Optimal Unbalance Response of Continuous Rotors

1995 ◽  
Author(s):  
Zdzislaw A. Parszewski ◽  
Dong-Xu Li
Keyword(s):  
System Dynamics ◽  
Industrial Application ◽  
Optimal Alignment ◽  
Bending Moments ◽  
Power Station ◽  
Laboratory Installation ◽  
Modal Approach ◽  
Unbalance Response ◽  
Non Linear ◽  
Independent Parameters

Abstract Dynamically optimal alignment of multi-bearing rotors has become one of the principal applications of the system dynamics in its configuration or layout parameters, (Parszewski, 1987). Using non-linear bearing effects and the independent parameters provided by their statical indeterminacy, the alignment of multi-bearing rotors has been optimised for least unbalance response. The rotor unbalance was estimated with the complex modal approach, using measured unbalance response. Some computed results and experiments on a four-bearing laboratory installation were presented in (Parszewski and Li, 1989). This present paper expands the analysis and provides an industrial application of the theory to a turbogenerator, operating in a power station. Comparison with the conventional catenary alignment is also given and shearing forces and bending moments on the couplings are revealed for both cases, showing the advantages of the optimal alignment of the rotor as a continuous shaft.

Instability and Unbalance Response of Dissymmetric Rotor-Bearing Systems

1988 ◽  
Vol 110 (3) ◽  
pp. 288-294 ◽  
Author(s):  
P. M. Guilhen ◽  
P. Berthier ◽  
G. Ferraris ◽  
M. Lalanne
Keyword(s):  
Differential Equations ◽  
Coordinate System ◽  
Transfer Matrix ◽  
Differential System ◽  
Industrial Application ◽  
Floquet Theory ◽  
Unbalance Response ◽  
Stationary Coordinate System ◽  
The Matrix ◽  
The Stability

The study deals with the instability and unbalance response of dissymmetric rotors, when periodic differential equations are impossible to avoid. The method which yields motion instability is based on an extension of the well-known Floquet theory. A transfer matrix over one period of the motion is obtained, and the stability of the system can be tested with the eigenvalues of the matrix. To find the instability and the unbalance response, the Newmark formulation is used. Here, the dissymmetry comes either from the rotor or from the bearings in such a way that it is possible to solve a regular differential system without periodic coefficients, either in the stationary coordinate system or in the rotating one. Three examples are given, including an industrial application. The results show that the method proposed is satisfactory.

Evaluation of Sealing Performance of Pipe Flange Connection Subjected to External Bending Moments

2009 ◽  
Author(s):  
Yoshio Takagi ◽  
Hiroyasu Torii ◽  
Toshiyuki Sawa ◽  
Kensuke Funada
Keyword(s):  
Bending Moment ◽  
Bending Moments ◽  
Stress Strain ◽  
Flange Connection ◽  
Strain Behavior ◽  
Leakage Test ◽  
Bolt Preload ◽  
Sealing Performance ◽  
Non Linear

The sealing performance of pipe flange connection subjected to an external bending moment was evaluated with the FEM and the experiments. The experimental leakage test using water revealed that the bending moment had an important effect on the sealing performance. The FE analyses suggested that the contact gasket stress, which was a function of the bolt preload, determines the leakage. The changes in contact gasket stress at tension side and compression side when the external bending moment applied were not symmetrical. The reduction in the contact gasket stress of tension side was larger than that of compression side due to the non-linear stress-strain behavior of the gasket. In addition, the hub stress of the flange when external bending moment applied, was evaluated from FE result and the discussion for optimizing the flange design subjected to external bending moment was done in this paper.

scholarly journals Dynamic Buckling of a Clamped Finite Column Resting on a Non – linear Elastic Foundation

2019 ◽  
pp. 1-47
Author(s):  
E. Julius, Bassey ◽  
M. Anthony, Ette ◽  
U. Joy, Chukwuchekwa ◽  
C. Atulegwu, Osuji
Keyword(s):  
Elastic Foundation ◽  
Governing Equation ◽  
Asymptotic Expansions ◽  
Perturbation Technique ◽  
Dynamic Buckling ◽  
Buckling Load ◽  
Linear Elastic ◽  
Non Linear ◽  
Relevant Variables ◽  
Independent Parameters

The analysis of the dynamic buckling of a clamped finite imperfect viscously damped column lying on a quadratic-cubic elastic foundation using the methods of asymptotic and perturbation technique is presented. The proposed governing equation contains two small independent parameters (δ and ϵ) which are used in asymptotic expansions of the relevant variables. The results of the analysis show that the dynamic buckling load of column decreases with its imperfections as well as with the increase in damping. The results obtained are strictly asymptotic and therefore valid as the parameters δ and ϵ become increasingly small relative to unity.

Project System Dynamics (SD)

2020 ◽  
pp. 131-142
Author(s):  
Yuri G. Raydugin
Keyword(s):  
Monte Carlo ◽  
System Dynamics ◽  
The Third ◽  
Free Model ◽  
Non Linear ◽  
Linear Behaviour

This chapter demonstrates project system dynamics (SD) models that mirror the Monte Carlo L-SCRA models developed in Chapter 5 (project Zemblanity). Historic overview of project system dynamics is undertaken: from claims and dispute resolutions to modelling of project rework cycles and project changes. Approaches to model extra risk-related works, out-of-sequence works, impacts on productivity of works, etc. are introduced. Three SD models are built that combine engineering and construction rework cycles (the two-rework-cycle models). The first is a risk-free model to become aligned with the project Zemblanity schedule. The second is a model that takes into account only quality-related risks. The third factors in all risks of project Zemblanity. Results of the SD modelling demonstrate good alignment with L-SCRA Monte Carlo outcomes and explain reasons for a non-linear behaviour of the project Zemblanity system. All three workable SD models are available on the book’s companion website.

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