Users:General FEM Analysis/Elements Reference/Shell NURBS KL

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* OPTIMAL: uses in the interior of the patch less quadrature points (some tests required for higher polynomial degrees >3
 
* OPTIMAL: uses in the interior of the patch less quadrature points (some tests required for higher polynomial degrees >3
 
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!rowspan="3" | THICKNESS = ''float''
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!THICKNESS "float"
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|thickness of the shell
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| Thickness of the shell
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|HEIGHT = ''float'' <br> WIDTH = ''float''
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|rectangular cross section defined by height and width. A = h*w, Iy = h^3*w/12 Iz = h*w^3/12 It= min(h,w)^3*max(h,w)/3
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| AREA = ''float'' <br> IY = ''float'' <br> IZ = ''float'' <br> IT = ''float''
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|cross section defined directly
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!AXIS
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|AXIS ''float1'' ''float2'' ''float3'' ''float4''
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|Definition of the cross sectional principal axis. Second axis is perpendicual to first and tangent of the curve. ''float1'' is the position on the curve and ''float'' - ''float4'' the direction (x,y,z). Base vectors are normalized and linearly interpolated for postions inbetween the defined ones. Axes for start and end knot of the NURBS curve are mandatory.
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|colspan="3" style="background:#efefef;"| Optional Parameters
 
|colspan="3" style="background:#efefef;"| Optional Parameters

Revision as of 06:31, 9 December 2016

Contents

General Description

This element is based on the Phd Thesis of J.Kiendl.

Example of a Complete Input Block 

EL-PROP 1 : SHELL_NURBS_KL  
  MAT= EL-MAT 1                                      !material property
  THICKNESS = 1.0
  COUPLING = EL-PROP 6                       !BRep coupling element to handle C^0 continuity inside the patch
! STABILIZATION = EL-PROP 7               !Stabilization element for improving condition number
  NEJA = NURBS !DIP or FULL                 !Method for handling the integration for trimmed elements(use NURBS)
  INT_TYPE_SHELL_NURBS_KL = USER !or FULL or OPTIMAL   !FULL means p+1 and q+1;OPTIML uses in the interior of the patch less quadrature points (some tests required for higher polynomial degrees >3
! GAUSS_U = 4                                          !# of quadratur points in u-dir in case of INT_TYPE = USER
! GAUSS_V = 4                                          !# of quadratur points in u-dir in case of INT_TYPE = USER


Element Type

  • The element formulation is well tested for static and dynamic linear and nonlinear analysis.
  • Stresses for nonlinear case need to be corrected.
  • Can be used for thin shell structures

Degrees of Freedom

The element uses three translatoric degrees of freedom (Disp_X, Disp_Y, Disp_Z) at each control point.

Parameter Description

Compulsory Parameters
Parameter Values, Default(*) Description
MAT EL-MAT int Linking to a material input block
INT_TYPE_SHELL_NURBS_KL FULL, USER, OPTIMAL Control of integration type.
  • FULL: p+1 and q+1 quadrature points are used (p and q are the polynomial degrees of the NURBS patch)
  • USER: the optional parameters GAUSS_U and GAUSS_V define the number of quadrature points
  • OPTIMAL: uses in the interior of the patch less quadrature points (some tests required for higher polynomial degrees >3
THICKNESS "float" Thickness of the shell
Optional Parameters
Parameter Values, Default(*) Description
GAUSS_U GAUSS_U = int Number of Gauss point per element. Must only to be defined when INT_TYPE_BEAM_3D_NURBS_KLRod = USER


Element Loading

The KL shell element is able to handle the following loads:

  • dead load
  • snow load
  • pressure load

Benchmarks

The main benchmark file in the Carat++-repository is

  • '../examples/benchmark_examples/isogeometric/KL_shell_trim_plate_hole/cbm_plate_with_hole.txt'.

It is further used in:

  • '../examples/benchmark_examples/isogeometric/isogeometric_trim_non_linear/cbm_PlateHoleLineSupHighAcc.txt.txt'

References





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