Application of Asymmetric Eigenvalue Method for Dynamic Analysis of Aqueducts

2012 ◽  
Vol 430-432 ◽  
pp. 799-802
Author(s):  
Yang Yang ◽  
Jian Min Ren ◽  
De Zhi Liu
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Properties ◽  
Dynamic Performance ◽  
Hydraulic Structures ◽  
Analysis Model ◽  
Irrigation Project ◽  
System A ◽  
Coupling System ◽  
Eigenvalue Method ◽  
Large Rectangle

Taking into consideration of the boundary conditions in fluid-solid interactions, the author built the FSI large rectangle aqueduct model of dynamic analysis according to the equation dynamic performance of the fluid-solid coupling system. Large aqueduct of the dynamic properties were analyzed with asymmetric eigenvalue method, dynamic properties rules were calculated by changing the depth of the water in the aqueduct. Aqueduct, also called elevated canal, is usually built over valley, lower land or river for conducting water from a distance or even for shipping.The aqueduct is one of the most important hydraulic structures in Yindaruqin Irrigation Project. After aqueduct is built, all kinds of reasons get its degree of safety descent so as to affect its ordinary running with the time going. Based on fluid-solid coupling system, a FSI analysis model of the aqueduct structure is established.

Dynamic Performance of Vehicle-Turnout-Bridge Coupling System in High-Speed Railway

2011 ◽  
Vol 50-51 ◽  
pp. 654-658
Author(s):  
Rong Chen ◽  
Wang Ping ◽  
Shun Xi Quan
Keyword(s):  
Relative Position ◽  
High Speed ◽  
Dynamic Performance ◽  
Dynamic Responses ◽  
Continuous Beam ◽  
Analysis Model ◽  
Wheel Load ◽  
System A ◽  
Coupling System ◽  
Contact Relation

In order to study dynamic behavior of vehicle-turnout-bridge coupling system, a vehicle-turnout-bridge dynamic analysis model is established by employing the dynamic finite element method (FEM). When No.18 crossover turnouts(with a speed of 350km/h) are laid symmetrically on the 6×32m continuous beam, influences of turnout/bridge relative position and wheel/rail contact relation in turnout zone on the system dynamic responses are analyzed. The result shows that: wheel/rail contact of turnout zone (especially the frog) has great effect on dynamic responses of turnout on bridge, thus the nose rail height of frog should be optimized to mitigate the wheel load transition and its longitudinal gradient. In terms of the 32m-span continuous beam, the best relative position is frog part of turnout arranged in the range of 1/8 and 1/4 of span.

Dynamic Leakage Analysis of Noncontacting Finger Seals Based on Dynamic Model

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Kaibing Du ◽  
Yongjian Li ◽  
Shuangfu Suo ◽  
Yuming Wang
Keyword(s):  
Dynamic Analysis ◽  
Design Optimization ◽  
Gas Turbine ◽  
Dynamic Model ◽  
Natural Frequency ◽  
Friction Force ◽  
Dynamic Performance ◽  
Excitation Amplitude ◽  
Analysis Model ◽  
Turbine Engine

Noncontacting finger seals are new compliant seal in gas turbine engine sealing technology. Their potential hydrodynamic and hydrostatic lifting capabilities make them preferable to brush seals and contacting finger seals. The work concerns the mechanism of dynamic leakage of noncontacting finger seal, and a novel dynamic leakage analysis model is proposed. The model combines seal dynamic analysis and seal leakage analysis together to estimate seal dynamic performance through seal leakage. The nature of dynamic leakage performance affected by the change of seal–rotor clearance is revealed. Dynamic leakage increasing is mainly affected by ratio of friction force to finger stiffness, finger mass natural frequency, and rotor excitation amplitude. Results show that the leakage increasing caused by the rotor eccentricity is inevitable. In the design optimization of the noncontacting finger seal, the ratio of friction force to finger stiffness and the rotor excitation should be as small as possible, and the finger natural frequency should be as large as possible.

Experimental Research of Characteristics of Fluid-Induced Force in Eccentric Seal

2011 ◽  
Vol 291-294 ◽  
pp. 2034-2040
Author(s):  
Wan Fu Zhang ◽  
Jian Gang Yang ◽  
Hao Cao ◽  
Rui Guo ◽  
Dan Sun
Keyword(s):  
Dynamic Analysis ◽  
Experimental Research ◽  
System Stability ◽  
Inlet Pressure ◽  
Analysis Model ◽  
Rotating Speed ◽  
Stiffness Coefficients ◽  
System A ◽  
The Difference ◽  
The Stability

This paper sets up a dynamic analysis model for cylinder-seal system. A new identification method for fluid-induced force and stiffness coefficients in eccentric seal is presented. The study shows that the system stability decreases with increasing cross-coupled stiffness in a certain range. Beyond this range, the system will be destabilized. Influences of rotating speed, inlet pressure, eccentricity and clearance on fluid-induced force were tested in the rig. It was found that a large tangential fluid-induced force was produced in the direction perpendicular to the eccentric displacement of rotor. The difference between the tangential and radial fluid-induced force became larger and larger with the increasing rotating speeds. Under the action of the seal force, the logarithmic decrement descended with increasing rotating speeds, and the stability of the system decreased. These effects became more and more serious for higher inlet pressure and tighter clearance.

Redesigning Mechanical Systems for Low Wear Using System Dynamics Modeling

1996 ◽  
Vol 118 (2) ◽  
pp. 415-422 ◽  
Author(s):  
O. S. Dinc ◽  
R. Cromer ◽  
S. J. Calabrese
Keyword(s):  
System Dynamics ◽  
Dynamic Analysis ◽  
Mechanical Design ◽  
Dynamic Performance ◽  
System Dynamics Model ◽  
Analysis Model ◽  
Dynamics Modeling ◽  
Dynamics Model ◽  
Large Complex ◽  
Inspection Data

This work describes a method of minimizing wear and extending the life of machinery components and large, complex machine structures by controlling the overall system dynamics. The method consists of the following steps: first, developing a system dynamics model for the entire machine structure using available rigid multi-body dynamic analysis computer codes; second, obtaining dynamic performance data from the system dynamics model for each sliding contact in the actual machine, and feeding this information into a suitable wear model which is either being used or developed for the particular material combination; third, matching the results of the wear prediction with actual machine wear inspection data; and last and most important, returning to the dynamic analysis model and modifying or redesigning the machine to minimize the intensity of the system dynamics, thus extending the wear life of the components. The method is being developed for application to large, complex machines which have numerous sliding contacts. Many of these contacts are at junctions between subcomponents assembled together. These junctions are often designed to accommodate relative motion due to vibration or thermal mismatches. After the initial analyses have been done, both minor and major mechanical design and material changes must be investigated to determine how effectively these could reduce wear. Each successive configuration can be evaluated using the dynamic analysis model. Application of this approach to the mechanical design of a gas turbine combustor reduced the noise level of the entire system and tripled the average machine life.

scholarly journals Dynamic Analysis for an Internally Coupled Fluid/Riser System

2010 ◽  
Author(s):  
Yongming Cheng ◽  
J. Kim Vandiver
Keyword(s):  
Dynamic Analysis ◽  
Natural Frequencies ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Vibration Absorber ◽  
Theoretical Formulation ◽  
System A ◽  
Concentric Cylinders ◽  
Effective Dynamic ◽  
Fluid Coupling

Risers are fluid conduits from subsea equipment to surface floating production platforms. The integrity of a riser system plays a very important role in deepwater developments. A top-tensioned riser generally consists of outer casing, inner casing and tubing. The pipes are coupled either through fluids in the annuli or through intermediate guides (centralizers) or through both. This paper investigates the dynamic analysis for such an internally coupled fluid/ riser system. This paper first presents a theoretical formulation for a general riser system coupled with fluids in the annuli and centralizers between pipes. Hydrodynamic forces associated with the viscous fluid in between concentric cylinders are considered. An effective dynamic stiffness matrix method is then developed to evaluate the added mass and damping influence of the fluid on the natural frequencies and the dynamic response of the coupled riser system. A riser example is used to illustrate the fluid coupling impact on the system’s dynamic performance. The coupling through the fluid and centralizers can be optimally designed such that an inner pipe acts as a vibration absorber to the outer casing.

Structure Sensitivity Analysis and Dynamic Performance Optimization of Marine Gearbox

2017 ◽  
Author(s):  
Tengjiao Lin ◽  
Daokun Xie ◽  
Ziran Tan ◽  
Bo Liu
Keyword(s):  
Sensitivity Analysis ◽  
Performance Optimization ◽  
Optimization Design ◽  
Dynamic Performance ◽  
Structure Sensitivity ◽  
Superposition Method ◽  
Structure Parameters ◽  
Analysis Model ◽  
Vibration Acceleration ◽  
Response Optimization

The aim of this paper is to investigate the influence of structure parameters on the vibration characteristics and improve the dynamic performance of marine gearbox. A finite element model was established to solve the dynamic response by using modal superposition method. Based on the theory of multi-objective optimization design, the structure sensitivity analysis model of marine gearbox was established, which takes the structure parameters of the housing as design variables. The modal and response sensitivity was obtained by using the optimal gradient method. According to the results of sensitivity analysis, a modal and response optimization model of marine gearbox was established. The objective was to avoid natural frequencies from the excitation frequencies and minimize the root mean square of vibration acceleration of the evaluating points on the surface of housing. Then the modal optimization and response optimization of gearbox were carried out by using zero-order and first-order optimization method. The results indicate that the dynamic optimization of the gearbox can be achieved. After optimization, the amplitude of vibration acceleration of the evaluating points on the housing surface has been reduced and the resonance of marine gearbox can be avoided.

Dynamic Analysis of Cage Stress in Tapered Roller Bearings Using Component-Mode-Synthesis Method

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Tomoya Sakaguchi ◽  
Kazuyoshi Harada
Keyword(s):  
Rigid Body ◽  
Dynamic Analysis ◽  
Boundary Point ◽  
Axial Load ◽  
Synthesis Method ◽  
Load Condition ◽  
Component Mode Synthesis ◽  
Analysis Model ◽  
Tapered Roller ◽  
Tapered Roller Bearings

In order to investigate cage stress in tapered roller bearings, a dynamic analysis tool considering both the six degrees of freedom of motion of the rollers and cage and the elastic deformation of the cage was developed. Cage elastic deformation is equipped using a component-mode-synthesis (CMS) method. Contact forces on the elastically deforming surfaces of the cage pocket are calculated at all node points of finite-elements on it. The location and pattern of the boundary points required for the component-mode-synthesis method were examined by comparing cage stresses in a static condition of pocket forces and constraints calculated by using the finite-element and the CMS methods. These results indicated that one boundary point lying at the center on each bar is appropriate for the effective dynamic analysis model focusing on the cage stress, especially at the pocket corners of the cages, which are actually broken. A behavior measurement of a polyamide cage in a tapered roller bearing was conducted for validating the analysis model. It was confirmed in both the experiment and analysis that the cage whirled under a large axial load condition and the cage center oscillated in a small amplitude under a small axial load condition. In the analysis, the authors discussed the four models including elastic bodies having a normal eigenmode of 0, 8 or 22, and rigid-body. There were small differences among the cage center loci of the four models. These two cages having normal eigenmodes of 0 and rigid-body whirled with imperceptible fluctuations. At least approximately 8 normal eigenmodes of cages should be introduced to conduct a more accurate dynamic analysis although the effect of the number of normal eigenmodes on the stresses at the pocket corners was insignificant. From the above, it was concluded to be appropriate to introduce one boundary point lying at the center on each pocket bar of cages and approximately 8 normal eigenmodes to effectively introduce the cage elastic deformations into a dynamic analysis model.

scholarly journals Modelling and Stability Analysis of Articulated Vehicles

2021 ◽  
Vol 11 (8) ◽  
pp. 3663
Author(s):  
Tianlong Lei ◽  
Jixin Wang ◽  
Zongwei Yao
Keyword(s):  
Stability Analysis ◽  
Critical Velocity ◽  
Equations Of State ◽  
Steering System ◽  
Analysis Model ◽  
Nonlinear Dynamic Model ◽  
Equilibrium Equations ◽  
Eigenvalue Method ◽  
Articulated Vehicles ◽  
The Stability

This study constructs a nonlinear dynamic model of articulated vehicles and a model of hydraulic steering system. The equations of state required for nonlinear vehicle dynamics models, stability analysis models, and corresponding eigenvalue analysis are obtained by constructing Newtonian mechanical equilibrium equations. The objective and subjective causes of the snake oscillation and relevant indicators for evaluating snake instability are analysed using several vehicle state parameters. The influencing factors of vehicle stability and specific action mechanism of the corresponding factors are analysed by combining the eigenvalue method with multiple vehicle state parameters. The centre of mass position and hydraulic system have a more substantial influence on the stability of vehicles than the other parameters. Vehicles can be in a complex state of snaking and deviating. Different eigenvalues have varying effects on different forms of instability. The critical velocity of the linear stability analysis model obtained through the eigenvalue method is relatively lower than the critical velocity of the nonlinear model.

Study on the Dynamic Performance of Asphalt Concrete under Passive Confined Pressure

2012 ◽  
Vol 226-228 ◽  
pp. 1755-1759
Author(s):  
Hua Zhang ◽  
Fei Li ◽  
Yu Wei Gao
Keyword(s):  
Elastic Modulus ◽  
Asphalt Concrete ◽  
Poisson Ratio ◽  
Dynamic Properties ◽  
Dynamic Performance ◽  
Dynamic Strength ◽  
Confining Pressure ◽  
Mechanical Behaviors ◽  
One Dimensional ◽  
Stress States

An improved passive confining pressure SHPB method was used to study the dynamic mechanical behaviors of asphalt concrete under quasi-one dimensional strain state. The effect of confining jacket material and its geometrical sizes on the confining pressure were discussed. The dynamic strength, dynamic modulus of elasticity and dynamic Poisson ratio of asphalt concrete were obtained. The influential rules of confining pressure on the dynamic properties were studied by comparing the stress-strain curves of asphalt concrete under different stress states. The study found that passive confining greater impact on the strength of asphalt concrete than elastic modulus and Poisson ratio, but the elastic modulus improved with the increase of confining pressure.

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