NX laminate pressure vessel

[George_4800]

Hello there,

I'm currently working on a FEA project that requires to use CFRP (60% Fibre Volume) to make an Hydrogen reservoir. I've modelled the tank with it's given dimensions and meshed it with shell elements. To those shells I've applied the laminate material option (I've previosly created the orthotropic material I'm working with)and applied the plys in the corresponding order.

As boundary conditions I've placed two pin supports on both ends of the tank, and loaded it with internal pressure.

The problem is that I don't get results with some sense and don't know what exactly could be the reason:

Just to make sure if there was some sort of proble with the mesh I only changed the material to common steel and the results were just as expected:

Is there something I could've not taken into account? I think it is some kind of set-up related problem, but to be honest I don't really know what else to do.

I'd appreciate any kind of help / tips.

Thank you in advance,
George

 

[FEA way]

You could probably use symmetry to simplify this model.

Double-check the laminate data, there might be some mistakes in the definition of the material or plies (e.g. too low thicknesses). Make sure that units are correct everywhere.

 

[George_4800]

Thanks for answering!

I checked again all the things you pointed out and everything seems in order.

Is there any particular type of piling I should set up?

I'll try a symmetric model just in case.

 

[FEA way]

A common and very good troubleshooting approach is to simplify the model and gradually add complexity to it. This way you should be able to identify the cause of the problem. In this case, it's most likely limited to laminate definition so you could focus on simplifying it as much as possible (for example, start with just one layer) and then adding more features.

 

[NRP99]

The max displacement of 2289mm for CFRP vis à vis 0.1mm for steel makes me wonder-Is CFRP able to contain that pressure? Its definitely some sort of mistake in material properties or pressure value or boundary conditions.

 

[George_4800]

Hey guys thank you both for your comments, it was indeed a set up error in the laminate section, now I get the results I expected with CFRP.

I found this video that really helps to undestand the set up. (This isn't promotion at all I'm just so grateful for it that I'd like to share it just in case someone read this in the future).

https://youtu.be/rnQk3zXwAK4

Thanks to all,

George.