Recent content by pitchtwit

Hi, Well alternative values could be: - Material: Polytherimide film Density - 1200 kg/m^3 Young's Modulus, E = 3.6 GPa Poisson's ratio, nu = 0.34 Membrane thickness = 0.076 mm Original tension = 5.7 GPa Circular membrane radius = 12 mm Central mass weight = 1 g Central mass radius = 2 mm I'd...

I need to know a realistic minimum biaxial tension per unit length - in N/m - for the surface of a membrane which is 27.4 mm square - with surface density 0.0912 kg/m^2 - so that it could be vertical and remain tense so that mode shapes due incoming acoustic energy would remain intact (if the...

Acoustic metamaterial - locally resonant. Yes of course. I'm trying to recreate a model that has already been created in COMSOL by a few researchers - one of which is Christina J Naify (she does a presentation on this here). It's for my Masters project. I plan to try out a few tweeks of my own...

Can I prevent setting up standing waves in my COMSOL model? I'm using integration over two opposing faces to get the pressure at the 'outlet' - but it seems that no matter what I do to prevent the standing waves, they won't go away. Any help would be great, Thanks

I have a model set up, that is a cuboid, with a membrane half-way along - a bit like an impedance tube setup. I've used Integration 1 & 2 with Explicit 1 & 2 to define an 'inlet' and 'outlet' at opposing faces of the tube. The Variables for the inlet and outlet are intop1(p0) and intop2(p)...

Thanks - that's good to know. I've been struggling to set up a simple model using square membrane like the one above. I've tried loads of ways but nothing seems to work, and if you'd be willing to give me some advice I'd be really appreciative. The model is simple - a small square isotropic...

I've just got a quick question that hopefully someone can answer. My question is - why does the membrane in COMSOL vibrate without you telling it to? Here are some specifics if required... In COMSOL here are my setup details: - Physics: (3D) Structural mechanics - Membrane Study...

The introduction of W_m and what it represents. Thanks for taking the time AlephZero. I did know about Wi,j and Wr,s, and how the first paper abbreviates those to Wm and Wn (actually the 2nd paper does this too, but later on in the calculation from equation 25 to 26). Also, although the...

Homework Statement I'm following a procedure in a particular paper as part of my Masters project. The paper is called 'Theoretical investigation of the sound attenuation of membrane-type acoustic metamaterials - Y Zhang, J Wen, Y Xiao, X Wen and J Wang (2012)' and can be seen...

New version of the solution Not sure who's around - have been working on this for a bit - would be grateful for a hand - my solution seems too hefty. The aim was to do an analytical Fourier transform using a couple of trigonometric identities. http://dl.dropbox.com/u/11341635/1st%20bit.png...

Okay - got it now. Many many thanks.

Well I checked the plus and minus signs quite a few times already. I'm not sure about the factor of m - where does that come in? I'm integrating from -0.1 to 0.1 because the original graph dies off towards -0.1 and 0.1

Actually I've been finding YouTube to be a pretty good place for tutorials on even some pretty hefty maths. Check out Matlab - it's like Excel but a million times better. Also check out Mathematica and their demos project - http://demonstrations.wolfram.com/ I wouldn't recommend Wikipedia as...

a solution of sorts Well I'm done. The end equation looks pretty weighty, so I've know idea if it's right or not. Thanks again for your help so far. http://dl.dropbox.com/u/11341635/Part%201.png http://dl.dropbox.com/u/11341635/Part%202.png http://dl.dropbox.com/u/11341635/Part%203.png

I've done the majority of the work I think. It'd be great if you'd be willing to give it a quick look. http://dl.dropbox.com/u/11341635/2nd%20attempt.png