scholarly journals Rotor Instability Induced by Radial Clearance in Ball Bearing Supports

1993 ◽  
Author(s):  
Yao-Qun Lin
Keyword(s):  
Experimental Investigation ◽  
Internal Friction ◽  
Natural Frequency ◽  
Computer Simulations ◽  
Ball Bearing ◽  
Rotor Dynamics ◽  
Experimental Results ◽  
Radial Clearance ◽  
Speed Range ◽  
Theoretical Predictions

In rotor dynamics, the rotor nonsynchronous natural frequency vibration, or rotor instability, has been mainly ascribed to two mechanisms, i.e., internal friction effects and fluid actions. It is shown, however, in this paper that the radial clearance in ball bearing supports can also induce rotor instability through an internal-impacts mechanism. The behavior of the rotor with radial clearance in its ball bearing supports is simulated numerically. The computer simulations show that there is a speed range in which the rotor will vibrate at both the synchronous frequency and the natural frequency. Below or above this speed range, the rotor has only the synchronous response and its harmonics. An experimental investigation was conducted to verify this analysis. The experimental results agree well with the theoretical predictions.

A Theoretical and Experimental Investigation of a Gas Operated Bearing Damper for Turbomachinery: Part II — Experimental Results and Comparison With Theory

1993 ◽  
Author(s):  
Padmanabhan Sundararajan ◽  
John M. Vance
Keyword(s):  
Experimental Investigation ◽  
High Temperature ◽  
Theoretical Model ◽  
Natural Frequency ◽  
Experimental Results ◽  
Experimental Measurements ◽  
Vibration Damper ◽  
Theoretical Predictions ◽  
Present Design ◽  
Gas Damper

Abstract This is the second of two papers describing results of a research project directed at developing a gas operated vibration damper for high temperature turbomachinery applications. This part presents the experimental measurements made on three variations of the gas damper hardware and compares them with the theoretical predictions presented in Part I. It is found that the isentropic theoretical model predicts the damper characteristics quite well. A maximum damping of 13.2 Ib-s/in was measured for a single actuator at a natural frequency of 100 hz using the present design and the results suggest that significantly higher damping levels are possible with design modifications.

A Theoretical and Experimental Investigation of the Dynamic Response of a Slider-Crank Mechanism With Radial Clearance in the Gudgeon-Pin Joint

1990 ◽  
Vol 112 (2) ◽  
pp. 183-189 ◽  
Author(s):  
K. Soong ◽  
B. S. Thompson
Keyword(s):  
Experimental Investigation ◽  
Dynamic Response ◽  
Dynamical Behavior ◽  
Kinematic Chain ◽  
Analytical Investigation ◽  
Rigid Bodies ◽  
Radial Clearance ◽  
Revolute Joints ◽  
Theoretical Predictions ◽  
Crank Mechanism

A comprehensive analytical investigation of the dynamic response of a general planar kinematic chain comprising an assemblage of articulating interconnected rigid-bodies with bearing clearances in the revolute joints is presented. The equations governing the dynamical behavior of this general mechanical system are established by incorporating a four-mode model of the phenomenological behavior of the principal elements of each revolute joint into the generalized form of Lagrange’s equations. The proposed methodology is then employed to predict the dynamic behavior of a planar slider-crank mechanism with radial clearance in the gudgeon-pin joint prior to comparing these theoretical predictions with the corresponding response-data from a complementary experimental investigation.

A Gas-Operated Bearing Damper for Turbomachinery—Theoretical Predictions Versus Experimental Measurements: Part II—Experimental Results and Comparison With Theory

1995 ◽  
Vol 117 (4) ◽  
pp. 750-756 ◽  
Author(s):  
P. Sundararajan ◽  
J. M. Vance
Keyword(s):  
High Temperature ◽  
Theoretical Model ◽  
Natural Frequency ◽  
Experimental Results ◽  
Experimental Measurements ◽  
Vibration Damper ◽  
Research Project ◽  
Theoretical Predictions ◽  
Present Design ◽  
Gas Damper

This is the second of two papers describing results of a research project directed at developing a gas-operated vibration damper for high-temperature turbomachinery applications. This part presents the experimental measurements made on a gas damper hardware and compares them with the theoretical predictions given in Part I. It is found that the isentropic theoretical model predicts the damper characteristics quite well. A maximum damping of 2310 N-s/m (13.2 lb-s/in.) was measured at a natural frequency of 118 Hz using the present design and the results suggest that significantly higher damping levels are possible with design modifications.

scholarly journals Generalized Resonance Sensor Based on Fiber Bragg Grating

Photonics ◽  
2021 ◽  
Vol 8 (5) ◽  
pp. 156
Author(s):  
Xinxin Chen ◽  
Enbo Wang ◽  
Yali Jiang ◽  
Hui Zhan ◽  
Hongwei Li ◽  
...  
Keyword(s):  
Fiber Bragg Grating ◽  
Natural Frequency ◽  
Pulse Signal ◽  
Basic Structure ◽  
Rolling Bearing ◽  
Experimental Results ◽  
Bragg Grating ◽  
Resonance Sensor ◽  
Theoretical Predictions ◽  
Bearing Damage

In response to the difficulty of weak detection of early bearing damage, resonance demodulation technology and the principle of fiber Bragg grating sensing strain were combined to design a fiber Bragg grating generalized resonance sensor, which can extract the weak pulse signal of weak detection of early bearing’s early damage from rolling bearing. First, a principle of resonance dynamics of second-order mechanical systems based on fiber Bragg grating and generalized resonance principles is proposed. Second, the basic structure of the sensor is designed. Then, ANSYS finite element simulation is used to analyze the natural frequency of the sensor. Finally, the natural frequency value of the sensor was obtained through experiments. The experimental results of proof-of-principle show that the experimental results are consistent with the theoretical predictions. The theoretical model is accurate, which verifies the feasibility of the sensor.

The Influence of Oil Supply Pressure on the Behavior of a Rigid Symmetrical Balanced Rotor in Journal Bearings With Circumferential Feeding

1992 ◽  
Vol 114 (4) ◽  
pp. 812-817 ◽  
Author(s):  
G. Capone ◽  
M. Russo ◽  
R. Russo
Keyword(s):  
Experimental Investigation ◽  
Journal Bearings ◽  
Experimental Results ◽  
Specific Load ◽  
Static Characteristics ◽  
Supply Pressure ◽  
Film Instability ◽  
Low Load ◽  
Theoretical Predictions ◽  
Load Conditions

A theoretical-experimental investigation was carried out on the behavior of a rigid symmetrical balanced rotor in short, cylindrical, circumferentially fed journal bearings under low load conditions. The influence of supply pressure on bearing static characteristics and oil film instability threshold was evaluated for the above system. The experimental results are shown along with the theoretical predictions of the static characteristics and limit stability curves for different values of the ratio between supply pressure and specific load.

Machining Forces: Some Effects of Tool Vibration

1965 ◽  
Vol 7 (2) ◽  
pp. 152-162 ◽  
Author(s):  
P. W. Wallace ◽  
C. Andrew
Keyword(s):  
Thrust Force ◽  
Chip Thickness ◽  
Experimental Results ◽  
Tool Vibration ◽  
Undeformed Chip Thickness ◽  
Speed Range ◽  
Theoretical Predictions ◽  
Thrust Forces ◽  
Good Agreement ◽  
Made In

When tool vibration occurs during machining both the undeformed chip thickness and the cutting forces have oscillating components. An examination of previous work reveals that both the relative phases and amplitudes of the oscillating forces and the oscillating undeformed chip thickness can be affected appreciably by changes in frequency. The explanations for this behaviour which have been put forward are not entirely consistent with previous experimental evidence. In the present work an analysis of the thrust forces occurring during tool vibration is proposed. The analysis is based on the assumption that there are two components to the oscillating thrust force: (1) a component proportional to, and in phase with, the oscillations in undeformed chip thickness and (2) a component, caused by contact between a small area of the tool flank and the freshly cut work surface, which leads the oscillation in undeformed chip thickness by 90°. Experimental results are presented which validate the assumptions made in the analysis. On applying the analysis to present and past experimental results, there is good agreement between theory and experiment when cutting at sufficient speed to prevent the formation of a substantial built-up edge: when cutting within the built-up edge speed range the theoretical predictions are less satisfactory, though still qualitatively correct. The results also show that changes in undeformed chip thickness have a smaller effect on the tool forces under vibratory conditions than under steady conditions.

Journal Bearing Lubrication and Design

1948 ◽  
Vol 158 (1) ◽  
pp. 250-254
Author(s):  
A. S. T. Thomson
Keyword(s):  
Experimental Investigation ◽  
Applied Load ◽  
Journal Bearing ◽  
Point Contact ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Experimental Results ◽  
Radial Clearance ◽  
Series Of Experiments ◽  
Loaded Side

The paper summarizes the results of an experimental investigation on the effects of variation in bearing width and radial clearance on the operating conditions of centrally loaded clearance journal bearings, the bearing arc being kept constant at 120 deg. The investigation, which was carried out prior to 1940, is complementary to an earlier paper by the author in which the effects of variations in bearing width and arc of embrace were investigated. The experimental results are compared with theoretical values modified by the relevant leakage coefficients. The measure of agreement obtained indicates that theoretical values so modified may be used with confidence in design. A short series of experiments is described; in these, high-point contact at starting and stopping is eliminated by supplying oil to a groove in the loaded side of the bearing at a pressure sufficiently great to overcome the applied load. The effect of a groove on the loaded side of the brass under various conditions of lubrication is investigated.

Experimental Investigation of a System With Multiple Nearly Identical Centrifugal Pendulum Vibration Absorbers

2003 ◽  
Author(s):  
Tyler M. Nester ◽  
Alan G. Haddow ◽  
Steven W. Shaw
Keyword(s):  
Experimental Investigation ◽  
Theoretical Background ◽  
Experimental Results ◽  
Circular Path ◽  
Vibration Absorbers ◽  
Test Apparatus ◽  
Controlled Experiments ◽  
Theoretical Predictions ◽  
Centrifugal Pendulum Vibration Absorbers ◽  
First Time

This paper presents experimental results from tests completed on a rotor system fitted with nearly-identical circular path centrifugal pendulum vibration absorbers. A brief review of theoretical background for the absorbers is given along with an overview of the test apparatus. The experimental results for one absorber and for four absorbers are presented and compared with theoretical predictions and expectations. To the best knowledge of the authors, this is the first time that systematic, controlled experiments that monitored both the response of the absorbers and the rotor have been undertaken.

Experimental Investigation of the Biaxial Load-Extension Properties of Plain, Weft-Knitted Fabrics

1977 ◽  
Vol 47 (4) ◽  
pp. 233-239 ◽  
Author(s):  
Brian M. Macrory ◽  
J. Roger Mccraith ◽  
A. B. McNamara
Keyword(s):  
Experimental Investigation ◽  
Theoretical Analysis ◽  
Experimental Results ◽  
Knitted Fabric ◽  
Knitted Fabrics ◽  
Test Instrument ◽  
Biaxial Load ◽  
Theoretical Predictions ◽  
End Use ◽  
Good Agreement

A test instrument is described which permits measurement of load and extension along the courses and wales of a knitted fabric as the latter is being extended in both directions simultaneously. The rates of extension may be chosen to deform the fabric in a variety of modes representative of end-use situations. Experimental results obtained for plain, weft-knitted fabrics using three different hosiery yarns are presented. Comparison is made with values predicted by the authors' theoretical analysis of the biaxially-loaded fabric configuration, and good agreement between the experimental results and the theoretical predictions is obtained.

Nonlinear resonant characteristics of shallow fluid layers

2007 ◽  
Vol 366 (1868) ◽  
pp. 1331-1346 ◽  
Author(s):  
J. Jonathan Kobine
Keyword(s):  
Experimental Investigation ◽  
Free Surface ◽  
Asymptotic Analysis ◽  
Natural Frequency ◽  
Small Amplitude ◽  
Nonlinear Resonance ◽  
Surface Configuration ◽  
Shallow Layer ◽  
Fluid Layers ◽  
Theoretical Predictions

Results are presented from an experimental investigation of the motion of a shallow layer of water in a square tank that was oscillated horizontally with small amplitude at frequencies close to the natural frequency of the layer. The aim was to assess the validity of certain theoretical predictions relating to nonlinear resonance in shallow layers based on asymptotic analysis. These concern the hysteretic nature of the resonance profile and the existence of non-trivial oscillatory components associated with shock-like discontinuities in the derived solution for the free surface configuration. The experimental results support the theoretical predictions and show a coincidence in parameter space between the regions of hysteresis and oscillatory transition.

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