Users:General FEM Analysis/Elements Reference/Shell9

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The element formulation is based on the Shell8.
  
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Coded and extensively tested.
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== Input Parameters ==
  
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Documentation will be coming soon!
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=== Parameter Description ===
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{| border="1" cellpadding="3" cellspacing="0"
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|colspan="3" style="background:#efefef;"| Compulsory Parameters
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|-
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!Parameter
 +
!Values, Default(*)
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!Description
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|-
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!MAT
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|EL-MAT ''int''
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|Linking to a material input block
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|-
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!INT_TYPE_SHELL9
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|FULL
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|Control of integration type
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|-
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!ANS
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|NONE, Q, T, QT, TQ
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|Assumed Natural Strains (ANS) method:
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* NONE: ANS is not activated
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* Q: ANS against shear locking is activated. It works for 4-noded and 9-noded elements. It causes a constant-linear (linear-quadratic, respectively) interpolation of the transverse shear strains and thus avoids transverse shear locking. The approach for the 4-noded element represents the well-known Bathe-Dvorkin-Element (MITC-4).
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* T: ANS against curvature thickness locking
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|-
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!EAS
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|''M,B,T,Q,S''
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|Enhances Assumed Strains (EAS) method
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* ''M'': Number of enhanced membrane modes. ''M'' = {1,(2),4,5,7} for 4-noded Elements, ''M'' = {(7),9,11} for 8- or 9-noded Elements
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* ''B'': Number of enhanced bending modes. ''B'' = {4,5,(6),7} for 4-noded Elements, ''B'' = {9,11} for 8- or 9-noded Elements
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* ''T'': Number of enhanced modes in thickness direction. ''T'' = {1,3,4,6,8,9} for all Elements. Recommended: 1 (3-noded), 4 (4-, 8- and 9-noded), 3 (6-nonded)
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* ''Q'': Number of const. transverse shear modes. ''Q'' = {2,4} for 4-noded Elements, ''Q'' = {2,4,6} for 8- or 9-noded Elements
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* ''S'': Number of lin. transverse shear modes. ''S'' = {2,4} for 4-noded Elements, ''S'' = {2,4,6} for 8- or 9-noded Elements
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|-
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!FORCE
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|XYZ, RST_ORTHO, RST
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|Output control for stress constraints
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* XYZ:
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* RST_ORTHO:
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* RST:
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|-
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!SDC
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|''real''
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|condition factor for director length, recommended value: 1.0
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|-
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!ROTATORIC_DOFS
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|DIR_DIFF, GLOB_6
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|Switch between director and rotational degrees of freedom.
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|-
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!STRESS_OUTPUT
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|PRIN_VM, SIG_EPS
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|Stress output type
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* PRIN_VM: Von Mises Stresses
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* SIG_EPS: Stress and strains
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|-
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!STRESS_EVAL
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|GP, SURF
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|Stress evaluation location.
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* Gauss Point
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* Surface
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|-
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|colspan="3" style="background:#efefef;"| Optional Parameters
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|-
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!Parameter
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!Values, Default(*)
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!Description
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|-
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!THICKNESS
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|''real''
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|Element thickness. This parameter is not compulsory, as the thickness can also be described via nodal values.
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|}
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=== Example of a Complete Input Block ===
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<pre>
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EL-PROP 1: SHELL9
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MAT=EL-MAT 1
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THICKNESS = 0.1
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INT_TYPE_SHELL9 = FULL
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SDC = 1.0
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EAS = 4,4,4,4,4
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ANS = NONE
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FORCE = XYZ
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MATERIAL_ANGLE = 0
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ROTATORIC_DOFS = DIR_DIFF
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STRESS_OUTPUT = PRIN_VM
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STRESS_EVAL  = SURF 
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</pre>
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== Benchmarks ==
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The main benchmark files in the ''Carat++''-repository are
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'../examples/benchmark_examples/elements/shell9_4_temperature_nln/cbm_SHELL_4NODED.dat'
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 +
'../examples/benchmark_examples/elements/shell9_8_temperature_nln/cbm_SHELL_8NODED.dat'
 +
 
 +
== Known issues ==
 +
 
 +
Eigenvalue analysis with DIR_DIFF gives wrong results (AE, SSH;2017)

Latest revision as of 12:16, 12 April 2017

The element formulation is based on the Shell8.

Contents

Input Parameters

Parameter Description

Compulsory Parameters
Parameter Values, Default(*) Description
MAT EL-MAT int Linking to a material input block
INT_TYPE_SHELL9 FULL Control of integration type
ANS NONE, Q, T, QT, TQ Assumed Natural Strains (ANS) method:
  • NONE: ANS is not activated
  • Q: ANS against shear locking is activated. It works for 4-noded and 9-noded elements. It causes a constant-linear (linear-quadratic, respectively) interpolation of the transverse shear strains and thus avoids transverse shear locking. The approach for the 4-noded element represents the well-known Bathe-Dvorkin-Element (MITC-4).
  • T: ANS against curvature thickness locking
EAS M,B,T,Q,S Enhances Assumed Strains (EAS) method
  • M: Number of enhanced membrane modes. M = {1,(2),4,5,7} for 4-noded Elements, M = {(7),9,11} for 8- or 9-noded Elements
  • B: Number of enhanced bending modes. B = {4,5,(6),7} for 4-noded Elements, B = {9,11} for 8- or 9-noded Elements
  • T: Number of enhanced modes in thickness direction. T = {1,3,4,6,8,9} for all Elements. Recommended: 1 (3-noded), 4 (4-, 8- and 9-noded), 3 (6-nonded)
  • Q: Number of const. transverse shear modes. Q = {2,4} for 4-noded Elements, Q = {2,4,6} for 8- or 9-noded Elements
  • S: Number of lin. transverse shear modes. S = {2,4} for 4-noded Elements, S = {2,4,6} for 8- or 9-noded Elements
FORCE XYZ, RST_ORTHO, RST Output control for stress constraints
  • XYZ:
  • RST_ORTHO:
  • RST:
SDC real condition factor for director length, recommended value: 1.0
ROTATORIC_DOFS DIR_DIFF, GLOB_6 Switch between director and rotational degrees of freedom.
STRESS_OUTPUT PRIN_VM, SIG_EPS Stress output type
  • PRIN_VM: Von Mises Stresses
  • SIG_EPS: Stress and strains
STRESS_EVAL GP, SURF Stress evaluation location.
  • Gauss Point
  • Surface
Optional Parameters
Parameter Values, Default(*) Description
THICKNESS real Element thickness. This parameter is not compulsory, as the thickness can also be described via nodal values.


Example of a Complete Input Block 

EL-PROP 1: SHELL9
MAT=EL-MAT 1 
THICKNESS = 0.1
INT_TYPE_SHELL9 = FULL
SDC = 1.0
EAS = 4,4,4,4,4
ANS = NONE
FORCE = XYZ
MATERIAL_ANGLE = 0

ROTATORIC_DOFS = DIR_DIFF
STRESS_OUTPUT = PRIN_VM 
STRESS_EVAL   = SURF

Benchmarks

The main benchmark files in the Carat++-repository are

'../examples/benchmark_examples/elements/shell9_4_temperature_nln/cbm_SHELL_4NODED.dat'

'../examples/benchmark_examples/elements/shell9_8_temperature_nln/cbm_SHELL_8NODED.dat'

Known issues

Eigenvalue analysis with DIR_DIFF gives wrong results (AE, SSH;2017)





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