method

The paper discusses direct and inverse problems of oscillations of the string taking into account symmetrical characteristics of the external environment. In particular, we propose a modified method of finding natural frequencies using power series, and also the problem of identification of the boundary conditions type and parameters for the boundary value problem describing the vibrations of a string is solved. It is shown that to identify the form and parameters of the boundary conditions the two natural frequencies is enough in the case of a symmetric potential q(x). The estimation of the convergence of the proposed methods is done.

Analysis of vibration in rotating pretwisted functionally graded graphene platelets reinforced nanocomposite laminated blades with an attached point mass

2021 ◽  
pp. 095440622110084
Author(s):  
Amin Ghorbani Shenas ◽  
Parviz Malekzadeh ◽  
Sima Ziaee
Keyword(s):  
Free Vibration ◽  
Boundary Conditions ◽  
Polymer Matrix ◽  
Natural Frequencies ◽  
Weight Fraction ◽  
Functionally Graded ◽  
Point Mass ◽  
Attached Mass ◽  
Graphene Platelets ◽  
Twisted Beam

This work presents an investigation on the free vibration behavior of rotating pre-twisted functionally graded graphene platelets reinforced composite (FG-GPLRC) laminated blades/beams with an attached point mass. The considered beams are constituted of [Formula: see text] layers which are bonded perfectly and made of a mixture of isotropic polymer matrix and graphene platelets (GPLs). The weight fraction of GPLs changes in a layer-wise manner. The effective material properties of FG-GPLRC layers are computed by using the modified Halpin-Tsai model together with rule of mixture. The free vibration eigenvalue equations are developed based on the Reddy’s third-order shear deformation theory (TSDT) using the Chebyshev–Ritz method under different boundary conditions. After validating the approach, the influences of the GPLs distribution pattern, GPLs weight fraction, angular velocity, the variation of the angle of twist along the beam axis, the ratio of attached mass to the beam mass, boundary conditions, position of attached mass, and geometry on the vibration behavior are investigated. The findings demonstrate that the natural frequencies of the rotating pre-twisted FG-GPLRC laminated beams significantly increases by adding a very small amount of GPLs into polymer matrix. It is shown that placing more GPLs near the top and bottom surfaces of the pre-twisted beam is an effective way to strengthen the pre-twisted beam stiffness and increase the natural frequencies.

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