Week 11 And 12...
Preliminary Experimental Requirement
For the purpose of the experiment the I was provided with one
motor shaped electromagnets. Since the aim was to observe the effect of their
magnetic fields on a freely rotating pinion by rack, a suitable experimental
setup was necessary. The initial setup arrangement involved fabrication of a
circular pinion of conducting material which was to be mounted on a motor that
would be held in place and rotate of the shaft couple with pinion. One end of
the rack (bicycle chain) would be connected linear to spring to drive motor
which would be given output power based on rotation of the pinion. The other
end of the output life and neutral was to be connected to a small signal
analyzer that would produce a voltage versus time output which could then be
calibrated to give a speed versus time decay output. The experimental setup
plan is shown in Figure 1
Figure 1
Shortcomings of the Initial Setup
After fabricating most of the apparatus required for the
setup, with the help of the laboratory technologists, including the Capacitor
and Rectifier, Rectifier are being use to convert the ac to dc voltage for
making the output can be record easier. For the first try i got the voltage
output are not stable although the capacitor are used. So the measurement cannot
be record because unstable output. Beside that the output current are very low
so the power cannot be determine because the oscilloscope cannot display the
small value .Such conditions were absolutely not useful for my experiment and
thus with little time left on my hands and the current setup being unable to
allow for any testing or readings to be taken, other alternatives needed to be
explored.
Rotating Magnet(MOTOR) based on Spring Damping
Finally, in this week I go further an experiment to observe
the damping effect on a rotating motor by rack and pinion showed that the
velocity at which the shaft rotates by the different mass will affect the
magnitude of the eddy currents induced. Hence, the higher weight, the greater
will be the opposing force acting on the spring and thus, the greater will be
the damping effect. Hence it will not be in the focus of our experiment to
re-prove experimentally this fact that can be predicted by theory according to
the Lorentz force density equation
F = J x B = s (v x B) x B
The motor used in the experiment are electromagnets as the
magnetic field can be effectively contained within a small area when in use.
Measured magnetic flux densities are about 50 G at 1 cm away from the magnets.
Also, during transportation from place to place, with no power supply, the
electromagnets will generate a magnetic field. This ensures that electrical or
magnetic devices are accidentally exposed to the magnetic field.
Figure 1
Figure 2
The damping result based on force was investigated by taking
digital multimeter. The data was transferred to an Excel spreadsheet to make
the plots. For a first approximation, the motion could be modeled as in figure
1 the spring damping data are recorded when not using the motor while figure2the result for spring damping when using the motor as pinion.
To make sure it damaged before I
got the value, I have to make it quickly and snap the result directly. After
this experiment, my next step is to determine efficiency of my RSA module then
the real absorber. I hope all is well as schedule. :)
