Abaqus drilling 2

[matmeanla]

Hi everyone,

I am simulating a drilling in Abaqus as in youtube tutorial. However, what I got was really weird. The element completed successfully but the visualization look excessively distorted. Anyone knew what exactly happened?


Here I uploaded the video.

Thank you

 

[mechdrive1]

Hello,

I am facing exactly similar problem in my simulation. I'm also trying to simulate something similar like drilling. Here's my thread link

http://www.eng-tips.com/viewthread.cfm?qid=424357

The elements are getting distorted for an unreal length. Can you share more info about your material modeling like material, damage model used, plasticity model used? What is the damage evolution criteria you've chosen?

Thanks.

 

[StefCon]

I remember something similar... There is a filter option in the result viewer where you can filter based on element variable "STATUS" or something like that. See attached.

 

[mechdrive1]

StefCon,

I didn't select 'status' variable output for the model which I've created a thread. I've resubmitted the model with 'status' variable output request and will update the results. But my other concern is regarding the damage evolution specification. Just like in drilling process, I need to get all the elements from the path of the tool completely deleted but it shouldn't significantly affect the surrounding elements. What I'm observing in some of my models due to zero energy specification or very low values for displacement at failure specifications for damage evolution, elements get deleted quite fastly not only in front the of the tool but also those that surround its side surfaces which result in a gap between tool and workpiece. I would like to mention that I have no idea how to calculate the damage evolution, either energy or displacement, for the process I'm trying to simulate. Although there are some basic equations which I've come across but they aren't of much help

 

[StefCon]

mechdrive1,

I am in the same boat regarding the lack of material data. I think that in order to get reliable data, a ton of testing is required to determine how the material failure depends on the stress triaxiality. Also, the failure starts somewhere first and therefore I think that a very fine mesh is required.

 

[matmeanla]

Hi mechdrive1;

I just follow the tutorial here before i get start with my project.

https://www.youtube.com/watch?v=c_eM173qLQo&t=9s

Hi StefCon,

Thank you for the advise, I just run my model again with the "status' updated.
It took a week to complete the simulation.

It look even more tougher when i read mechdrive1 comment.

I agreed, we need more experimental data to understand the drilling failure behavior.

Cheers

 

[mechdrive1]

StefCon,

Like I mentioned in my original thread about this problem, I changed the value of 'D3' constant from -ve to +ve and also requested 'status' variable output and got the desired results. I've searched a good number of papers available in the literature domain but there seems to be little clarity regarding the damage evolution calculation. I have been going the trial and error method way which is quite time-consuming and for this reason, I've settled for a relatively low-density mesh. Very fine mesh do result in better results though.

Matmeanla,

I would request you to share any available material data regarding the damage and plasticity models if you come across any. All the best for your project!

Thanks to both of you!

 

[matmeanla]

Hi there,

After I run the model this morning, I got this error

"the ratio of deformation speed to wave speed exceeds 1 in at least one moment. This is usually indicates an error with the model definition.Additional diagnostic information may be found in the message file"

Normally what it exact meaning..

Thank you

 

[mechdrive1]

Matmeanla,

It means the element(s) in your model is/are distorted and you need to check the .msg, .sta files to find out where exactly element(s) has failed and why so.

 

[Dave442]

This is addressed well in a previous post on the forum:

http://www.eng-tips.com/viewthread.cfm?qid=80443

 

[matmeanla]

Hi there,

finally i solved the over distortion element. However, the element still not removed even though the drill bit go through the workpiece.

http://files.engineering.com/getfil...90-adf2-3768e509df14&file=20170522_163943.jpg

 

[BILL_mce]

I have seen that deformation wave speed error show up when density was incorrectly specified due the consistent units requirement when imperial/US customary units where used - density was not in slinches it was in lbm/in^3.

Bill McEachern, P.Eng.
Redstone Six Consulting Ltd.

http://www.redstone6.com

 

[matmeanla]

Hi BILL mce,

My components is in mm, so that i used tonne/mm3 for the density. is it ok for that?

 

[BILL_mce]

for stress in MPa that works - so it is something in the order of 7e-9. It must be something else.

Bill McEachern, P.Eng.
Redstone Six Consulting Ltd.

http://www.redstone6.com

 

[matmeanla]

Hi there,
I manage to drill the workpiece. However, i dont know why the chips did not produce while drilling. As in my picture attached

 

[mechdrive1]

Matmeanla,

The way elements will be deleted and whether or not chips will be produced depends on the material property assigned which includes both J-C plastic and damage criteria. It would be good to verify the values you are using in the material property definition.

 

[matmeanla]

Hi mechadrive1,
Sure, i ll check it
Thank you