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Phononic Band-Gap Structure Eigenfrequency Analysis
Nagi Elabbasi, Veryst Engineering
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Phononic crystals are artificially manufactured structures, or materials, with periodic constitutive or geometric properties designed to influence the characteristics of mechanical wave propagation. They can be engineered to isolate vibration in a certain frequency range. Vibration in that frequency range, called a band gap, is attenuated by a mechanism of wave interferences within the periodic system.
To illustrate, we created this model involving a 2D periodic structure with a unit cell composed of a stiff inner core and a softer outer matrix material, designed to have a band gap around 60-70 kHz. We applied Bloch boundary conditions to constrain the displacements of the unit cell, and set up a complex Eigenfrequency Study with a Parametric Sweep spanning the wave vectors that represent the boundaries of the irreducible Brillouin zone. When we plot the wave propagation frequencies for all wave numbers, a band gap appears as a region where no wave propagation branches exist.
User Comments
Ahmed Nagaty Feb 11, 2016 at 11:37am UTC |
please i am using comsol 4.4 and this module can't open with ....if you could help me in that by a pdf or any thing please ,because really i need it .. |
Nagi Elabbasi Entry submitter Feb 11, 2016 at 11:36pm UTC |
Unfortunately I do not have an older version of the model. If you read this related recent COMSOL blog post (http://www.comsol.com/blogs/modeling-phononic-band-gap-materials-and-structures/) you should hopefully be able to recreate the model in version 4.4. |
Nagi Elabbasi Entry submitter Feb 12, 2016 at 2:26pm UTC |
If it helps here is a copy of the parameter definitions: |
Ahmed Nagaty Feb 13, 2016 at 7:43pm UTC |
thank you |
Saeid Jamilan Feb 14, 2016 at 12:23am UTC |
Thanks for your help in advance. How it is possible to get band gap diagram for TM or TE ploarization? I am using COMSOL 5.1 |
Nagi Elabbasi Entry submitter Feb 16, 2016 at 8:51pm UTC |
You should be able to use a very similar approach for photonic band gap calculation. Check out COMSOL Application ID 798 called Bandgap Analysis of a Photonic Crystal. |
Saeid Jamilan Feb 17, 2016 at 1:17am UTC |
Many thanks for your response and help. I used that instructions and could simulate. The problem is that it is simulating for TE Polarization. I do not know how to adjust COMSOL settings to extract band gap data for TM polarization. |
Ahmed Nagaty Feb 19, 2016 at 2:10pm UTC |
how can i control the filling fraction in the phononic crystal to know its effect on the band gap ?? |
said said Feb 20, 2016 at 2:14am UTC |
please what is the version which are you worked this model? |
Ahmed Nagaty Feb 22, 2016 at 7:03pm UTC |
version 5.2 |
Yuning Guo Mar 4, 2016 at 9:35pm UTC |
Hello Sir, does it possible to obtain equifrequency contour of Phononic crystal in Comsol? If possible, could you tell me how to achieve it? Thanks a lot. |
Ahmed Nagaty Mar 6, 2016 at 8:56pm UTC |
hi , i have aproblem in calculation of phononic band gap for 2D phononic crystal , i have calculated it but i have a oroblem in the wave vector axis , i want to be MX (coordinates of the first brillion zone not numbers)... |
Thibaut Jacqmin Mar 14, 2016 at 9:11pm UTC |
Thanks for the nice model. Maybe it would be nice if you could export it as a *.m (matlab) file so that even people who don't have the right version of Comsol can see how to implement it. I thank you very much in advance. |
Zhaoxuan Zhang Mar 17, 2016 at 8:51am UTC |
Hi, Mr. Elabbasi, |
Edoardo Belloni Mar 24, 2016 at 9:03am UTC |
Dear Mr. Elabbasi, |
Clinton Potts Mar 26, 2016 at 3:24am UTC |
Dr. Elabbasi |
said said Apr 1, 2016 at 9:54am UTC |
Comment removed by said said. |
said said Apr 1, 2016 at 9:55am UTC |
Mr. Nagi hello please i want to calculate the band structure of a hexagonal mesh how exchange parameters in your loop? |
Nagi Elabbasi Entry submitter Apr 1, 2016 at 1:54pm UTC |
Thank you Edoardo for pointing out the mistake. Yes it should be (kx, ky) for both boundary conditions instead of (kx, kx) for one and (ky, ky) for the other. It does not affect the results though in any way because the dot product of k_F and (r_dst – r_src) will zero out the wrong terms. Thank you for pointing it out though, I will upload a corrected version soon. |
Nagi Elabbasi Entry submitter Apr 1, 2016 at 1:55pm UTC |
Dear Clinton, you are referring to the animations I showed in this Blog (https://www.comsol.com/blogs/modeling-phononic-band-gap-materials-and-structures/). I applied the excitation as a horizontal displacement at the left boundary in a Frequency Domain analysis, and I ran that analysis at 27, 67.5 and 88 kHz. |
Nagi Elabbasi Entry submitter Apr 1, 2016 at 1:58pm UTC |
Dear Said, you follow the same approach basically. You model the unit cell with the proper Floquet boundary conditions, and solve over the wave numbers that span the Irreducible Brillouin Zone of the hexagonal structure. The IBZ still has three “sides” as in this example so the changes to the model should be relatively minor. |
lei xiao May 10, 2016 at 8:12am UTC |
Comment removed by lei xiao. |
lei xiao May 10, 2016 at 8:14am UTC |
Dr. Elabbasi |
Zhuhua Tan May 16, 2016 at 7:17am UTC |
Hi Nagi, |
Nagi Elabbasi Entry submitter May 22, 2016 at 11:49pm UTC |
Thanks Zhuhua! If you follow the logic of the IF statements you will find that for 0<k<1 kx and ky define the “horizontal” edge of the IBR, for 1<k<2 they define the vertical edge, and for 2<k<3 they define the diagonal edge. |
工 王 Jun 12, 2016 at 8:25am UTC |
Thanks! |
Omar Najera Nov 7, 2016 at 8:49pm UTC |
this model is only for the diagonal direction or for all directions in the crystal? |
Henrik Asendorf Dec 6, 2016 at 9:22am UTC |
Hello, |
Xukun Su Dec 25, 2016 at 9:50am UTC |
Dear Mr. Elabbasi, |
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