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doc:user:elements:shells:shell

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doc:user:elements:shells:shell [2013/07/10 13:45] – [Lois] jorisdoc:user:elements:shells:shell [2016/03/30 15:23] (current) – external edit 127.0.0.1
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 +====== Shells======
  
 +===== Materials =====
 +
 +The definition of shell finite elements follows the same logic as volume elements. First, a material is defined: 
 +
 +  materialno = materialset.define (number, type)
 +  materialno = materialset(number)
 +  materialno.put(param, value)
 +  materialno.depend(param, fct, Key(Lock)))
 +  ...
 +
 +|''number'' | material number (must be unique with respect to all elements in ''materialset'', not to shells) |
 +|''type'' | shell type (for example ''LinearShellMaterial'') |
 +|''param'' | name of the shell parameter (for example ''ELASTIC_MODULUS'') |
 +|''value'' | value of the corresponding parameter ''param''|
 +|''fct'' | function which characterizes the dependency of the property (optional: no fct if no dependency) |
 +|''Lock'' | [[doc:user:general:locks|Lock]] which defines the dependency variable of the property (compulsory if there is a dependency) |
 +
 +
 +====  LinearShellMaterial ====
 +
 +=== Description ===
 +
 +Simple linear elastic law (small strains and displacements).
 +
 +=== Parameters ===
 +^   Name                                          ^     Metafor Code      Dependency ^
 +| Density                                           ''MASS_DENSITY''    |              |
 +| Young modulus                                    ''ELASTIC_MODULUS''  |              |
 +| Poisson ratio                                     ''POISSON_RATIO''                |
 +
 +===== Elements =====
 +
 +After defining the [[#Materials|material]], it must be associated to an ''[[doc:user:elements:general:def_element_properties|ElementProperties]]'':
 +
 +  prp = ElementProperties(typeEl)
 +  prp.put(param1, value1)
 +  prp.depend(param1, fct1, Lock1)) #facultatif
 +  ...
 +
 +where
 +
 +|''typeEl'' | desired element (for example ''LinearShellFirstDegreeElement'')|
 +|''param1''| name of the property associated to the element (for example ''MATERIAL'' to associate the desired material)|
 +|''value1''| value of the corresponding property |
 +|''fct1''| function which characterizes the dependency of the property (optional: no fct if no dependency) |
 +|''Lock1''| [[doc:user:general:locks|Lock]] which defines the dependency variable of the property (compulsory if there is a dependency) |
 +
 +====  LinearShellFirstDegreeElement ====
 +
 +Linear shell elements (small strains small displacements). 4-nodes linear quadrangles.
 +
 +By default, stresses are integrated of ''dim*2'' integration points. 
 +
 +A thickness must be defined, see table below.
 +
 +
 +====  LinearShellSecondDegreeElement ====
 +
 +Same as ''LinearShellFirstDegreeElement'' but based on a second order mesh ([[doc:user:geometry:mesh:2d]]).
 +
 +The membrane part can be integrated over ''dim*3'' integration points, considering EAS modes, see table below.
 +The bending part can be integrated over ''dim*3'' integration points, considering EAS modes, see table below.
 +
 +
 +
 +====  LinearShellNineNodeSecondDegreeElement ====
 +
 +Same as ''LinearShellSecondDegreeElement'' but based on a 9-nodes second order mesh ([[doc:user:geometry:mesh:2d]]).
 +
 +The membrane part can be integrated over ''dim*3'' integration points, considering EAS modes, see table below.
 +The bending part can be integrated over ''dim*3'' integration points, considering EAS modes, see table below.
 +
 +
 +====  LinearShellSixteenNodeThirdDegreeElement ====
 +
 +Same as ''LinearShellNineNodeSecondDegreeElement'' but based on a 16-nodes third order mesh ([[doc:user:geometry:mesh:2d]]).
 +
 +The membrane part can be integrated over ''dim*4'' integration points, without EAS modes (no locking), see table below.
 +The bending part can be integrated over ''dim*4'' integration points, without EAS modes (no locking), see table below.
 +
 +
 +=== Parameters ===
 +^   Name                                                 Metafor Code      Dependency ^
 +| ''MATERIAL''    | Number of the shell material to consider              -  |
 +| ''STIFFMETHOD'' | Method used to compute the stiffness matrix \\ = ''STIFF_ANALYTIC'' : analytic matrix (default) \\ = ''STIFF_NUMERIC''  : numerical matrix            -  |
 +| ''GRAVITY_X'' / ''GRAVITY_Y'' / ''GRAVITY_Z'' | gravity  |  time |
 +| ''THICKNESS'' | initial thickness  |  -  |
 +| ''MEMBRANE_NPG'' | Number of integration points along one direction for membrane solving \\ = 2 classical solving  (second order)\\ = 3 EAS solving with 11 or 13 added modes (8 or 9-nodes second order)\\ = 4 solving without EAS (16-nodes third order)  |  -  |
 +| ''BENDING_NPG''  | Number of integration points along one direction for membrane solving \\ = 2 classical solving  (second order)\\ = 3 EAS solving with 22 or 7 added modes (8 or 9-nodes second order)\\ = 4 solving without EAS (16-nodes third order)  |  -  |
 +
 +===== Interactions =====
 +
 +Shell elements are then generated as [[doc:user:elements:volumes:volumeelement|volume elements]], using a ''FieldApplicator'' interaction. Then, they must be completed with a [[doc:user:elements:shells:interface|DG interface element]] to be consistent.
 +
 +  app = FieldApplicator(no)
 +  app.push(gObject1)
 +  app.push(gObject2)
 +  ...
 +  app.addProperty(prp)        # association of an ElementProperties
 +  interactionset.add(app)     #  the interaction is added in InteractionSet 
 +
 +or
 +
 +  app = interactionset.add(FieldApplicator(no)) #add returns a reference
 +  app.push(gObject1)
 +  app.push(gObject2)
 +  ...
 +  app.addProperty(prp)        # association of an ElementProperties
 +
 +
 +where 
 +| ''no''  | number of the ''Interaction'' (which is to say the ''FieldApplicator'') | 
 +|''gObject1''  | mesh geometric entity where the finite elements are applied |
 +| ''prp'' | [[doc:user:elements:general:def_element_properties|Properties]] of shell elements to generate.| 

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