|
Mass | Damping
| Stiffness |
Initial
displacement | Impact | Transducers
|
|
A more detailed discussion of system parameter values
can be found in the Initial Displacement Project Assignment currently in
use at U Mass Lowell. |
| RUBE Initial Displacement
Project Assignment |
PDF |
|
|
Mass
|
The moving
mass of the system consists of the sum of the mass of the water and the
mass of all of the other moving parts of the system.
The water
tank has total volume of 12 oz which contributes to a mass
variability of approx 20%. The height of the water in the tank for each
run can be determined from the video/photograph of the system.
Though the level of water in the tank is changing continuously, the mass
of water in the tank only changes at an average rate of 0.1% during one
system run. A discussion of system parameters can be found in the Project
Assignment
|
|
|
Damping
 |
A
variable dashpot is used to add damping to the system. As is the
case with virtually all real physical systems, detailed information
is not given on the magnitude of the damping . |
|
|
Stiffness
The spring portion of the system consists of a leaf
spring with varying support conditions and a coil spring. the stiffness of
the system can vary by approximately 20%. Detailed discussion of stiffness can be found in
the Project Assignment.
|
|
Initial
displacement
|
A tri-lobed cam is used to
give the system an initial displacement. Each of the three lobes
applies a different displacement. The magnitude of the initial
displacement for each run can be determined from the LVDT
displacement data. |
Impact
|
|
An electric solenoid is used to
give the system an impact excitation. . The magnitude of the impact for each run can be determined from the
force transducer data.
|
|
|
Transducers
Five
transducers obtain data from the system: three accelerometers, one LVDT (Linear Variable Displacement Transducer),
and one force transducer. Good transducers are available, which provide
relatively clean data. However "bad" transducers, contaminated by noise,
drift, bias, quantization error and filtering are also used.
| Column number in dataset |
Data description |
Sensitivity of transducer |
| 1 |
Time (sec) |
- |
| 2 |
LVDT (V) |
9.97 V/in |
| 3 |
Accelerometer 1 (V) |
10.4 mV/g |
| 4 |
Accelerometer 2 (V) |
92.9 mV/g |
| 5 |
Accelerometer 3 (V) |
994 mV/g |
| 6 |
Force Transducer (V) |
51.5 mV/lbf |
|
