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Modelling of crack

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Modelling of crack

Muhammad waqas tofique
Hello everyone!!
 
Well I am a beginner in using ABAQUS......I am using ABAQUS 6.7......i have to model a simple 2D crack in a 2D domain......
 
please can any one guide me about the *simple steps to model a 2D crack.......
 
I have been reading all the ABAQUS manuals bt to understand them one should have a very good prior knowledge about this topic which unfortunately i dont have.
I will be very relieved if anyone helps me out bcoz m stuck at ths point.
 
Regards
Waqas


     

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Re: Modelling of crack

Parisa Khoshnood
Muhammad,
go in this way:
Introduce a partition to the part you want to crack.
Go to interaction and introduce seam into your model, Also add crack to the model in the same module.
Go to the step and use of CONTOUR INTEGRAL and ask for few contour integral.
Depending on crack length stress intensities are calculated at the crack length for you.
Use stress intensities in LEFM for predicting failure load.
Thank you,
Parisa

--- On Sat, 4/24/10, Muhammad waqas tofique <[hidden email]> wrote:

From: Muhammad waqas tofique <[hidden email]>
Subject: [Abaqus] Modelling of crack
To: [hidden email]
Date: Saturday, April 24, 2010, 4:38 PM







 



 


   
     
     
      Hello everyone!!

 

Well I am a beginner in using ABAQUS...... I am using ABAQUS 6.7......i have to model a simple 2D crack in a 2D domain......

 

please can any one guide me about the *simple steps to model a 2D crack.......

 

I have been reading all the ABAQUS manuals bt to understand them one should have a very good prior knowledge about this topic which unfortunately i dont have.

I will be very relieved if anyone helps me out bcoz m stuck at ths point.

 

Regards

Waqas



[Non-text portions of this message have been removed]





   
     

   
   


 



 






     

[Non-text portions of this message have been removed]

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Re: Modelling of crack

Ali31
Parisa,

Could you please tell me what field and history outputs i should request to be able to examine the stress intensity at tip of the crack.
Another question:
I made an analysis with xfem functionality in abaqus 6.9-1 with "MAXPS" damage evolution. An arbitrary crack initiates in middle of the elements and propagates through the thicness but when i hover the mouse over the cracked elements, it looks like the damaged elements are still there without damage. My question is what is the main difference between the XEFEM and an analysis where the crack initiation is predefined by the user. I also suspect that my analysis with xfem is not correct because the global stresses are not falling while the crack propagates.
Have somebody tried xfem analysis in abaqus and experienced the same as i?
I appreciate any help.

Ali

--- In [hidden email], Parisa Khoshnood <parisa71@...> wrote:

>
> Muhammad,
> go in this way:
> Introduce a partition to the part you want to crack.
> Go to interaction and introduce seam into your model, Also add crack to the model in the same module.
> Go to the step and use of CONTOUR INTEGRAL and ask for few contour integral.
> Depending on crack length stress intensities are calculated at the crack length for you.
> Use stress intensities in LEFM for predicting failure load.
> Thank you,
> Parisa
>
> --- On Sat, 4/24/10, Muhammad waqas tofique <eskeemo_aries@...> wrote:
>
> From: Muhammad waqas tofique <eskeemo_aries@...>
> Subject: [Abaqus] Modelling of crack
> To: [hidden email]
> Date: Saturday, April 24, 2010, 4:38 PM
>
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>      
>      
>       Hello everyone!!
>
>  
>
> Well I am a beginner in using ABAQUS...... I am using ABAQUS 6.7......i have to model a simple 2D crack in a 2D domain......
>
>  
>
> please can any one guide me about the *simple steps to model a 2D crack.......
>
>  
>
> I have been reading all the ABAQUS manuals bt to understand them one should have a very good prior knowledge about this topic which unfortunately i dont have.
>
> I will be very relieved if anyone helps me out bcoz m stuck at ths point.
>
>  
>
> Regards
>
> Waqas
>
>
>
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RE: Re: Modelling of crack

tobadooor-2

Hi Muhammad,

I just get back from Abaqus workshop for modeling Fracture and Failure with Abaqus.

For the background you need the following:

1-Fracture mechanics book for Anderson.  It has lots of examples.
2-If you can by the handout for the workshop you will have a complete examples on how to do crack analysis and crack probagation. it available on Simulia.com of you want to buy it.

Now if you want to do crack analysis you have to decide first

1- What is your material behavior? ( Brittel or Ductile)
2- Do you want LEFM or EPFM? (thats linear elastic fracture mechanics and elasto-plastic fracture mechanics).
3- Do you want to do stationary crack or crack propagation?


your history out put you asked for depend on your answers for the above questions.

Anyway, for LEFM you can use the seam but for EPFM you have to do a blunt crack (no seam).

if your problem is stationary then you can request stress intensity then from the output chose  K1 and which contour you want , chose the 3rd,4th, and 5th contours and average them(your step should be nonlinear).  If you want nonlinear then you can request J-Integral but not K since the difference is big for nonlinear problems.

For crack propagation: you can use cohesive, VCCT or XFEM.

alot of explanation on the hand outs.  The best is XFEM but you need to many material properties to do that.  This is because you need to specify damage initiation criteria and then damage evolution ( this is needed for cohesive and VCCT as will).

you should start with LEFM problem from the book i mentioned and do a linear problem first.  I hope this will help.

Regards,

Badr Bedairi







To: [hidden email]
From: [hidden email]
Date: Mon, 26 Apr 2010 17:06:10 +0000
Subject: [Abaqus] Re: Modelling of crack


















 



 


   
     
     
      Parisa,



Could you please tell me what field and history outputs i should request to be able to examine the stress intensity at tip of the crack.

Another question:

I made an analysis with xfem functionality in abaqus 6.9-1 with "MAXPS" damage evolution. An arbitrary crack initiates in middle of the elements and propagates through the thicness but when i hover the mouse over the cracked elements, it looks like the damaged elements are still there without damage. My question is what is the main difference between the XEFEM and an analysis where the crack initiation is predefined by the user. I also suspect that my analysis with xfem is not correct because the global stresses are not falling while the crack propagates.

Have somebody tried xfem analysis in abaqus and experienced the same as i?

I appreciate any help.



Ali



--- In [hidden email], Parisa Khoshnood <parisa71@...> wrote:

>

> Muhammad,

> go in this way:

> Introduce a partition to the part you want to crack.

> Go to interaction and introduce seam into your model, Also add crack to the model in the same module.

> Go to the step and use of CONTOUR INTEGRAL and ask for few contour integral.

> Depending on crack length stress intensities are calculated at the crack length for you.

> Use stress intensities in LEFM for predicting failure load.

> Thank you,

> Parisa

>

> --- On Sat, 4/24/10, Muhammad waqas tofique <eskeemo_aries@...> wrote:

>

> From: Muhammad waqas tofique <eskeemo_aries@...>

> Subject: [Abaqus] Modelling of crack

> To: [hidden email]

> Date: Saturday, April 24, 2010, 4:38 PM

>

>

>

>

>

>

>

> Â

>

>

>

>  

>

>

>    

>      

>      

>       Hello everyone!!

>

> Â

>

> Well I am a beginner in using ABAQUS...... I am using ABAQUS 6.7......i have to model a simple 2D crack in a 2D domain......

>

> Â

>

> please can any one guide me about the *simple steps to model a 2D crack.......

>

> Â

>

> I have been reading all the ABAQUS manuals bt to understand them one should have a very good prior knowledge about this topic which unfortunately i dont have.

>

> I will be very relieved if anyone helps me out bcoz m stuck at ths point.

>

> Â

>

> Regards

>

> Waqas

>

>

>

> [Non-text portions of this message have been removed]

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Re: Modelling of crack

Panagiotis-4
Hi Ali,
 if you are using XFEM there is a good website with basic examples:
http://sites.google.com/site/matthewjpais/abaqus
I hope it helps,
            Panos

--- In [hidden email], bador hamz <tobador@...> wrote:

>
>
> Hi Muhammad,
>
> I just get back from Abaqus workshop for modeling Fracture and Failure with Abaqus.
>
> For the background you need the following:
>
> 1-Fracture mechanics book for Anderson.  It has lots of examples.
> 2-If you can by the handout for the workshop you will have a complete examples on how to do crack analysis and crack probagation. it available on Simulia.com of you want to buy it.
>
> Now if you want to do crack analysis you have to decide first
>
> 1- What is your material behavior? ( Brittel or Ductile)
> 2- Do you want LEFM or EPFM? (thats linear elastic fracture mechanics and elasto-plastic fracture mechanics).
> 3- Do you want to do stationary crack or crack propagation?
>
>
> your history out put you asked for depend on your answers for the above questions.
>
> Anyway, for LEFM you can use the seam but for EPFM you have to do a blunt crack (no seam).
>
> if your problem is stationary then you can request stress intensity then from the output chose  K1 and which contour you want , chose the 3rd,4th, and 5th contours and average them(your step should be nonlinear).  If you want nonlinear then you can request J-Integral but not K since the difference is big for nonlinear problems.
>
> For crack propagation: you can use cohesive, VCCT or XFEM.
>
> alot of explanation on the hand outs.  The best is XFEM but you need to many material properties to do that.  This is because you need to specify damage initiation criteria and then damage evolution ( this is needed for cohesive and VCCT as will).
>
> you should start with LEFM problem from the book i mentioned and do a linear problem first.  I hope this will help.
>
> Regards,
>
> Badr Bedairi
>
>
>
>
>
>
>
> To: [hidden email]
> From: akhaje@...
> Date: Mon, 26 Apr 2010 17:06:10 +0000
> Subject: [Abaqus] Re: Modelling of crack
>
>       Parisa,
>
>
>
> Could you please tell me what field and history outputs i should request to be able to examine the stress intensity at tip of the crack.
>
> Another question:
>
> I made an analysis with xfem functionality in abaqus 6.9-1 with "MAXPS" damage evolution. An arbitrary crack initiates in middle of the elements and propagates through the thicness but when i hover the mouse over the cracked elements, it looks like the damaged elements are still there without damage. My question is what is the main difference between the XEFEM and an analysis where the crack initiation is predefined by the user. I also suspect that my analysis with xfem is not correct because the global stresses are not falling while the crack propagates.
>
> Have somebody tried xfem analysis in abaqus and experienced the same as i?
>
> I appreciate any help.
>
>
>
> Ali
>
>
>
> --- In [hidden email], Parisa Khoshnood <parisa71@> wrote:
>
> >
>
> > Muhammad,
>
> > go in this way:
>
> > Introduce a partition to the part you want to crack.
>
> > Go to interaction and introduce seam into your model, Also add crack to the model in the same module.
>
> > Go to the step and use of CONTOUR INTEGRAL and ask for few contour integral.
>
> > Depending on crack length stress intensities are calculated at the crack length for you.
>
> > Use stress intensities in LEFM for predicting failure load.
>
> > Thank you,
>
> > Parisa
>
> >
>
> > --- On Sat, 4/24/10, Muhammad waqas tofique <eskeemo_aries@> wrote:
>
> >
>
> > From: Muhammad waqas tofique <eskeemo_aries@>
>
> > Subject: [Abaqus] Modelling of crack
>
> > To: [hidden email]
>
> > Date: Saturday, April 24, 2010, 4:38 PM
>
>>
> >       Hello everyone!!
>
> >
>>
> > Well I am a beginner in using ABAQUS...... I am using ABAQUS 6.7......i have to model a simple 2D crack in a 2D domain......
>
> >
>
> > please can any one guide me about the *simple steps to model a 2D crack.......
>
> >
>
> > Â
>
> >
>
> > I have been reading all the ABAQUS manuals bt to understand them one should have a very good prior knowledge about this topic which unfortunately i dont have.
>
> >
>
> > I will be very relieved if anyone helps me out bcoz m stuck at ths point.
>
> >
>
> > Â
>
> >
>
> > Regards
>
> >
>
> > Waqas
>
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Re: Re: Modelling of crack

Ranil Banneyake
In reply to this post by Ali31
In XFEM the element will not disappear but will deform as if there is a
crack. To visualize the crack you have to use the varialbe STUTUSXFEM

Also look at the PHILSM for the crack surface.

Ranil

On Mon, Apr 26, 2010 at 12:06 PM, denzel_washington25
<[hidden email]>wrote:

>
>
> Parisa,
>
> Could you please tell me what field and history outputs i should request to
> be able to examine the stress intensity at tip of the crack.
> Another question:
> I made an analysis with xfem functionality in abaqus 6.9-1 with "MAXPS"
> damage evolution. An arbitrary crack initiates in middle of the elements and
> propagates through the thicness but when i hover the mouse over the cracked
> elements, it looks like the damaged elements are still there without damage.
> My question is what is the main difference between the XEFEM and an analysis
> where the crack initiation is predefined by the user. I also suspect that my
> analysis with xfem is not correct because the global stresses are not
> falling while the crack propagates.
> Have somebody tried xfem analysis in abaqus and experienced the same as i?
> I appreciate any help.
>
> Ali
>
>
> --- In [hidden email] <Abaqus%40yahoogroups.com>, Parisa Khoshnood
> <parisa71@...> wrote:
> >
> > Muhammad,
> > go in this way:
> > Introduce a partition to the part you want to crack.
> > Go to interaction and introduce seam into your model, Also add crack to
> the model in the same module.
> > Go to the step and use of CONTOUR INTEGRAL and ask for few contour
> integral.
> > Depending on crack length stress intensities are calculated at the crack
> length for you.
> > Use stress intensities in LEFM for predicting failure load.
> > Thank you,
> > Parisa
> >
> > --- On Sat, 4/24/10, Muhammad waqas tofique <eskeemo_aries@...> wrote:
> >
> > From: Muhammad waqas tofique <eskeemo_aries@...>
>
> > Subject: [Abaqus] Modelling of crack
> > To: [hidden email] <Abaqus%40yahoogroups.com>
> > Date: Saturday, April 24, 2010, 4:38 PM
> >
> >
> >
> >
> >
> >
> >
> > Â
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Hello everyone!!
> >
> > Â
>
> >
> > Well I am a beginner in using ABAQUS...... I am using ABAQUS 6.7......i
> have to model a simple 2D crack in a 2D domain......
> >
> > Â
>
> >
> > please can any one guide me about the *simple steps to model a 2D
> crack.......
> >
> > Â
>
> >
> > I have been reading all the ABAQUS manuals bt to understand them one
> should have a very good prior knowledge about this topic which unfortunately
> i dont have.
> >
> > I will be very relieved if anyone helps me out bcoz m stuck at ths point.
> >
> > Â
>
> >
> > Regards
> >
> > Waqas
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>  
>


[Non-text portions of this message have been removed]



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Re: Modelling of crack

cheikhemse
This post was updated on .
In reply to this post by Panagiotis-4


Hello dears,

I am a new abaqus user and i am trying to model a crack propagation in 3D. I have seen the tutorial of Matthiew but it doesn't work! the crack does not propagate.

I need a help. Do somebody have a tutorial which works nicely. I am using 6.9 version

Thank you  in advance

Cheikh
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Re: Re: Modelling of crack

cheikhemse
In reply to this post by Ranil Banneyake

Hello dears,

I am a new abaqus user and i am trying to model a crack propagation in 3D. I have seen the tutorial of Matthiew but it doesn't work! the crack does not propagate.

I need a help. Do somebody have a tutorial which works nicely. I am using 6.9 version

Thank you  in advance

Cheikh
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Re: Modelling of crack

sangsazeh
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Re: Modelling of crack

M Abdullah
This post has NOT been accepted by the mailing list yet.
In reply to this post by Parisa Khoshnood
Hi Muhammad

I am trying to model a 2D edge crack using FEM but I do not understand the instructions.
The following are stated:
Partitioned
Select the crack front (first contour region);
Select the crack tip region;
Specify crack extensiondirection using Normal to crack plane;
Select start point;
Select end point.

there are then 3 green crosses

I then created a part using 2D wire next to where the green crosses start.
Job completed but no higher stresses at the crack area.
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