Periodic Boundary Conditions for uniaxial compression

[Gouse]

Dear All,

I am trying to simulate mechanical behaviour of a concrete unit cell for uniaxial compression laoding. I have apllied periodic bounadary conditions on both lateral edges using linear equation option available in ABAQUS where as on top and bottom edges load is apllied. Deformed structure shows there is no lateral deformation and unit cell behaves as if it is confined laterally on both sides. I am confused about my boundary conditions whether they are correct or not.

 Equation used to aplly periodic bounadary condition are

** Constraint: Constraint-18
*Equation
2
R17, 1, 1.
L17, 1, -1.

where R17 and L17 are nodes on the right and left of the unit cell.

The above eqn I could use from your earlier suggestion but

Can any body suggest what exactly I should use  for my unit cell. Unit cell is a plane square with a circular inclusion at the centre.

 Regards

 Gouse

[jeffergj]

the equation you want is LU=RU+constant. You have effectively set the constant to zero -- so not allowing 'poisson' expansion.

To use this approach your equation will have 4 terms,
L17,1,1.,R17,1,-1.,L1,1,-1.,R1,1,1.
where the 'master' node pair (1) appears in every equation.

note I may have mixed up the signs but if you see how it works you should figure it out.


--- In Abaqus@..., Gouse <gouse_wiz@...> wrote:

>
>
> Dear All,
>
> I am trying to simulate mechanical behaviour of a concrete unit cell for
> uniaxial compression laoding. I have apllied periodic bounadary conditions
> on both lateral edges using linear equation option available in ABAQUS where
> as on top and bottom edges load is apllied. Deformed structure shows there
> is no lateral deformation and unit cell behaves as if it is confined
> laterally on both sides. I am confused about my boundary conditions whether
> they are correct or not.
>
>  Equation used to aplly periodic bounadary condition are
>
> ** Constraint: Constraint-18
> *Equation
> 2
> R17, 1, 1.
> L17, 1, -1.
>
> where R17 and L17 are nodes on the right and left of the unit cell.
>
> The above eqn I could use from your earlier suggestion but
>
> Can any body suggest what exactly I should use  for my unit cell. Unit cell
> is a plane square with a circular inclusion at the centre.
>
>  Regards
>
>  Gouse
>
> --
> View this message in context: http://www.nabble.com/Periodic-Boundary-Conditions-for-uniaxial-compression-tp24318476p24318476.html
> Sent from the Abaqus Users mailing list archive at Nabble.com.
>

[Gouse]

Hi,

I understood that I am not allowing it to expand by setting it to zero and the modified equation with 4 terms. But what are these L1 and R1 whether they are dummy nodes or any nodes on the left and right sides which are set as master nodes. If these L1 and R1 are master nodes, how to define master nodes, I could not see any provision of defining master nodes while defining equation.

Thank you

Regards

Gouse




________________________________
From: jeffergj <george.jefferson@...>
To: Abaqus@...
Sent: Sunday, 5 July, 2009 6:46:54 PM
Subject: [Abaqus] Re: Periodic Boundary Conditions for uniaxial compression





the equation you want is LU=RU+constant. You have effectively set the constant to zero -- so not allowing 'poisson' expansion.

To use this approach your equation will have 4 terms,
L17,1,1.,R17, 1,-1.,L1, 1,-1.,R1, 1,1.
where the 'master' node pair (1) appears in every equation.

note I may have mixed up the signs but if you see how it works you should figure it out.

--- In Abaqus@yahoogroups. com, Gouse <gouse_wiz@. ..> wrote:

>
>
> Dear All,
>
> I am trying to simulate mechanical behaviour of a concrete unit cell for
> uniaxial compression laoding. I have apllied periodic bounadary conditions
> on both lateral edges using linear equation option available in ABAQUS where
> as on top and bottom edges load is apllied. Deformed structure shows there
> is no lateral deformation and unit cell behaves as if it is confined
> laterally on both sides. I am confused about my boundary conditions whether
> they are correct or not.
>
>  Equation used to aplly periodic bounadary condition are
>
> ** Constraint: Constraint-18
> *Equation
> 2
> R17, 1, 1.
> L17, 1, -1.
>
> where R17 and L17 are nodes on the right and left of the unit cell.
>
> The above eqn I could use from your earlier suggestion but
>
> Can any body suggest what exactly I should use  for my unit cell. Unit cell
> is a plane square with a circular inclusion at the centre.
>
>  Regards
>
>  Gouse
>
> --
> View this message in context: http://www.nabble. com/Periodic- Boundary- Conditions- for-uniaxial- compression- tp24318476p24318 476.html
> Sent from the Abaqus Users mailing list archive at Nabble.com.
>

   


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