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Random Vibration: Probabilistic Forces
Published in Haym Benaroya, Mark Nagurka, Seon Han, Mechanical Vibration, 2017
Haym Benaroya, Mark Nagurka, Seon Han
Random vibration testing is more realistic than sinusoidal vibration testing as it simultaneously includes all the forcing frequencies and excites resonances. Under a sinusoidal test, a particular resonance frequency may be found for one part of the device and at a different frequency another part of the device may resonate. Arriving at separate resonance frequencies at different times may not cause any kind of failure, but when both resonance frequencies are excited at the same time, a failure may occur. Random vibration testing will cause both resonances to be excited at the same time, because all frequency components in the testing range will be present at the same time.30
Random Vibration
Published in Dhanesh N. Manik, Vibro-Acoustics, 2017
Random vibration is the one that is not deterministic; it will generally be arbitrary and cannot be expressed as a function of time of known characteristics. Much of the vibration arising from nature falls into this category, for example, earthquake, wind loading, and turbulence, etc. So, new techniques will have to be devised to analyze the response of structures to such excitations. Fortunately, much of random vibration has a certain statistical regularity and therefore statistics can be used effectively for such a study.
Environmental Isolation
Published in Richard Leach, Stuart T. Smith, Basics of Precision Engineering, 2017
Waiel Elmadih, Marwène Nefzi, Eric S. Buice
Random vibration is a non-deterministic dynamic motion, in which different frequencies, that do not comprise rational integer multiples of frequency, exist concurrently. The amplitudes and phases of the frequency components composing the signal are random. A graph of a generic, relatively broad bandwidth, random vibration is illustrated in Figure 13.8.
Fatigue failure of pb-free electronic packages under random vibration loads
Published in International Journal for Computational Methods in Engineering Science and Mechanics, 2018
Saravanan S., Prabhu S., Muthukumar R., Gowtham Raj S., Arun Veerabagu S.
A random vibration can be broken up into a series of overlapping sinusoidal vibrations with each vibration having its own frequency and amplitude. Each sinusoidal vibration will have its associated stress cycle. The cumulative fatigue damage ‘D’ for random vibration process can then be defined as [18]; where ni is the total number of cycles in the ith block of constant stress amplitude Sa, i, Nf, i is the number of cycles to failure under Sa, i, and k is the total number of blocks. Failure of components when subjected to random vibrations, occurs when D ≥ 1. The relationship between stress amplitude Sa, i and the fatigue life Nf, i is given by [18][19]
Vibration Testing of Absolute Pressure Sensor for a Flush Air Data System (FADS)
Published in IETE Journal of Research, 2021
M. Jayakumar, N. Shyam Mohan, S. B. Vidya, K. C. Finitha, A. K. Abdul Samad, Shashi Krishna, Aisha Sidhick, M.V. Narasimha Prasad
While sine vibration is an excellent means of investigating dynamic properties and identifying frequencies of damage-potential, if any, the service conditions are usually random vibration. Random vibration environments are characterized by non-repetitiveness in time or simultaneous presence of mechanical energy at all frequencies over a range. Random Vibration Tests are intended To verify the test item design capability with adequate margin.To screen the workmanship, integrity of the flight/components/sub-assembly under high-frequency excitations.