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Elastic wave propagation in Solids

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EngTipX

Mechanical
May 23, 2011
28
How to simulate elastic wave propagation in Solids?
a) How to model an incident P-wave (Pressure Primary longitudinal wave) or SV, SH-wave
The incident wave will be harmonic and it has periodicity in the direction of propagation
P-wave is P=P0e1i.K.xe1i.omega.t
S-wave is P=P0e1i.k.xe1i.omega.t
such that omega is the incident wave frequecny, K is longitudinal wave number, k is the shear wave number, P0 is the amplitude of pressure
e is the exponetial, 1i is the imaginary 1i=sqrt(-1)
b) How to model non reflecting boundary conditions? So the waves are not refelected on the boundaries?

Here are my thoughts:
this is a harmonic analysis this takes care of e1i.omega.t, then how to simulate periodicity in propagation direction which is x?
the non reflecting boundary can simulated as far away with damping elements?

If you can suggest with command snippet would be great, however any input would be appreciated
 
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I have few ideas but I do not know how to implement them with my current APDL knowledge
The first idea is to apply a pressure in the Harmonic analysis
the harmnic analysis takes care of the time peridocity however to add the translational or simulate a propagating wave
the pressure has to be a function in frequency which ANSYS permits in Harmonic Analysis, all you need to do is apply a pressure function with the following
P0e1i.k.x such that x is the distance where your pressure will be applied and k=2*pi*frequency/c all are constants except for frequency
This is similar to the way ANSYS simulates harmonic analysis with rotating forces or ocean wave procdure. In these two harmonic analysis the forces are not just the real or quasi-static amplitudes but also have an imaginary or changing phase or their amplitudes change with frequency


The second idea is using transient and I still do not know how to apply a function pressure which will change in both time and position, however you will still need to apply complex pressure on nodes
These are the ideas but how to go about doing them!
 
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