Vibration Measurement - Pearl HiFi

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

DisplacementLVDTEddy currentCapacitiveHall

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

Acceleration Levels

http://www2.usfirst.org/2005comp/Manuals/Acceler1.pdf

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