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.
A V-shaped tube with a cross-section A contains a perfect liquid with mass density and length L plus and the angles between the horizontal plane and the tube arms as shown in the attached figure.
We displace the liquid from its equilibrium position with a distance and without any initial...
Hi, I am trying to get the transfer function from a wall between rooms. From one side I have the force of a hammer as an input ,and in the other side of the wall (next room) I have an accelerometer. Is it possible to get the TF without know the damping, stiffness and mass of the wall partition...
Summary: How to express ωₙ in terms of only mass (m) and stiffness (k)? I tried doing it with F=kx but it is out of my ability to simplify it to only m and k.
Here is my approach:
I have general equation for undamped forced oscillations (no friction) which is:
I just wonder about,what type of motion should occur when initial conditions are both 0 (i.e v0=0 and x0=0). My intuitive expectation is that as there is no 'natural' oscillations at beginning,vibration has to be...
My query here is,
Suppose there is a 2 kg mass
To oscillate it/vibrate it, it will take some force and it will have some natural frequency
Now I increase the mass to 5 kg
so to vibrate it, won't it take more force and so at the end, won't the natural frequency of the object increase? as its more...
The ##Q## factor of an oscillating system is defined as ##\omega_{r}/\Delta \omega##, where ##\omega_{r}## is the resonant frequency, and ##\Delta \omega## the resonance width. As I understand, ##Q## measures how sharp the resonance curve is.
Why is it that the resonance curve gets...
How is the transient vibration of a piston engine usually simulated?
I know that in order to define the vibration loading you need the mass properties and dimensions of the moving components plus the cylinder pressure curve. And of course you need to know the firing order, V-angle (if...
Dear forum members,
We have a water cooled chiller device (see its model in attached link) and we use it to cool a hot mirror element.
Unfortunately the chiller is vibrating and the vibrations couple all the way to the mirror
through a pair of rubber tubes (1cm in diameter, 2m in length) and a...
So I am almost sure I know how to solve this, just curious about the maximum velocity. Anyway, if you could double check my calculations, here it is.
##T = \frac{t}{n} = \frac{10s}{15} = \frac{2}{3}s##
##\omega = \frac{2\pi}{T} = 2\pi \frac{3}{2} = 3\pi##
a). position at ##t = 0.8s##...
Description of the Problem:
Consider a spring-mass system with spring constant ##k## and mass ##m##. Suppose I apply a force ##F_0 \cos(\omega t)## on the mass, but the frequency ##\omega## is very small, so small that it takes the system, say, a million years to reach a maximum and to go to 0...
Homework Statement
This problem is taken from Problem 2.3, Introduction to Vibration and Waves, by H.J. Pain and P. Rankin:
A critically mechanical system consisting of a pan hanging from a spring with a damping. What is the value of damping force r if a mass extends the spring by 10cm without...
The setup: I have a mass (m1)connected to a much, much larger mass (m2) via a preloaded spring. They start out in contact because the preloaded spring holds them together. Now suppose the large mass is subject to vibrations, possibly at the resonance of the structure. Will the two masses...
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...
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...
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...
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...
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
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...
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...
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...
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...
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...
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...
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.
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.
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...
The square seat (?) for the accelerometer has started to fall apart and I need to find a replacement for it. If this helps, the accelerometers are placed equidistant apart from each other, and the tester hits it - the cantilever beam - with a mallet to simulate vibration.
Please refer to the...
Homework Statement
I have a 2-DOF system, whereby I have one body that is grounded by a spring (body A), and a second body (body B) attached to the first by a spring and a viscous damper. For body A, I know the velocity and amplitude (before body B is added). I think I also have the stiffness...
I've always wondered this. Let's say we're not limited by the type of vibration, e.g. if choppy vibration doesn't constitute continuous movement, then some sort of oscillating vibration.
Homework Statement
Assume that there is a tank on a 200 ft pedestal type support. When full the tank and contents have a weight of 50,000 lbs and it is never drained to a point where the tank and contents have a weight less than 20,000 lbs. Assume the pedestal weight is negligible compared to...
Homework Statement
Homework Equations
w = √k/m
w = 2π/P
ƒ = 1/P
The Attempt at a Solution
I feel like I'm so close to the answer, I think it has something to do with the fact that there's a spring and pulley in the system that is throwing my answer off. I have
√k/m = 2π/P
So,
P =...
I've been searching the web for this answer and can't seem to find it anywhere. Can anyone help me? Is sound a renewable energy or non-renewable energy?
Hi there,
I'm solving the equation for the transverse vibrations of a Euler-Bernoulli beam fixed at both ends and subject to axial loading. It's a similar problem to that described by Rao on page 355 of his book "Vibration of Continuous Systems" (Google books link), except the example he uses...
Hi All.
I am stuck in a problem.
Please check the image attached.
It's part of a foldable mechanism of a quad copter arm.
The red part is fixed to the body, the grey part is fixed to arms. The transparent part is a threaded collar/sleeve.
The yellow part is a stopper. The hinge is a connecting...
So I just poured water in a glass to clench my thirst. Hit the 2/3 empty glass with a pen and a high frequency started resonating for a brief moment, which I percepted as sound. When I tilted the glass the tilt resulted in change of frequency. When the glass was empty there was no change in...
G'Day Everybody, I am computing buckling of a rectangular(edges: a*b) specially orthotropic composite plate. The boundary conditions are clamped-clamped at the opposing loaded edges and the other two edges are free (also known as CFCF). After having the boundary conditions and the governing...
Can anybody suggest a free SW to simulate the behavior of a gyroscope upon adding/removing a mass in various places with respect its rotational axis and/or baricenter? It looks like it's quite complex to manually calculate or just "imagine" it.
A gyro standing on a floor does behave in a...
Hello, I have a question on the nature of vibrations due to thermal energy. Earlier today I read this article which talked about cooling a glass string to near absolute zero using feedback from a high precision sensor. http://phys.org/news/2015-08-smallest-vibration.html
what I understood from...
A rod is radially mounted on a motor shaft and provided with a flat end plate. By turning movement, the end plate will touch a pointed object, and the angle turned is measured.By the torque of the motor during acceleration and deceleration, a vibration and deflection happens on the rod. The...
Hi guys. It could be an easy question but I started at the deepest. I wonder how it works like a car suspension system. How does damper work with spring? What is the difference between forced-nonforced systems? Why do we calculate frequency of spring? What does it provide us? What is the point...
I'm trying to find a solution to a system in which a clamped free Euler-Bernoulli Beam system rests on top of a mass-spring-damper system. The MSD system has nonlinearities in both the spring and the damper and is of the form:
I have extended the nonlinear restoring force to its 3rd term and...
I am trying to reduce the noise created from a machine that makes contact (impact) with a thin plate. I just don't have anyone to bounce ideas off of.
I can change the support geometry to whatever I want as long as it will with stand a static load and the impact. I can handle this, but the...
If I mount an unbalanced piece of wood on my lathe, it causes vibration. i.e. I'm spinning an offset mass at a high rate of speed. If I add weight to the base of the lathe (e.g. sand bags, concrete blocks, bolting it to the floor), I can stop the vibration. My question is, where is the force...
I have created such vibrating feeder model on SW but on ANSYS I'm only analyzing the frame.
1)How do I set up boundary conditions, I think I need elastic supports?
2)In modal analysis I have elastic, fixed supports, remote displacement - which should I use and in what directions?
3)Do I perform...
Hi there!
Im trying to do an analysis in Abaqus of a cantilever pipe, with a tip mass at the free end, that is decelerating to a stop at 10 m/s2 from 10m/s, causing it to vibrate. To validate my results I am doing some handcalcs. I have done a static analysis and calculated the maximum...
So, here's the set-up:
A small stereo speaker is connected to a function generator. A concave lens, bearing a ball is place over the speaker.
Now, the frequency is slowly increased in the function generator. My question is,
Will the ball really bounce at a certain frequency? Because I am not...
I've found several accelerometer apps for smartphones (for example http://www.iseismometer.com and http://www.now-instruments.com/products/3-vibsensor ). Are these useful for doing quantitative vibration analysis, and if not, what are their deficiencies?
Homework Statement
three harmonic function of frequency p, 2p ,3p were added together. what is the frequency of resultant periodic function?
Homework Equations
X=Asin(wt)
A-amplitude w-frequency
X=X1+X2+X3
The Attempt at a Solution
need a hint ..
Homework Statement
A half-full water tank mounted on the top of a building is modeled as shown below. Find the shear force it can produce?
m = 500 kg
k = 1000 N/m
model: https://app.box.com/s/qke2kbwag2mp9a23kkqq
Homework Equations
Transfer Matrix Method:
Point & Field Matrices...