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Abaqus Standard - Dynamic Implicit - Contact - Scratch/Gouge Damage

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ben010

Mechanical
Jul 18, 2011
8
Hi all,

I've been trying to learn Abaqus and model a slow speed scratching process which replicates an experiment to analyse residual stress.

So far I've been able to model the indentation step but cannot seem to drag the tool across the surface to create the scratch.

I'm not 100% sure I am using the right solver (maybe explicit) or mesh (maybe ALE?), i.e.

*************************************

Model basics and error messages:

- 2D section and analytical rigid body conical tool.
- tip radius 50micron
- cone angle 90 deg.
- RHA elastic - plastic material properties.
- Node to surface interaction discretization.
- Structured quad mesh
- Error / Warning Messages
- Element are distorrting excessively, convergence is unlikely (but it working in the indentation step)
- Sereve contact overclosure exist, convergence is unlikely.
- Excessive distortion at 20 integration points.
- strain increment has exceeded fifty times yield.
-
 
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Robert,

Thankyou for the response. I've attached the .inp and .cae files which were modelled on Abaqus 6.9-1 and a picture of the mesh density.

- Specimen part is 4mm x 1.5mm
- Tool is 50 microns tip raduis
- Indentation is 25 microns.
- Mesh
- 200 element (4mm slave surface length)
- Bias ratio 10:1 at 60 elements (1.5mm depth)
 
 http://files.engineering.com/getfile.aspx?folder=1873c8ce-864b-4493-8d6e-110ca6a2fa18&file=Job_-_Indent_-_2D_-_Profile_-_Implicit_-_Complete.cae
Ben,

Here is a running list of comments and suggestions.
1.I looked at your simulation and believe that your mesh density is too little near the indentor and too fine away from it.
2. Why not standard?
3. If you move the indentor to be exactly touching then computational load will be reduced.
4. Why symmetry on the left face?
5. This only has the indention step not the sliding step.

I hope this helps.

Rob Stupplebeen
 
Thanks for the suggestions Robert.

I've been working on a model which is in contact at the initial step and has a simple linear mesh as you suggested, see attached. It seems to produce very similar error and warning messages as other model I've been playing around with today. I've also enabled another symm face to simulate the fact that in reality the specimen is larger.
I think it's something to do with my Step module step-up or the elements distorting too much.

Either way, when the indentation works the second horizontal step doesn't get past the first increment. I was hoping that I wouldn't have to get into complex machining modelling but I fear it may be the case.

If you have any additional suggestion as to the potential source of these error message it would greatly appreciated. I was thinking that Tri elements might put up with a bit more punishment in terms of distortion, what do you think?

Simplified CAE file attached.
 
 http://files.engineering.com/getfile.aspx?folder=fa8d5363-4798-4bde-9df9-61e6087a8720&file=8._Job_(default)(mesh-2e-03seed).cae
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