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Define a Young Modulus that increases within a sphere
Posted Oct 10, 2016, 12:49 p.m. EDT Version 5.2a 3 Replies
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Hello,
For my research I need to work on a sphere with a young modulus that will increase if close to the center of the sphere. The young modulus is then not anymore a constant.
From now I tried to create a sphere with multiple layers of different young modulus but I would like to be able to use an equation for that and get rid of the layers.
So my questions are:
Do we have a variable already in Comsol that defines the distance between each points within the sphere and its center ?
Do I have to use the non linear Elastic material from the non-linear structural materials module ? Or something else ?
Thanking you in advance,
Michael
For my research I need to work on a sphere with a young modulus that will increase if close to the center of the sphere. The young modulus is then not anymore a constant.
From now I tried to create a sphere with multiple layers of different young modulus but I would like to be able to use an equation for that and get rid of the layers.
So my questions are:
Do we have a variable already in Comsol that defines the distance between each points within the sphere and its center ?
Do I have to use the non linear Elastic material from the non-linear structural materials module ? Or something else ?
Thanking you in advance,
Michael
3 Replies Last Post Oct 11, 2016, 8:07 a.m. EDT
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Posted:
8 years ago
Hi Michael,
Material properties can be functions of coordinates. Just type the expression you need. In your case it can depend on sqrt((x-x0)^2+(y-y0)^2+(z-z0)^2) where x0,y0,z0 are the coordinates of the center of the sphere. Alternatively, you can define a spherical coordinate system centered at x0,y0,z0 and then use sys2.r in your expression. If you have not defined coordinate systems in COMSOL before, you can read about that topic in the Reference Manual, version 5.2a, page 304 and following.
Best,
Jeff
Material properties can be functions of coordinates. Just type the expression you need. In your case it can depend on sqrt((x-x0)^2+(y-y0)^2+(z-z0)^2) where x0,y0,z0 are the coordinates of the center of the sphere. Alternatively, you can define a spherical coordinate system centered at x0,y0,z0 and then use sys2.r in your expression. If you have not defined coordinate systems in COMSOL before, you can read about that topic in the Reference Manual, version 5.2a, page 304 and following.
Best,
Jeff
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Posted:
8 years ago
Hi Jeff,
Thank you very much for your quick answer.
In my model I created a 3D model of the sphere but the mesh contained too many elements so I created a work plane that cut the sphere to be able to reduce the model to a 2D radial symmetric one.
My coordinate system is then r, phi, z.
For convenience I have centered my sphere to the origin.
I finally characterized the sphere as a linear Elastic material with a young modulus defined as:
E= f(r);
where "f" is the function I will apply and "r" is the distance from the center.
Am I correct ?
Michael
Thank you very much for your quick answer.
In my model I created a 3D model of the sphere but the mesh contained too many elements so I created a work plane that cut the sphere to be able to reduce the model to a 2D radial symmetric one.
My coordinate system is then r, phi, z.
For convenience I have centered my sphere to the origin.
I finally characterized the sphere as a linear Elastic material with a young modulus defined as:
E= f(r);
where "f" is the function I will apply and "r" is the distance from the center.
Am I correct ?
Michael
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Posted:
8 years ago
Hi Michael,
Yes, you are!
Enjoy COMSOL,
Jeff
Yes, you are!
Enjoy COMSOL,
Jeff