CycLiqCP Material: Difference between revisions

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{{CommandManualMenu}}


This command is used to construct a multi-dimensional material object that that
follows the constitutive behavior of a cyclic elastoplasticity model for large post-
liquefaction deformation.
{|
| style="background:yellow; color:black; width:800px" | '''nDmaterial CycLiqCP $matTag $G0 $kappa $h $Mfc $dre1 $Mdc $dre2 $rdr $alpha $dir $ein <$rho>'''
|}
CycLiqCP material is a cyclic elastoplasticity model for large post-liquefaction
deformation, and is implemented using a cutting plane algorithm. The model is
capable of reproducing small to large deformation in the pre- to post-liquefaction
regime. The elastic moduli of the model are pressure dependent. The plasticity in the
model is developed within the framework of bounding surface plasticity, with special
consideration to the formulation of reversible and irreversible dilatancy.
This model does not take the state of sand into consideration, which could limit
its simulation performance during large variations of void ratio or confining pressure.
The model has been validated against VELACS centrifuge model tests and has used
on numerous simulations of liquefaction related problems.
When this material is employed in regular solid elements (e.g., FourNodeQuad,
Brick), it simulates drained soil response. When solid-fluid coupled elements (u-p
elements and SSP u-p elements) are used, the model is able to simulate undrained and
partially drained behavior of soil.
During the application of gravity load (and static loads if any), the user is suggested to
set the material behavior to be linear elastic, with the updateMaterialStage command:
updateMaterialStage -material $matTag -stage 0
After the gravity load stage, the material stage should be updated to achieve the
desired elastic-plastic stress-strain response.
updateMaterialStage -material $matTag -stage 1
----
{|
|  style="width:150px" | '''$matTag ''' || integer tag identifying material
|-
|  '''$G0 ''' || A constant related to elastic shear modulus
|-
|  '''$kappa ''' || A constant related to elastic bulk modulus
|-
| '''$h ''' || Model parameter for plastic modulus
|-
|  '''$Mfc''' || Stress ratio at failure in triaxial compression
|-
|  '''$dre1''' || Coefficient for reversible dilatancy generation
|-
| '''$Mdc''' || Stress ratio at which the reversible dilatancy sign changes
|-
| '''$dre2''' || Coefficient for reversible dilatancy release
|-
| '''$rdr''' || Reference shear strain length
|-
| '''$alpha''' || Parameter controlling the decrease rate of irreversible dilatancy
|-
| '''$dir''' || Coefficient for irreversible dilatancy potential
|-
| '''$ein''' || Initial void ratio
|-
| '''$rho''' || Saturated mass density
|}
The material formulations for the CycLiqCP object are "ThreeDimensional" and "PlaneStrain".
----
REFERENCES:
Zhang J.M. and Wang G., 2012, “Large post-liquefaction deformation of sand, part I: physical mechanism, constitutive description and numerical algorithm”, Acta Geotechnica.
----
Code Developed by: <span style="color:blue"> Rui Wang, Tsinghua University</span>

Latest revision as of 01:05, 24 April 2014