Reentrant Corners

[Juju]

Hi, I have made an analysis where I have a reentrant corner :


View attachment 2308


I used only shells for this model and here are some results I have got :


View attachment 2309


View attachment 2310


<?:namespace prefix = v ns = "urn:schemas-microsoft-com:vml" />because of the reentrant corner, the VM stress doesn t converge. I understand that the result cannot be trusted but how should I do to get a good model ?</v:shape>


</v:shape>Which conclusion can be made with such a model ?


- does it mean that I should not use Shells for this model ?


- Is it possible to have the same kind of problems while using solids ?


- What are the solutions in order to do a correct analysis ?


Thanks for your help

 

[Natewebb]

to converge you will need a small fillet in the corner.

 

[Juju]

Thanks for your reply Nate.


so it means that shell idealization is not possible in this case because it is not possible to make a filet with shells ? tell me if I am wrong...The only way is to use solids but it takes lot of time to do the calculation.


I guess that the problem of reentrant corner happens very often, does it mean that idealization with shellsis almost never possible ?

 

[Natewebb]

you should definitely use shells. just add the fillet, make the shells, it's not a problem at all. I think you could probably do it as a single part, but if it has a hard time shelling with the fillet, try a little 3 component assembly instead of a part, or a sheetmetal model.

 

[Juju]

Indeed I had some problems with making the shell with the filet. By doing a 3 coponents assemly, it works well. Thanks.

 

[Juju]

I am trying to understand the 'philosophy' of FEA... so, while analysing a part, the filet at the reentrant corneris the most important thing in the model. It is always there that thereis the highest stress... Am I right ?


I have tried the following thing :


View attachment 2319


and here are some results :


View attachment 2320


we can see clearly that the filet has an important effect. When the parts are manufactured, do they pay attention to the dimension of the filet ? if they don t respect accurately the dimension, the stress can be much higher than expected and the part could be damaged ?


Please tell me wether I am having a right reasoning. Thanks...
Edited by: Juju

 

[Juju]

Sorry, the unit of the filet on the previous graph is not 'cm' but 'mm'