Transcript
BJ Furman SJSU MAE
Vibration Measurement
BJ Furman22NOV05
San Jose State UniversityDepartment of Mechanical and Aerospace Engineering
ME 120 Experimental Methods
BJ Furman SJSU MAE
Vibration
Potential Kinetic energy interchange in bodies with finite stiffness and mass that arises from time dependent energy input
Unbalance in rotating machinesAcoustic energy inputFluid flowElectromagnetic
Y(t)
F(t)
BJ Furman SJSU MAE
Quantifying Vibration Amplitude
Peak level
Peak-to-peak
Average (rectified)
RMSTakes into account the timehistory of vibration
http://www.bksv.com/pdf/Measuring%20Vibration.pdf
BJ Furman SJSU MAE
Vibration Measurement Transducers cont.
VelocityGeophone
• Very sensitive, 20 V/g• Low frequencies• Low cost
Laser doppler vibrometer• Rate of change of phase
between reference beamand measurement beamproportional to velocity of target detector
fixed
vibration
laser
http://micromachine.stanford.edu/smssl/projects/Geophones/
( ) dyV t BDNdt
π=
Ref. beam
Meas. beam
BJ Furman SJSU MAE
Laser Doppler Vibrometer, cont.
Polytec PI
Velocity ranges (3): 5, 25 and 125 mm/s/V
Full scale output velocity: ±10 Volts analog
Max. signal frequency: 250 kHzDisplacement ranges (5):version OFV-2200-H
0,5 2, 8, 20 & 80 µm/V[Resolution: 2nm to 320nm (*)]
Displacement ranges (5):version OFV-2200-L
20, 80, 320, 1280 & 5120µm/V[Resolution: 80nm to 20µm (*)]
Full scale output displacement : ±8 Volts analogMaximum velocity for thedisplacement decoders: 1.6 m/s
Remote focus control: Standard with OFV-303
Interfaces: NoneDimensions:W x H x D
450mm x 360mm x 145mm17.7in. x 14.2in. x 5.7in.
Approximate Weight: 10.8kg (23.8lbs)
Compatible with sensor heads: OFV-303, OFV-353, OFV-511, OFV-512
http://www.polytec.de/polytec-com/index.html
OFV-2200
BJ Furman SJSU MAE
Vibration Measurement Transducers cont.
AccelerationAccelerometer
• PiezoelectricCompressionShearBending
http://www.endevco.com/PDFs/technical-data-sheets/TD530.pdf
http://www.mmf.de/PDF/AN3E-Accelerometer_Designs.pdf
Piezoresistive
BJ Furman SJSU MAE
Accelerometer Specifications
Endevco model 221 – 10,000 Hz0.14 gm
http://www.endevco.com/data-sheets/0-99/22.pdf
BJ Furman SJSU MAE
Accelerometers, cont.
MEMS accelerometersADXL150
http://www.analog.com/library/techArticles/mems/Sensor971/index.html
0.1 μgm
1.6 micron separation of mass to substrate
1.3 micron separation of cap plates
0.2 Angstrom beam deflection resolution
10 kHz – 20 kHz resonant frequency
http://archives.sensorsmag.com/articles/0201/20/index.htm
BJ Furman SJSU MAE
MEMS Accelerometers, cont.
ADXL105 single-axis accelerometer±5g range250 mV/g output (2 mg resolution achievable)DC sensitivityTilt and acceleration effects are confounded
Drive, sense, amplification, and signalconditioning on a single chipApplications:
Airbag crash sensorTilt sensorMachine condition monitoring
• Unbalance• Bearing or bushing failure• Tool failure
http://www.analog.com/productSelection/pdf/ADXL105_a.pdf
BJ Furman SJSU MAE
MEMS Accelerometers, cont.ADIS16201 - Programmable Dual-Axis Inclinometer/Accelerometer
Features• Dual-axis inclinometer/accelerometer
measurements• 12/14-bit digital inclination/acceleration sensor
outputs• +1.7 g accelerometer measurement range• +90o inclinometer measurement range• 12-bit digital temperature sensor output• Digitally controlled sensitivity and bias
calibration• Digitally controlled sample rate• Digitally controlled frequency response• Dual alarm settings with rate/threshold limits• Auxiliary digital I/O• Digitally activated self-test• Digitally activated low power mode• SPI® compatible serial interface• Auxiliary 12 bit ADC input and DAC output• Single-supply operation – 3.0 to 3.6V• 3500 g powered shock survivability
BJ Furman SJSU MAE
Thermal Accelerometers
http://www.memsic.com/memsic/products/technology.html
http://archives.sensorsmag.com/articles/0601/98/index.htm
BJ Furman SJSU MAE
References
Analog Devices, Inc., “Accelerometer Design and Applications, http://www.analog.com/library/techArticles/mems/sensor971.pdf, November 2002.Analog Devices, Inc., “Analog Devices Introduces Highly Integrated Motion Sensor For Industrial Applications,”http://www.analog.com/en/content/0,2886,764%255F800%255F86889,00.htmlBruel & Kjaer, “Measuring Vibration,” September, 1982. http://www.bksv.com/pdf/Measuring%20Vibration.pdfEndevco Corporation, “Vibration Application and Theory,”Application Note 530, October 1979, http://www.endevco.com/PDFs/technical-data-sheets/TD530.pdfFigliola, R. S., Beasley, D. E., Theory and Design for Mechanical Measurements, 3rd ed., J. Wiley & Sons, New York, 2000.Accelerometers and How They Work, http://www2.usfirst.org/2005comp/Manuals/Acceler1.pdf
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