(DOWNLOAD) "Random Vibration Testing Standards" by Wayne Tustin, Deepak Jariwala & Jaime Boscá * Book PDF Kindle ePub Free
eBook details
- Title: Random Vibration Testing Standards
- Author : Wayne Tustin, Deepak Jariwala & Jaime Boscá
- Release Date : January 23, 2014
- Genre: Engineering,Books,Professional & Technical,Education,
- Pages : * pages
- Size : 9579 KB
Description
Recognize, please, that specifying random vibration tests only in terms of RMS g is not sufficient. A wide variety of spectra could all enclose the same area and thus provide the same RMS g. We must specify spectral details. That’s why we first focus on the frequency domain. Don’t expect to find simple spectra per the MIL standards on board real vehicles in the “real world”. “Real world” spectra, greatly affected by structural and panel resonances, tend to be very jagged.
I hope you’re comfortable with spectrum tolerances given in dB units. If not, you might want to review ebook 1, section 1.27. We can never achieve exactly the PSD that the MIL standards show as straight lines. Our equalization is never perfect. How high above the 0 dB (specified) line may peaks go? How far below the line may notches go? The tolerance is usually stated in deciBels and a common value is ±3 dB. +3dB is a very wide tolerance (-50% +100%). It was appropriate for the old analog controllers. +1.5dB is more appropriate and more commonly seen currently.
22.1 Why are standards not effective?
22.2 Military Standard 810, IEC, ASTM
22.3 Earthquake (seismic) testing - NEBS
22.4 How do we interpret what standards say?
22.5 Focus on frequency domain
22.6 “Real world” spectra not so simple
22.7 Interpreting dB tolerances
22.8 Shaker force requirement; spectrum area
22.9 Multiple sine + random testing
22.10 Analyzing narrow bandwidth peaks
22.11 Spectral graphs misleading
22.12 Statistical degrees of freedom
22.13 Don’t forget the time domain
22.14 Clipping
22.15 Multiple zones
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