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. K

    Unfingered Guitar String Vibration Frequency: 627 Hz

    Homework Statement When unfingered, a string on a guitar vibrates at 627 Hz. What frequency will the string produce when fingered one third of the way from the end, that is only two thirds of the string can vibrate? Homework EquationsThe Attempt at a Solution I am not too sure what equations...
  2. Mohrcircle

    Where to find answers for "Mechanical Vibration" textbook (Haym Baneroya)?

    I really liked this book but the problems don't have answers at all (not even numerical one's at the back of the book). There is not even a solution manual to download or buy online. How am I supposed to use this book otherwise?
  3. tomadevil

    General Question about Vibrations

    Hello Everyone, I conducted an experiment with a metal beam which had a motor attached to it in with an eccentric mass on it. The two ends of the beams were fixed with a roller and a hinge(as I remember). This was a one degree of freedom experiment. I had to collect data during free/forced...
  4. Tunalover

    I A common 2nd order ODE from dynamics but....

    Consider a simple single degree-of-freedom (SDOF) spring-mass-dashpot dynamic system with spring rate k, mass m, and viscous damping coefficient c. Dimension x is the absolute displacement of the mass. The base input translation is y. A dot notation indicates differentiation with respect to...
  5. M

    A Calculating Vibration Modes of a Cylinder (Drum Shell)?

    I am working on some acoustic synthesis models of real world instruments. The Bessel Function zeros give the vibration modes of a circular membrane, which can be used to model a drum head or even roughly a cymbal. However, much of a drum's sound (especially snare) comes from the "ring" of the...
  6. J

    Vibration Energy Harvester from Brownian motion

    Hi all, been a while since I studied physics but I saw something that I found strange, This device: https://researchfrontiers.uark.edu/good-vibrations/ from University of Arkansas A free floating graphene sheet extracting energy from brownian motion and converting that to electric current...
  7. L

    B Why aren't molecular vibrations synchronized in a way that can be observed?

    why are molecular vibrations never synchronized in a way that would make them macroscopically observable?
  8. S

    How to select vibration dampers

    Hello i have asd value of 0.015 g2/hz and freq range of 1 to 100hz. How to select a damper for isolating my equipment from the above mentioned vibration?
  9. R

    Modes of Vibration of 3-DOF Spring Mass System

    Homework Statement Homework Equations a11 = a21 = a31 = a12 = a13 a22 = a32 = a23 $$ \begin{bmatrix} x_{1} \\ x_{2} \\ x_{3} \end{bmatrix} =ω^2m \begin{bmatrix} a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \\ a_{31} & a_{32} & a_{33}...
  10. robindymer

    B How does vibration affect the Higgs field interaction?

    I have been thinking about the Higgs field and how things interacts with it. I thought about why photons for example does not interact with it while quarks does. It could be because of the size and if when a particle is a certain size it will interact with the Higgs bosons and then slow down and...
  11. S

    What Factors Should I Consider when Building an Accelerometer Vibration Circuit?

    Good afternoon. I am currently attempting to build a circuit for my university dissertation. I am looking to build a cct that would use an accelerometer to sense vibration from say a gearbox of a helicopter to a storage device before being transferred via Bluetooth to a laptop. My questions are...
  12. deuel18

    How can I solve a dynamic vibration problem?

    Hello. I need some help for my HW. I've been trying this particular problem but I don't know if I am on the right track. The problem and my progress in answering the problem is down below.
  13. M

    Steel Vibration Synthesizer: Crafting Musical Shapes

    Homework Statement Hello there, I thought a fully analog , cutting vibrational shapes on steel plate and hit to each shape by fingers and produce whichever sine , square , triangle vibration you want and filter of those collections of vibrations by another steel cut shape and make a synthesizer...
  14. S

    Reducing Vibration in Home: How & Why?

    Homework Statement How can one reduce the vibrations entering the house? And why do certain sounds vibrate more in certain place, but quiet fown if you move a bit further away. Homework EquationsThe Attempt at a Solution I was thinking it's something to do with the fact that sounds wave are...
  15. C

    2-DoF system characterization with 2 dual axis accelerometers

    I've been having some trouble with this problem for a while. (Its not a homework or coursework problem) Its a part of an experimental set up that I'm building and this is a simplified version of it. I have a rigid rod which is hinged at a point and can pitch or heave about that location. There...
  16. Felix Gonzales

    I don't understand the derivation process here, help?

    Homework Statement I understand the derivation it showed that included the sin (15.7 in the image) I just don't understand the following (15.8 in the image). Does "t" get pulled out of the equation? If so what do we derive for then? Does it become 0? If so, it would remain 0 and sin(0) is just...
  17. Mohamed_Wael

    Can I use symmetry in modal analysis in FEA

    I am doing FE analysis for symmetric shape in boundary conditions and geometry, I would like to know if I can use symmetry in my analysis or not. I have tried to run trials, the results are very similar but I am not sure if this just a coincident
  18. Feodalherren

    Vibration of a cantilever beam problem

    Homework Statement A rectangular cantilever beam of length L and side lengths b with negligible mass is attached horizontally to a wall. A mass m is attached to the end of the beam where a motor is also located. The motor applies a force on the end of the beam described by the equation...
  19. Spinnor

    Stratolaunch carrier plane, active vibration reduction?

    Interesting new jet plane has rolled out of its hanger. https://img.purch.com/h/1400/aHR0cDovL3d3dy5zcGFjZS5jb20vaW1hZ2VzL2kvMDAwLzA2Ni80NjMvb3JpZ2luYWwvZHJvbmUxX3dlYnNpdGUuanBnPzE0OTYyNjgyNTY= It looks like there are vibration modes of the plane that during normal operation would shake the...
  20. chinmay

    Simulation of Dynamic Charateristics

    I have an assembly (a cuboid shaped structure). The vibration test data of this structure is available with me. I want to study the effect of vibration generated by a system mounted on top panel on another system mounted on same top panel. In order to complete this, I have prepared the FE model...
  21. chinmay

    Torsional Vibration of Rotor-Shaft

    I have developed a mathematical model to study the dynamic behavior of rotor (with 6 dof). It is assumed that rotor is rigidly mounted at the mid point of shaft, and both end of the shaft is attached to ball bearing. I have developed the FE model for it too, and the frequencies in X, Y, Theta...
  22. Saumya Kar

    Automotive Random Vibration and PSD spectrum profiles

    I am starting work on structural durability area for after treatment systems and deal with Random Vibration and PSD profiles quite often. However there are few fundamental questions about PSD profiles that I could not get answer to after a lot of search on internet. So finally decided to write...
  23. flamespirit919

    Frequency of Vibration of Two Masses Joined by a Spring

    Homework Statement Two masses ##m_1## and ##m_2## are joined by a spring of spring constant ##k##. Show that the frequency of vibration of these masses along the line connecting them is: $$\omega =\sqrt{\frac{k(m1+m2)}{m1m2}}$$ Homework Equations ##x(t)=Acos(\omega t)## ##\omega...
  24. kipinaac

    I What does it mean for a particle to vibrate?

    I intuitively understand macroscopic vibration, but trying to understand what it means for a particle to vibrate doesn't seem to make sense from the classical understanding I have of momentum and energy. First, are particles even said to vibrate or have vibrational energy? If so, how is momentum...
  25. W

    Get vibration frequency form absorption spectra line

    Homework Statement [/B] "Absorption spectra of gaeous HCl show a line at 3.5 μm which results form molecular vibration (oscillation from interatomic distance)" How do I get the frequency of vibration from this? Homework Equations ? If I knew this, then I could probably solve the problem The...
  26. K

    Free vibration of 100 DOF spring

    Hi, I have just started reading of "finite element model updating" which is a statistical means of updating the finite element model when there is source of uncertainty in the modelling parameters, modelling error, etc. My question below is NOT related to finite element model updating but to a...
  27. R

    Vibration Problem: Determine Period

    Homework Statement The uniform rod shown has mass 6 kg and is attached to a spring of constant k = 820 N/m. End B of the rod is depressed 10 mm and released. Determine the period of vibration. Picture is attached below Homework Equations Fs = kx W = mgThe Attempt at a Solution I honestly...
  28. C

    A Phonon energy and atomic vibration energy

    When we say that a phonon vibration mode has an average energy <E> are we saying that all atoms (or harmonic oscillators) in a piece of matter (eg. a nanoparticle) will also has that energy, or that the piece of matter as a whole will have that energy ? In the second case the amplitude of the...
  29. JLD Co

    Automotive Effect of vibration on engine efficiency

    It has been stated in previous threads that engine inefficiencies are caused by: Pumping losses (induction and exhaust) Frictional losses (in bores, bearings, and ancilliaries) Thermal losses to exhaust, coolant (jacket, charge and oil), and surroundings Does engine vibration have an effect on...
  30. H

    Natural Frequency for torsional vibration

    I am trying to calculate natural frequency for torsional vibration of fixed fixed beam using following formula. =1/2*3.142 sqrt(K*g/mr^2) hz Where K=J*G/L and G=Modulus of rigidity g=acceleration due to gravity=386.4 in/se2 m=mass hanging on the beam at distance 'r' from the longitudenal...
  31. Kaiera Ai Tanay

    I Modulus in Metals versus Sound Vibration

    So I'm trying to understand how the modulus works in metals. I understand that when the temperature rises, that means that the modulus decreases. But I do not understand exactly what it is or how it affects the way that the molecules would vibrate for instance, as kinetic sound energy moved...
  32. sempiternum

    Vibration in "cantilever" rotating bar

    Hi. I'm working in the design of an auotomatic bar feeder for a CNC lathe. I've established that the bars will not be longer than 1.2 m and will not have a diameter of more than 75 mm. Suppose they are steel bars, which would make them have a mass of about 80 kg So, bars are tightly held in one...
  33. Roy1984

    I Overall energy input in random vehicle vibration tests

    Hello Everyone I have got a question concerning the calculation of the overall energy input in random vehicle vibration tests. I have got different power spectral density levels for different random vehicle vibration tests and would like to compare them with each other concerning the overall...
  34. N

    How can I cancel out vibration and noise coming from my upstairs neighbors?

    Hello gentlemen! So I have a situation. Concrete floor (ceiling actually) slabs like these has many cylindrical spaces in it. And noisy neighbors on top! The slab receives shocks / impacts and human shouts. First I found Tuned Mass Damper. It is good for continuous vibration but not for first...
  35. louisnach

    Vibration membrane exercice physics

    Homework Statement We have a square membrane and a circular membrane, both fixed from the edges. They are made of the same material with a surface mass σ , and their surface tension is T. We want to tune the lowest eigenfrequency (the fundamental frequency) of both membranes to the same...
  36. P

    Temperature as a function of vibration energy quanta

    Homework Statement Consider a small cluster of four copper atoms. Assume, that each atom can oscillate around its equilibrium position independently of the other atoms. Let us model each direction of vibration as a harmonic oscillator, whose energy is quantized Evib = ¯hω(n +1/2), where ω =...
  37. K

    Forced vibration on mass between two pull springs

    Consider a mass m with a prestressed pull spring on either end, each attached to a wall. Let k1 and k2 be the pull spring constants of the springs. A displacement of the mass by a distance x results in the first spring k1 lengthening by a distance x(and pulling in the - direction), while the...
  38. A

    I with the free vibration of bar problem

    Homework Statement Find the free vibration of the bar supported by a spring and a viscous damper (See attached figure) Homework Equations (a)Derive the equation of motion (b) Obtain the moment of inertia of bar (c) obtain natural frequency when d=0. The Attempt at a Solution
  39. B

    Does a Belt drive actuator isolate motor vibration?

    Trying to build a case for a belt driven ball screw axis versus a Planetary gear box, with the fact that the motor vibration would carry down the gearbox to the axis, but the timing belt drive would isolate the motor vibration. How would I model this? and ideally a way to get a factor of...
  40. S

    Vibration Damping Help: CR3-100 Damper Cutoff Frequency

    Hello i was looking at the damper CR3-100 as seen in the pic. Howver from the tech sheet given i cudnt make out what's the cutoff freq of this damper...i mean which is the frequency beyond which it doesn't let the frequency pass...what to make of this KN/m value?
  41. Mohamed_Wael

    Air Resonance Frequency: Effects of Excitation

    I wonder of the air has resonance frequency or not, if yes what would happen if we excite it at this frequency
  42. C

    Peak-hold equivalent amplitude for transient vibration

    I have a question regarding transient vibration data I received that was processed into a peak-hold equivalent amplitude (units = g). I have come across peak-hold before which is a type of "averaging" that retains the highest values from each estimate in random vibration overlap processing and...
  43. J

    A Free damped vibration of a system of 2 dof, demostration

    Hi,I need help please, i want to know how to solve de differential equation of a system of two degree of freedom using eigenvalues or eigenvectors or if I can use any another way to solve this kind of equations.
  44. J

    A Free damped vibration of a system of 2 dof, demostration

    Hi,I need help please, i want to know how to solve de differential equation of a system of two degree of freedom using Heigenvalues or Heigenvectors or if I can use any another way to solve this kind of equations.
  45. L

    Free Vibration simulation in Ansys

    Hi everyone, i facing a problem which is the ansys simulation setting problem. I had use modal analysis simulate and get the result. But the problem is the result for three axis which is x, y and z axis also have same value for the frequency. Is that any setting i missed up?
  46. W

    Vibration of wine tanks using music

    hello I'm a belgian wine maker. We play music in our wine celler (with a very powerfull baffle) because it creates small vibrations on the tanks. Thanks to this we mix he wines less and so they keep more aromas . I would like to get more "powerfull" vibrations. Does somebody have an idea of how...
  47. WORLDOKO

    Boundary conditions of that beam.

    Hi all! I have to calculate the natural frequency of the system. Any idea of boundary conditions of this case? There is beam supported by two springs on the left side.
  48. L

    Force vibration analysis (ansys)

    Hi everyone, i have a question related with ansys. I request to do free vibration and force vibration for my final year project, my project title is optimum baby hammock stand. For free vibration i search from online to get the result by using modal solver (attachment below). For force vibration...
  49. M

    What is causing strange sounds from glasses in my apartment at night?

    In our apartment, for the last few months, my wife and I are being puzzled by strange sounds coming from the dining area while we remain in the bedroom at night. The first time we heard, I was quiet. Then my wife said, "Did you hear that?" So, it was no hallucination whatsoever. It is a distinct...
  50. john c3na

    B Exploring Vibration: Understanding the Experiment

    How does this experiment relate to vibration? he doesn't explain it well
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