scholarly journals Model Reduction Methods for Rotor Dynamic Analysis: A Survey and Review

2010 ◽  
Vol 2010 ◽  
pp. 1-17 ◽  
Author(s):  
Matthew B. Wagner ◽  
Amir Younan ◽  
Paul Allaire ◽  
Randy Cogill
Keyword(s):  
Model Reduction ◽  
Dynamic Systems ◽  
Dynamic Models ◽  
Careful Consideration ◽  
Rotor Systems ◽  
Current State ◽  
Reduction Methods ◽  
Nonproportional Damping ◽  
Gyroscopic Effects ◽  
Rotor Dynamic

The focus of this literature survey and review is model reduction methods and their application to rotor dynamic systems. Rotor dynamic systems require careful consideration in their dynamic models as they include unsymmetric stiffness, localized nonproportional damping, and frequency-dependent gyroscopic effects. The literature reviewed originates from both controls and mechanical systems analysis and has been previously applied to rotor systems. This survey discusses the previous literature reviews on model reduction, reduction methods applied to rotor systems, the current state of these reduction methods in rotor dynamics, and the ability of the literature to reduce the complexities of large order rotor dynamic systems but allow accurate solutions.

scholarly journals Eigensolution Reanalysis of Rotor Dynamic Systems by the Generalized Receptance Method

1982 ◽  
Author(s):  
A. B. Palazzolo ◽  
Bo Ping Wang ◽  
W. D. Pilkey
Keyword(s):  
Optimal Design ◽  
Dynamic Systems ◽  
Natural Frequencies ◽  
Rotor Systems ◽  
Receptance Method ◽  
Rotor Bearings ◽  
Rotor Dynamic

A method is presented for efficiently calculating the damped natural frequencies of complex rotor bearings systems. The procedure is applicable to the repeated reanalysis of rotor systems during the search for an optimal design. The generalized receptances used in the method are calculated with a series of formulas that improves the convergence characteristics when only an incomplete set of modes is available. A nonsynchronous gyroscopic rotor example is examined to illustrate the reanalysis procedure.

Experimental Verification of a Combi-Bearing Model for Vertical Rotor Systems

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Jean-Claude Luneno ◽  
Jan-Olov Aidanpää ◽  
Rolf Gustavsson
Keyword(s):  
Dynamic Models ◽  
Contact Point ◽  
Element Model ◽  
Experimental Results ◽  
Small Scale ◽  
Rotor Systems ◽  
Vertical Rotor ◽  
Bearing Design ◽  
Rotor Bearings ◽  
Rotor Dynamic

Combi-bearing is a combined thrust-journal bearing design used in vertical hydropower rotors. The dynamic characteristics of this component (combi-bearing) were analytically modeled by Luneno et al. (2011, “Model Based Analysis of Coupled Vibrations Due to the Combi-Bearing in Vertical Hydroturbogenerator Rotors,” ASME J. Vib. Acoust., 133, p. 061012). This analytic model was inserted into a finite element model of a vertical rotor rig and numerically simulated. In this paper, the simulated vertical rotor-bearings system is a small-scale vertical machine constructed to validate the analytically derived combi-bearing model. Good agreement was found between the simulation and experimental results. The simulation and experimental results showed that the journal (radial) bearing's position relative to the contact point between the combi-bearing's collar and the rotor influences the rotor system's fundamental natural frequencies. Therefore, the combi-bearing model needs to be included into rotor dynamic models. Neglecting the effect of this component may cause significant errors in the predicted results.

Eigensolution Reanalysis of Rotor Dynamic Systems by the Generalized Receptance Method

1983 ◽  
Vol 105 (3) ◽  
pp. 543-550 ◽  
Author(s):  
A. B. Palazzolo ◽  
Bo Ping Wang ◽  
W. D. Pilkey
Keyword(s):  
Optimal Design ◽  
Dynamic Systems ◽  
Natural Frequencies ◽  
Rotor Systems ◽  
Receptance Method ◽  
Rotor Bearings ◽  
Rotor Dynamic

A method is presented for efficiently calculating the damped natural frequencies of complex rotor bearings systems. The procedure is applicable to the repeated reanalysis of rotor systems during the search for an optimal design. The generalized receptances used in the method are calculated with a series of formulas that improves the convergence characteristics when only an incomplete set of modes is available. A nonsynchronous gyroscopic rotor example is examined to illustrate the reanalysis procedure.

scholarly journals Lightweight Stacked Hourglass Network for Human Pose Estimation

2020 ◽  
Vol 10 (18) ◽  
pp. 6497
Author(s):  
Seung-Taek Kim ◽  
Hyo Jong Lee
Keyword(s):  
Receptive Field ◽  
Pose Estimation ◽  
Network Architecture ◽  
Human Pose Estimation ◽  
Current State ◽  
Reduction Methods ◽  
Substantial Progress ◽  
Human Pose ◽  
Residual Block ◽  
Point Detection

Human pose estimation is a problem that continues to be one of the greatest challenges in the field of computer vision. While the stacked structure of an hourglass network has enabled substantial progress in human pose estimation and key-point detection areas, it is largely used as a backbone network. However, it also requires a relatively large number of parameters and high computational capacity due to the characteristics of its stacked structure. Accordingly, the present work proposes a more lightweight version of the hourglass network, which also improves the human pose estimation performance. The new hourglass network architecture utilizes several additional skip connections, which improve performance with minimal modifications while still maintaining the number of parameters in the network. Additionally, the size of the convolutional receptive field has a decisive effect in learning to detect features of the full human body. Therefore, we propose a multidilated light residual block, which expands the convolutional receptive field while also reducing the computational load. The proposed residual block is also invariant in scale when using multiple dilations. The well-known MPII and LSP human pose datasets were used to evaluate the performance using the proposed method. A variety of experiments were conducted that confirm that our method is more efficient compared to current state-of-the-art hourglass weight-reduction methods.

Rotor-Dynamics of Different Shaft Configurations for a 6 kW Micro Gas Turbine for Concentrated Solar Power

2016 ◽  
Author(s):  
A. Arroyo ◽  
M. McLorn ◽  
M. Fabian ◽  
M. White ◽  
A. I. Sayma
Keyword(s):  
Gas Turbines ◽  
High Speed ◽  
Dynamic Models ◽  
Solar Power ◽  
Critical Issue ◽  
Rotor Dynamics ◽  
Mode Shapes ◽  
Concentrated Solar Power ◽  
Element Analysis ◽  
Rotor Dynamic

Rotor-dynamics of Micro Gas Turbines (MGTs) under 30 kW have been a critical issue for the successful development of reliable engines during the last decades. Especially, no consensus has been reached on a reliable MGT arrangement under 10 kW with rotational speeds above 100,000 rpm, making the understanding of the rotor-dynamics of these high speed systems an important research area. This paper presents a linear rotor-dynamic analysis and comparison of three mechanical arrangements of a 6 kW MGT intended for utilising Concentrated Solar Power (CSP) using a parabolic dish concentrator. This application differs from the usual fuel burning MGT in that it is required to operate at a wider operating speed range. The objective is to find an arrangement that allows reliable mechanical operation through better understanding of the rotor dynamics for a number of alternative shaft-bearings arrangements. Finite Element Analysis (FEA) was used to produce Campbell diagrams and to determine the critical speeds and mode shapes. Experimental hammer tests using a new approach based on optical sensing technology were used to validate the rotor-dynamic models. The FEA simulation results for the natural frequencies of a shaft arrangement were within 5% of the measurements, while the deviation for the shaft-bearings arrangement increased up to 16%.

Periodic Solutions in Rotor Dynamic Systems With Nonlinear Supports: A General Approach

1989 ◽  
Vol 111 (2) ◽  
pp. 187-193 ◽  
Author(s):  
C. Nataraj ◽  
H. D. Nelson
Keyword(s):  
Dynamic Systems ◽  
Original Problem ◽  
Squeeze Film ◽  
Algebraic Equations ◽  
Trigonometric Collocation ◽  
Nonlinear Algebraic Equations ◽  
The Stability ◽  
Future Work ◽  
Rotor Dynamic ◽  
Large Rotor

A new quantitative method of estimating steady state periodic behavior in nonlinear systems, based on the trigonometric collocation method, is outlined. A procedure is developed to analyze large rotor dynamic systems with nonlinear supports by the use of the above method in conjunction with Component Mode Synthesis. The algorithm discussed is seen to reduce the original problem to solving nonlinear algebraic equations in terms of only the coordinates associated with the nonlinear supports and is a big improvement over commonly used integration methods. The feasibility and advantages of the procedure so developed are illustrated with the help of an example of a typical rotor dynamic system with an uncentered squeeze film damper. Future work on the investigation of the stability of the periodic response so obtained is outlined.

scholarly journals Analysis of parameters effects on crack breathing and propagation in shaft of rotor dynamic systems

2013 ◽  
Vol 16 (4) ◽  
pp. 867-873 ◽  
Author(s):  
M. Serier ◽  
A. Lousdad ◽  
K. Refassi ◽  
A. Megueni
Keyword(s):  
Dynamic Systems ◽  
Rotor Dynamic

scholarly journals Implementing model reduction to the JuliaFEM platform

2018 ◽  
Vol 51 (1) ◽  
pp. 36-54 ◽  
Author(s):  
Marja Liisa Rapo ◽  
Jukka Aho ◽  
Hannu Koivurova ◽  
Tero Frondelius
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Model Reduction ◽  
Open Source ◽  
Degrees Of Freedom ◽  
Mass Matrices ◽  
Dynamic Condensation ◽  
Dynamic Analyses ◽  
Reduction Methods ◽  
Large Model

JuliaFEM is an open source finite element method solver written in the Julia language. This paper presents an implementation of two common model reduction methods: the Guyan reduction and the Craig-Bampton method. The goal was to implement these algorithms to the JuliaFEM platform and demonstrate that the code works correctly. This paper first describes the JuliaFEM concept briefly after which it presents the theory of model reduction, and finally, it demonstrates the implemented functions in an example model. This paper includes instructions for using the implemented algorithms, and reference the code itself in GitHub. The reduced stiness and mass matrices give the same results in both static and dynamic analyses as the original matrices, which proves that the code works correctly. The code runs smoothly on relatively large model of 12.6 million degrees of freedom. In future, damping could be included in the dynamic condensation now that it has been shown to work.

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