How to simulate static crack propagation in Abaqus?

[eispiata]

Hi everybody,

I am trying to simulate crack propagation in rubber material. As you can see in the attached pictures, i aim at trying to propagate the crack along the horizontal line.

I have browsed through the help and found out that ther is a feature called "Debond" that permits crack propagation.

But i don't know how to use it....

Should i use static or dynamic analysis??

Moreover, given that i want to open it till it breaks with the middle horizontal line playing the role of the line along which the crack is going to propagate, should i impose a constraint "Master -Slave surface " onto that horizontal line?

I mean how can i work this out..?

Thanks,

Malik

 

[amubashar]

Hi,

I would suggest that you should consider using cohesive zone elements.

Regards

Aamir

 

[eispiata]

Dear Amubashar,

How can i make use of these types of elements to simulate "crack propagation"?

To be honest i never used such elements but according to you they might be useful to me.

What are "cohesive zone elements" regarding crack propagation? I aim at modeling a rubber material (hyperelastic) with crack propagation along the horizontal center line...

I would like to make use of the J-integral as a Fracture Criteron. Is this criterion compatible with "cohesive zone elements"?

I am looking forward to your comments and remarks.

Regards,

Malik

 

[amubashar]

Hi Malik,

Cohesive zone elements are used for damage and failure modelling. They are governed by a traction seperation law and the fracture energy can be related to the cohesive energy. This is a very general explanation. The Abaqus manual provides a detailed explanation of the theory and implementation. There are also a few examples given in Example Problems Manual.

I would recommend that you start by reading Abaqus Analysis User's Manual Sec 27.5 and Examples 1.4.5, 1.4.6 and 1.4.7 in Abaqus Example Problems Manual. (I am referring to Abaqus 6.8-1 Manuals).

Regards

Aamir

 

[eispiata]

Hi,

I read up more on "crack propagation" and "cohesive elements" in Abaqus. But i am still struggling to make it run and frankly i am running out of time.

I recall the problem that i want to simulate:

A piece of rubber (hyperelastic neo-hokean) material is subjected to static uniaxial tension untill it fractures. As you can see in the picture, there is initially no crack in the geometry. However there is a singularity that is likely to be the crack initiation point. And the crack is going to propagate along the horizontal dotted line.

To begin with i sketched the geometry in the Part module and then i partitioned the geometry to create an interface that is going to play the role of the crack propagation line. My idea is that by making use of "cohesive elements" in the interface i could be able to get a crack propagation.

So in the property module i created a "hyperelastic neo-hookean material" to account for the rubber material outside of the interface. I then created two sections:
- a "solid homogeneous" section to account for the hyperelastic material outside of the interface
- a "cohesive section" with the same material properties as rubber

In the Interaction Module i didn't impose any constraint on the interface faces. I don't really understanf i should modify of create something in this Module.

Then i got to the Mesh Module and i tried to mesh the interface. But when i tried to run the analysis i got an error message like "some elements have no property". And it turns out these elements correspond to the elements in the interface.

Please let me know what was wrong in my model.

Regards,

Malik

 

[eispiata]

Sorry i forgot to attach the pictures: