Adaptive mesh with explicit elements

[Shervin]

Dear Folks,

I am doing a static analysis with large deformations
(nonlinear geometry activated) using solid linear
elements. According to the help descriptions I should
be able to use explicit elements for this problem
using adaptive mesh.

I would appreciate if you help me with the following
issues:

1) Warning? 10353 elements(s) were removed from
Adaptive Mesh. The elements have been identified in
element set WarnElemRemovedFromAdaptMesh.

Why it gives such a warning and what does it mean
here?

2)Why explicit and standard elements give the same
results?

3)However, using explicit elements, I get the
following warning on the top of previous ones:

Relax stiffness is not a valid choice for the
hourglass parameter on the *section controls option in
abaqus/standard; hence, it will be replaced with the
default (hourglass=stiffness) for the current
analysis. The original choice will, however, be stored
for any subsequent abaqus/explicit import analysis

The parameter hourglass = stiffness on the section
controls option is relevant for these elements: c3d8r,
cax4r, cgax4r, cpeg4r, cpe4r, cps4r, m3d4r, m3d9r,
s4r5, s4r, s8r5, s9r5, sc6r, sc8r and their hybrid,
thermal and pressure counterparts wherever applicable.
This warning can be ignored if the feature is applied
to these element types only.

any explanation?

4) the problem does not converge with quadratic
elements, any suggestions.

Thanks you all in advance
Shervin





__________________________________
Yahoo! Mail - PC Magazine Editors' Choice 2005
http://mail.yahoo.com




------------------------ Yahoo! Groups Sponsor --------------------~-->
Get fast access to your favorite Yahoo! Groups. Make Yahoo! your home page
http://us.click.yahoo.com/dpRU5A/wUILAA/yQLSAA/PMYolB/TM
--------------------------------------------------------------------~->

[v***@netscape.net]

I am not 100% sure, but it seems to me that u r running standard analysis and that your adaptive meshing is not activated at all. How many elements do u have? Why r u running standard analysis with explicit elements? If u want to activate adaptive meshing try using qasy-static procedure in explicit. These topics were covered nicely with during last several of months.
Regards and good luck
Natasa

Post by Shervin
Dear Folks,
I am doing a static analysis with large deformations
(nonlinear geometry activated) using solid linear
elements. According to the help descriptions I should
be able to use explicit elements for this problem
using adaptive mesh.
I would appreciate if you help me with the following
1) Warning? 10353 elements(s) were removed from
Adaptive Mesh. The elements have been identified in
element set WarnElemRemovedFromAdaptMesh.
Why it gives such a warning and what does it mean
here?
2)Why explicit and standard elements give the same
results?
3)However, using explicit elements, I get the
Relax stiffness is not a valid choice for the
hourglass parameter on the *section controls option in
abaqus/standard; hence, it will be replaced with the
default (hourglass=stiffness) for the current
analysis. The original choice will, however, be stored
for any subsequent abaqus/explicit import analysis
The parameter hourglass = stiffness on the section
controls option is relevant for these elements: c3d8r,
cax4r, cgax4r, cpeg4r, cpe4r, cps4r, m3d4r, m3d9r,
s4r5, s4r, s8r5, s9r5, sc6r, sc8r and their hybrid,
thermal and pressure counterparts wherever applicable.
This warning can be ignored if the feature is applied
to these element types only.
any explanation?
4) the problem does not converge with quadratic
elements, any suggestions.
Thanks you all in advance
Shervin
__________________________________
Yahoo! Mail - PC Magazine Editors' Choice 2005
http://mail.yahoo.com

__________________________________________________________________
Switch to Netscape Internet Service.
As low as $9.95 a month -- Sign up today at http://isp.netscape.com/register

Netscape. Just the Net You Need.

New! Netscape Toolbar for Internet Explorer
Search from anywhere on the Web and block those annoying pop-ups.
Download now at http://channels.netscape.com/ns/search/install.jsp




------------------------ Yahoo! Groups Sponsor --------------------~-->
Get fast access to your favorite Yahoo! Groups. Make Yahoo! your home page
http://us.click.yahoo.com/dpRU5A/wUILAA/yQLSAA/PMYolB/TM
--------------------------------------------------------------------~->

[amarendraatre]

Shervin,
You might be confused with using explicit elements for your analysis
as opposed to performing an explicit analysis. For a large
deformation static analysis if you run it in standard using
quadratic elements you use standard elements with default hourglass
control. See if your problem runs this way. If your problem is large
def as you say and that is causing large convergence problems then
you must perform an explicit analysis and not just simply use
explicit elements. Explicit analysis has other hourglass modes you
can use for the elements and hence you get the second warning. In
performing the explicit analysis you will need to perform it as
quasi-static to ensure its validity.
Amar

Post by v***@netscape.net
I am not 100% sure, but it seems to me that u r running standard

analysis and that your adaptive meshing is not activated at all. How
many elements do u have? Why r u running standard analysis with
explicit elements? If u want to activate adaptive meshing try using
qasy-static procedure in explicit. These topics were covered nicely
with during last several of months.

Post by v***@netscape.net
Regards and good luck
Natasa

Post by Shervin
Dear Folks,
I am doing a static analysis with large deformations
(nonlinear geometry activated) using solid linear
elements. According to the help descriptions I should
be able to use explicit elements for this problem
using adaptive mesh.
I would appreciate if you help me with the following
1) Warning? 10353 elements(s) were removed from
Adaptive Mesh. The elements have been identified in
element set WarnElemRemovedFromAdaptMesh.
Why it gives such a warning and what does it mean
here?
2)Why explicit and standard elements give the same
results?
3)However, using explicit elements, I get the
Relax stiffness is not a valid choice for the
hourglass parameter on the *section controls option in
abaqus/standard; hence, it will be replaced with the
default (hourglass=stiffness) for the current
analysis. The original choice will, however, be stored
for any subsequent abaqus/explicit import analysis
The parameter hourglass = stiffness on the section
controls option is relevant for these elements: c3d8r,
cax4r, cgax4r, cpeg4r, cpe4r, cps4r, m3d4r, m3d9r,
s4r5, s4r, s8r5, s9r5, sc6r, sc8r and their hybrid,
thermal and pressure counterparts wherever applicable.
This warning can be ignored if the feature is applied
to these element types only.
any explanation?
4) the problem does not converge with quadratic
elements, any suggestions.
Thanks you all in advance
Shervin
__________________________________
Yahoo! Mail - PC Magazine Editors' Choice 2005
http://mail.yahoo.com

__________________________________________________________________
Switch to Netscape Internet Service.
As low as $9.95 a month -- Sign up today at

http://isp.netscape.com/register

Post by v***@netscape.net
Netscape. Just the Net You Need.
New! Netscape Toolbar for Internet Explorer
Search from anywhere on the Web and block those annoying pop-ups.
Download now at http://channels.netscape.com/ns/search/install.jsp

------------------------ Yahoo! Groups Sponsor --------------------~-->
Get fast access to your favorite Yahoo! Groups. Make Yahoo! your home page
http://us.click.yahoo.com/dpRU5A/wUILAA/yQLSAA/PMYolB/TM
--------------------------------------------------------------------~->

[saheb34]

Folks,

Thank you for your responses,

amarendraatre, could you please tell me how I can define my problem
to be quasi-static when I have large deformation model meshed (free)
with linear 4 node tetrahedron solid elements?

also, there are two problems:
1. problem does not converge with standard and quadratic elements. it
aborts with finding 3 negative eigen values.

2. Although, it seems that adaptive mesh would be removed in standard
linear problems, I get different answers using adaptive mesh for
linear elements, which seems to be more reasonable. So, I think it
works!

Could you please help me with these two issues?

Post by amarendraatre
Shervin,
You might be confused with using explicit elements for your

analysis

Post by amarendraatre
as opposed to performing an explicit analysis. For a large
deformation static analysis if you run it in standard using
quadratic elements you use standard elements with default hourglass
control. See if your problem runs this way. If your problem is

large

Post by amarendraatre
def as you say and that is causing large convergence problems then
you must perform an explicit analysis and not just simply use
explicit elements. Explicit analysis has other hourglass modes you
can use for the elements and hence you get the second warning. In
performing the explicit analysis you will need to perform it as
quasi-static to ensure its validity.
Amar

Post by v***@netscape.net
I am not 100% sure, but it seems to me that u r running standard

analysis and that your adaptive meshing is not activated at all. How
many elements do u have? Why r u running standard analysis with
explicit elements? If u want to activate adaptive meshing try using
qasy-static procedure in explicit. These topics were covered nicely
with during last several of months.

Post by v***@netscape.net
Regards and good luck
Natasa

Post by Shervin
Dear Folks,
I am doing a static analysis with large deformations
(nonlinear geometry activated) using solid linear
elements. According to the help descriptions I should
be able to use explicit elements for this problem
using adaptive mesh.
I would appreciate if you help me with the following
1) Warning? 10353 elements(s) were removed from
Adaptive Mesh. The elements have been identified in
element set WarnElemRemovedFromAdaptMesh.
Why it gives such a warning and what does it mean
here?
2)Why explicit and standard elements give the same
results?
3)However, using explicit elements, I get the
Relax stiffness is not a valid choice for the
hourglass parameter on the *section controls option in
abaqus/standard; hence, it will be replaced with the
default (hourglass=stiffness) for the current
analysis. The original choice will, however, be stored
for any subsequent abaqus/explicit import analysis
The parameter hourglass = stiffness on the section
controls option is relevant for these elements: c3d8r,
cax4r, cgax4r, cpeg4r, cpe4r, cps4r, m3d4r, m3d9r,
s4r5, s4r, s8r5, s9r5, sc6r, sc8r and their hybrid,
thermal and pressure counterparts wherever applicable.
This warning can be ignored if the feature is applied
to these element types only.
any explanation?
4) the problem does not converge with quadratic
elements, any suggestions.
Thanks you all in advance
Shervin
__________________________________
Yahoo! Mail - PC Magazine Editors' Choice 2005
http://mail.yahoo.com

__________________________________________________________________
Switch to Netscape Internet Service.
As low as $9.95 a month -- Sign up today at

http://isp.netscape.com/register

Post by v***@netscape.net
Netscape. Just the Net You Need.
New! Netscape Toolbar for Internet Explorer
Search from anywhere on the Web and block those annoying pop-ups.
Download now at http://channels.netscape.com/ns/search/install.jsp

------------------------ Yahoo! Groups Sponsor --------------------~-->
Get fast access to your favorite Yahoo! Groups. Make Yahoo! your home page
http://us.click.yahoo.com/dpRU5A/wUILAA/yQLSAA/PMYolB/TM
--------------------------------------------------------------------~->