Is Abaqus software suitable for structural analysis?

[chrislaope]

Hello all:

We have an argument on Abaqus CAE software, whether it is suitable for structural design/analysis or not.

Basically, we found, for example in a bolt connection, when we design base on AISI standard, the other party using Abaqus CAE software to check will reject the design because they say Abaqus CAE software analysis shows that at the location of bolt hole contacting with bolt, the stress exceed yield strength of steel.

In my opinion, Abaqus CAE software looks like for machine part design, not suitable for structural analysis.

What is your opinion? Have anybody ever used Abaqus CAE software to do structural design/analysis?

Thanks.

 

[jayrod12]

In structural design, we tend to allow slight localized yielding of connected parts provided it can be accommodated in the overall performance of the structure. Abaqus is a great program for in depth detailed FEA however as a global structural design tool I have not seen it used.

You could point out to them the reference capacity from the applicable standard and have them try to argue against the published capacities.

 

[TLHS]

This is more a question about general finite element methods. They're appropriate for use, but you need to understand the application and what the output means. I constantly have arguments with our mechanical group about stress concentrations or assumptions that are overly conservative compared to traditional design methods. There are places where you're going to see stress concentrations or peaks in a finite element model that are acceptable in real life. A lot of our steel design assumes yielding at factored load.

If one were to take a wide flange, model it in a finite element program that doesn't take plasticity into account, and apply the factored load it would show the flange exceeding yield by a fair factor. In design, we've assumed that this has yielded and that loads have redistributed to get a capacity based on the yield stress across the whole section (plastic section modulus).

This is the same in connections. Steel codes generally allow you to exceed yield locally. You can also sometimes decide that it's acceptable based on engineering judgement because there's no failure mechanism associated with a local yielding case, because there's a load path available for redistribution.

The tricky bit can be taking this kind of analysis and figuring out how to smooth it. You need to be sure there actually *is* an alternate load path and that once you redistribute a high stressed area. Once you redistribute your stress concentrations, it can turn out that you're yielding the whole section.

Basically, all sorts of analysis methods are suitable for structural engineering, but you need to know what the actual design limit states are and what software output is telling you so that you can interpret it. Yield doesn't necessarily mean failure.

 

[3DDave]

You could ask on the Abaqus forum what they do in these cases, but for other FEA I've seen that the models need to allow for contact loading and plastic deformation, which is computationally expensive and therefore slow and probably why the other party doesn't want to do that.

Abaqus forum:

http://www.eng-tips.com/threadminder.cfm?pid=799

 

[KootK]

My vote: no, Abaqus is not appropriate for routine structural design. The design standard approaches are vetted against testing and experience and trump FEM for typical conditions in my opinion.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[klaus.]

Well I would say....the ENGINEER must be suitable for doing structural design

The software (any software) is just a matter of help


best regards
Klaus