Composite Modeling in Abaqus

[SamiraT]

Hi Friends,

I am new to Abaqus and also to composites.
I have a thin plate, meshed with shell elements and i want to assign a layup with three plies to it.
and apply a tensile load on one end, constraining the other end.
When i select mid surface(zero offset) for shell modelling, i read from the abaqus manual that reference surface is taken as middle of the element.
So how are the three plies modelled in each element? Say each ply is 0.2 mm thick, then is the midsurface of each element at 0.3mm?
And when i apply a load, is the load by default applied at the midsurface?

Also, I tried initally with two +45 plies, pulled it on one side, I did not see any out of plane displacements. But with one 45 and one -45 degree ply i see out of displacement.
+45 and -45 are used so that it is balanced, then why there is out of plane displacement for that and not for two +45 degree plies which is not balanced.
I know these are pretty basic questions. But, i need to understand these to know what i am modelling matches with what i intend to model.

Thanks a lot!

Regards,

 

[DrBwts]

Would you be willing to post your models?

 

[SamiraT]

Hi DrBwts,

Thanks for replying.
Sure, please find input deck attached.
We can see out of plane displacements, which is strange.
Since, I did not get expected results with composite layup, I tried isotropic material and checked with hand calculations. I was puzzled to see that the max displacement obtained from abaqus was 50 times more than the displacement from hand calculations. It is a simple plate modeled with shell elements and a tensile load applied on one end while constraining the other end. Wondering what could possibly go wrong.

Your inputs will be very helpful.

Thanks,
Sam

 

[Mustaine3]

Maybe your deformation is too large for linear analysis and NLGEOM makes the difference.

And I think -45 and +45 is not self balancing. It creates a moment. -90 and +90 would be self balancing.