you need to activate the element deletion option in element definition, go to your element definition and you will find the option of deleting and element Yes/No, choose yes and your elements will be removed from the model once they satisfy the failure criteria which you have used, also in your field output request you should select status in order to remove the elements from the model once they completely fail.

Best wishes

Hi,

 have you activated distortion control in abaqus?

Things might get better with hexahedral elements.

I assume that this is an explicit model with material removal; it might be that your failure criterion is too strict.

It is difficult to say more without seeing the model and the result in detail.

Maybe it's not so useful but further information can be find here:

http://imechanica.org/files/l6-adaptive-mesh.pdf

Hi, Thank you for your response, 

I active distortion control in element type (Yes, length ratio 0.1) but It had distortion again. 

I tried with hexahedral elements but it has problem with distortion again. 

The model is explicit . tool is rigid solid. workpiece is Al. failure criteria and damage defined with johnson cook. 

reduce the time scaling factor to 0.5 or 0.1, it causes more time to finish but lets the software do high speed problems more correct.  

Dear Armin,

Thank you for your response. I will run the modeling with lower time scaling again. in my model time scaling was 0.1 . I reduce it to 0.01 to see the results. 

One further thing to check is hourglassing (if you use linear reduced integration elements like C3D8R) - hourglassing may easily lead to excessive distortions and is very common in machining simulations. To check for it, increase the hourglass stiffness (but be aware that this influences things like the cutting force as well, it usually needs some trial and error to find reasonable values for hourglass stiffness).

And, as stated above, also try (just to see what goes wrong) to change the material failure criterion.

there are different techniques (lagrange remeshing, ALE...) but I will check the papers of Prof P. Arrazola how has been working on that the last 10 years.

Check that you've defined a failure criteria like johnson cook either with shear failure or damage initiation so it can allow the material to fail

 Hi Behzad, have you solved your problem? In my implicit model I got the error message too many attempts for the increment. In the warning area file I saw the excessive distortion message.  My model also contains contact, I think probably due to the non-linearity in the model. Just write to ask how you solved your issue in the end. Thanks.

you need to activate the element deletion option in element definition, go to your element definition and you will find the option of deleting and element Yes/No, choose yes and your elements will be removed from the model once they satisfy the failure criteria which you have used, also in your field output request you should select status in order to remove the elements from the model once they completely fail.

Best wishes

Khaled, it seems that the element deletion in abaqus/implicit is only for visualization purpose. The element is not deleted as that in abaqus/explicit?

Hi Qing, I am not sure how element deletion is performed in Aabqus Standard , usually I use Abaqus Explicit  and element deletion should be selected to remove the element from the model and allow the cutting tool to progress into the next layers of elements in the model.

another suggestion would be to make sure that all the numbers you entered for material properties and cutting parameters are consistent, i.e all in KG/meter/Pascal units or similar 

why are you using Abaqus standard for machining modelling? 

I suggest you to check P. Arrazola's papers on machining simulations. Different techniques are used in his works to avoid element distortion.

I have axisymmetric problem. The same waring and error is coming. Please suggest. (It is just a deformation problem, hyperelsatic material). How my simulation will run smoothly?

 I have the same problem as well, a 2D axisymmetrical closed die forging problem where the simulation stopped due to material distort excessively, I'm not sure whether if it's the boundary condition I've set or the meshing is the problem.

For my boundary condition, I've fixed both x and y axisymmetric on the workpiece on the initial step and a boundary condition on the die to deform down 20 units for the deform step.

Can anyone help?

3 problems may cause this error:

1- Coarse meshing

2- Wrong material properties ( be careful when omitting the tension or compression in elastic models definition)

3-Interaction conflict. You might have defined interaction of different properties on surfaces sharing same edges or points.

Same issue that I am having. Today I have followed an online video tutorial. Althrough I have pursued the same procedure as mentioned in the tutorial, Still I am having same problem. Even if the element deletion option is activated.

I anyone has the solution please welcome....

VUMAT can be a solution 

It is under Field Output Request->STATUS VARIABLE

I'm modeling a welding process in ABAQUS/explicit, and facing the same distortion problem. the step chosen is dynamic, temp-disp, explicit and am stuck at solving distortion of mesh due to the rigid tool. the model runs for 0.8 seconds (out of time period of 4 secs). I have even tried applying mesh constraints, but the problem isnt resolved yet !!  I'm attaching a meshed model of my assembly.

Anyone with any valuable suggestion, please comment or message me !! 

thanks.

i faced the same problem, but after remeshing my model with hypermesh i reduced the number of distorted elements considerably. 

Dear Yagoub,

I have changed my approach and now I'm modeling using CEL approach. I've tried every setting in ABAQUS explicit suitable for my model and found that the elements get only compresses further and further and only delay but not avoid distortion. I may give a try by meshing using hypermesh.

Thanks

Hi,

This is a typical case of shear locking Your mesh isn't particularly great to start with. You have too many elements with sharp angle in both the tool and the piece and C3D8 elements won't do a nice job under large deformations.

Here is a possible solution:

1. Use Abaqus/Implicit if possible;

2. Partition both the tool and the piece along the principal planes (make sure the partitions coincide);

3. Use regular quadratic elements to optimize the mesh quality. C3D20R are ideal for this type of model.

If problem persists:

- Partition further;

- Refine mesh close to the area of contact;

- Use double precision.

Hope this help.

C

Elements are elongated in dynamic explicit analysis

How to remove this problem?

For details go through the attachment.

In previous version abaqus 6.10. it was run but latest version 6.14.1 it is not run.

Warning in abaqus monitoring-

The option *boundary,type=displacement has been used; check status file between steps for warnings on any jumps prescribed across the steps in displacement values of translational dof. For rotational dof make sure that there are no such jumps. All jumps in displacements across steps are ignored

Good day Hemant,

I advise you to use hexahedral elements.

Why you do not use CEL ?

Hello Sir, (Valery Anpilov)

Thanks for the reply.

As per your instruction, I used C3D8R element as hexahedral element but its also elongate and merge into another body.

Can you specify the specific Hexahedral element?

Hi Hemant,

I have just seen you geometry in the file:

Abaquserror.docx

Please let me know - Why do you try to use explicit solver?

What is the reason?

As I understand - in your model - you will have not significant distortions of element.

May be you should to use implicit solver?

Before to continue our our convesation - I need to understand the aim of your simulation.

Thanks Khaled..ur suggestion worked.

Following,,

For this issue, I would recommend to include failure modelling as well. This will cause the element to be deleted before it gets excessively distorted.

For distortion control, the constraint penalty forces are applied when the node moves to a point a small offset distance away from the actual plane of constraint.. The offset distance can be calculated by using r (distortion length ratio) x Le ( element characteristic length). The default value of the distortion length ratio, r, is 0.1. You can increase r in order to increase the offset distance.

Where is "element defination" for element deletation in abaqus?