Vibration Measurement Report - Tinkers AFB - Report Number 1669_Redacted.pdf

Vibration Measurement and Analysis

For

Tinker AFB at

Tinker Air Force Base Building 3001

3001 Staff Drive Tinker AFB, OK 73145

Date: March 26, 2018

Report No. 1669

Table of Contents

1.0 Purpose of Site Survey

2.0 Summary of Site Survey

3.0 Test Equipment Used

4.0 Results

5.0 Conclusions

Appendix I Hard Copy of Site Survey Results

3.0 Test Equipment Used

Portable FFT Analyzer, Model: Quarttro DP240, Manufacture: Data Physics, Serial Number: 20523.

Signal Processing and Analyzing Software, Model: SignalCalc 240 V 4.6.162, Manufacture: Data Physics. FFT Settings – Flattop Window, 75% overlap, T span 3.2 seconds, F span 125 Hz, Lines 400.

CH 1 – Low Frequency Seismic Accelerometer, Model 731A, Manufacture Wilcoxon Research, Sensitivity 10.6 V/g, Range 0.1 to 450 Hz, S/N 3625.

CH 2 – Low Frequency Seismic Accelerometer, Model 731A, Manufacture Wilcoxon Research, Sensitivity 10.5 V/g, Range 0.1 to 450 Hz, S/N 10493.

CH 3 – Low Frequency Seismic Accelerometer, Model 731A, Manufacture Wilcoxon Research, Sensitivity 10.3 V/g, Range 0.1 to 450 Hz, S/N 10494.

3 axis setup, Accelerometers are attached to the floor with petro wax

The vibration data is displayed in;

Acceleration Amplitude (mm/s2) Vs Time (Sec) X1;X2;X3 – This is the Amplitude Vs Time data.

Acceleration Amplitude (mm/s2 Peak to Peak) Vs Frequency (Hz) G1,1;G2,2;G3,3 – This is the FFT of the Amplitude Vs Time data.

The measurements were recorded on all 3 channels simultaneously;

CH 1 G1,1 or X1; Vertical – X Direction (Red) CH 2 G2,2 or X2; Horizontal – Z Direction (Green) CH 3 G3,3 or X3; Horizontal – Y Direction (Blue)

The measurements taken were recorded using extended run using peak hold. The extended run peak hold measurement runs a predetermined number of consecutive

3.2 second frames and captures the highest level measured at each frequency of the FFT. FFT Settings; FSpan 125 Hz, dF 0.3125 Hz, TSpan 3.2 Sec, dT 0.008 sec, resolution 400 lines, windowing Flattop, 75% overlap.

4.0 Results

The measurement location and runs are described below;

Run # Location # Description

1 1 On isolated block at Front Left Corner, all three axis

2 2 On isolated block at Rear Left Corner, all three axis

3 3 Off isolated block between Front and Rear Left Corner (Close to aisle), all three axis

4 CH 1 on isolated block between Front and Rear Left Corner CH 2 off isolated block between Front and Rear Left Corner CH 3 not used

5 CH 1 on isolated block between Front and Rear Left Corner CH 2 on top of isolator floating frame CH 3 not used

6 4 On isolated block at Front Right Corner, all three axis

7 On floating tube frame at front middle, all three axis

8 Not Used

9 CH 1 on floating tube frame at front middle, vertical CH 2 on table base, vertical CH 3 on table base, X direction (horiz.)

10 CH 1 on floating tube frame at front middle, vertical CH 2 on floating tube frame at front middle, X direction (horiz.)

CH 3 on table base, X direction (horiz.)

11 CH 1 on floating tube frame at front middle, vertical CH 2 on floating tube frame at front middle, Y direction (horiz.)

CH 3 on table base, Y direction (horiz.)

12 CH 1 on floating tube frame at front middle, vertical CH 2 on floating tube frame at front middle, X direction (horiz.)

CH 3 on table base, X direction (horiz.)

13 Not Used

14 5 On isolated block at Rear Right Corner, all three axis

15 5 On isolated block at Rear Right Corner, all three axis

16 5 On isolated block at Rear Right Corner, all three axis

On the pages that follow are graphs showing four different conditions that were investigated;

1. Measurements taken on isolated concrete block in all three axis to find the amplitudes and frequencies going into the isolation system.

2. Measurements taken on the isolated block and on the floor to look at the performance of the isolated block.

3. Measurements taken on isolated block and on floating frame to look at the performance of the current air spring isolation system.

4. Measurements taken on floating frame and gantry table that is supported by three aluminum cylinders with rubber pads between the floating frame and cylinders.

the position of the floating gantry is disturbed by a small push (by hand) a system natural frequency of 2.81 Hz was measured. The higher natural frequency when there are very small displacements is inherent in the design of the 2 chamber passive air spring. When there is almost no movement, the air spring is only working with the small volume of the loading chamber. For large movements the entire air volume, loading chamber plus damping chamber, is used. The natural frequency of the air spring is a function of the air volume it is using, larger air volume = lower natural frequency. The Bilz AIS is a one chamber design and does not have this problem.

4. The measurements taken on floating frame and gantry table that is supported by three aluminum cylinders with rubber pads between the floating frame and cylinders showed the following;

Vertical Some isolation effect of the rubber pads at higher frequencies (above 93 Hz).

Large resonance peaks at 40 and 60 Hz

Horizontal X Some isolation effect of the rubber pads at higher frequencies (above 90 Hz).

Large resonance peaks at 18, 33, 40 and 60 Hz

Horizontal Y Some isolation effect of the rubber pads at higher frequencies (above 45 Hz).

Small resonance peaks at 23 Hz

5. The measurements with all the air handlers off were compared to measurements with all the air handlers on. The predominate peaks from the air handlers in all three axis were 53 Hz and 108 Hz.

Appendix I

Hard Copy of Test Results