Modeling of Oil-Film Forces in Squeeze-Film Bearings

1986 ◽  
Vol 108 (2) ◽  
pp. 262-269 ◽  
Author(s):  
C. R. Burrows ◽  
M. N. Sahinkaya ◽  
N. C. Kucuk
Keyword(s):  
Parameter Estimation ◽  
System Performance ◽  
Critical Speed ◽  
Nonlinear Models ◽  
Squeeze Film ◽  
Model Structure ◽  
Oil Film ◽  
Model Oil ◽  
Stiffness And Damping ◽  
Parameter Estimation Techniques

The role played by bearings in determining the dynamic characteristics of rotor-bearing systems is well known. This has led to various attempts to model oil-film force coefficients in terms of linearized stiffness and damping elements. The inadequacy of these theoretical coefficients to predict performance under certain conditions has led some authors to propose the use of nonlinear models. An alternative philosophy, developed in this paper, is to retain a linear model structure and seek to determine optimized coefficient values using modern parameter estimation techniques. It is shown that these estimated linearized parameters predict system performance more accurately than the theoretical linear coefficients; particularly when the rotor is operating near a critical speed.

Development of an Efficient Oil Film Damper for Improving the Control of Rotor Vibration

1991 ◽  
Vol 113 (4) ◽  
pp. 557-562 ◽  
Author(s):  
Shiping Zhang ◽  
Litang Yan
Keyword(s):  
High Speed ◽  
Porous Metal ◽  
Porous Matrix ◽  
Squeeze Film ◽  
Oil Film ◽  
Squeeze Film Damper ◽  
Outer Race ◽  
Typical Experiment ◽  
Stiffness And Damping ◽  
Film Stiffness

An efficient oil film damper known as a porous squeeze film damper (PSFD) was developed for more effective and reliable vibration control of high-speed rotors based on the conventional squeeze film damper (SFD). The outer race of the PSFD is made of permeable sintered porous metal materials. The permeability allows some of the oil to permeate into and seep out of the porous matrix, with remarkable improvement of the squeeze film damping properties. The characteristics of PSFD oil film stiffness and damping coefficients and permeability, and also, the steady-state unbalance response of a simple rigid rotor and flexible Jeffcott’s rotor supported on PSFD and SFD are investigated. A typical experiment is presented. Investigations show that the nonlinear vibration characteristics of the unpressurized SFD system such as bistable jump phenomena and “lockup” at rotor pin-pin critical speeds could be avoided and virtually disappear under much greater unbalance levels with properly designed PSFD system. PSFD has the potential advantage of operating effectively under relatively large unbalance conditions.

An Experimental Study of Nonlinear Oil-Film Forces in a Tilting-Pad Journal Bearing

2015 ◽  
Author(s):  
Phuoc Vinh Dang ◽  
Steven Chatterton ◽  
Paolo Pennacchi ◽  
Andrea Vania ◽  
Filippo Cangioli
Keyword(s):  
High Speed ◽  
Nonlinear Models ◽  
Reaction Force ◽  
Taylor Series Expansion ◽  
Test Model ◽  
Oil Film ◽  
Hydrodynamic Bearing ◽  
Dynamic Coefficients ◽  
Stiffness And Damping ◽  
Tilting Pad Journal Bearing

Journal bearings have been widely used in high-speed rotating machinery. The dynamic coefficients of oil-film force affect the machine unbalance response and machine stability. The oil-film force of hydrodynamic bearing is often characterized by a set of linear stiffness and damping coefficients. However the linear oil-film coefficients with respect to an equilibrium position of the journal are inaccurate when the bearing system vibrates with large amplitudes due to a dynamic load. The study on nonlinear oil-film forces is still rare and most papers are confined to theoretical analyses. The purpose of this paper is to derive some new non-linear force models (28-co., 24-co. and 36-co. models) to identify these dynamic coefficients based on experimental data. The fundamental test model is obtained from a Taylor series expansion of bearing reaction force. Tests were performed with a nominal diameter of 100mm and a length–to–diameter ratio of 0.7 using a suitable test rig in which it is possible to apply the static load in any direction. The results show that these three models are feasible to identify the oil-film forces in which the second-order oil-film coefficients received from the 24-co. model are more stable compared to those of other two nonlinear models.

Linearized Squeeze-Film Dynamics: Model Structure and the Interpretation of Experimentally Derived Parameters

1990 ◽  
Vol 204 (4) ◽  
pp. 263-272 ◽  
Author(s):  
C R Burrows ◽  
N C Kucuk ◽  
M N Sahinkaya ◽  
R Stanway
Keyword(s):  
Experimental Study ◽  
Parameter Estimation ◽  
Squeeze Film ◽  
Model Structure ◽  
Vibration Isolator ◽  
Dynamics Model ◽  
Squeeze Film Dampers

In this paper the authors address the problem of parameter estimation in linearized models of squeeze-film dampers. After demonstrating how the choice of an unsuitable model structure can lead to the misinterpretation of experimentally derived coefficients, a technique is described for assessing the significance of individual inertia, damping and stiffness effects associated with the squeeze-film. An experimental study involving a squeeze-film vibration isolator is described. It is shown how the technique allows the model structure to be simplified in a systematic way.

A Sensitivity Analysis of Squeeze-Film Bearings

1982 ◽  
Vol 104 (4) ◽  
pp. 516-522 ◽  
Author(s):  
C. R. Burrows ◽  
O. S. Turkay
Keyword(s):  
Sensitivity Analysis ◽  
Amplitude Spectrum ◽  
Squeeze Film ◽  
Valuable Insight ◽  
Model Structure ◽  
Oil Film ◽  
Phase Spectra ◽  
Insight Into

It is shown that amplitude and phase spectra should not be used to assess the quality of estimates of oil-film coefficients unless the results are interpreted in conjunction with a sensitivity analysis of the bearing model. The implications of using only the amplitude spectrum are discussed. Sensitivity analysis is shown to give valuable insight into the problem of selecting test signals for estimating oil-film coefficients. Moreover the analysis gives an indication of the validity of the model structure.

Development of an Efficient Oil Film Damper for Improving the Control of Rotor Vibration

1990 ◽  
Author(s):  
Shiping Zhang ◽  
Litang Yan
Keyword(s):  
High Speed ◽  
Porous Metal ◽  
Squeeze Film ◽  
Oil Film ◽  
Squeeze Film Damper ◽  
Outer Race ◽  
Squeeze Film Damping ◽  
Typical Experiment ◽  
Stiffness And Damping ◽  
Film Stiffness

An efficient oil film damper known as porous squeeze film damper (PSFD) was developed for more effective and reliable vibration control of high speed rotors based on the conventional squeeze film damper (SFD). The outer race of the PSFD is made of permeable sintered porous metal materials. The permeability allows some of the oil to permeate into and seep out the porous matix, with remarkebly improvement of the squeeze film damping properties. The characteristics of PSFD oil film stiffness and damping coefficients and permeability, also, the steady state unbalance response of a simple rigid rotor and flexible Jeffcott’s rotor supported on PSFD and SFD are investigated. A typical experiment is presented. Investigations show that the nonlinear vibration characteristis of the unpressurized SFD system such as bistable jump phenomena and “lockup” at rotor pin–pin critical speeds could be avoided and virtually disappear under much greater unbalance level with properly designed PSFD system. PSFD has the potential advantages to operate effectively under relative large unbalance conditions.

Design of a Squeeze-Film Damper for a Multi-Mass Flexible Rotor

1975 ◽  
Vol 97 (4) ◽  
pp. 1383-1389 ◽  
Author(s):  
Robert E. Cunningham ◽  
David P. Fleming ◽  
Edgar J. Gunter
Keyword(s):  
Computer Program ◽  
Critical Speed ◽  
Lubrication Theory ◽  
Squeeze Film ◽  
Flexible Rotor ◽  
Squeeze Film Damper ◽  
Flexible Support ◽  
Single Mass ◽  
Damper Design ◽  
Stiffness And Damping

A single mass flexible rotor analysis was used to optimize the stiffness and damping of a flexible support for a symmetric five-mass rotor. The flexible support attenuates the rotor motions and forces transmitted to the support bearings when the rotor operates through and above its first bending critical speed. An oil squeeze-film damper was designed based on short bearing lubrication theory. The damper design was verified by an unbalance response computer program. Rotor amplitudes were reduced by a factor of 16 and loads reduced by a factor of 36 compared with the same rotor on rigid bearing supports.

A coherent strategy for estimating linearized oil-film coefficients

1980 ◽  
Vol 370 (1740) ◽  
pp. 89-105 ◽  
Keyword(s):  
Parameter Estimation ◽  
Binary Sequence ◽  
Analytical Investigation ◽  
Basic Requirement ◽  
Structural Identifiability ◽  
Standard Methods ◽  
Estimation Techniques ◽  
Oil Film ◽  
Stiffness Coefficients ◽  
Parameter Estimation Techniques

This paper presents an analytical investigation of the problem of estimating the linearized inertia, damping and stiffness coefficients of a bearing oil film. The principle of structural identifiability has been used to define and compare the conditions to be fulfilled in order to estimate the coefficients when using various types of test signal. The analysis demonstrates the limitations of many standard methods for determining the coefficients and shows how these restrictions can be overcome by using pseudo-random binary sequence forcing. The necessity is stressed for parameter estimation to be performed without any prejudgement of the significance of particular coefficients. It is shown that this basic requirement can be satisfied by using modern parameter estimation techniques.

Ball bearing turbocharger vibration management: application on high speed balancer

2020 ◽  
Vol 21 (6) ◽  
pp. 619
Author(s):  
Kostandin Gjika ◽  
Antoine Costeux ◽  
Gerry LaRue ◽  
John Wilson
Keyword(s):  
Dynamic Behavior ◽  
High Speed ◽  
Internal Combustion Engines ◽  
Ball Bearing ◽  
Squeeze Film ◽  
Design And Technology ◽  
Squeeze Film Damper ◽  
Damping Coefficients ◽  
Bearing Loads ◽  
Stiffness And Damping

Today's modern internal combustion engines are increasingly focused on downsizing, high fuel efficiency and low emissions, which requires appropriate design and technology of turbocharger bearing systems. Automotive turbochargers operate faster and with strong engine excitation; vibration management is becoming a challenge and manufacturers are increasingly focusing on the design of low vibration and high-performance balancing technology. This paper discusses the synchronous vibration management of the ball bearing cartridge turbocharger on high-speed balancer and it is a continuation of papers [1–3]. In a first step, the synchronous rotordynamics behavior is identified. A prediction code is developed to calculate the static and dynamic performance of “ball bearing cartridge-squeeze film damper”. The dynamic behavior of balls is modeled by a spring with stiffness calculated from Tedric Harris formulas and the damping is considered null. The squeeze film damper model is derived from the Osborne Reynolds equation for incompressible and synchronous fluid loading; the stiffness and damping coefficients are calculated assuming that the bearing is infinitely short, and the oil film pressure is modeled as a cavitated π film model. The stiffness and damping coefficients are integrated on a rotordynamics code and the bearing loads are calculated by converging with the bearing eccentricity ratio. In a second step, a finite element structural dynamics model is built for the system “turbocharger housing-high speed balancer fixture” and validated by experimental frequency response functions. In the last step, the rotating dynamic bearing loads on the squeeze film damper are coupled with transfer functions and the vibration on the housings is predicted. The vibration response under single and multi-plane unbalances correlates very well with test data from turbocharger unbalance masters. The prediction model allows a thorough understanding of ball bearing turbocharger vibration on a high speed balancer, thus optimizing the dynamic behavior of the “turbocharger-high speed balancer” structural system for better rotordynamics performance identification and selection of the appropriate balancing process at the development stage of the turbocharger.

scholarly journals Set-membership identifiability of nonlinear models and related parameter estimation properties

2016 ◽  
Vol 26 (4) ◽  
pp. 803-813 ◽  
Author(s):  
Carine Jauberthie ◽  
Louise Travé-MassuyèEs ◽  
Nathalie Verdière
Keyword(s):  
Mathematical Model ◽  
Parameter Estimation ◽  
Dynamic System ◽  
Nonlinear Models ◽  
Differential Algebra ◽  
Related Parameter ◽  
Set Membership ◽  
Estimation Problems ◽  
The Mathematical Model

Abstract Identifiability guarantees that the mathematical model of a dynamic system is well defined in the sense that it maps unambiguously its parameters to the output trajectories. This paper casts identifiability in a set-membership (SM) framework and relates recently introduced properties, namely, SM-identifiability, μ-SM-identifiability, and ε-SM-identifiability, to the properties of parameter estimation problems. Soundness and ε-consistency are proposed to characterize these problems and the solution returned by the algorithm used to solve them. This paper also contributes by carefully motivating and comparing SM-identifiability, μ-SM-identifiability and ε-SM-identifiability with related properties found in the literature, and by providing a method based on differential algebra to check these properties.

Sign in / Sign up

Export Citation Format

Share Document