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.

View More On Wikipedia.org
  1. H

    Find damping coefficient at a given vibration mode

    I am working on a motorcycle dynamics problem. I have written the equations of motion in matrix form in MATLAB (and mathcad). It is a 4 degree of freedom system, so I have a mass, damping and stiffness matrix all 4X4. I am able to find from these matrices the natural frequencies, and damping...
  2. D

    Find Frequency of Molecular Vibration for Melanin, Serotonin, & Insulin

    Molecular Vibration... I'm not sure if this is a Chemistry question or a Physics question. Please take time to correct me if I have posted in the wrong area. How do you find the frequency which a certain molecule vibrates? Like Melanin, or Serotonin, or Insulin. My brother and I are...
  3. N

    Does amorphous solids support phonons or nomal modes of vibration.?

    Does amorphous solids support phonons or nomal modes of vibration.?? Can we apply the concept of phonons and Debye Model in case of amorphous and poly-crystalline solids?? http://en.wikipedia.org/wiki/Phonon http://en.wikipedia.org/wiki/Debye_model The links I have attached above...
  4. S

    Direction of vibration of molecule with respect to transfer of heat

    the heat causes the molecule to vibrate.how does the molecule vibrate in terms of angle formed by vibrating molecule and the direction of tranfer of heat in conduction, convention and radiation?
  5. R

    Forced Vibration: Amplitude Of Vibration Changes Periodically?

    In forced vibration, amplitude of vibration changes periodically. Is it right ? I think it is a correct statement, since the amplitude of vibration is a periodic function.
  6. S

    Atomic Vibration in Einstein & Debye Models

    according to Einstein all atoms in solid vibrating with the same frequency , while in the Debye's mode there are a band of frequency i.e not all the atoms would have the same frequency, my question is that , that is the idea behind the Debye's model? or why the frequency of vibrating of atoms...
  7. M

    Vibrationel energy of vibration drop?

    I want to calculate the vibrational energy of vibrating water drops. To start with I assume water is inviscid. The frequency spectrum can be found in for example Landau and Lifshitz. But I would like to know the vibrational energy of each mode. How should I proceed? Would it be correct to...
  8. D

    Vibration Formulas: Frequency, Amplitude & Acceleration

    What are the relationships between frequency, amplitude (double) and acceleration?
  9. H

    Disc Material and Vibration: Which Causes Higher Vibration, Iron or Aluminum?

    Hi all, I´m sorry for my sort of trivial issue to solve. Anyway, imagine two discs rotating at the same rpm. They are the same size - same radius, same thickness. The mass is ideally distributed around the axis, so there is originally no disbalance. One of the disc is made of iron, the...
  10. A

    Optimizing Vibration Control for Off-Road Vehicle Roll Cage Attachment

    I am designing a plate that will attach to the roll cage of my off-road vehicle. The plate will be supported on each end by the frame. I want to make sure that vibrations from the engine do not cause the plate to oscillate out of control. How do I calculate this out?
  11. N

    Undamped 2 DOF vibration. What should the eigen vectors be here

    Normal modes of vibration, two masses, two spring, arranged vertically with m2 at the top, m1 underneath arranged (top to bottom) m2, k2, m1, k1, rigid support I have solved the first part of an undamped coupled spring problem to give m_1m_2 \omega ^ 4 + ((m_1+m_2)k_2+m_2k_1)\omega ^2...
  12. N

    Free Vibration of Spring system with two DOF

    In some questions I am doing, you set of a pair of simultaneous equations and in the notes we have that . For a non trivial solution of X1 and X2,the determinant of coefficients of X1 and X2 must be zero. An equation might typically look like this (m \omega^2 +k_1)x_1 +k_2 x_2=0 Why must...
  13. P

    Radial accelerometer measuring vertical vibration

    I am working with existing accelerometers attached to the shell of a simply supported cylinder. Accelerometers are oriented radially at +/- 45 degrees from horizontal. There is a forced vibration on the cylinder in the vertical and horizontal directions and the cylinder is also exposed to...
  14. M

    Amount of photons released during decrease of energy of vibration

    An atom has the following energy of vibration: E= nhv. n can only be in the range of whole numbers. So if an vibrating atom changed energy, say from 6hv to 2hv, it means that 4hv of energy is released in light/photons Does that mean that 4 photons are "released" by the atom (?), because...
  15. Y

    Vibration profile calculation for shaker table

    Hi guys, I hope we got some expert out here for vibration profile problems. I have a device that need to be on a shaker table but I need to "find" its profile to see if the shaker table can actually run this experiment. The Shaker table is Unholtz-Dickie system SA30-560B and I have data...
  16. N

    Vibration Analysis, Eigenvalues

    Hello, I have a 3D COMSOL model which I am using for the purpose of vibration analysis. Up to now I've got analytical eigenvalues using COMSOL with MATLAB. I have to correlate the results with the measured eigenvalues results, using MAC criterion. The problem is that my analytical results...
  17. micromass

    Classical How Does Vibration and Waves Enhance Understanding in Physics and Engineering?

    Author: George King Title: Vibration and Waves Amazon Link: https://www.amazon.com/dp/0470011890/?tag=pfamazon01-20
  18. T

    How to model vibration motor in mobile phone

    Hi, I am working with the vibration motor in smartphone. I want to calculate to force comes from the vibration motor through time. In this case, I only measure the force in 3 direction, like x, y and z axes. I expect it has sinuous form but I don't know exactly the mathematics equation to...
  19. G

    Frequency Vibration: Exploring Its Applications

    When presented with different phenomenons it can be hard to imagine the relationship between each other. Although I am able to work out different problems involving it and sometimes provide good arguments around it I haven't yet gained enough confidence on how to imagine frequency. Is...
  20. D

    Vibration Experiment. Equipment and Setup

    I am trying to set-up an experiment to measure vibrations on different surfaces and how connected surfaces react; I need some advice on the correct equipment and how to set-up the experiment. I need between 3 and 5 vibrating pads, these need to be approximately 10 to 30 mm diameter and be...
  21. B

    Natural Vibration of Beam - Algebraic Query

    Folks, Just wondering what the author is doing here, given ##\displaystyle \left (\frac{2EI}{L^3} \begin {bmatrix} 6&3L\\3L&2L^2 \end {bmatrix} -\omega^2 \frac{\rho A L}{420} \begin {bmatrix} 156&22L\\22L&4L^2 \end{bmatrix} \begin {bmatrix} W\\ \theta \end {bmatrix} \right )=\begin...
  22. B

    Natural Vibration of Beam - PDE

    I am just wondering the author is doing in this calculation step. Given ##\displaystyle \rho A \frac {\partial^2 w}{\partial x^2} - \rho I \frac{\partial^4 w}{\partial t^2 \partial x^2} +\frac {\partial^2 }{\partial x^2}EI \frac {\partial^2 w}{\partial x^2}=q(x,t)## where ##w(x,t)=W(x)e^{-i...
  23. F

    How to transform non-linear frequency vibration to constant frequency?

    How to transform non-linear frequency vibration to constant frequency of vibration of 2 Hz? Such as transform the different frequency of waves to constant frequency and then maintain it..
  24. B

    How to find the stiffness? vibration

    Homework Statement a machine of mass 100 tonne generates a simple harmonic disturbing force when operating at a speed of 200rpm. to protect the floor and surrounding machinery it is proposed tp mount the machine on helical springs so that the transmissibility ratio is reduced to 0.1 Q1...
  25. B

    Vibration: find the stiffness of the spring

    Homework Statement a machine of mass 100 tonne generates a simple harmonic disturbing force when operating at a speed of 200rpm. to protect the floor and surrounding machinery it is proposed tp mount the machine on helical springs so that the transmissibility ratio is reduced to 0.1 Q1...
  26. D

    Energy of a Hydrogen Flouride molecule in normal mode vibration

    Homework Statement Hi everyone! first post here :) Basically, the question is as follows: Consider a hydrogen fluoride molecule (atomic mass of H is 1g/mole and of F is 19 g/mole). 1. Write the energy of the system in terms of the displacements of both atoms. There are other questions...
  27. nukeman

    Some questions about Vibration and Quantum Physics(Pretty simple I think)

    Hey all! Does vibration create a wave or a disturbance? If I have something like a particle or something more massive like a molecule, and it vibrates, does it create a wave function? If you have a stadium of people (yea I know, silly example) and one line of people start a wave or...
  28. D

    Phase Lag between Force & Displacement in Forced Vibration w/ Viscosity Damping

    Dear all, Can anyone explain the the phase lag between force and displacement in single degree of freedom forced vibration with viscosity damping? The response of phase angle derived by mechanical vibration as below ( assuming force is excited harmonically) : Phi(ω) = arctan( C*ω / ( K...
  29. T

    Differentials/ second order/ electrical vibration

    Homework Statement A simple series circuit has an inductor of 1 henry, a capacitor of 10^-6 farads, and a resistor of 1000 ohms. The initial charge on the capacitor is zero. If a 12V battery is connected is connected to the circuit, and the circuit is closed at t=0, find the charge on the...
  30. A

    Atom Vibration: Temperature & Conservation of Momentum

    I know this question is probably fairly basic but I had a hard time finding an answer on google. Does a single atom vibrate/jiggle/oscillate if it has a temperature (ie is not at absolute zero)? Is this vibration random in direction? If it is random, wouldn't this violate the law of...
  31. Y

    Is my stepper motor causing vibration on my wooden plate?

    Hi everyone, For a project I'm working on, I'm mounting a stepper motor against a wooden, round plate. This wooden plate is again fixed on a table. The stepper motor is fixed to the wooden plate using 2 metal brackets. The stepper motor itself drives a round object of about 0.4 kg that is...
  32. C

    What is the Role of Springs in Guitar Vibration?

    Hi all, I have a bit of a practicality problem here I was hoping I could get community consensus regarding. This question revolves around vibration throughout a mechanical setup and I haven't exactly studied said topic in any sort of depth in my schooling yet (coming up winter quarter)...
  33. J

    Equation of motion: spring mass system - free undamped vibration

    Homework Statement i have uploaded my question. please check out the attached .pdf file. Homework Equations The Attempt at a Solution
  34. V

    Chemistry Full Excitation of Molecular Vibration Modes

    Homework Statement Given the relationship Cp/R as a function of Temperature, approximate the number of fully excited vibration modes at a given temperature for a given molecule. 2. The attempt at a solution I have looked through several textbooks and many web sites, but I can't find this...
  35. H

    Vibration of a diaphragm pump in a soldering hot air station

    All, I am an engineer that occasionally needs to modify or rework circuit boards. I have a hot air rework station that uses a diaphragm pump to push air through a heating element. The result is air up to 550 degrees celcius. I can effectively rework most circuit boards. Unfortunately the...
  36. P

    Force Vibration Music Instrument: Increase Vibration w/out Electricity

    I am working on a forced vib project involving a musical instruments I am trying to have the vibration of my classical acoustic guitar increase, however NO ELECTRICITY CAN BE INVOLVED, and also trying to make the vibration of a piece of tightly folded aluminum that is attached to my guitar to...
  37. R

    Engineering Mechanical vibration -> proving a larger motor will vibrate more

    Homework Statement I have a task of essentially proving that bigger motor = bigger vibration. I have certain data such as the running speed of the motor (), moment of inertia of the rotor, weight of the motor and shaft and the diameter of the shaft. Homework Equations |X| = \frac{me}{M}...
  38. Y

    Calculate Vibration Amplitude, Frequency Range for Derrick Drilling

    I have a steel drilling Derrick 240 feet high mounted central to a ship, this is used for drilling for oil. Calculations have been done on the Derrick in regards to reaction forces in different modes of operation(drilling, transit etc). I need to do a vibration analysis of different points on...
  39. B

    General procedure for finding stiffness in vibration problems

    Hi, I have forgotten quite a bit of my vibration studies, so I have a fairly basic question. Essentially, when you want to find the natural frequency of a single dof system, you use ω=√k/m. However, does anyone know a general procedure (not problem-specific) for finding "k" that is applicable to...
  40. V

    Electron-hole pair damping of vibration, thin film resistivity

    Hello, I'm reading something about adsorbate induced surface resistivity changes in thin metal films and there is often mentioning of electron-hole pair damping, as for example: "electron-hole pair damping of the parallel(to the surface of thin film) frustrated vibration of the...
  41. S

    How is the natural period of vibration obtained experimentally?

    Hi, I had been reading the book on 'Dynamics of Structures' authored by Prof.Anil K Chopra of University of Berkeley. In his book, the author has provided the natural period of vibration of some buildings like: 1) Transamerical building of San Francisco- California which is 2.90 seconds...
  42. M

    Comparison vibration level of nylon and pvc pipe

    Homework Statement comparison nylon and pvc pipe which one vibration level is higher ? depend on which material properties ? Homework Equations The Attempt at a Solution
  43. S

    MHB Troubleshooting Damped Free Forced Vibration Solutions

    Something i am doing is not adding up. I don't understand the part with the external force. here's the question: Show that the solution for the damped free forced vibration given by is when , where something along the way I'm doing wrong, because not for heck can i get that fraction with...
  44. K

    What is the equation for natural frequencies of a rod in torsional oscillation?

    Homework Statement Determine the equation for the natural frequencies of a uniform rod in torsional oscillation with one end fixed and the other end free Homework Equations Theta = [A*sin(omega*(rho/G)^(1/2)*x)+B*cos((omega*(rho/G)^(1/2)*x)]*[C*sin(omega*t)+D*cos(omega*t)] The...
  45. F

    Analysis of Fatigue due to random vibration

    Hi! I'm trying to find a good way to predict fatigue caused by a random vibration (given PSD). I know at least 2 ways of doing it but I'm questioning them both. One of them is using the rain flow count algorithm at a simulated acceleration/time signal to generate a certain amount of...
  46. B

    Thermodynamic energy of vibration

    I have read that every body possesses some energy of vibration due to the thermodynamic character and it is equal to 1/2 kT. Does this mean that we can detect the vibrations of bodies? Or ,as it is, does it ultimately end up as heat? Regards, Boltzmann2012
  47. M

    Comparing Vibration Levels of PVC & Nylon Pipes

    Homework Statement i want to check out which material of pipe vibration level higher . comparison between pvc pipe and nylon pipe. nylon pipe is more soft and flexible than pvc pipe. which one vibration more ? Homework Equations The Attempt at a Solution
  48. S

    Vibration of a cantilevered beam with a Tip mass

    Hey guys, I was wondering if anyone could point me in the next, correct direction for this problem. I understand how to determine the mode shapes and the natural frequencies of a cantilevered beam without a tip-mass, but adding the tip-mass baffles me a little bit. The boundary...
  49. A

    Finding Modes of Vibration in ANSYS

    Hi, I'm playing around with ANSYS to find the modes of vibration of a structure. How do I know which are the most important modes? I understand that there are infinite modes of vibration - getting higher and higher in frequency. I'm guessing that it has something to do with the effective...
  50. R

    Frequency response mode of vibration

    I'm working on an analysis problem using Abaqus. I would like to compare my results with an exact equation. My problem is modeled as a simply supported beam with a lumped mass at the end. The equation that I'm using for the exact solution is as follows: k=3EI/L3 ωn=\sqrt{k/(M + 0.23m)} How do...
Back
Top