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Mechanica..Elasto-plastic

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Mechanica..Elasto-plastic

Is there any benchmark for a elasto-platic material or even a Hyperelstic material.

It will be interesting to see accurancy which this two material models with real or even software comparation study (mechanical-ansys or mechanical abaqus etc..)

Could be possible from somebody in PTC to give me an anwser about it?.

-Let see how many in PTC gives an anwser about it..---

17 REPLIES 17
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Re: Mechanica..Elasto-plastic

it appears PTC aren't part of this community

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Re: Mechanica..Elasto-plastic

Hi

I do not know the answer. But for PTC; maybe have some patiens till the normal workweek begins for them. They seem to answer when no-one else knows the answer.

Regards

Chris

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Re: Mechanica..Elasto-plastic

Napoleon,

Here's a presentation on analyses with Hyper-elastic materials in Mechanica. I hope you will find it useful. We don't have anything similar for elasto-plastic materials yet.

Thanks,

Christos

Christos Katsis, Ph.D.

Vice President, R&D - Simulation Products

PTC

2665 North First Street, Suite 110

San Jose, CA 95134

408.434.8557

-

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Re: Mechanica..Elasto-plastic

Hello Christos

Thanks for the pdf, but I already had it (in fact is the only material about Hyper-elastic that PTC as issued, I believe)

Basically I am looking something similar to that document, but for Elasto-plastic plus a benchmark with a lab test if possible, I don't find really useful the helping WF5 for this last point, there is not much information ( I thing is because it could be quite early due to the recent launch of WF5, but as well we are already in M050!!! and still not info).

I really will appreciate if you can find for me something similar, (and even better with a benchmark to evaluate this new material model in WF5). I have been waiting for the version since quite long time (elasto-plastic), and now I am in appoint to decide if we move from FEA software or not, (there are others ones with such capabilities but the cost are more expensive and even some of those software are over dimensioned for what I need, so decision need to be taken in a cost/value point of view.

That is why I need more info about this new material model in WF5.

P.d: Is there any intention to include a basic material data base for hyper-elastic and elasto-plastic (common rubber , plastics and some metals) in WF5 in future cuttings (let say M100), so people can perform analysis with them), That is something that other competitive software companies have includes in their programs.

I really will appreciate if you can find something for me, and I will be happy if you can give your opinion about this last point.

Napoleon Motaban

Msc. Mechanical Engineer.

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Re: Mechanica..Elasto-plastic

Hi Napoleon,

Unfortunately, we haven't created yet a similar document for elasto-plastic analyses in Mechanica. It is in our plans, but at this point, I cannot commit to a date when such a document will become available.

Regarding hyper-elastic and elasto-plastic material properties in Mechanica, most users use properties that they have obtained through lab experiments or by access to available material databases, e.g. MatWeb. But you make a good point. We will consider including a few common hyper-elastic and elasto-plastic materials in the Mechanica database in a future release.

Thanks,

Christos

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Re: Mechanica..Elasto-plastic

Thank for your replay Christos

Is still hard to belive that there is not a benchmark for elasto plastic done by PTC

how can be possible to release a software whithout knowing what sort of results you can get.?

I don't want to be critic ( I am really happy with my PTC products) but not having a bechmark to compare

the software accuracy it sound hard to belive,

I still think it should be something in PTC to deal with this point...(for sure somebody in the development team have done something)

P.d:I will apreciate if PTC will include some hyperelatic and elasto-plastic material in the future cuts of WF5

that will be really usefull.

Thanks for your help.

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Re: Mechanica..Elasto-plastic

Hello Christos

If you remember this post (now time ago).

Have you got news about any publication with elasto-plastic material?.

 

How is the experience with Creo simulation and the ASME vlll div "design by analysis".

I am interested in the use and benchmarking elastoplastic and limit load analysis using de pressure vessel design code.

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Re: Mechanica..Elasto-plastic

there's not much new here.
Plasticity works, but not extensively.

PS: Christos Katsis (PhD, MIT, MECHANICA founder 1987-2013) can no longer answer the question.

 

regards

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Re: Mechanica..Elasto-plastic

Any documentation come out on elasto-plastic analysis yet ?

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Re: Mechanica..Elasto-plastic

Hello,

Can we find an answer to this discussion.

Examples of material are they created and made available to an address.

Interested in this topic for a long time.

Cordially.

Denis.

http://communities.ptc.com/message/208467#208467

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Re: Mechanica..Elasto-plastic

Hello Christos,

https://www.ptc.com/appserver/cs/view/solution.jsp?n=CS66550

claims to allow:

  • Ability to include plasticity, hyper-elasticity and contact effects in the same analysis

This implies plasticity in assembly with contacts, yet the plasticity option is greayed out for me. I have one part with elastoplastic properties defined of a two part assembly .

I am running Creo 2.0 M070. Am I missing something? Is thisindeed available?

Thank you,

Randy Speed

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Re: Mechanica..Elasto-plastic

Randy,

Indeed you can have sliding contact and elasto-plastic materials in the same LDA analysis in Creo 2 M070. I don't know why the option is not available to you. Is it possible that you have effects / idealizations that are not supported in LDA? e.g. shells? If you cannot figure it out, please contact TS with a model that you can submit and that shows the symptom

Thanks,

Christos

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Re: Mechanica..Elasto-plastic

Christos,

I may have just solved the issue, but would like to confirm with you if I may.

The model is a simple pin and lug assembly. I had previously assigned transverse orthotropic properties to the pin in order to shrink it in the axial direction only using a cooling temperature in order to get preload in the pin. The elastoplastic properties are assigned to the lug, not to the pin. For grins just now, I changed the pin properties to isotropic and now the plasticity option is available.

Must ALL materials in the assembly be isootropic for the contact+plasticity to be available? Perhaps I can assign preload to the pin using the new preload option in Creo? Not famiiar with that functionality.

Thank you,

Randy Speed

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Re: Mechanica..Elasto-plastic

Randy,

Anisotropic materials are not yet supported in LDA. Unfortunately, the same is true for preloads in LDA since that requires a similar formulation. Sorry. Not very difficult to implement. We just haven't done it yet. We should definitely consider it for a future release.

Thanks,

Christos

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Re: Mechanica..Elasto-plastic

Thank you for this post!

I was also wondering why suddenly the LDA was not available and the reason was that I was using an anisotropic material. Not sure how clear this restriction is reported in the documentation, have to check...

I also vote for having anisotropic materials in LDA. It is an easy way to do a kind of “thermal actuator" - allowing it to expand only on its length but not along its cross section. This solution works very fine in linear analysis.

Actually some nice new features are simply not available in LDA in Creo2.0. Advances springs, resultant forces over a surface... each time a new "surprise".

R. Rabe

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Re: Mechanica..Elasto-plastic

For those following this thread I am finally getting around to summarizing what I found. I have discovered certain limitations using LDA, specifically the plasticity combined with contact, but I mangaged to get around them for now. Although plasticity with contact is indeed possible, I was attempting to simulate a preloaded bolt in a hole with contact under the bolt head using anisotropic materials for a directional temperature cooling load as a way to apply preload. What I didn't know at the time was that anistropy is not yet available in LDA. Let me explain.

PRELOAD analysis is not available with LDA (plasticity + contact) so I am unable to use the preload analysis option to load the pin (bolt). So I attempted the use of a cooling temperature load. To avoid the pin shrinking in all three directions and only have the axial direction shrink, I attempted using orthotropic CTEs. However, I am unable to use orthotropic material properties with this LDA so for now I am using isotropic CTEs and ignoring the fact that the pin will contract in all directions; not what I had hoped for, but it works.

Finally, I wanted to separate the preload (temperature load) from my applied mechanical load. Unfortunately I am unable to run the mechanical load and the temperature load as separate load conditions in the same analysis for this LDA. To see their separate effects, I must run two separate LDA analyses. Since I cannot combine the results of two different analyses, I would need to run a third and final analysis with the loads combined in the same load set. In summary, I must have isotropic materials, no preloads, and place all desired loads in a single load set.

I believe I am getting along OK now and appreciate Christos Katsis' help.

One other thing I found in attempting to see animated results (stresses, etc.) is that animations for the final set of results in the LDA did not appear to be possible. To see results animations, I must solve for multiple load steps and request results for each load step.

Randy Speed

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Re: Mechanica..Elasto-plastic

 

Folks,

 

You should find useful information about elasto-plasticity in my new blog “Rolos Simulate Sources”. Simply download the following presentation from there:

 

Basics of Elasto-Plasticity in Creo Simulate – Theory and Application

 

Hope it helps,

 

Roland

 

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