ROMAC Stability Test Fig

Superior Essays
subsection{Experiment description}
In order to validate this data procedure and estimation method, we carried out experiment on the ROMAC stability test rig as depicted in Fig. ef{fig2:subfig:a}. The fluid and magnetic bearing configurations were in cite{cloud2007stability}, and during the excitation process, the temperature of inlet oil was 37 ${}^{circ}mathrm{C}$. The shaft rotates at 3500 rpm, and the actuator #2 that is located at the node 47 in the FE model excited this test rig at six frequencies (55 Hz to 80 Hz by step of 5 Hz). The excitation force is expressed in Eq.( ef{eq32}). egin{equation}label{eq32}
m{F}{
m{ = }}left( {egin{array}{*{20}{c}}
{{F_{ex}}}\
{{F_{ey}}} end{array}} ight) = {F_e}left( {egin{array}{*{20}{c}}
{Xcosleft( {omega t} ight)}\ {Ysin left( {omega t} ight)} end{array}} ight) end{equation} The coefficients of X and Y are used to adjust the amplitude of the excitation force in 푋 and 푌 directions.By adjusting the excitation force according to Table ef{tab10}, we did multiple excitations for every excitation frequency to obtain high quality estimation in Eq.( ef{eq16}) and ( ef{eq17}).
…show more content…
egin{table}[htbp] small caption{Comparison between measured and predicted rotor free-free natural frequencies}label{tab10} centering egin{tabular}{lcc} oprule Excitation method& X& Y\ midrule Excitation in X& 1.0& 0\ Excitation in Y& 0& 1.0\ Forward and backward& 1.0& $pm$1.0\ Cross-coupled excitation 1& 1.0& $pm$0.5\ Cross-coupled excitation 2& $pm$0.5& 1.0\ ottomrule end{tabular} end{table} In the test, vibrations at five sections (Nodes 6, 13, 44, 56 and 62) were measured, and the data of four sections (Nodes 6, 13, 56 and 62) were used to identify the coefficients of bearing by using this interpolation-iteration method. Moreover, the location of the sensors is shown in Fig. ef{fig11}, and the sensors at node 62 are supported by portable magnetic base. All the measured vibrations and excitation magnetic force were transferred to the same coordinate that is plotted in Fig. ef{fig11}. egin{figure}[htbp] centering includegraphics[width=5cm]{Fig11} caption{Sensor positions} label{fig11} end{figure} subsection{Experiment results} Figures ef{fig12} and ef{fig13} show the estimated force coefficients of bearings with test data. Figure ef{fig12} depicts the estimated principle coefficients of the two bearings. With the increase of the excitation frequency, the principle stiffness coefficients of the left bearing remain nearly invariant, while those of the right bearing decrease a little. The principle damping coefficients of the left bearing slightly decrease with the excitation frequency, and those of the right bearing almost keep horizontal except for a small projection at 70Hz. Moreover, the principle stiffness $Kxx$ and $Kyy$ of the left bearing are larger than those of right bearing, and $Cxx$ and $Cyy$ of the left bearing are smaller than those of the right bearing. For each bearing, $Kxx$ and $Kyy$ are very close, and so are the …show more content…
ef{fig15}. The first forward log decrement remain nearly invariant in the excitation frequency range, while the first backward frequency drops a little.

egin{figure}[htbp] centering includegraphics[width=8cm]{Fig15.pdf} caption{Mode paramenters} label{fig15} end{figure} Using the sine-swept excitation method, we did both backward and forward excitaions for the test rig, and Fig. ef{fig16:subfig} shows the full spectrum waterfall for the left bearing (Node 10). Using the idenitification method [Li], the first mode parameters are estimated (1B: f=85.3Hz, LogDec=0.726; 1F: 86.3Hz, LogDec=0.442). By comparing the prdicted and measured first forward mode parameters, we can drow conclusion that the force coeffients of bearings are reasonably

Related Documents

  • Improved Essays

    The Sandlot Analysis

    • 605 Words
    • 3 Pages

    Legends Never Die The Sandlot is a movie I could appreciate as a kid and continue to appreciate as an adult. Every time I watch this film, I find myself nodding with approval. It's a simple yet entertaining portrait about life as a young boy and the various adventures that create nothing but fond memories. The Sandlot is an unforgettable film, filled with friendship and adventure.…

    • 605 Words
    • 3 Pages
    Improved Essays
  • Decent Essays

    Nt1310 Unit 1 Lab 1

    • 737 Words
    • 3 Pages

    Conclusion: This experiment provides an experience on how to apply stresses test in real-world problems. For solving a problem economically, multiple factors should be considered, for example, the crank set’s power efficiency, maximum possible normal and shears stress; weight should be tested for manufacturing. Before building a prototype of a design, build its mathematical model can solve many potential problems in advance, in this experiment, it mathematical model predicts the performance of the system very close to the experiment result. The stress out put of the system is not consistent, for the rider’s speed is not necessarily consistent, further experiment can be performed under consistent speed, for it can influence experiment result a…

    • 737 Words
    • 3 Pages
    Decent Essays
  • Decent Essays

    Unit 4 Ps154 Assignment

    • 421 Words
    • 2 Pages

    PS154 Assignment Submission 2015/2016 by Ali Clarke, ali.clarke45@mail.dcu.ie Student No.: 15342121 Physics Module PS154 Assignment 1 Notes: Use this document as your assignment submission template Use as many pages as necessary The assignment that you submit should be entirely your own work.…

    • 421 Words
    • 2 Pages
    Decent Essays
  • Improved Essays

    This could also lead to evolution, survival of the fittest, overpopulation and the extinction of others. Limiting factors can be many things like space, food, light and many other things. For Sunflowers and example that would lead to carrying capacity would be if all the organisms that consumed or killed the plant would be removed from its environment by an invasive species or environmental changes, then the Sunflowers would grow faster and closer to each other. This would cause space, water, and sunlight to become a limiting factor. Helianthus need lots of space for their long roots to receive water.…

    • 909 Words
    • 4 Pages
    Improved Essays
  • Improved Essays

    Each test yielded its own unique set of observations, calculations and results. In order to determine these various values through calculation, the experimental data as well as the chemical reaction of calcium hydroxide was used for all calculations. The chemical equation is displayed below: The first experiment determined the molarity of OH- and Ca2+, the Ksp and the ΔG for saturated calcium hydroxide at 21°C. In order to determine these values, the experimental data as well as the chemical reaction of calcium hydroxide was used.…

    • 889 Words
    • 4 Pages
    Improved Essays
  • Great Essays

    A Fault Tree Essay

    • 1481 Words
    • 6 Pages

    Nanjing University of Aeronautics and Astronautics Graduation Thesis Assignment Letter College College of International Education Major _ Aeronautic Engineering __ Topic Fault tree Analysis of Main Landing Gear System for Civil Aircraft Student Name Zeshan Ellahi ID Number191261230 Deadline _______2016.06.08____________ Location __Jiangning District_11501B__ Faculty Advisor Lu Zhong…

    • 1481 Words
    • 6 Pages
    Great Essays
  • Improved Essays

    Essay On Kinetic Friction

    • 612 Words
    • 3 Pages

    Purpose: To study sliding friction and to determine the coefficients of static and kinetic friction. Theory: Friction is a force that opposes motion. Static friction prevents an objects being set into motion by an external force. Kinetic friction opposes the progress of a sliding object.…

    • 612 Words
    • 3 Pages
    Improved Essays
  • Great Essays

    Results improve only after the application of filters. A free from filtering T-F analysis for the varying spectral characteristics of pressure signals is recommended. In STFT, window size limits to either fine spectral or fine temporal resolutions. Although, compromizing on time resolution in our case, STSF identified rotating stall frequency on waterfall plot and spectrogram but left a question mark on temporal resolution and hence in detecting the rotating deisturbance. AWT features both Fourier transform and wavelet transform.…

    • 1521 Words
    • 7 Pages
    Great Essays
  • Improved Essays

    The mini torsion device that will be designed for this senior design project will apply a torsional load to a small cylindrical sample with a diameter of 5 mm or 6 mm. The device will need to fit under an optical microscope and will not be able to exceed the weight limits of the sample stage on the optical microscope so that Raman microscopy can be performed on the sample while it is under a torsional load. The device will also need to collect data and calculate the angle of twist of the sample. A significant part of the device design is the data acquisition and angle of twist measurement. The purpose of this tech memo is to research possible options for data acquisition and measurement of the angle of twist that can be used in the design of…

    • 1387 Words
    • 6 Pages
    Improved Essays
  • Superior Essays

    The Hale family, though not of the working class, also relocates to the dreary and smoke filled city of Milton. Margaret’s father, a former vicar of England “[suffers] for conscience’ sake” and can no longer fulfill his religious duties. They arrive in Milton, and are met with the reality of factories being over saturated with not only men, but some women and children too. The city's true forthcomings originally leave Margaret, and especially that of her mother, distraught; but once she makes the acquaintance of Bessy Higgins, a factory worker’s daughter, she starts to care more for the city and hardworking people in it. Elizabeth Gaskell does a fine job of thoroughly writing the accounts of her character’s, and by doing so, provides a rather realistic window into the working and civilian life among those living in the rush of…

    • 1216 Words
    • 5 Pages
    Superior Essays
  • Improved Essays

    Elekta Synergy S linear accelerator (LINAC) was used to produce the 6, 10, and 15MV photon beams for measurements. The accelerator is fitted with the new Agility multileaf collimators (MLC) thinner than the previously used MLC’s to improve a field definition (Kantz et al. 2015; Thompson et al. 2014). The quality assurance was carried out monthly to ensure the LINAC response does not vary from the commissioning data (CPQR 2013). The LINAC has been calibrated to 100 cGy/MU at Dmax for a 10×10 cm2, and daily output checking was performed to ensure that LINAC operated within the ±3% limit (Andreo et al. 2006). 3.2 Film 3.2.1 Kodak X-OMAT V/EDR2 film 3.2.2.1 Calibration curve…

    • 1563 Words
    • 7 Pages
    Improved Essays
  • Great Essays

    Crank Arms Case Study

    • 1496 Words
    • 6 Pages

    2. Crank Arms The crank arms presented here have never been evaluated experimentally. All discussions on performances are speculative only.…

    • 1496 Words
    • 6 Pages
    Great Essays
  • Improved Essays

    Chemical Formula Essay

    • 1225 Words
    • 5 Pages

    While engine performance like brake power, brake specific fuel consumption, brake thermal efficiency, brake mean effective pressure and volumetric efficiency are calculated. The torque is determined by the following relation, [3and63]: T= m g r (3.4) Where g : The acceleration due to gravity= 9.81 m.s-2 The brake power developed is calculated from the relation: P_b= 2πNT (3.5) The fuel consumption is determined by measuring the time (t) taken for the engine to consume a given volume of fuel and can be determined by the following equation: ṁ_f=(ρ_f…

    • 1225 Words
    • 5 Pages
    Improved Essays
  • Improved Essays

    Bearing Ring Essay

    • 726 Words
    • 3 Pages

    Fatigue and spalling are common failure modes in the process of using rolling bearing, they mainly appear on surface of the raceway and rolling body[1]. The micro level defects in bear 's surface will affect the performance of the whole system, which requires the surface quality of the parts to be greatly improved after mechanical processing[1]. The surface quality of bearing ring has great influence on the normal operation under complicated working conditions. Roughness, hardness and residual stress will affect the normal service life and durability of the bearing…

    • 726 Words
    • 3 Pages
    Improved Essays
  • Great Essays

    Figure 5.8 is a pulse height spectrum of the net counts of the beta- emitting radionuclide, 137Cs as a function of pulse height voltage. Within Figure 5.8, the majority of the counts reside in the low voltage region, below 25 mV. It is possible to discriminate the between the different particle types by virtue of the pulse height distribution and establishing detection window threshold within the detection unit. As discussed earlier, it is possible to establish a lower threshold limit that eliminates pulses from background and noise. In addition establishing an upper threshold would determine a region where the majority of the beta pulses will be detected. This region will be identified at the Beta (βo) window.…

    • 1980 Words
    • 8 Pages
    Great Essays