Job not running when increasing Youngs Modulus

[Nassasa]

Heelo everyone,
im starting this thread again because the last one didnt get solved and im still getting the same problem, ill make it clear, my model consists of two vertebrae and a cage, the cage have youngs modulus of 45000 MPa and a poisson ratio of 0.3, my mobel till this point is working well i got results close to literature. after that i increased the youngs modulus to 115000 MPa and the poisson ratio to 0.41, the increments keeps attempting until it aborts.
what i tried to slove the issue is the following, i checked my units and they are all good, then i decrease the increment size from 0.0001 to 1E-5, after decreasing the first couple successful increments, abaqus starts attempting to finish till it aborts.
so if anyone please can help it will be appreciated, and if someone can explain why this is happeing, whats the relation between increasing the youngs modulus, and my job stop running.
and thanks

 

[FEA way]

More information will be necessary. Is geometric nonlinearity enabled ? What are the boundary conditions and loads ? What is the purpose of this change in Young’s modulus (which material do you want to simulate) ? Please attach a picture showing geometry and mesh of this model. And try running this with automatic stabilization.

 

[bkal]

As FEAway said, you will need to provide more information. Not being into bioengineering I might be asking a silly question, but: you state the Young's modulus for the cage, what about vertebrae? What non-linearity are you modelling?

 

[IceBreakerSours]

Think of time step size related warnings/errors as symptoms, not the cause. Naturally, if you try to fix the symptoms, that won't fix anything. The message/dat/sta files will come in handy. Go through the contents and tell us what you see in them.

Now, the following is one possible avenue to explore -

In all likelihood, the cage is contacting the end plates of the two vetebral bodies and the increase in the modulus of the cage has resulted an internal change in the penalty stiffness of the contact algorithm. This change is likely causing penetration which causes the (implicit) scheme to cut back on the step size and so on. So, try to reduce the penalty stiffness by an order of magnitude or two and see if that helps.

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[Nassasa]

sorry everyone for the late reply, first as IceBreakerSours suggested i tried decreasing thepenalty stiffness and it didnt work. and (FEA way), the reason for the change is to check how the model react to change of material 45000 MPa as in Mg lets say, with plsaticity table added , and 115 GPa as in ti6al4v. and any files required for more details ill upload it, just tell me which files plz. and thankss

 

[Nassasa]

and something i just figured out, increasing my load from 500n to 5000n made the model work.

here is an image of the model. RP1 is were the load is applied and RP5 is the fixed point in all DoFs.

 

[IceBreakerSours]

Although you have got the model to run, you have not identified the technical issue that was causing the model to diverge. Given what I have read so far, I must say you must seek expert supervision.

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[oldNail]

I agree with the comments so far. To fix a convergence problem you must first understand why it is not converging. Hints for that reason are in the .msg file.
Engineers in our office have come to rely upon the free online msg file buddy to help interpret what's gone wrong.