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Concerning the calculation of the contact surface deformation
Posted 30 giu 2010, 07:45 GMT-4 4 Replies
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Dear all,
I'm currently doing a simulation of nanoparticles deposited on the cell membrane's surface.
I would like to know how to calculate how much area of the surface has been deformed so that I could compare with the surface where it has not been deformed yet.
Thank you very much. Hope to hear from you all.
Ben
I'm currently doing a simulation of nanoparticles deposited on the cell membrane's surface.
I would like to know how to calculate how much area of the surface has been deformed so that I could compare with the surface where it has not been deformed yet.
Thank you very much. Hope to hear from you all.
Ben
4 Replies Last Post 5 ott 2010, 02:19 GMT-4
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Posted:
1 decade ago
Hi
if you membrane is in structural (or mems-structural) you should apply a body load as -g_const*solid.rho (or correct to whatever your physics name is) to get the gravity sag of the membrane alone, and then add the force from the extra mass of the nanoparticles. I would apply a surface load on the top of themembrane and define its extend locally (where the nanoparticlaes are), and make it like a load as -g_const*Nano_rho*Nano_volume where the two latter values are defined as parameters. And if it is a time series you should replace the Nano_volume by Nano_volume_increase_rate*t where "t" is the internal COMSOL time variable.
This is for V4, in V3.5 you must adapt the names and define the constant G=9.81[m/s^2] or just 1[lbf/lb]
Good luck
Ivar
if you membrane is in structural (or mems-structural) you should apply a body load as -g_const*solid.rho (or correct to whatever your physics name is) to get the gravity sag of the membrane alone, and then add the force from the extra mass of the nanoparticles. I would apply a surface load on the top of themembrane and define its extend locally (where the nanoparticlaes are), and make it like a load as -g_const*Nano_rho*Nano_volume where the two latter values are defined as parameters. And if it is a time series you should replace the Nano_volume by Nano_volume_increase_rate*t where "t" is the internal COMSOL time variable.
This is for V4, in V3.5 you must adapt the names and define the constant G=9.81[m/s^2] or just 1[lbf/lb]
Good luck
Ivar
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Posted:
1 decade ago
Dear Ivar,
Thank you for your information.
Ben
Thank you for your information.
Ben
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Posted:
1 decade ago
Hello,
I am performing a similar analysis but for ball bearings. I want to calculate the contact stress on a ball bearing if I apply a load on one side of the bearing assembly and leave the other side of the assembly fixed. I could not get the geometry to render correctly for a 3D model because COMSOL could not supposedly resolve the tangent point between the ball bearing and the assembly housing.
I am now the model in 2D and I do not have the same problem but I still get an error where the solution does not converge. Does anyone have any suggestions about this? I think that this is a fairly straightforward problem so I must be modeling it slightly incorrectly.
Also how can we show the deformed shape in 2D or 3D model?
Kevin
I am performing a similar analysis but for ball bearings. I want to calculate the contact stress on a ball bearing if I apply a load on one side of the bearing assembly and leave the other side of the assembly fixed. I could not get the geometry to render correctly for a 3D model because COMSOL could not supposedly resolve the tangent point between the ball bearing and the assembly housing.
I am now the model in 2D and I do not have the same problem but I still get an error where the solution does not converge. Does anyone have any suggestions about this? I think that this is a fairly straightforward problem so I must be modeling it slightly incorrectly.
Also how can we show the deformed shape in 2D or 3D model?
Kevin
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Posted:
1 decade ago
Hi
one difficulty with contact problems is the large difference between pressure in [GPa] and the deformations in [nm] of the ball bearings. knowing that the binary number representation can only survive soem 2.22E-16 in ratio between two numbers (and that with 100% relative error) you probably need to "rescale" manually your solver variables. Check the doc and the fields for "scaling" in the solver.
And be sure your local mesh and boundaries are represnetaitve of the small deformation you have in the contact region
--
Good luck
Ivar
one difficulty with contact problems is the large difference between pressure in [GPa] and the deformations in [nm] of the ball bearings. knowing that the binary number representation can only survive soem 2.22E-16 in ratio between two numbers (and that with 100% relative error) you probably need to "rescale" manually your solver variables. Check the doc and the fields for "scaling" in the solver.
And be sure your local mesh and boundaries are represnetaitve of the small deformation you have in the contact region
--
Good luck
Ivar