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Victor
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Yes, that's the problem and it's a big limitation of CCX's 2D shell output. The internal solver keeps those 3 values (top, middle, and bottom stress) separate in its 2D element solution so you can view each layer's stress individually whereas CCX av…
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Thanks for sharing the excellent pictures at usual. What will be tied to the loop? Not a wing-walker, I hope!
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The cutting plane slider at the top right of the toolbar does this, but it only cuts along element boundaries so you get a jagged surface. You can also hide individual components by right clicking them under Solution -> Components in the outline…
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Good to hear. Shell offset works for differential thermal expansion with the CCX solver but not internal. I would prefer to use solids for that if possible though. Or at least validate part of it against a solid model if your structure is too comple…
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It should be possible with various ways: * Bonded contact with CCX and the Elastic option * Internal solver with bonded contact * Merge the nodes of the 3 layers and use Shell offset in element properties to position them. * Laminate materi…
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Hello kiran Once you have a contact model, add contact stress through Solution -> New stress and strain -> contact stress then solve it. The contact pressure (negative normal stress) is only shown on the slave surface. If you don't have a c…
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I got it two work in two ways: A ) Changed the fixed support to get rid of the stress singularities at the ends. Might not really be practical for a real structure. (plastic composite v3.liml) B ) Added another stress-strain point to the brittle m…
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I see. Thanks. Though for symmetry, you can use frictionless support instead which is much easier as long as the element surfaces are all in the symmetry plane.
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Could you clarify what's not easy? Finding them in the list or setting the parameters on the big form or something else?
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I can't find a way to do that, sorry. Other than requesting enough modes to exceed zero. You can also do linear buckling with modal vibration (frequency / modal) analysis if you have some idea of the critical load. You adjust the loads until the fr…
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Oh, good find. The demo version has no missing features except being limited to 1000 nodes. It doesn't have any CCX convergence options in the UI but you can enter the CCX card for that (*CONTROLS) in CCX -> custom model definition.
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I don't know much about soil and can't help there, sorry. It sounds like a more general engineering problem that perhaps you could ask on eng-tips.com
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The most complete way is to use contact with nonlinear static 3D analysis and CCX and model the soil too. But if the whole surface remains held by static friction and doesn't separate from the soil, you can just use fixed support and look at the sh…
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You're right that the failure criteria won't help - they are only for calculating factors of safety. The internal solver doesn't do progressive failure for composites. The CCX solver looks like it can if you define the brittle material using a pla…
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A useful new option in 2.15 is *CONTROLS,PARAMETERS=CONTACT which allows you to increase the maximum number of iterations before it gives up. I just used that to get a difficult contact problem to solve which looked like it was converging but wouldn…
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There appears to be one on this page: http://www.dhondt.de/ It's the last item in the CCX download list, confusingly called "files". Direct link http://www.dhondt.de/calculix_2.15_4win.zip
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You could make it double thickness by extruding from both sides of each surface as shown in the attached picture. The corner nodes will end up a bit out of place so you'd have to reposition them manually. It should work pretty well using shells tho…
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Yes. Tools -> Options -> Default model. You can also use File -> Import to add a model containing only a material to the currently open model.
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You could try to use an actual solid mesh made from tet10 elements. You might need more than one element in the thickness direction for good accuracy but since it's fairly simple, you might get by without having too many elements. Sometimes you can…
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All IGES files have this problem with Mecway. Please use STEP instead. IGES support is only really there for very old CAD software that somehow doesn't export STEP. I might remove that in future versions.
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Thanks for this suggestion Steve. I'm trying to work out a cohesive way to include rigid body type features for bonding a beam to a whole surface, pivoting joints between solid mesh parts, and possibly fastener spiders. So loads and constraints dist…
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You know, I'm not sure. It might simply be a lack of tests. They seem to work if you switch to Static 3D to set them up then back to modal vibration to solve. I'll look into enabling them properly.
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Thanks for the suggestion Eduart. What I'm thinking about for that problem is named folders which you can use to group items into. Would that work just as well for you?
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CCX has some error estimates. See the CCX manual for details. I don't know much about them though. There's a rule of thumb to not have the stress change by more than 10% of the whole range over a single element, which means no more than two colors …
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You can define a nonlinear stress-strain curve by entering the CCX cards under CCX -> custom model definition. There's an example of that in the manual section 14.1 Custom model definition. I don't know about nonlinear Poisson's ratio. There are…
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It's not just the reference values, but some of your results don't seem to be converging at all, such as σ_eq,s and σ_sθ which decrease with refinement until local refinement where they suddenly jump up to near the values from the coarsest mesh. Are…
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I'm comparing to the finest solid mesh. I don't trust the theoretical values to use as a reference because the formulas seem too simple - No Poisson's ratio? Is stress inside or outside? Linear or nonlinear? Where do the k factors come from? Where d…
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I'm still not seeing much problem. Where are you measuring the stresses? I checked some of them a small distance from the base, and von Mises is 0.5% error with 10,000 nodes. Axial is worse, but approximately 0 error for 39,000 nodes. Shear is the w…
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I don't really see much of an accuracy problem. I tried to recreate the model from your PDF - 6.015 m diameter and 5 mm wall thickness, clamped at the base. I didn't get anywhere near the same stress so I probably have some parameter wrong, but I di…
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You could try S8R instead of S8. I think that might perform better but I'm not sure about thin-walled structures in particular. It's now under CCX -> custom element type. The stress near the clamp presumably won't be correctly predicted by the t…
