24 Apr 2008 19:18

## Cylindrical cup drawing analysis - PEEQ

Dear group members,

I am simulating deep drawing of a cylindrical cup made of mild steel. The material model applied is the nonlinear isotropic/kinematic combined hardening model provided ABAQUS. Usually applied for metals under cyclic loading. Applied blank holder force is 70kN and friction coefficient is 0.01. I ran the simulation using the implicit ABAQUS/Standard since comparison is to be carried on with UMAT.
Given maximum PEEQ is 46%.

Friction coefficient is then increased to 0.03. I applied the general finite-sliding contact interaction. Though the analysis was completed, however the mesh around punch fillet area is distorted and given PEEQ values for elements at this area are more than 100%. What does this suppose to mean?
Does it mean:
1. Nothing can be concluded since the mesh is distorted
2. Correspondingly to the highly distorted mesh, it is natural that PEEQ is very high.
3. Actually the material would tear apart however this is simulated as the significantly streched elements?

Can ABAQUS simulate cases when the material would actually be torn apart ?

I would appreciate any suggestions or comments.

Best regards,

Vivian

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25 Apr 2008 12:50

### RE: Cylindrical cup drawing analysis - PEEQ

1 & 2 -- It is tricky to say with out seeing the mesh/simulation and
your material curve's failure limit. This is more of engineering
judgment. Try remeshing and re-run. You could try adaptive

3 - Element failure is meant for such cases. However this is available
in Explicit only for some good reasons (stability, convergence etc..).
Take a look at abaqus manual. I would attempt all these only if the
failure and element removal are important in your studies. Otherwise you
could live with results you have so far.

Regards,
Sridharan

________________________________

From: Abaqus <at> yahoogroups.com [mailto:Abaqus <at> yahoogroups.com] On Behalf
Of Vivian Tini
Sent: Thursday, April 24, 2008 10:49 PM
To: ABAQUS <at> yahoogroups.com
Subject: [Abaqus] Cylindrical cup drawing analysis - PEEQ

Dear group members,

I am simulating deep drawing of a cylindrical cup made of mild steel.
The material model applied is the nonlinear isotropic/kinematic combined
hardening model provided ABAQUS. Usually applied for metals under cyclic
0.01. I ran the simulation using the implicit ABAQUS/Standard since
comparison is to be carried on with UMAT.
Given maximum PEEQ is 46%.

Friction coefficient is then increased to 0.03. I applied the general
finite-sliding contact interaction. Though the analysis was completed,
however the mesh around punch fillet area is distorted and given PEEQ
values for elements at this area are more than 100%. What does this
suppose to mean?
Does it mean:
1. Nothing can be concluded since the mesh is distorted
2. Correspondingly to the highly distorted mesh, it is natural that PEEQ
is very high.
3. Actually the material would tear apart however this is simulated as
the significantly streched elements?

Can ABAQUS simulate cases when the material would actually be torn apart
?

I would appreciate any suggestions or comments.

Best regards,

Vivian

__________________________________________________________
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24 Apr 2008 22:47

### Re: Cylindrical cup drawing analysis - PEEQ

Dear Vivian,

We have quite often simulate the deep drawing processes. Since you are not using a damage criteria, thickness of the blank at corner radii is decreasing and decreasing with small force.

Element supports less and less forces and finally mesh distorts a lot.

Of course results could be not realible.

As summary, I would say that material and results are valid until you reach the critical PEEQ or critical FLD points (different criterias for maximum elongation capacity of material). Then mesh is distorted, results are not the real ones and no conclusions can be obtained. If it is a cold process 100% of PEEQ is not reachable.

You can also try with a fine initial mesh.

I hope this helps.

Lander

--- El jue, 24/4/08, Vivian Tini <viviantini <at> yahoo.com> escribió:

De: Vivian Tini <viviantini <at> yahoo.com>
Asunto: [Abaqus] Cylindrical cup drawing analysis - PEEQ
Para: ABAQUS <at> yahoogroups.com
Fecha: jueves, 24 abril, 2008 7:18

Dear group members,

I am simulating deep drawing of a cylindrical cup made of mild steel. The material model applied is the nonlinear isotropic/kinematic combined hardening model provided ABAQUS. Usually applied for metals under cyclic loading. Applied blank holder force is 70kN and friction coefficient is 0.01. I ran the simulation using the implicit ABAQUS/Standard since comparison is to be carried on with UMAT.
Given maximum PEEQ is 46%.

Friction coefficient is then increased to 0.03. I applied the general finite-sliding contact interaction. Though the analysis was completed, however the mesh around punch fillet area is distorted and given PEEQ values for elements at this area are more than 100%. What does this suppose to mean?
Does it mean:
1. Nothing can be concluded since the mesh is distorted
2. Correspondingly to the highly distorted mesh, it is natural that PEEQ is very high.
3. Actually the material would tear apart however this is simulated as the significantly streched elements?

Can ABAQUS simulate cases when the material would actually be torn apart ?

I would appreciate any suggestions or comments.

Best regards,

Vivian

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