Users:General FEM Analysis/Elements Reference/NURBS BRep Edge coupling

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=== Element Type ===
 
=== Element Type ===
  
* This element provides a geometrically nonlinear, isogeometric spatial cable.
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* This element allows to coupling trimmed NURBS surfaces for geometrically linear and nonlinear analysis.
* Mass computation is implemented.
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The formulation is stabilized by an additional bending stiffness based on Raknes et al.<ref>S.B. Raknes, X. Deng, Y. Bazilevs, D.J. Benson, K.M. Mathisen, T. Kvamsdal: „Isogeometric rotation-free bending-stabilized cables: Statics, dynamics, bending strips and coupling with shells“, in „Computer methods in applied mechanics and engineering“, Vol. 263, 2013, Seiten 127-143 http://dx.doi.org/10.1016/j.cma.2013.05.005</ref>. The bending stiffness is computed out of the area with the assumption of a circular cross section.  
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The formulation is based on Breitenberger et al. <ref>Breitenberger, M.; Apostolatos, A.; Philipp, B.; Wüchner, R.; Bletzinger, K.-U.: Analysis in computer aided design: Nonlinear isogeometric B-Rep analysis of shell structures. Computer Methods in Applied Mechanics and Engineering 284, 2015, 401--457</ref>.  
  
 
=== Degrees of Freedom ===
 
=== Degrees of Freedom ===
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!Values, Default(*)
 
!Values, Default(*)
 
!Description
 
!Description
|-
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!INT_TYPE_NURBS_EDGE_COUPLING
!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_CORD_3D_NURBS
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|FULL, USER
 
|FULL, USER
 
|Control of integration type.  
 
|Control of integration type.  
 
* FULL: p+1 Gauss points are used (p = polynomial degree of the NURBS patch)  
 
* FULL: p+1 Gauss points are used (p = polynomial degree of the NURBS patch)  
 
* USER: the optional Parameter GAUSS_U defines the number of Gauss points
 
* USER: the optional Parameter GAUSS_U defines the number of Gauss points
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!BL_FACTOR_DISP
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|BL_FACTOR_DISP= ''float''
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|penalty factor for the displacement
 
|-
 
|-
!CROSS SECTION
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!BL_FACTOR_ROT
|AREA = ''float''
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|BL_FACTOR_ROT= ''float''
|area of the cross section
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|penalty factor for the rotation
|-
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!PRESTRESS
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|PRESTRESS = ''float''
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|prestress of the cable element
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|-
 
|-
 
|colspan="3" style="background:#efefef;"| Optional Parameters
 
|colspan="3" style="background:#efefef;"| Optional Parameters

Revision as of 08:48, 9 December 2016

Contents

General Description

Example of a Complete Input Block

EL-PROP 1 : NURBS_BREP_EDGE_COUPLING  
  BREP_TYPE = COUPLING_DISP ! or: COUPLING_ROT, COUPLING_DISP_ROT
  !NITSCHE=AUTO
  BL_FACTOR_DISP = 10000
  BL_FACTOR_DISP = 10000
  INT_TYPE_NURBS_EDGE_COUPLING = USER or FULL
  GAUSS_U = 4

Element Type

  • This element allows to coupling trimmed NURBS surfaces for geometrically linear and nonlinear analysis.

The formulation is based on Breitenberger et al. [1].

Degrees of Freedom

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

Parameter Description

Compulsory Parameters
Parameter Values, Default(*) Description INT_TYPE_NURBS_EDGE_COUPLING FULL, USER Control of integration type.
  • FULL: p+1 Gauss points are used (p = polynomial degree of the NURBS patch)
  • USER: the optional Parameter GAUSS_U defines the number of Gauss points
BL_FACTOR_DISP BL_FACTOR_DISP= float penalty factor for the displacement
BL_FACTOR_ROT BL_FACTOR_ROT= float penalty factor for the rotation
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_CORD_3D_NURBS = USER

Example of a Complete Input Block

EL-PROP 1 : NURBS_BREP_CHORD  
  MAT= EL-MAT 1
  AREA = 1
  PRESTRESS = 4000
  INT_TYPE_NURBS_BREP_CHORD = USER or FULL
  GAUSS_U = 4

Element Loading

The NURBS_BRep_Edge_Cord element is able to carry the following loads:

  • dead load
  • snow load
  • pressure load
  • temperature load (not tested)

Benchmarks

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

  • '../examples/benchmark_examples/isogeometric/iga_formfinding_4point_with_trusses/cbm_4PointSailwTrusses.txt'.

References

  1. Breitenberger, M.; Apostolatos, A.; Philipp, B.; Wüchner, R.; Bletzinger, K.-U.: Analysis in computer aided design: Nonlinear isogeometric B-Rep analysis of shell structures. Computer Methods in Applied Mechanics and Engineering 284, 2015, 401--457




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