FourNodeQuad u-p Element: Difference between revisions

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This command is used to construct an eFourNodeQuadUP element object.  A FourNodeQuadUP element is a four-node plane-strain element using bilinear isoparametric formulation. This element is implemented for simulating dynamic response of solid-fluid fully coupled material, based on Biot's theory of porous medium. Each element node has 3 degrees-of-freedom (DOF): DOF 1 and 2 for solid displacement (u) and DOF 3 for fluid pressure (p).  
This command is used to construct an eFourNodeQuadUP element object.  A FourNodeQuadUP element is a four-node plane-strain element using bilinear isoparametric formulation. This element is implemented for simulating dynamic response of solid-fluid fully coupled material, based on Biot's theory of porous medium. Each element node has 3 degrees-of-freedom (DOF): DOF 1 and 2 for solid displacement (u) and DOF 3 for fluid pressure (p).  
The arguments for the construction of this element are:
The arguments for the construction of this element are:
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{|
{|
|  style="width:150px" | '''$eleTag''' || unique element object tag
|  style="width:150px" | '''$eleTag''' || unique element object tag
|-
|-
|'''$iNode $jNode $kNode $lNode''' || Four element node (previously defined) numbers in counter-clockwise order around the element
|'''$Node1 .. $Node4''' || Four element node (previously defined) numbers in counter-clockwise order around the element
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|-
| '''$thick''' || Element thickness
| '''$thick''' || Element thickness
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NOTE:
NOTE:


This element requires 3 degrees-of-freedom (ndf=3), the 3rd degree-of-freedom being pore pressure. The Pore pressure can be recorded at an element node using OpenSees Node Recorder:
#This element requires 3 degrees-of-freedom (ndf=3), the 3rd degree-of-freedom being pore pressure. The Pore pressure can be recorded at an element node using OpenSees Node Recorder:
 
recorder Node <-file $fileName> <-time> <-node ($nod1 $nod2 …)> -dof 3 vel
recorder Node <-file $fileName> <-time> <-node ($nod1 $nod2 …)> -dof 3 vel
 
#The valid queries to a quadUP element when creating an ElementRecorder are 'force',  and 'material matNum matArg1 matArg2 ...', where matNum represents the material object at the corresponding integration point.
The valid queries to a quadUP element when creating an ElementRecorder are 'force',  and 'material matNum matArg1 matArg2 ...', where matNum represents the material object at the corresponding integration point.
#TYPICAL RANGE OF PERMEABILITY COEFFICIENT (cm/s)
 
TYPICAL RANGE OF PERMEABILITY COEFFICIENT (cm/s)


{| border="1" cellspacing="0" cellpadding="5" align="center"
{| border="1" cellspacing="0" cellpadding="5" align="center"
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Please visit http://cyclic.ucsd.edu/opensees for examples.
Please visit http://cyclic.ucsd.edu/opensees for examples.


REFERENCES:
REFERENCES:
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Code Developed by: <span style="color:blue"> Zhaohui Yang, UC San Diego</span>
Code Developed by: <span style="color:blue"> Zhaohui Yang, UC San Diego</span>

Latest revision as of 23:33, 25 March 2010



This command is used to construct an eFourNodeQuadUP element object. A FourNodeQuadUP element is a four-node plane-strain element using bilinear isoparametric formulation. This element is implemented for simulating dynamic response of solid-fluid fully coupled material, based on Biot's theory of porous medium. Each element node has 3 degrees-of-freedom (DOF): DOF 1 and 2 for solid displacement (u) and DOF 3 for fluid pressure (p). The arguments for the construction of this element are:

element quadUP $eleTag $Node1 $Node2 $Node3 $Node4 $thick $matTag $bulk $fmass $PermX $PermY <$b1=0 $b2=0 $t=0>


$eleTag unique element object tag
$Node1 .. $Node4 Four element node (previously defined) numbers in counter-clockwise order around the element
$thick Element thickness
$matTag Tag of an NDMaterial object (previously defined) of which the element is composed
$bulk Combined undrained bulk modulus Bc relating changes in pore pressure and volumetric strain, may be approximated by: where Bf is the bulk modulus of fluid phase (2.2x106 kPa for water), and n the initial porosity.
$fmass Fluid mass density
$PermX Permeability coefficient in X direction
$PermY Permeability coefficient in Y direction
$bX, $bY Optional gravity acceleration components in X and Y directions respectively (defaults are 0.0)
$t Optional uniform element normal traction, positive in tension (default is 0.0)


NOTE:

  1. This element requires 3 degrees-of-freedom (ndf=3), the 3rd degree-of-freedom being pore pressure. The Pore pressure can be recorded at an element node using OpenSees Node Recorder:

recorder Node <-file $fileName> <-time> <-node ($nod1 $nod2 …)> -dof 3 vel

  1. The valid queries to a quadUP element when creating an ElementRecorder are 'force', and 'material matNum matArg1 matArg2 ...', where matNum represents the material object at the corresponding integration point.
  2. TYPICAL RANGE OF PERMEABILITY COEFFICIENT (cm/s)
Gravel Sand Silty Sand Silt Clay
>1.0x10-1 1.0x10-3 ~ 1.0x10-1 1.0x10-5 ~ 1.0x10-3 1.0x10-7 ~ 1.0x10-5 <1.0x10-7


EXAMPLE:

Please visit http://cyclic.ucsd.edu/opensees for examples.


REFERENCES:



Code Developed by: Zhaohui Yang, UC San Diego

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