COMSOL Forums: Calculting Young's modulus of a complex shape using Comsol

Re: Calculting Young's modulus of a complex shape using Comsol

Sun, 14 Mar 2010 19:23:30 +0000

Hi

I would use either the basic structural or the "full" structural module, but you have also structural in the MEMS module

If your shape is simple you should use the simplebar in compression k=E*A/L formula (E young modulus, A section area, L length of bar in compression), for bars in flexure it's more the k=3*E*I/L^3 were I=1/12*w*h^3 the inertia with w bar width (defining axis of rotation), h bar height, L bar length that yu should use. Have a look at one of the numerous books on elasticity (i.e. Timoshenko or others)

For complex geometries, the CAD 3D shape and directly the FEM in COMSOL is the best, but always check coherence with the simple formulas above

Good luck
Ivar

Re: Calculting Young's modulus of a complex shape using Comsol

Sun, 14 Mar 2010 17:08:54 +0000

you load with an Applied force such as 1 or 1000[N] and you calcualte the average displacements of your interface, then

k[N/m] = (Applied_force [N]) / average(dz [m])

Calculate with which module/submodule? I can draw the shape using Inventor, for example, and import it into Comsol. Then, which module do I use?

Thanks,

Amit

Re: Calculting Young's modulus of a complex shape using Comsol

Sun, 14 Mar 2010 15:53:37 +0000

Hi

if it's the stiffness "k[N/m]" you want, then it is straightforward, provided you have correct material data: E, nu, rho, the geometry and the load boundary case:

you load with an Applied force such as 1 or 1000[N] and you calcualte the average displacements of your interface, then

k[N/m] = (Applied_force [N]) / average(dz [m])

Good luck
Ivar

Re: Calculting Young's modulus of a complex shape using Comsol

Sun, 14 Mar 2010 13:06:33 +0000

Hi

from my understanding the Young modulus remains a material property that is linked to the stiffness and the inertia of the part, no ?

So if you have the geometry, the density and experimental values for the siffness under known load conditions you should be able to recalculate back (via anoptimisation or a series of parametric sweep solving and the old "abaque" way) to estimate the material Young modulus.

But you must also assume your model is correct and all "important" terms are included

Good luck
Ivar

Re: Calculting Young's modulus of a complex shape using Comsol

Sun, 14 Mar 2010 11:32:13 +0000

Hi,

Do you know whether one can calculate Young's modulus of a complex shape using Comsol?

Thanks,

Amit

Sorry, I meant the spring constant of a material assuming it has a homgeneous Young's constant

Calculting Young's modulus of a complex shape using Comsol

Sun, 14 Mar 2010 11:30:49 +0000

Hi,

Do you know whether one can calculate Young's modulus of a complex shape using Comsol?

Thanks,

Amit