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Cervenka Consulting Forums → ATENA → How to model an insulation with shear capasity?
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I have to model a heat insulation layer between concrete plates. I did not find any elastic element type which could handle the shear capasity of the insulation too. Not in ATENA 2D or 3D.
Is there any element type I could use or is there any other way to model this layer?
Best regards,
Auli Lastunen
Dear Mr. Lastunen,
I am not sure if I understand what is your problem - first of all, if you need to run thermal analysis, you need ATENA Science. If you only need to model the static behavior of the structure with the insulation (possibly with a simple temperature load - more or less this is limited to prescribing a constant temperature that can cause some strains due to the thermal expansion coeff. alpha), you can use ATENA Engineereing (2D or 3D).
I assume you have tried normal brick/quad or tetrahedra/triangular elements and some elastic material with low stiffness (elastic modulus) - what was the problem with the results (e.g., OK in tension/compression but too stiff in shear or vice versa)?
I think the most effective way is to send us your model to the support email (cervenka@...).
Best regards.
Thanks for your answer, but...
I did not descripe my problem good enough. I did not even think about thermal problem because I am interested in static problem.
I have so stiff insulation layer between concrete panels that it can bear the weight of the external panel without any diagonal ties. It is a sandwich structure.
How should I model this insulation layer? It has quite large shear capasity.
Best regards,
Ms. Auli Lastunen
Dear Auli,
I think that you first must present the type of materials you use for panel and insulation and also the usage of the structure.
Is the insulation material also able to handle tensile forces from winds suction and have enough adhesion to keep the panels coupled.
Is it an elastic isotropic material or anisotropic? Or it elasto-plastic?
Best regards
Jerry
Dear All,
The panel material is concrete and the insulation material is very stiff mineral wool. The prefabricated unit is a part of the bearing wall.
The insulation layer can handle tensile forces untill certain point and the adhesion is enough to keep parts together. Insulation material is not isotropic, but in this model I can assume it to be isotropic. We can also think it as an elastic material.
Best regards,
Auli
How large is the difference in E modulus between the concrete and the insulation? If up to about 10-100 times, it should work by just using the elastic material model for the insulation. But as you are asking here, I assume there was some problem with that approach?
If you see in the results that the tensile or shear stresses in the elastic insulation layer exceed the tensile/shear capacity, you need to switch to some nonlinear material (or add an interface between the insulation and the concrete). In that case, I would suggest to use Cementitious2 (i.e., the material model normally used for concrete), generate the parameters from a cubic strength to get the tensile strength and elastic modulus close to the rock wool properties (and maybe change one of them a bit).
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Cervenka Consulting Forums → ATENA → How to model an insulation with shear capasity?
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