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1. MUMiles
   

   Member
   Joined: Jul '15
   Posts: 3

   Hello,

   First off thank you so much for offering this package free of charge. I am trying to simulate more than two layers of elastic/viscoelastic materials and am running into a problem when coding more than two layers. Here is the general process I am using:

   % Define properties of the first layer (FOAM)
   medium.sound_speed_compression = 2278*ones(Nx, Ny); % [m/s]
   medium.sound_speed_shear = 30*zeros(Nx, Ny); % [m/s]
   medium.density = 1265*ones(Nx, Ny); % [kg/m^3]

   % Define properties of the second layer (Steel)
   medium.sound_speed_compression(Nx/2:end, :) = 5164; % [m/s]
   medium.sound_speed_shear(Nx/2:end, :) = 2164; % [m/s]
   medium.density(Nx/2:end, :) = 7500; % [kg/m^3]

   % Define properties of the third layer (PMMA)
   medium.sound_speed_compression(3/Nx:end, :) = 11663; % [m/s]
   medium.sound_speed_shear(Nx/3:end, :) = 1663; % [m/s]
   medium.density(Nx/3:end, :) = 11185; % [kg/m^3]

   etc...

   But it seems as though I always end up with just two materials. Any insight into what I'm doing wrong is greatly appreciated. Also, it there a way to make the layers circular? Like if I wanted to take a cross section of a sphere in the center. My problem involves coated spheres. Thanks!

   Posted 8 years ago #

2. Anthony
   

   Member
   Joined: Apr '13
   Posts: 96

   Hi MUMiles,

   First of all, you have a 3/Nx instead of Nx/3. Then, if you look at the order of your material definition, the third one comprises (and though erases) the second one. Try 2*Nx/3, and it will work ;-)

   makeDisc will help you for the circles.

   Anthony

   Posted 8 years ago #

3. MUMiles
   

   Member
   Joined: Jul '15
   Posts: 3

   Thanks Anthony, that did the trick! As far as using makeDisc I am still a little confused. I can populate my grid points for a material but when I try to define a disc in the center the plot just becomes "grayed out". Here is how I am trying to define different material parameters for a disc in the center:

   medium.sound_speed_compression = 5000*makeDisc(Nx, Ny, Nx/2, Ny/2, 2, 'true');
   medium.sound_speed_shear = 2000*makeDisc(Nx, Ny, Nx/2, Ny/2, 2);
   medium.density = 6000*makeDisc(Nx, Ny, Nx/2, Ny/2, 2);

   Posted 8 years ago #

4. MUMiles
   

   Member
   Joined: Jul '15
   Posts: 3

   Solved!

   I was going about this wrong. The correct way is to define your grid and then use:

   medium.sound_speed_compression = medium.sound_speed_compression + 5000*makeDisc(Nx, Ny, Nx/2 ... etc

   Posted 8 years ago #

5. buagciar
   

   Member
   Joined: Oct '14
   Posts: 1

   thank you!!!

   i can not figure this out, wokr for me!

   Posted 8 years ago #

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