What is Vibration: Definition and 471 Discussions

Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. The word comes from Latin vibrationem ("shaking, brandishing"). The oscillations may be periodic, such as the motion of a pendulum—or random, such as the movement of a tire on a gravel road.
Vibration can be desirable: for example, the motion of a tuning fork, the reed in a woodwind instrument or harmonica, a mobile phone, or the cone of a loudspeaker.
In many cases, however, vibration is undesirable, wasting energy and creating unwanted sound. For example, the vibrational motions of engines, electric motors, or any mechanical device in operation are typically unwanted. Such vibrations could be caused by imbalances in the rotating parts, uneven friction, or the meshing of gear teeth. Careful designs usually minimize unwanted vibrations.
The studies of sound and vibration are closely related. Sound, or pressure waves, are generated by vibrating structures (e.g. vocal cords); these pressure waves can also induce the vibration of structures (e.g. ear drum). Hence, attempts to reduce noise are often related to issues of vibration.

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  1. C

    Vibration Amplitude: Structure Withstands # of Cycles w/ X,Y

    A structure withstands a vibration of amplitude x and frequency y for z number of cycles. How many number of cycles the structure will withstand if the vibration amplitude is doubled. How many number of cycles the structure will withstand if the vibration frequency is doubled?
  2. E

    Forced Vibration Questions: Solve Equations for Answers

    Questions: (a) At what resonance (\omega = \omega_0), what is the value of the phase angle \phi? (b) What, then, is the displacement at a time when the driving force F_{ext} is a maximum, and at a time when F_{ext} = 0? (c) What is the phase difference (in degrees) between the driving force...
  3. C

    Noise vibration harshness(NVH)-fea

    What do these terms mean. I am doing static analysis using fea on some parts. But what do automotive people do in NVH. Please give examples
  4. T

    Maximum Vibration Period for Object Losing Mass

    hello guys getting a bit stuck with this problem? was wondering if anyone could help me please? how would one work out the maximum vibration period during harmonic oscillation of a an object moving up and down with amplitude 50mm if it is constantly losing mass? :cry:
  5. T

    The correlation between vibration and flow rate

    Hi all. Suppose I am increasing the flow rate of the water through a sprinkler or a tube, there should be some vibration induced by this increment of flow rate, right? On the other hand, if I decrease the flow rate of the water through the same sprinker, there should also be vibration induced...
  6. O

    Vibrational Energy to Sound: Possible?

    Is there a way to turn vibrational energy(if such a thing) into acoustic energy. Like for simplicity, i say you bank a tuning fork, which sends vibrational energy through a copper wire, and it is then transformed into audible sound from a speaker. possible?
  7. O

    Tuning fork to stop engine vibration?

    I have a 62cc engine on the back of a scooter frame made for an unmodified 41.5 cc engine. The engine is putting out a ton of power for what it is, 8hp maybe from 5 stock, and i sheared two of the 4 engine mount bolts right off. I am going to tap out the threads to accept a bigger diameter bolt...
  8. K

    Nonlinear Vibration: Find Behaviors of 3D Structures

    how can we find the nonlinear behaviour of an assembled Structure...what are useful links regarding Nonlinear Vibration of 3D Structures...what are basic steps to predict the Nonlinear Behavior ?
  9. P

    Forced Vibration of a Cantilever Beam

    If a cantilever beam is subject to forced vibration (from a shaker at fixed end), what will the effect be of placing a mass at a)nodes and b)between nodes? I presume that as there is no displacement from the normal at the nodes, the mass will have little effect, but what about between the...
  10. P

    Forced Vibration on a Cantilever Beam

    If a cantilever beam is subject to forced vibration (from a shaker at fixed end), what will the effect be of placing a mass at a)nodes and b)between nodes? I presume that as there is no displacement from the normal at the nodes, the mass will have little effect, but what about between the...
  11. M

    Vibration Question relating to People

    I have a quick question about vibrations. Is there such thing as a natural frequency of the human body? I tried to google some information, but couldn't find anything. The reason for this is that we have a couple of big heat exchangers here at work, and some operators were complaining about...
  12. L

    Tacoma Bridge Collapse: Physics of Vibration and Sound

    I changed my mind, I'm not fickle, th stethescope was all i could remember... Anyway, apparently the tacoma bridge collapse was due to the bridge 'vibrating', and obviously the supports couldn't hold it... If you know anything about how the sound part of physics fits into this your help...
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    Vibration Switch: Does It Return to Normally Open?

    Say a vibration switch is used as a trigger in a bike alarm. I know it will be more sensitive than a tilt switch, but once the vibration switch has been triggered, does it return to its "normally open" status simultaneously?
  14. F

    Finding Amplitude of Air Vibration from Frequency and Intensity

    I'm given two things: frequency, f = 313 Hz intensity, I = 1.13 uW/m^2 (microWatts per square meter) I'm supposed to find the amplitude of the air vibrations caused by this sound. As always, a push in the right direction is greatly appreciated.
  15. O

    Do perfectly dense incompressible particles vibrate when struck?

    Imagine you have a perfectly dense incompressible fundamental particle. Strike that particle with another of the same type. Will they vibrate? If something is not compressible. then I don't see how there could be any sort of shockwave that would cause the particle to vibrate. Am I correct...
  16. W

    Is there any software to simulate lattice vibration?

    I really want to see the lattice wave.Who knows where could I get the software simulating it? Thank you very much!
  17. R

    Designing a Vibration Absorber for a Two Degree of Freedom System

    I'm trying to design a vibration absorber that will reduce the vibration of a machine by about 60%. I found the equations of motion of the machine without the absorber to be.. c1x1’+m1x1”+k1x1+k2(x1-x2)+c2(x1’-x2’)=Fosinwt and the absorber alone to be.. m1x2”+k2(x1-x2)+c2(x2’-x1’)=0 How...
  18. Z

    Natural Vibration Data: Materials Info Guide

    where can I find data about the natural vibration of differrent materials ?
  19. Z

    Natural Vibration: Data on Materials

    where can I find data about the natural vibration of differrent materials ?
  20. S

    Two Degree of freedom Damped free vibration

    I am trying to calculate the force and velocity of a primary and secondary suspension. I know the damping constant of the dampers and the spring constant of the springs. I see where an expression can be calculated where you input time and get x.
  21. M

    How far away is the farmer? Speed of sound and wave vibration in physics

    PHYSICS help please! Due 2morrow! I'm learning about vibration and wave and sound. And I have to explain and solve this problem below, can someone please help me out...Thanks You watch a distant farmer driving a stake into the ground w/ a sledgehammer. he hits the stake at a regular rate of...
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