scholarly journals Discussion: “The Determination of Squeeze Film Dynamic Coefficients From Transient Two-Dimensional Experimental Data” (Roberts, J. B., Ellis, J., and Hosseini Sianaki, A., 1990, ASME J. Tribol., 112, pp. 288–296)

1990 ◽  
Vol 112 (2) ◽  
pp. 296-297
Author(s):  
Meng Guang ◽  
J. M. Vance
Keyword(s):  
Experimental Data ◽  
Squeeze Film ◽  
Two Dimensional ◽  
Dynamic Coefficients

The Experimental Determination of Squeeze-Film Dynamic Coefficients Using the State Variable Filter Method of Parametric Identification

1989 ◽  
Vol 111 (2) ◽  
pp. 252-259 ◽  
Author(s):  
J. Ellis ◽  
J. B. Roberts ◽  
M. D. Ramli
Keyword(s):  
Parametric Identification ◽  
Squeeze Film ◽  
Filter Method ◽  
State Variable ◽  
Dynamic Coefficients ◽  
Low Weight ◽  
State Variable Filter ◽  
Film Stiffness ◽  
Forced Excitation

The state variable filter method of parametric identification is applied in the determination of squeeze-film dynamic coefficients from forced excitation tests on an experimental rig. The experimental squeeze-film damper had a centralizing spring, a central circumferential oil feed groove, and no end seals. Forced excitation tests are recorded at various journal support system natural frequencies and at different journal eccentricities. From these tests, estimates of the direct squeeze-film damping, stiffness and inertial coefficients are derived and presented. These results are shown to be in good agreement with results recently obtained using an independent frequency domain technique. The experimental damping and inertial coefficients were found to be considerably larger than values predicted by conventional short-bearing theory, but relatively insensitive to the support system’s natural frequency (and the forcing frequency) for most of the range investigated. The fluid film stiffness coefficient values at low values of the system’s natural frequency agreed with results from static stiffness tests. Two geometrically identical journals were used, one of steel and one of a low-weight, magnesium alloy. The use of the low weight journal markedly reduced the scatter in the inertial and film stiffness coefficients.

Determination of Squeeze-Film Dynamic Coefficients From Experimental Transient Data

1987 ◽  
Vol 109 (1) ◽  
pp. 155-163 ◽  
Author(s):  
M. D. Ramli ◽  
J. B. Roberts ◽  
J. Ellis
Keyword(s):  
Parametric Identification ◽  
Optimization Techniques ◽  
Squeeze Film ◽  
Dynamic Coefficients ◽  
Free Decay ◽  
Transient Data

A technique for obtaining estimates of the direct damping and inertial coefficients of a squeeze-film bearing is described. This involves applying parametric identification and optimization techniques to digitized, free-decay experimental displacement records. The experimentally obtained coefficients, derived by this technique, were found to be significantly higher in magnitude (in some cases by a factor of about 10) than the corresponding values derived from conventional short-bearing theory, and to be virtually independent of the frequency of vibration.

The Determination of Squeeze Film Dynamic Coefficients From Transient Two-Dimensional Experimental Data

1990 ◽  
Vol 112 (2) ◽  
pp. 288-296 ◽  
Author(s):  
J. B. Roberts ◽  
J. Ellis ◽  
A. Hosseini Sianaki
Keyword(s):  
Experimental Data ◽  
Simulated Data ◽  
Degree Of Freedom ◽  
Squeeze Film ◽  
Two Dimensional ◽  
Computationally Efficient ◽  
Response Data ◽  
Lumped Parameter ◽  
Experimental Trials ◽  
State Variable Filter

A state variable filter (SVF) method of identifying parameters in lumped-parameter systems is extended to accommodate multi-degree-of-freedom problems. The method is computationally efficient and can be used with both transient and forced squeeze-film response data. In this paper the method is successfully applied to the analysis of transient simulated data both with and without signal noise. Finally the method is shown applied in the analysis of two-dimensional transient experimental data from a squeeze-film bearing rig. The identified results for the dynamic film coefficients compare well with results from earlier single-degree-of-freedom experimental trials.

Modelling of Moisture Movement in Wood during Outdoor Storage

2001 ◽  
Vol 6 (2) ◽  
pp. 3-14 ◽  
Author(s):  
R. Baronas ◽  
F. Ivanauskas ◽  
I. Juodeikienė ◽  
A. Kajalavičius
Keyword(s):  
Experimental Data ◽  
Finite Difference ◽  
Climatic Conditions ◽  
Two Dimensional ◽  
Moisture Movement ◽  
Finite Difference Technique ◽  
Long Term Storage ◽  
Space Formulation ◽  
Term Storage

A model of moisture movement in wood is presented in this paper in a two-dimensional-in-space formulation. The finite-difference technique has been used in order to obtain the solution of the problem. The model was applied to predict the moisture content in sawn boards from pine during long term storage under outdoor climatic conditions. The satisfactory agreement between the numerical solution and experimental data was obtained.

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