PSI - Issue 14

G Vamsi Krishna et al. / Procedia Structural Integrity 14 (2019) 820–829 G. Vamsi Krishna / Structural Integrity Procedia 00 (2018) 000–000

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Fig. 10: Vibration response on bracket

4.2. The test input specifications.

 Test Range: 20Hz-2000 Hz as per the test profile shown in Table 2 and Fig. 11 below  No. of Axes: Three (Longitudinal, Pitch and Yaw axes)  Test Duration: 30 seconds in each axis

Table 2. Vibration input parameters

10 -1

Freq, Hz

PSD, g2/Hz +6 dB/octave.

20

10 -2

100

0.02 0.02

Rms = 5.35

1000 2000

-6 dB/octave.

10 -3 PSD (g2 / Hz)

Overall Test Level

5.35 grms

Test axis

Three

10 -4

Test duration

30 seconds/axis

100

1000 2000

Frequency(Hz)

Fig. 11: Test Profile

Subsystem assembly and mechanical integration of test article was carried out at test facility. Accelerometers were mounted at internal locations by test team before integrating aluminium mounting plate and honey comb plate in test article. The details of accelerometers used for vibration measurement are given in Table 1. In order to carry out the test in pitch axis, fixture run was given to see its controllability by using two-point average control at its end. The test article was first mounted in pitch axis. Test was carried out at full level at 5.35 g rms . Responses were recorded and analysed. To carry out the test in Yaw-axis, fixture and test article were removed and rotated by 90 ° and mounted on the slip table. The test was carried out at full level at 5.35 g rms . The responses were recorded and analysed for these locations. In order to carry out the test in longitudinal axis, shaker was modified to vertical mode. First head expander was fitted on shaker (vertical orientation) with air bellows. Fixture was mounted and its controllability was ensured with four-point average control before mounting the test article. Test article was integrated to the test fixture. The test was carried out at full level at 5.35 g rms . During the test run, responses (3 channels) were monitored/recorded using DEWETRON vibration Analysers. Test was successfully completed in all three axes. Similar tests were repeated for honeycomb plate also. Packages were mounted on honey comb plate and vibration test was carried out at full level at 5.35 g rms . g rms response in longitudinal, pitch and yaw axes are indicated in Table 3.