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Yeoh model for hyperelasticity

Hi everybody,

I am new to Hyperworks, and I am working on a hyperelastic model. I found out that it is possible to use MATHE for the material, but with the Student Edition, I can't access to the Yeoh model, I only have the Mooney-Rivlin one. Is the Yeoh model accessible in the full 14.0 version? Also, why can’t I put the Young module when I use MATHE?
I still tried with the Mooney-Rivlin model (first order), to check out the behavior of my model, but I was not sure of how to use the properties, load collectors, and loadsteps in this case. Here the steps I followed, could you tell me what you think and if it seems correct?

•   Material > Isotropic > MATHE (parameters: MOONEY, E=1,37MPa, nu=0,49, rho=1,08e-9(T/mm^3), C10=0.236, NA=1, ND= 0??)
•   Property > 3D > PSOLID
•   Assigned to object
•   3D > Tetramesh > Volume tetra > Trias
•   Create Loadcollector > Constraints > NL_SPC
•   Create Loadcollector > Pressure > NL_LOAD > magnitude = 17,3e-3 MPa > select surf > PLOAD
•   Create Loadcollector > Constraints > NL_BOUNDARY > stop in y translation, and x, y ,z rotation

I also don’t understand what is ND, and what I am supposed to put.
In the analysis section, I don’t know which non-linear analysis I am supposed to choose. I am, for now, working on a static model, but in the future I will work on a dynamic one.

To finish, what is NLPARM? I don’t understand how to use it. Is it for incremental loads? How to use it? And, how to be in large displacement?

Thanks a lot for your help,
Best regards,
Lisa

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Altair Forum User

Hi @lisawood

14.0 Student Edition has only Mooney Rivlin model in MATHE card, unfortunately. But one can use Yeoh or any other hyperelastic material models using Full license. In coming version Student Edition has all HE material models.

You can use this turorial OS-1500: Nonlinear Implicit Analysis of Bending of a Plate learn more about how to use NLPARAM and other non-linear analysis details.

Altair Forum User

Hi Prakash,

Is the next version Student Edition coming soon? Also, is it possible to study large displacement with the Student Edition?

Thanks for this tutorial, I will try it. And thanks for your answer!

Altair Forum User

yeah it is possible to run a large displacement analysis either using NLSTAT with LGDISP option or using NLGEOM analysis type.

Altair Forum User

Hi,

In the Hyperworks Help, I found that large displacement can be set with NLPARM :

'The setup for the large displacement nonlinear static solution is as follows.

1.	PARAM, LGDISP,1 is used to activate large displacement analysis for all subcases containing the NLPARM Subcase Information Entry in the model. Subcase-specific Large Displacement Analysis can be activated via NLPARM(LGDISP)=SID, wherein, SID references a NLPARM Bulk Data Entry.'

I don't understand what is 'PARAM', but I tried with NLPARM, and I wasn't able to find the 'LGDISP' using a MATHE material (as you can see on the picture). Where can I find the LGDISP for the large displacement? I am not working on a static model, so I am not using NLSTAT.

Also, I have two different models to mesh. When I mesh one in 3D (using Volume tetra), an added component for the mesh appears. For the other model, no other component appears. So, I don't know what to think. Which one is correct? And why the other doesn't work?

Thanks a lot for your help!

Lisa

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Hi,

I don't understand what is 'PARAM', but I tried with NLPARM, and I wasn't able to find the 'LGDISP' using a MATHE material (as you can see on the picture). Where can I find the LGDISP for the large displacement? I am not working on a static model, so I am not using NLSTAT.

Go to Analysis page>>Control Cards>>PARAM>>LGDISP and change value to 1. See the attached image.

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Also, I have two different models to mesh. When I mesh one in 3D (using Volume tetra), an added component for the mesh appears. For the other model, no other component appears. So, I don't know what to think. Which one is correct? And why the other doesn't work?

Before you mesh, you can organize the elements to either current active component or to surface/solid component. Since you have already meshed the geometry and were organized in a new component, you can move these elements to parent component.

Go to Organize panel (SHift+F11 is shortcut)>> select the elements and select the destination component and click Move,

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Thanks for your answer. I 'made current' my solid, and used 'volume tetra', it didn't create a second component and meshed properly.

I tried again from the beginning to understand properly. I am still having issues :

- when I want to create a solid from my 3D model (IGS file from solidworks), the error 'No closed volume found' appears. I checked the free edges, and used 'edge edit' to toggle red lines (that are green now). What is wrong? Is it a problem?

- I also want to create 2 different constraints on my structure. Is it possible? In the load steps, I can choose only one 'SPC' component. I also have a pressure ('load') on my model.

Thank you so much,

Lisa

Altair Forum User

when I want to create a solid from my 3D model (IGS file from solidworks), the error 'No closed volume found' appears. I checked the free edges, and used 'edge edit' to toggle red lines (that are green now). What is wrong? Is it a problem?

Hi Lisa,

The problem is with the IGES file. Do you see any yellow lines? Is it possible to share the 3D model which is corrected?

I also want to create 2 different constraints on my structure. Is it possible? In the load steps, I can choose only one 'SPC' component. I also have a pressure ('load') on my model.

You can create two SPCs and can have two load steps. Or if you want to use both SPCs you can add two spcs using SPCADD (which is a load collector) and use the same in Loadstep

Altair Forum User

Hi Prakash,

How can I share my model?

Concerning the SPCs, is it possible to ' Goto Organize panel (SHift+F11 or Tools page>> Organize) select SPC and destination load collector, Click Move. ' ? I found this answer (yours) in the forum. Is it the same thing?

Also, is it possible to apply constraints regarding the faces of the model and not the axis (dof1 to 6)? My model isn't well orientated, and my constraints are not applied correctly on the faces.

Thanks,

Lisa

Altair Forum User

Hi Lisa,

How can I share my model?

Please use the secure file transfer link in my signature to share files.

Concerning the SPCs, is it possible to ' Goto Organize panel (SHift+F11 or Tools page>> Organize) select SPC and destination load collector, Click Move. ' ? I found this answer (yours) in the forum. Is it the same thing?

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Altair Forum User

Also, is it possible to apply constraints regarding the faces of the model and not the axis (dof1 to 6)? My model isn't well orientated, and my constraints are not applied correctly on the faces.

I did not understand what you mean, Could you please explain with a picture?