Page 175 - Intro Predictive Maintenance

166 An Introduction to Predictive Maintenance

Maximum frequency
F MAX
Minimum frequency
F MIN
External force
F 0
Spring force
F s
G Gravitational constant, 32.17ft/sec 2
H Elongation caused by the weight of the mass
Hz Hertz
i.e., That is
in. Inches
Ips Inches per second or inches/second
ips-PK Inches per second, zero-to-peak
K Torsional stiffness
K Spring constant or stiffness
Lbf Pounds-force
Lbm Pounds-mass
Unelongated spring length
L 0
M Mass
MHz Megahertz
PK Zero-to-peak
RMS Root-mean-square
Rpm Revolutions per minute or revolutions/minute
sec 2 Seconds squared
T Time
T Period or Torque
External torque
T 0
VPM Vibrations per minute or vibrations/minute
W Weight
X Displacement
Static displacement
X i
X 0 Amount of displacement from X i
1¥, 2¥, 3¥ 1 times, 2 times, 3 times

APPENDIX 7.2 Glossary

Acceleration The rate of change of velocity with respect
2
2
to time (ft/sec ) or (in/sec ).
Accelerometer Transducer used to measure acceleration.
Incorporates a piezoelectric crystal or film to
convert mechanical energy into electrical
signals.
Amplitude The magnitude or size of a quantity such as
displacement, velocity, acceleration, etc.,
measured by a vibration analyzer in con-
junction with a displacement probe, velocity
transducer, or accelerometer.