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17
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1answer
629 views

Vibrational anharmonic coupling and noise-induced spontaneous symmetry breaking in a hexagonal finite mechanical lattice

Happy holidays, everyone! The following is part question, part visual gallery, and part classical mechanics problem. Inspired by snow over the weekend I began simulating the vibrations of the ...
4
votes
1answer
296 views

Equations of motion of displacement field

We have an action: $$S[\boldsymbol{u}] = \frac{1}{2} \int dt \int d^3x \left\{ \mu (\frac{\partial u_{i}}{\partial t})^{2} - \nu (u_{ii})^{2} - \rho(u_{ij})^{2}\right\} $$ Where $u_{ij} = (\partial_{...
3
votes
1answer
53 views

Amplitude at successive wavefronts?

Consider spherical waves emanating from a point source initially the amplitude is A, as wave travels forming wavefronts will the amplitude of each point in all the secondary wavelets be the same and ...
3
votes
1answer
122 views

Degenerate vibrating modes of a metal plate

My question is based around this video: https://www.youtube.com/watch?v=1yaqUI4b974 The video shows sand settling in vibrational nodes of a plate at certain resonance frequencies. It appears that ...
2
votes
1answer
27 views

Outbalancing vibrations

Consider a ship vibrating in the fundamental/principal/first symmetric mode shape (similar to that of a Bernoulli-Euler beam), induced by the main engine (similar to that of a vibration shaker). I ...
1
vote
1answer
102 views

Deriving the equation of motion for a rigid system

I want to derive equation of motion for the system shown in picture. How do I choose a generalized coordinate in order to calculate kinetic and potential energy of the system? I need the ...
1
vote
1answer
33 views

Energy corresponding to the peak of velocity power spectrum

I ran a MD simulation for a number of N molecular hydrogen. I used the velocity time history of system for each atom and subtract the velocity of center of mass of each molecule from the velocity of ...
5
votes
0answers
283 views

Physical meaning of Laplace-Beltrami eigenfunctions?

The eigenfunctions of Laplace-Beltrami operator are often used as the basis of functions defined on some manifolds. It seems that there is some kind of connection between eigen analysis of Laplace-...
3
votes
0answers
288 views

Modelling an Inelastic Collision

I've attempted to model the inelastic collision between a moving mass and a large stationary object, e.g. dropping an ball on the floor, for analysing the approximate kinematics and heat dissipation ...
3
votes
0answers
117 views

Sound - for purposes of vibration

What is the best way to distribute noise from more than one source (I'm envisioning a system with many), within a dome, with the ground as its primary target, at optimal frequencies and volumes to ...
2
votes
0answers
24 views

Creating a structural dynamic model using only modal test data

Short version: Suppose I excite a vibrational response in some structure and measure its mode shapes and natural frequencies. Is it possible to create a structural dynamic model of the structure ...
2
votes
0answers
53 views

What is the effect of vibrations on an object's properties?

What do vibrations do to an object's properties? By making an object vibrate at a high frequency (compared to its static state) would vibrations: Increase or reduce its moment of inertia? Increase ...
2
votes
0answers
102 views

De-excitation and vibrational frequency

By utilising energetic beams of particles it is possible to set atomic nuclei into vibration. For a certain nucleus the subsequent de-excitation results in the emission of photons of energy $1$ $MeV$. ...
2
votes
0answers
318 views

Modal analysis with aerodynamic damping

I'm using modal decomposition to predict the steady state response of a beam structure to harmonic loading. The structure itself is very lightly damped, but we know from experiments that the ...
2
votes
0answers
1k views

Chladni Plate Mathematics

I am a high school student doing an IB Extended Essay investigation concerning the resonant frequencies of Chladni plates of differing materials and sizes. Would someone please explain the definition ...
1
vote
0answers
25 views

What's the effect called when vibrations move through a cable under tension?

I'm not sure how to describe it, but there is a certain sound of vibrations through a tensioned cable, you might hear it as sound effects in a movie where cables are snapping, some have described it ...
1
vote
0answers
33 views

Is there any solution manual to A.P. French's 'Vibrations and Waves'?

I'm trying to work through A.P. French's Vibrations and Waves. Unfortunately, I can't check the details of my solutions since the solutions aren't given with the textbook. Does someone know where I ...
1
vote
0answers
30 views

What is Lamè mode?

I am trying to read some of the articles that says Lamè mode. But I can't find in google that describes Lamè mode. Can anyone quote good reference for this term?
1
vote
0answers
34 views

Is disturbance propagation velocity equal to wave velocity in a solid body?

How do the disturbance propagation velocity and wave propagation velocity relate to each other? To explain my question in details I will describe the following situation from the theory of acoustic ...
1
vote
0answers
25 views

What is the highest frequency for ripples on water

I want to transmit sound vibrations as ripples on water, as an experimental audio delay effect. Can I make ripples at audio frequencies, that will travel over about 10cm or more? How about other ...
1
vote
0answers
26 views

How can frequency of waving in water change the direction object on the surface goes?

In an Australian experiment the physicists studied effects of a simple object that causes waves in fluid. They found that if it vibrates slow, the objects on the surface moves away from the vibration ...
1
vote
0answers
38 views

Models for vibrations and stress waves generated due to impact?

Say that a small metal ball impacts a long thin cylindrical rod from above (let's say height of around 10 cm) in an elastic collision and causes stress waves to propagate left and right from the point ...
1
vote
0answers
56 views

Non-linearity of a guitar pickup

I basically understand induction and why a pickup generates a signal. (From: http://www.brighthubengineering.com/consumer-appliances-electronics/64277-the-physics-behind-the-electric-guitar/) What ...
1
vote
0answers
45 views

Vibrational modes of a plate

What is the distinction between thickness-extensional, contour-mode/Lamb wave, in-plane shear, and the flexural modes of a plate, and under which conditions are each mode excited? Pictures for ...
1
vote
0answers
35 views

Can an axisymmetric solution produce antisymmetric eigenfunctions?

I'm solving a vibrating membrane. In order to simplify my calculations, it's tempting to assume axisymmetric behaviour. If I solve an axisymmetric problem, am I going to lose all the antisymmetric ...
1
vote
0answers
92 views

stopping, moving of mobile phone when vibrating

A mobile phone move aside when it vibrates. How is that happening ? and most importantly is it possible to make any changes to the vibration motor to stop moving when vibrating or any other methods to ...
1
vote
0answers
62 views

Closed pipe/sound resonance sound type sound coming from mineral processing plant

I work near a very large mineral processing plant which does vibrate our building and there is also a sound/feeling very similar to the closed pipe/sound resonance that is achieved when opening a back ...
1
vote
0answers
61 views

Modeling Acoustic Lubrication

I thought about posting this question in the Biology StackExchange site but really it is just the application of my question that applies to biology not the core of the question itself. Can anyone ...
0
votes
0answers
19 views

Derivation of differential governing equation of Hartnell governor?

I tried to derive the differential governing equation using energy conservative method and newton's second law, but I came up with very large and complex equations, even with assumption of small angle ...
0
votes
0answers
21 views

Overtone Transition Probability

For an anharmonic potential, like the morse potential, higher order transitions (overtone) with $\Delta n=\pm2,\pm3,..$ are allowed. How do I calculate the probability $P$ for such transitions? My ...
0
votes
0answers
8 views

What's the difference between vibrational relaxation and internal conversion?

According to the following diagram, an excited state can dissipate via vibrational relaxation or internal conversion. Aren't they the same thing? (source: Barltrop and Coyle, Principles of ...
0
votes
0answers
30 views

How to get the vibratonal frequency of a bond using FFT of velocity autocorrelation function?

I guess there is some errors in the way I am calculating VAC since I ma ending up with a peak whose frequency is two times the actual frequency. I ran an MD simulation long enough with 60 molecules of ...
0
votes
0answers
37 views

Does frequency of a vibration wave of a cantilever depend on its deflection?

cantilever= a beam fixed at one end only deflection is the initial displacement of the free end. the beam is let go when the free end reached its position it will vibrate, does the frequency of ...
0
votes
0answers
44 views

Is it possible to generate deep infrasound with subwoofer and a pipe?

I would like to check if infrasound noise can make people feel weird (as in a "haunted" house). Some people claim that noises of such frequency may be the cause of "paranormal" sensation in humans. ...
0
votes
0answers
26 views

Natural Frequencies determination using F.E.M analysis - Damping ratio

Good day. Assume a 3d underwater tether problem, which is modelled using FEM analysis. Global equation, after assembling terms associated with corresponding elements to a single entity, should look ...
0
votes
0answers
43 views

Interpreting solution of the 1-D wave equation (vibrating string)

An ideally flexible string of length $x=L$ vibrating in one dimension ($xy$ plane) in the absence of gravity obeys the wave equation \begin{equation} \dfrac{\partial^2 y}{\partial t^2} = c^2 \dfrac{\...
0
votes
0answers
43 views

How was the “vibrating string” studied?

The vibrating string is used to derive a lot of theory regarding strings, such as the theory about harmonics. However, since the string movement and specifically the phenomenon of harmonics seems ...
0
votes
0answers
67 views

Difference between three mutually complementary methods: Raman, Infra-red spectroscopy and inelastic incoherent neutron spectroscopy?

When I read the wiki on Raman spectroscopy, I found a paragraph explaining what system is suitable for using Raman and what others do not. It provide two other method as shown in title: infrared ...
0
votes
0answers
38 views

Are there lattice waves/vibrational modes in materiels at room temperature and above?

The following excerpt is from: http://encyclopedia2.thefreedictionary.com/Lattice+Vibrations 'At room temperature and above, most of the thermal energy resides in the waves of highest frequency. ...
0
votes
0answers
86 views

Vibrating water container problem

I am struggling with visualising and understanding the phrasing of this question - cross posted from Math stack exchange since this forum is more appropriate: "A water-filled container is ...
0
votes
0answers
300 views

How to compare natural frequencies for different pendulum-spring systems oscilating around the vertical equilibrium?

Im trying to compare the natural frequency of different pendulum oscilation systems around the vertical equilibrium. For the first case the balance of momentum is very simple and the natural ...
0
votes
0answers
55 views

What is the frequency associated to the orbitals within an atom?

I was told that there's a vibrational frequency associated to the orbitals within an atoms, but it is a frequency related not to a classical vibration. What Hz frequencies would these be?
0
votes
0answers
265 views

Effect on Q factor and resonant frequency when scaling down a damped oscillator to micro / nano scales

I've always just accepted that as you scale down a mechanical system the frequency and Q factor both increase. But how exactly do they scale? Linearly? With the square of reduction in size? Or maybe ...
0
votes
0answers
329 views

What affects the period and the frequency of a longitudinal vibration?

In a lab experiment, our objective is to observe the characteristics of longitudinal waves/vibrations. If we changed the mass and amplitude, I feel that they either affect the period and frequency of ...
0
votes
0answers
60 views

Isolate an electronic drum from the ground

Please note that I know nothing about this part of physics, so sorry if I make some mistakes. Drum is an awesome instrument, yet it can easily make your neighbours very angry.The vibrations caused by ...
0
votes
0answers
78 views

What equation can be used to solve an ideal string/membrane in a non-vacuum medium?

I'm interested in the eigenmodes of the membrane for various mediums, such as vacuum, air, water, etc., which impose a damping effect on the membrane. This cannot be done by merely changing the value ...
0
votes
0answers
36 views

Varying vibration frequencies

Im currently testing vibrations through materials. I have a vibration motor that runs 200hz. Problem; the pressure I apply to the motor change the frequencies I pick up. Why? Example: If I use a ...
0
votes
0answers
401 views

Saddle point and transition state of a molecule

During a transition of a molecule from one state to another, it pass through a transition state. This transition state, mathematically speaking, is a saddle point. That means, the second derivative ...
0
votes
0answers
63 views

How can this formula be analyzed intuitively?

Given $$ \bar{U}_{vib}(T) = R \sum_{\text{n.m.}} \left( \frac{\theta_{vib, n.m.}}{2} \right) + \frac{\theta_{vib, n.m.} e^{-\theta_{vib, n.m.}/T}}{1-e^{-\theta_{vib, n.m.}/T}} $$ where $\bar{U}_{vib}...
0
votes
0answers
168 views

Can I transfer vibration with hydraulics?

I need to transfer vibration to 10 meters. I can do this with solid metal rod, but its making mechanical design complex. So, I am thinking to do it hydraulically (tubes can easily be bend). But, I am ...