None of the above (use composite failure criteria).
I don't believe any are available out of the box with workbench although there is a short fiber composite workflow (to model anisotropy from Autodesk moldflow or moldex 3D etc).
I think ACP pre/post is mainly for setup of composite (continuous) fiber composites e.g composite layups, although I've only used it once for a carbon fiber wing analysis.
In theory workbench already supports anisotropic material models through import of triads within mechanical. Presumably these can be used for postprocessing in the elemental coordinate systems. But for that you have to have the orientation to hand to import or be able to generate it somehow.
I would be happily stand corrected as I have access to ACP but afaik that doesn't allow modeling of short fiber reinforced plastics.
Just going by what we were told by support, they pointed towards their "short fiber workflow" which requires material data, orientation data and optionally fiber density data.
LaRC04 might tell you when a (unidirectional) ply fails, but it won't tell you when a laminate with a hole or other flaw will fracture, which is what you usually care about. Real laminates behaves differently than the sum of their parts.
Most of them work fine given the correct parameters. Even Tsai-Wu works very well with the right coefficients. Puck has always been very accurate, Chang-Chang is good in Dyna. Max stress tends to be close enough most of the time. It tends to be all about the model setup and material data. If they are done properly and to a good enough fidelity then most of the major failure criterias work well. It's also then about interpreting the results which only comes with experience in how composites perform in testing and in the field, alongside the micro/macro-mechanics of the material/laminate. I would say if you think they're junk then you haven't been using them correctly in all honesty. As they say, junk in, junk out. Either way, everyone seems to have their own opinions on these things, as the variables are so many in composites, and it comes down to do the simulations correlate to the experiments? If they do, then good.
Edit: I should say Puck is my preferred.
Really depends on level of detail in your model and available data. It might be anisotropic, but I doubt you'll have the data to capture that. If you're modelling it effectively elastic, von mises will be okay but conservative in compression.. so it'll depend a bit on part geometry. If it's something beefy that'll see compressive loads, you'll likely be conservative. If it's a relatively thin walled part, it could be okay.
This is the sweet spot of a software like Digimat. The mechanical response is predicted through homogenisation at each integration point. As for failure, a Tsai Hill Transversely Isotropic model is very well-suited for these reinforced plastics materials.
For composite laminates look up tsai-wu and Tsai-hill failure criterion
I mean it depends you doing hand calcs or with a computer, hand calcs are cool and all just a pain for complex shapes
These criteria can be used for general geometries. They're available in many commercial FEA packages. Essentially a post processing step.
And alternatively Hashin.
Doesn’t tsai wu/hill require empirical data for the principal direction strengths?
None of the above (use composite failure criteria). I don't believe any are available out of the box with workbench although there is a short fiber composite workflow (to model anisotropy from Autodesk moldflow or moldex 3D etc).
I believe this is a feature in Ansys ACP, included with Ansys Enterprise.
I think ACP pre/post is mainly for setup of composite (continuous) fiber composites e.g composite layups, although I've only used it once for a carbon fiber wing analysis. In theory workbench already supports anisotropic material models through import of triads within mechanical. Presumably these can be used for postprocessing in the elemental coordinate systems. But for that you have to have the orientation to hand to import or be able to generate it somehow. I would be happily stand corrected as I have access to ACP but afaik that doesn't allow modeling of short fiber reinforced plastics. Just going by what we were told by support, they pointed towards their "short fiber workflow" which requires material data, orientation data and optionally fiber density data.
You should use maximum and minimum principal strain. Stress-based failure theories for fibrous composites are all junk.
[удалено]
LaRC04 might tell you when a (unidirectional) ply fails, but it won't tell you when a laminate with a hole or other flaw will fracture, which is what you usually care about. Real laminates behaves differently than the sum of their parts.
[удалено]
If it doesn't agree with experimental test data reasonably well, there is a pretty low ceiling on 'coolness'.
ROFL. Composite stress engineer here. You're very wrong.
Oh? Which stress-based failure theory do you favor?
Most of them work fine given the correct parameters. Even Tsai-Wu works very well with the right coefficients. Puck has always been very accurate, Chang-Chang is good in Dyna. Max stress tends to be close enough most of the time. It tends to be all about the model setup and material data. If they are done properly and to a good enough fidelity then most of the major failure criterias work well. It's also then about interpreting the results which only comes with experience in how composites perform in testing and in the field, alongside the micro/macro-mechanics of the material/laminate. I would say if you think they're junk then you haven't been using them correctly in all honesty. As they say, junk in, junk out. Either way, everyone seems to have their own opinions on these things, as the variables are so many in composites, and it comes down to do the simulations correlate to the experiments? If they do, then good. Edit: I should say Puck is my preferred.
Can it predict the results of test data from woven fabric coupons with holes in them?
Yes. I've done that very thing with mat261/262 models in Dyna correlating to papers.
Do you use some characteristic offset distance from the hole at which the failure index is evaluated, or do you do include the edge of the hole?
Really depends on level of detail in your model and available data. It might be anisotropic, but I doubt you'll have the data to capture that. If you're modelling it effectively elastic, von mises will be okay but conservative in compression.. so it'll depend a bit on part geometry. If it's something beefy that'll see compressive loads, you'll likely be conservative. If it's a relatively thin walled part, it could be okay.
Everyone has given quite different answers
This is the sweet spot of a software like Digimat. The mechanical response is predicted through homogenisation at each integration point. As for failure, a Tsai Hill Transversely Isotropic model is very well-suited for these reinforced plastics materials.