## [GiDlist] Help with GID

Moderator: GiD Team

amit Dhankhar

### [GiDlist] Help with GID

Hi,

Can you post my question to the GID List? I am a first time user of GID.

How can I model a crack in GID? I have a simple cubical geometry in which I
want to define a crack right in the middle of the cube going upto the
centre (basically a surface crack). I am very new to GID but till now I
have not been able to define a crack (basically I'd need double nodes at
the crack front for meshing purpose) Would appreciate any help!

Thanks,
Amit
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escolano
Posts: 1701
Joined: Thu Sep 18, 2014 3:31 pm

### [GiDlist] Help with GID

You can try to use Mesh-Mesh criteria-Duplicate

And select the surfaces where do you want to ‘double nodes’

In fact could be created more than 2 nodes, e.g. for the T join of the next picture there are created 3 nodes, and for the ends of the crack lines only 1 node

Note: it is compulsory for the volume mesh that the surface belong to the boundary of the volume, else tetrahedral nodes won’t be on the surface,

then your first step is to create extra surfaces joined to your ‘crack surface’ to split your volume in two volumes sharing these splitting surfaces.

Then when generating the mesh the tetrahedral will have its nodes on the surfaces.

And to force the nodes duplication on the crack surface must apply on it Mesh-Mesh criteria-Duplicate

This is the help of the GiD reference manual about Mesh criteria-Duplicate:

Use the Duplicate option when you want to create a discontinuity in the mesh in a particular place by duplicating nodes. This is interesting, for example, when dealing with very thin shapes where it is difficult to represent the domain with two overlapped surfaces, and it is easier to have a single surface marked with this meshing option (like sails embedded in a volume, material cracks, etc.).

Marked lines and the deformed mesh after an structural analysis

It is possible to mark lines embedded in a 2D domain, or surfaces in the case of 3D domains.

Regards

Enrique Escolano

De: gidlist-bounces at listas.cimne.upc.edu [mailto:gidlist-bounces at listas.cimne.upc.edu] En nombre de amit Dhankhar
Enviado el: viernes, 26 de septiembre de 2014 8:17
Para: gidlist at listas.cimne.upc.edu
Asunto: [GiDlist] Help with GID

Hi,

Can you post my question to the GID List? I am a first time user of GID.

How can I model a crack in GID? I have a simple cubical geometry in which I want to define a crack right in the middle of the cube going upto the centre (basically a surface crack). I am very new to GID but till now I have not been able to define a crack (basically I'd need double nodes at the crack front for meshing purpose) Would appreciate any help!

Thanks,
Amit

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amit Dhankhar

### [GiDlist] Help with GID

Hi,

Regarding creating duplicate nodes on the crack surface- the crack surface
only runs upto the half width of my object- so how do deal with this case?
If we divide the cube completely into two smaller volumes - that just
represents two separate entities, isn't it? I am not sure if that would
serve my purpose. Can you suggest anything?

Thanks,
Amit

On Fri, Sep 26, 2014 at 4:41 AM, Enrique Escolano escolano at cimne.upc.edu
wrote:

You can try to use Mesh-Mesh criteria-Duplicate

And select the surfaces where do you want to ‘double nodes’

In fact could be created more than 2 nodes, e.g. for the T join of the
next picture there are created 3 nodes, and for the ends of the crack lines
only 1 node

Note: it is compulsory for the volume mesh that the surface belong to the
boundary of the volume, else tetrahedral nodes won’t be on the surface,

then your first step is to create extra surfaces joined to your ‘crack
surface’ to split your volume in two volumes sharing these splitting
surfaces.

Then when generating the mesh the tetrahedral will have its nodes on the
surfaces.

And to force the nodes duplication on the crack surface must apply on it
Mesh-Mesh criteria-Duplicate

This is the help of the GiD reference manual about Mesh
criteria-Duplicate:

Use the Duplicate option when you want to create a discontinuity in the
mesh in a particular place by duplicating nodes. This is interesting, for
example, when dealing with very thin shapes where it is difficult to
represent the domain with two overlapped surfaces, and it is easier to have
a single surface marked with this meshing option (like sails embedded in a
volume, material cracks, etc.).

Marked lines and the deformed mesh after an structural analysis

It is possible to mark lines embedded in a 2D domain, or surfaces in the
case of 3D domains.

Regards

Enrique Escolano

*De:* gidlist-bounces at listas.cimne.upc.edu [mailto:
gidlist-bounces at listas.cimne.upc.edu] *En nombre de *amit Dhankhar
*Enviado el:* viernes, 26 de septiembre de 2014 8:17
*Para:* gidlist at listas.cimne.upc.edu
*Asunto:* [GiDlist] Help with GID

Hi,

Can you post my question to the GID List? I am a first time user of GID.

How can I model a crack in GID? I have a simple cubical geometry in which
I want to define a crack right in the middle of the cube going upto the
centre (basically a surface crack). I am very new to GID but till now I
have not been able to define a crack (basically I'd need double nodes at
the crack front for meshing purpose) Would appreciate any help!

Thanks,
Amit

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

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escolano
Posts: 1701
Joined: Thu Sep 18, 2014 3:31 pm

### [GiDlist] Help with GID

You must create the ‘extra surfaces joined to your crack surface’, to be able to split your volume, else your crack surface not belong to any volume!!

The two volumes are not separated entities, because they share the same surfaces, when meshing it is like a single volume.

In fact to duplicate the nodes of crack surface you can use the Mesh-Mesh criteria-Duplicate or modify the geometry creating another copy of the surface and its lines

and points and then each surface will have its own nodes.

The difference is that the amount and location of nodes on each surface could be different. Using Mesh criteria-Duplicate you will have exactly the same amount nodes and on the same location.

And modify the geometry creating two surfaces and its lines and points on the same location could be a nightmare, probably you will connect parts in a wrong way. Mesh criteria-Duplicate is much easier, you must only have a single surface and the separation will be done automatically at meshing time.

Enrique

De: gidlist-bounces at listas.cimne.upc.edu [mailto:gidlist-bounces at listas.cimne.upc.edu] En nombre de amit Dhankhar
Enviado el: viernes, 26 de septiembre de 2014 13:06
Para: gidlist at listas.cimne.upc.edu
Asunto: Re: [GiDlist] Help with GID

Hi,

Regarding creating duplicate nodes on the crack surface- the crack surface only runs upto the half width of my object- so how do deal with this case? If we divide the cube completely into two smaller volumes - that just represents two separate entities, isn't it? I am not sure if that would serve my purpose. Can you suggest anything?

Thanks,

Amit

On Fri, Sep 26, 2014 at 4:41 AM, Enrique Escolano escolano at cimne.upc.edu wrote:

You can try to use Mesh-Mesh criteria-Duplicate

And select the surfaces where do you want to ‘double nodes’

In fact could be created more than 2 nodes, e.g. for the T join of the next picture there are created 3 nodes, and for the ends of the crack lines only 1 node

Note: it is compulsory for the volume mesh that the surface belong to the boundary of the volume, else tetrahedral nodes won’t be on the surface,

then your first step is to create extra surfaces joined to your ‘crack surface’ to split your volume in two volumes sharing these splitting surfaces.

Then when generating the mesh the tetrahedral will have its nodes on the surfaces.

And to force the nodes duplication on the crack surface must apply on it Mesh-Mesh criteria-Duplicate

This is the help of the GiD reference manual about Mesh criteria-Duplicate:

Use the Duplicate option when you want to create a discontinuity in the mesh in a particular place by duplicating nodes. This is interesting, for example, when dealing with very thin shapes where it is difficult to represent the domain with two overlapped surfaces, and it is easier to have a single surface marked with this meshing option (like sails embedded in a volume, material cracks, etc.).

Marked lines and the deformed mesh after an structural analysis

It is possible to mark lines embedded in a 2D domain, or surfaces in the case of 3D domains.

Regards

Enrique Escolano

De: gidlist-bounces at listas.cimne.upc.edu [mailto:gidlist-bounces at listas.cimne.upc.edu] En nombre de amit Dhankhar
Enviado el: viernes, 26 de septiembre de 2014 8:17
Para: gidlist at listas.cimne.upc.edu
Asunto: [GiDlist] Help with GID

Hi,

Can you post my question to the GID List? I am a first time user of GID.

How can I model a crack in GID? I have a simple cubical geometry in which I want to define a crack right in the middle of the cube going upto the centre (basically a surface crack). I am very new to GID but till now I have not been able to define a crack (basically I'd need double nodes at the crack front for meshing purpose) Would appreciate any help!

Thanks,
Amit

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

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amit Dhankhar

### [GiDlist] Help with GID

Hey,

Thanks a lot for your help. I did what you have mentioned- I have two
surfaces in the middle of my element (one of them being the crack surface),
I split the volume in two halves and assigned Mesh criteria- Duplicate to
the crack surface. But now when I try to assign a structured mesh
(tetrahedral), a warning shows up and GID doesn't mesh my element (It says
"Volume number 2 can't be semi-structured"). Crack surface is in the middle
and goes down from top to bottom to half the length of the element. Here's
a screenshot-

[image: Inline image 1]

Any idea what can I do? Would really appreciate some help.

Thanks,
Amit

On Fri, Sep 26, 2014 at 7:26 AM, Enrique Escolano escolano at cimne.upc.edu
wrote:

You must create the ‘extra surfaces joined to your crack surface’, to be
able to split your volume, else your crack surface not belong to any
volume!!

The two volumes are not separated entities, because they share the same
surfaces, when meshing it is like a single volume.

In fact to duplicate the nodes of crack surface you can use the Mesh-Mesh
criteria-Duplicate or modify the geometry creating another copy of the
surface and its lines

and points and then each surface will have its own nodes.

The difference is that the amount and location of nodes on each surface
could be different. Using Mesh criteria-Duplicate you will have exactly
the same amount nodes and on the same location.

And modify the geometry creating two surfaces and its lines and points on
the same location could be a nightmare, probably you will connect parts in
a wrong way. Mesh criteria-Duplicate is much easier, you must only have a
single surface and the separation will be done automatically at meshing
time.

Enrique

*De:* gidlist-bounces at listas.cimne.upc.edu [mailto:
gidlist-bounces at listas.cimne.upc.edu] *En nombre de *amit Dhankhar
*Enviado el:* viernes, 26 de septiembre de 2014 13:06
*Para:* gidlist at listas.cimne.upc.edu
*Asunto:* Re: [GiDlist] Help with GID

Hi,

Regarding creating duplicate nodes on the crack surface- the crack surface
only runs upto the half width of my object- so how do deal with this case?
If we divide the cube completely into two smaller volumes - that just
represents two separate entities, isn't it? I am not sure if that would
serve my purpose. Can you suggest anything?

Thanks,

Amit

On Fri, Sep 26, 2014 at 4:41 AM, Enrique Escolano escolano at cimne.upc.edu
wrote:

You can try to use Mesh-Mesh criteria-Duplicate

And select the surfaces where do you want to ‘double nodes’

In fact could be created more than 2 nodes, e.g. for the T join of the
next picture there are created 3 nodes, and for the ends of the crack lines
only 1 node

Note: it is compulsory for the volume mesh that the surface belong to the
boundary of the volume, else tetrahedral nodes won’t be on the surface,

then your first step is to create extra surfaces joined to your ‘crack
surface’ to split your volume in two volumes sharing these splitting
surfaces.

Then when generating the mesh the tetrahedral will have its nodes on the
surfaces.

And to force the nodes duplication on the crack surface must apply on it
Mesh-Mesh criteria-Duplicate

This is the help of the GiD reference manual about Mesh
criteria-Duplicate:

Use the Duplicate option when you want to create a discontinuity in the
mesh in a particular place by duplicating nodes. This is interesting, for
example, when dealing with very thin shapes where it is difficult to
represent the domain with two overlapped surfaces, and it is easier to have
a single surface marked with this meshing option (like sails embedded in a
volume, material cracks, etc.).

Marked lines and the deformed mesh after an structural analysis

It is possible to mark lines embedded in a 2D domain, or surfaces in the
case of 3D domains.

Regards

Enrique Escolano

*De:* gidlist-bounces at listas.cimne.upc.edu [mailto:
gidlist-bounces at listas.cimne.upc.edu] *En nombre de *amit Dhankhar
*Enviado el:* viernes, 26 de septiembre de 2014 8:17
*Para:* gidlist at listas.cimne.upc.edu
*Asunto:* [GiDlist] Help with GID

Hi,

Can you post my question to the GID List? I am a first time user of GID.

How can I model a crack in GID? I have a simple cubical geometry in which
I want to define a crack right in the middle of the cube going upto the
centre (basically a surface crack). I am very new to GID but till now I
have not been able to define a crack (basically I'd need double nodes at
the crack front for meshing purpose) Would appreciate any help!

Thanks,
Amit

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

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amit Dhankhar

### [GiDlist] Help with GID

One last thing I want to ask is- how can we generate an input file after
premeshing from GID (a file having node numbers, nodal coordinates and
element connectivity)- so that it can be fed into a solver like abaqus?

Thanks,
Amit

On Fri, Sep 26, 2014 at 10:43 AM, amit Dhankhar amit12kd at gmail.com wrote:

Hey,

Thanks a lot for your help. I did what you have mentioned- I have two
surfaces in the middle of my element (one of them being the crack surface),
I split the volume in two halves and assigned Mesh criteria- Duplicate to
the crack surface. But now when I try to assign a structured mesh
(tetrahedral), a warning shows up and GID doesn't mesh my element (It says
"Volume number 2 can't be semi-structured"). Crack surface is in the middle
and goes down from top to bottom to half the length of the element. Here's
a screenshot-

[image: Inline image 1]

Any idea what can I do? Would really appreciate some help.

Thanks,
Amit

On Fri, Sep 26, 2014 at 7:26 AM, Enrique Escolano escolano at cimne.upc.edu
wrote:

You must create the ‘extra surfaces joined to your crack surface’, to be
able to split your volume, else your crack surface not belong to any
volume!!

The two volumes are not separated entities, because they share the same
surfaces, when meshing it is like a single volume.

In fact to duplicate the nodes of crack surface you can use the
Mesh-Mesh criteria-Duplicate or modify the geometry creating another copy
of the surface and its lines

and points and then each surface will have its own nodes.

The difference is that the amount and location of nodes on each surface
could be different. Using Mesh criteria-Duplicate you will have exactly
the same amount nodes and on the same location.

And modify the geometry creating two surfaces and its lines and points on
the same location could be a nightmare, probably you will connect parts in
a wrong way. Mesh criteria-Duplicate is much easier, you must only have a
single surface and the separation will be done automatically at meshing
time.

Enrique

*De:* gidlist-bounces at listas.cimne.upc.edu [mailto:
gidlist-bounces at listas.cimne.upc.edu] *En nombre de *amit Dhankhar
*Enviado el:* viernes, 26 de septiembre de 2014 13:06
*Para:* gidlist at listas.cimne.upc.edu
*Asunto:* Re: [GiDlist] Help with GID

Hi,

Regarding creating duplicate nodes on the crack surface- the crack
surface only runs upto the half width of my object- so how do deal with
this case? If we divide the cube completely into two smaller volumes - that
just represents two separate entities, isn't it? I am not sure if that
would serve my purpose. Can you suggest anything?

Thanks,

Amit

On Fri, Sep 26, 2014 at 4:41 AM, Enrique Escolano escolano at cimne.upc.edu
wrote:

You can try to use Mesh-Mesh criteria-Duplicate

And select the surfaces where do you want to ‘double nodes’

In fact could be created more than 2 nodes, e.g. for the T join of the
next picture there are created 3 nodes, and for the ends of the crack lines
only 1 node

Note: it is compulsory for the volume mesh that the surface belong to the
boundary of the volume, else tetrahedral nodes won’t be on the surface,

then your first step is to create extra surfaces joined to your ‘crack
surface’ to split your volume in two volumes sharing these splitting
surfaces.

Then when generating the mesh the tetrahedral will have its nodes on the
surfaces.

And to force the nodes duplication on the crack surface must apply on it
Mesh-Mesh criteria-Duplicate

This is the help of the GiD reference manual about Mesh
criteria-Duplicate:

Use the Duplicate option when you want to create a discontinuity in the
mesh in a particular place by duplicating nodes. This is interesting, for
example, when dealing with very thin shapes where it is difficult to
represent the domain with two overlapped surfaces, and it is easier to have
a single surface marked with this meshing option (like sails embedded in a
volume, material cracks, etc.).

Marked lines and the deformed mesh after an structural analysis

It is possible to mark lines embedded in a 2D domain, or surfaces in the
case of 3D domains.

Regards

Enrique Escolano

*De:* gidlist-bounces at listas.cimne.upc.edu [mailto:
gidlist-bounces at listas.cimne.upc.edu] *En nombre de *amit Dhankhar
*Enviado el:* viernes, 26 de septiembre de 2014 8:17
*Para:* gidlist at listas.cimne.upc.edu
*Asunto:* [GiDlist] Help with GID

Hi,

Can you post my question to the GID List? I am a first time user of GID.

How can I model a crack in GID? I have a simple cubical geometry in which
I want to define a crack right in the middle of the cube going upto the
centre (basically a surface crack). I am very new to GID but till now I
have not been able to define a crack (basically I'd need double nodes at
the crack front for meshing purpose) Would appreciate any help!

Thanks,
Amit

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

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escolano
Posts: 1701
Joined: Thu Sep 18, 2014 3:31 pm

### [GiDlist] Help with GID

Why do you need a structured mesh? You can mesh it unstructured simply removing the structured information (can reset all mesh information and set again the duplicate)

It is only possible to mesh a volume structured if it has exactly 6 surfaces (topologically is a cube).

If do you really need this structured mesh, must divide your geometry in 4 volumes, each one with exactly 6 faces.

And about semi-structured volumes, they must have two opposite tops with exactly the same amount of lines, and each pair of its lines must be

connected by a 4-sided surface (along a extrusion direction, where the amount of structured divisions is set)

De: gidlist-bounces at listas.cimne.upc.edu [mailto:gidlist-bounces at listas.cimne.upc.edu] En nombre de amit Dhankhar
Enviado el: viernes, 26 de septiembre de 2014 17:43
Para: gidlist at listas.cimne.upc.edu
Asunto: Re: [GiDlist] Help with GID

Hey,

Thanks a lot for your help. I did what you have mentioned- I have two surfaces in the middle of my element (one of them being the crack surface), I split the volume in two halves and assigned Mesh criteria- Duplicate to the crack surface. But now when I try to assign a structured mesh (tetrahedral), a warning shows up and GID doesn't mesh my element (It says "Volume number 2 can't be semi-structured"). Crack surface is in the middle and goes down from top to bottom to half the length of the element. Here's a screenshot-

Inline image 1

Any idea what can I do? Would really appreciate some help.

Thanks,
Amit

On Fri, Sep 26, 2014 at 7:26 AM, Enrique Escolano escolano at cimne.upc.edu wrote:

You must create the ‘extra surfaces joined to your crack surface’, to be able to split your volume, else your crack surface not belong to any volume!!

The two volumes are not separated entities, because they share the same surfaces, when meshing it is like a single volume.

In fact to duplicate the nodes of crack surface you can use the Mesh-Mesh criteria-Duplicate or modify the geometry creating another copy of the surface and its lines

and points and then each surface will have its own nodes.

The difference is that the amount and location of nodes on each surface could be different. Using Mesh criteria-Duplicate you will have exactly the same amount nodes and on the same location.

And modify the geometry creating two surfaces and its lines and points on the same location could be a nightmare, probably you will connect parts in a wrong way. Mesh criteria-Duplicate is much easier, you must only have a single surface and the separation will be done automatically at meshing time.

Enrique

De: gidlist-bounces at listas.cimne.upc.edu [mailto:gidlist-bounces at listas.cimne.upc.edu] En nombre de amit Dhankhar
Enviado el: viernes, 26 de septiembre de 2014 13:06
Para: gidlist at listas.cimne.upc.edu
Asunto: Re: [GiDlist] Help with GID

Hi,

Regarding creating duplicate nodes on the crack surface- the crack surface only runs upto the half width of my object- so how do deal with this case? If we divide the cube completely into two smaller volumes - that just represents two separate entities, isn't it? I am not sure if that would serve my purpose. Can you suggest anything?

Thanks,

Amit

On Fri, Sep 26, 2014 at 4:41 AM, Enrique Escolano escolano at cimne.upc.edu wrote:

You can try to use Mesh-Mesh criteria-Duplicate

And select the surfaces where do you want to ‘double nodes’

In fact could be created more than 2 nodes, e.g. for the T join of the next picture there are created 3 nodes, and for the ends of the crack lines only 1 node

Note: it is compulsory for the volume mesh that the surface belong to the boundary of the volume, else tetrahedral nodes won’t be on the surface,

then your first step is to create extra surfaces joined to your ‘crack surface’ to split your volume in two volumes sharing these splitting surfaces.

Then when generating the mesh the tetrahedral will have its nodes on the surfaces.

And to force the nodes duplication on the crack surface must apply on it Mesh-Mesh criteria-Duplicate

This is the help of the GiD reference manual about Mesh criteria-Duplicate:

Use the Duplicate option when you want to create a discontinuity in the mesh in a particular place by duplicating nodes. This is interesting, for example, when dealing with very thin shapes where it is difficult to represent the domain with two overlapped surfaces, and it is easier to have a single surface marked with this meshing option (like sails embedded in a volume, material cracks, etc.).

Marked lines and the deformed mesh after an structural analysis

It is possible to mark lines embedded in a 2D domain, or surfaces in the case of 3D domains.

Regards

Enrique Escolano

De: gidlist-bounces at listas.cimne.upc.edu [mailto:gidlist-bounces at listas.cimne.upc.edu] En nombre de amit Dhankhar
Enviado el: viernes, 26 de septiembre de 2014 8:17
Para: gidlist at listas.cimne.upc.edu
Asunto: [GiDlist] Help with GID

Hi,

Can you post my question to the GID List? I am a first time user of GID.

How can I model a crack in GID? I have a simple cubical geometry in which I want to define a crack right in the middle of the cube going upto the centre (basically a surface crack). I am very new to GID but till now I have not been able to define a crack (basically I'd need double nodes at the crack front for meshing purpose) Would appreciate any help!

Thanks,
Amit

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

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amit Dhankhar

### [GiDlist] Help with GID

I am using a simple cube geometry and splitting it into two sub cuboids
(the crack surface passes in between the cuboids up to half length), so
each partition has six surfaces. Yet it shows the same warning. Would it be
possible for you to illustrate it via the file, I can send you my file and
if you could have brief look, that'd be extremely helpful.

Thanks,
Amit
On Sep 26, 2014 11:20 AM, "Enrique Escolano" escolano at cimne.upc.edu wrote:

Why do you need a structured mesh? You can mesh it unstructured simply
removing the structured information (can reset all mesh information and set
again the duplicate)

It is only possible to mesh a volume structured if it has exactly 6
surfaces (topologically is a cube).

If do you really need this structured mesh, must divide your geometry in 4
volumes, each one with exactly 6 faces.

And about semi-structured volumes, they must have two opposite tops with
exactly the same amount of lines, and each pair of its lines must be

connected by a 4-sided surface (along a extrusion direction, where the
amount of structured divisions is set)

*De:* gidlist-bounces at listas.cimne.upc.edu [mailto:
gidlist-bounces at listas.cimne.upc.edu] *En nombre de *amit Dhankhar
*Enviado el:* viernes, 26 de septiembre de 2014 17:43
*Para:* gidlist at listas.cimne.upc.edu
*Asunto:* Re: [GiDlist] Help with GID

Hey,

Thanks a lot for your help. I did what you have mentioned- I have two
surfaces in the middle of my element (one of them being the crack surface),
I split the volume in two halves and assigned Mesh criteria- Duplicate to
the crack surface. But now when I try to assign a structured mesh
(tetrahedral), a warning shows up and GID doesn't mesh my element (It says
"Volume number 2 can't be semi-structured"). Crack surface is in the middle
and goes down from top to bottom to half the length of the element. Here's
a screenshot-

[image: Inline image 1]

Any idea what can I do? Would really appreciate some help.

Thanks,
Amit

On Fri, Sep 26, 2014 at 7:26 AM, Enrique Escolano escolano at cimne.upc.edu
wrote:

You must create the ‘extra surfaces joined to your crack surface’, to be
able to split your volume, else your crack surface not belong to any
volume!!

The two volumes are not separated entities, because they share the same
surfaces, when meshing it is like a single volume.

In fact to duplicate the nodes of crack surface you can use the Mesh-Mesh
criteria-Duplicate or modify the geometry creating another copy of the
surface and its lines

and points and then each surface will have its own nodes.

The difference is that the amount and location of nodes on each surface
could be different. Using Mesh criteria-Duplicate you will have exactly
the same amount nodes and on the same location.

And modify the geometry creating two surfaces and its lines and points on
the same location could be a nightmare, probably you will connect parts in
a wrong way. Mesh criteria-Duplicate is much easier, you must only have a
single surface and the separation will be done automatically at meshing
time.

Enrique

*De:* gidlist-bounces at listas.cimne.upc.edu [mailto:
gidlist-bounces at listas.cimne.upc.edu] *En nombre de *amit Dhankhar
*Enviado el:* viernes, 26 de septiembre de 2014 13:06
*Para:* gidlist at listas.cimne.upc.edu
*Asunto:* Re: [GiDlist] Help with GID

Hi,

Regarding creating duplicate nodes on the crack surface- the crack surface
only runs upto the half width of my object- so how do deal with this case?
If we divide the cube completely into two smaller volumes - that just
represents two separate entities, isn't it? I am not sure if that would
serve my purpose. Can you suggest anything?

Thanks,

Amit

On Fri, Sep 26, 2014 at 4:41 AM, Enrique Escolano escolano at cimne.upc.edu
wrote:

You can try to use Mesh-Mesh criteria-Duplicate

And select the surfaces where do you want to ‘double nodes’

In fact could be created more than 2 nodes, e.g. for the T join of the
next picture there are created 3 nodes, and for the ends of the crack lines
only 1 node

Note: it is compulsory for the volume mesh that the surface belong to the
boundary of the volume, else tetrahedral nodes won’t be on the surface,

then your first step is to create extra surfaces joined to your ‘crack
surface’ to split your volume in two volumes sharing these splitting
surfaces.

Then when generating the mesh the tetrahedral will have its nodes on the
surfaces.

And to force the nodes duplication on the crack surface must apply on it
Mesh-Mesh criteria-Duplicate

This is the help of the GiD reference manual about Mesh
criteria-Duplicate:

Use the Duplicate option when you want to create a discontinuity in the
mesh in a particular place by duplicating nodes. This is interesting, for
example, when dealing with very thin shapes where it is difficult to
represent the domain with two overlapped surfaces, and it is easier to have
a single surface marked with this meshing option (like sails embedded in a
volume, material cracks, etc.).

Marked lines and the deformed mesh after an structural analysis

It is possible to mark lines embedded in a 2D domain, or surfaces in the
case of 3D domains.

Regards

Enrique Escolano

*De:* gidlist-bounces at listas.cimne.upc.edu [mailto:
gidlist-bounces at listas.cimne.upc.edu] *En nombre de *amit Dhankhar
*Enviado el:* viernes, 26 de septiembre de 2014 8:17
*Para:* gidlist at listas.cimne.upc.edu
*Asunto:* [GiDlist] Help with GID

Hi,

Can you post my question to the GID List? I am a first time user of GID.

How can I model a crack in GID? I have a simple cubical geometry in which
I want to define a crack right in the middle of the cube going upto the
centre (basically a surface crack). I am very new to GID but till now I
have not been able to define a crack (basically I'd need double nodes at
the crack front for meshing purpose) Would appreciate any help!

Thanks,
Amit

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

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escolano
Posts: 1701
Joined: Thu Sep 18, 2014 3:31 pm

### [GiDlist] Help with GID

The normal way to deal with a specific calculation program is to write a GiD problemtype, that is a collection of files inside a .gid folder inside \problemtypes that define

the kind of boundary conditions, material properties, etc. that could be applied to geometry and/or mesh entities, and also define a template to export the calculation file in the format expected by the solver,

and usually also start the solver and convert its results to GiD posprocess format if necessary.

You can also simply export the mesh without any problemtype with Files-Export-GiD mesh… (this write a simple ASCII file, easy to be read)

Then can load the problemtype from Data-Problemtype-abaqus

And pressing calculate will automatically write the calculation file (or can use Files-Export-Calculation file=

These are very basical things about GiD, please have a look to our GiD tutorials included in the GiD help.

Enrique

De: gidlist-bounces at listas.cimne.upc.edu [mailto:gidlist-bounces at listas.cimne.upc.edu] En nombre de amit Dhankhar
Enviado el: viernes, 26 de septiembre de 2014 18:14
Para: gidlist at listas.cimne.upc.edu
Asunto: Re: [GiDlist] Help with GID

One last thing I want to ask is- how can we generate an input file after premeshing from GID (a file having node numbers, nodal coordinates and element connectivity)- so that it can be fed into a solver like abaqus?

Thanks,

Amit

On Fri, Sep 26, 2014 at 10:43 AM, amit Dhankhar amit12kd at gmail.com wrote:

Hey,

Thanks a lot for your help. I did what you have mentioned- I have two surfaces in the middle of my element (one of them being the crack surface), I split the volume in two halves and assigned Mesh criteria- Duplicate to the crack surface. But now when I try to assign a structured mesh (tetrahedral), a warning shows up and GID doesn't mesh my element (It says "Volume number 2 can't be semi-structured"). Crack surface is in the middle and goes down from top to bottom to half the length of the element. Here's a screenshot-

Inline image 1

Any idea what can I do? Would really appreciate some help.

Thanks,
Amit

On Fri, Sep 26, 2014 at 7:26 AM, Enrique Escolano escolano at cimne.upc.edu wrote:

You must create the ‘extra surfaces joined to your crack surface’, to be able to split your volume, else your crack surface not belong to any volume!!

The two volumes are not separated entities, because they share the same surfaces, when meshing it is like a single volume.

In fact to duplicate the nodes of crack surface you can use the Mesh-Mesh criteria-Duplicate or modify the geometry creating another copy of the surface and its lines

and points and then each surface will have its own nodes.

The difference is that the amount and location of nodes on each surface could be different. Using Mesh criteria-Duplicate you will have exactly the same amount nodes and on the same location.

And modify the geometry creating two surfaces and its lines and points on the same location could be a nightmare, probably you will connect parts in a wrong way. Mesh criteria-Duplicate is much easier, you must only have a single surface and the separation will be done automatically at meshing time.

Enrique

De: gidlist-bounces at listas.cimne.upc.edu [mailto:gidlist-bounces at listas.cimne.upc.edu] En nombre de amit Dhankhar
Enviado el: viernes, 26 de septiembre de 2014 13:06
Para: gidlist at listas.cimne.upc.edu
Asunto: Re: [GiDlist] Help with GID

Hi,

Regarding creating duplicate nodes on the crack surface- the crack surface only runs upto the half width of my object- so how do deal with this case? If we divide the cube completely into two smaller volumes - that just represents two separate entities, isn't it? I am not sure if that would serve my purpose. Can you suggest anything?

Thanks,

Amit

On Fri, Sep 26, 2014 at 4:41 AM, Enrique Escolano escolano at cimne.upc.edu wrote:

You can try to use Mesh-Mesh criteria-Duplicate

And select the surfaces where do you want to ‘double nodes’

In fact could be created more than 2 nodes, e.g. for the T join of the next picture there are created 3 nodes, and for the ends of the crack lines only 1 node

Note: it is compulsory for the volume mesh that the surface belong to the boundary of the volume, else tetrahedral nodes won’t be on the surface,

then your first step is to create extra surfaces joined to your ‘crack surface’ to split your volume in two volumes sharing these splitting surfaces.

Then when generating the mesh the tetrahedral will have its nodes on the surfaces.

And to force the nodes duplication on the crack surface must apply on it Mesh-Mesh criteria-Duplicate

This is the help of the GiD reference manual about Mesh criteria-Duplicate:

Use the Duplicate option when you want to create a discontinuity in the mesh in a particular place by duplicating nodes. This is interesting, for example, when dealing with very thin shapes where it is difficult to represent the domain with two overlapped surfaces, and it is easier to have a single surface marked with this meshing option (like sails embedded in a volume, material cracks, etc.).

Marked lines and the deformed mesh after an structural analysis

It is possible to mark lines embedded in a 2D domain, or surfaces in the case of 3D domains.

Regards

Enrique Escolano

De: gidlist-bounces at listas.cimne.upc.edu [mailto:gidlist-bounces at listas.cimne.upc.edu] En nombre de amit Dhankhar
Enviado el: viernes, 26 de septiembre de 2014 8:17
Para: gidlist at listas.cimne.upc.edu
Asunto: [GiDlist] Help with GID

Hi,

Can you post my question to the GID List? I am a first time user of GID.

How can I model a crack in GID? I have a simple cubical geometry in which I want to define a crack right in the middle of the cube going upto the centre (basically a surface crack). I am very new to GID but till now I have not been able to define a crack (basically I'd need double nodes at the crack front for meshing purpose) Would appreciate any help!

Thanks,
Amit

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

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amit Dhankhar

### [GiDlist] Help with GID

thanks, you have been really helpful. My work with GID needs a very
specific type of meshing - that's why I need structured meshing- so I have
to decide if I would continue to use GID as a premeshing tool. I'll look
over the options and tutorials and would seek some more help if it doesn't
work out.

Thanks,
Ami

On Fri, Sep 26, 2014 at 11:32 AM, Enrique Escolano escolano at cimne.upc.edu
wrote:

The normal way to deal with a specific calculation program is to write a
GiD problemtype, that is a collection of files inside a .gid folder inside
\problemtypes that define

the kind of boundary conditions, material properties, etc. that could be
applied to geometry and/or mesh entities, and also define a template to
export the calculation file in the format expected by the solver,

and usually also start the solver and convert its results to GiD
posprocess format if necessary.

You can also simply export the mesh without any problemtype with
Files-Export-GiD mesh… (this write a simple ASCII file, easy to be read)

About Abaqus, we have a simple problemtype to write its format, you can

Then can load the problemtype from Data-Problemtype-abaqus

And pressing calculate will automatically write the calculation file (or
can use Files-Export-Calculation file=

These are very basical things about GiD, please have a look to our GiD
tutorials included in the GiD help.

Enrique

*De:* gidlist-bounces at listas.cimne.upc.edu [mailto:
gidlist-bounces at listas.cimne.upc.edu] *En nombre de *amit Dhankhar
*Enviado el:* viernes, 26 de septiembre de 2014 18:14

*Para:* gidlist at listas.cimne.upc.edu
*Asunto:* Re: [GiDlist] Help with GID

One last thing I want to ask is- how can we generate an input file after
premeshing from GID (a file having node numbers, nodal coordinates and
element connectivity)- so that it can be fed into a solver like abaqus?

Thanks,

Amit

On Fri, Sep 26, 2014 at 10:43 AM, amit Dhankhar amit12kd at gmail.com
wrote:

Hey,

Thanks a lot for your help. I did what you have mentioned- I have two
surfaces in the middle of my element (one of them being the crack surface),
I split the volume in two halves and assigned Mesh criteria- Duplicate to
the crack surface. But now when I try to assign a structured mesh
(tetrahedral), a warning shows up and GID doesn't mesh my element (It says
"Volume number 2 can't be semi-structured"). Crack surface is in the middle
and goes down from top to bottom to half the length of the element. Here's
a screenshot-

[image: Inline image 1]

Any idea what can I do? Would really appreciate some help.

Thanks,
Amit

On Fri, Sep 26, 2014 at 7:26 AM, Enrique Escolano escolano at cimne.upc.edu
wrote:

You must create the ‘extra surfaces joined to your crack surface’, to be
able to split your volume, else your crack surface not belong to any
volume!!

The two volumes are not separated entities, because they share the same
surfaces, when meshing it is like a single volume.

In fact to duplicate the nodes of crack surface you can use the Mesh-Mesh
criteria-Duplicate or modify the geometry creating another copy of the
surface and its lines

and points and then each surface will have its own nodes.

The difference is that the amount and location of nodes on each surface
could be different. Using Mesh criteria-Duplicate you will have exactly
the same amount nodes and on the same location.

And modify the geometry creating two surfaces and its lines and points on
the same location could be a nightmare, probably you will connect parts in
a wrong way. Mesh criteria-Duplicate is much easier, you must only have a
single surface and the separation will be done automatically at meshing
time.

Enrique

*De:* gidlist-bounces at listas.cimne.upc.edu [mailto:
gidlist-bounces at listas.cimne.upc.edu] *En nombre de *amit Dhankhar
*Enviado el:* viernes, 26 de septiembre de 2014 13:06
*Para:* gidlist at listas.cimne.upc.edu
*Asunto:* Re: [GiDlist] Help with GID

Hi,

Regarding creating duplicate nodes on the crack surface- the crack surface
only runs upto the half width of my object- so how do deal with this case?
If we divide the cube completely into two smaller volumes - that just
represents two separate entities, isn't it? I am not sure if that would
serve my purpose. Can you suggest anything?

Thanks,

Amit

On Fri, Sep 26, 2014 at 4:41 AM, Enrique Escolano escolano at cimne.upc.edu
wrote:

You can try to use Mesh-Mesh criteria-Duplicate

And select the surfaces where do you want to ‘double nodes’

In fact could be created more than 2 nodes, e.g. for the T join of the
next picture there are created 3 nodes, and for the ends of the crack lines
only 1 node

Note: it is compulsory for the volume mesh that the surface belong to the
boundary of the volume, else tetrahedral nodes won’t be on the surface,

then your first step is to create extra surfaces joined to your ‘crack
surface’ to split your volume in two volumes sharing these splitting
surfaces.

Then when generating the mesh the tetrahedral will have its nodes on the
surfaces.

And to force the nodes duplication on the crack surface must apply on it
Mesh-Mesh criteria-Duplicate

This is the help of the GiD reference manual about Mesh
criteria-Duplicate:

Use the Duplicate option when you want to create a discontinuity in the
mesh in a particular place by duplicating nodes. This is interesting, for
example, when dealing with very thin shapes where it is difficult to
represent the domain with two overlapped surfaces, and it is easier to have
a single surface marked with this meshing option (like sails embedded in a
volume, material cracks, etc.).

Marked lines and the deformed mesh after an structural analysis

It is possible to mark lines embedded in a 2D domain, or surfaces in the
case of 3D domains.

Regards

Enrique Escolano

*De:* gidlist-bounces at listas.cimne.upc.edu [mailto:
gidlist-bounces at listas.cimne.upc.edu] *En nombre de *amit Dhankhar
*Enviado el:* viernes, 26 de septiembre de 2014 8:17
*Para:* gidlist at listas.cimne.upc.edu
*Asunto:* [GiDlist] Help with GID

Hi,

Can you post my question to the GID List? I am a first time user of GID.

How can I model a crack in GID? I have a simple cubical geometry in which
I want to define a crack right in the middle of the cube going upto the
centre (basically a surface crack). I am very new to GID but till now I
have not been able to define a crack (basically I'd need double nodes at
the crack front for meshing purpose) Would appreciate any help!

Thanks,
Amit

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

_______________________________________________
GiDlist mailing list
GiDlist at listas.cimne.upc.edu
http://listas.cimne.upc.edu/cgi-bin/mailman/listinfo/gidlist

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