Hi Armando,

Check that the damage initiation criteria is appropriately defined. Otherwise plot the SIF by defining a crack front, and compare it with fatigue threshold and fracture toughness of the material.

Cheers

Hi Sagheer,

Thanks for your msn.

The criteria is suppost defined appropriately. Note that I am not including any crack on the model but the pogram start and grow a crack where the criterium is reached. The problem is no other crack starts after the first one and the stress level is very high in other regions.

thanks again

I do not use ABAQUS so I do not know how it is implemented. I write my own code for crack initiation and propagation. For a given load, it is possible that the criterion is satisfied at many points, so there is a choice for the code writer to decide at how many points cracks are to be initiated, or a crack may be initiated at point where the criterion value is maximum (due to numerical accuracy, there is a maximum value). Also when a crack or cracks propagates, initiation of new cracks may not be considered. It is possible that ABAQUS is implemented in this way. Check the manual of ABAQUS.

I found the same problem with you. Hope you will find the reason and share with us.

I have developed extended finite element method (XFEM) crack propagation model in ABAQUS.

Evaluate the SIFs by defining a crack front under the considered loading and boundary conditions to clear the picture. 

Hope this will help.

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Hi Armando,

from the Abaqus documentation (chapter 10.7.1):

"However, multiple cracks can nucleate in a single enriched feature only when the damage initiation criterion is satisfied in multiple elements in the same time increment. Otherwise, additional cracks will not nucleate until all the pre-existing cracks in an enriched feature have propagated through the boundary of the given enriched feature. If several crack nucleations are expected to occur at different locations sequentially during an analysis, multiple enriched features can be specified in the model."

So, you could partition your model and define multiple enriched regions to allow crack initiation in varying time increments.

Espero que ajude.

If you consider the multiple crack using ABAQUS. It will be difficult to modifi it because the crack configuration depend on crack length and depth. If the cracks are different, the latgest or the depest crack, which is the first appeared maximum value, will propagate like a single crack when you using XFEM.

Hi Markus,

Do you know how to set multiple enriched features in abaqus?

If you have a single part, just partition it to get multiple cells. Then you can assign an individual crack region to each of them.

hi 

this videos can help 

1/ https://www.youtube.com/watch?v=hleGKlOAeK0

2/ https://youtu.be/eEtVxAhExJA

Hi, Markus,

In my model i have like 50 cracks, and i need crack propagation simulation. But if i partition small regions for each crack, will they grow beyond that partitioned region? Because they need to be interacted for the following steps.

Thanks

Hi Armando,

Having exactly same problem. Have you manage to solve the issue. I will appreciate if you could share how you worked with the problem. Thanks.

Hi Sujakhu,

You must create a small region for each crack as suggested by Berkay. I am not sure that the crack will  cross the region border. If this not work well, I reccomend to create an biggest region containing both cracks. I hope this work.