Results

Success

The team was able to build a mechanically functioning machine. The split collar fits almost perfectly on the shaft and in the bearing, and is very well balanced (by virtue of its fabrication on a balanced lathe). The delicate shaft mounts appropriately on its supports without damage, and is rotated very easily by the motor. The motor speed is varied successfully with the controller built by the team, and it receives enough power from the AC/DC converter to rotate the shaft at and above the maximum speed of interest (by visual inspection).

Figure – Complete set-up

The analysis portion of the software was a success as well. Tested with simulated signals, it acquires the raw data from both the tachometer and accelerometer, processes them through filters and FFT, and performs all the required calculations appropriately. Results are shown on the Front Panel display on the Measure tab. See figures below.

Figure – Front panel display showing operation buttons, tachometer readout for rot/s, and inputs for trial mass and radius of trial mass.

Figure – Graphs showing output for raw accelerometer data with noise, FFT power spectrum, and the isolated shaft signal with displacement amplitude (cm).

Figure – The tachometer tab shows the output of the tachometer and the isolated shaft signal overlaid on each other. This information is used to find the phase of the signal.