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== General Description ==

Coded and testing is in progress.

=== Element Type ===

* This element provides a geometrically nonlinear, isogeometric spatial cable.
* Mass computation is implemented.

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. 

=== Degrees of Freedom ===

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

=== Parameter Description ===

{| border="1" cellpadding="3" cellspacing="0"
|colspan="3" style="background:#efefef;"| Compulsory Parameters
|-
!Parameter
!Values, Default(*)
!Description
|-
!MAT
|EL-MAT ''int''
|Linking to a material input block
|-
!INT_TYPE_CORD_3D_NURBS
|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
|-
!CROSS SECTION 
|AREA = ''float''
|area of the cross section
|-
!PRESTRESS
|PRESTRESS = ''float''
|prestress of the cable element
|-
|colspan="3" style="background:#efefef;"| 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
|-
!PRESTRESS_CURVE
|PRESTRESS_CURVE = ''int''
|if the prestress of the cable element is linked to the load-curve, i.e. scaled by the global load factor. The parameters 1 (yes) and 0 (no, Default) are valid. 
|-
|}

=== Example of a Complete Input Block ===
<pre>
EL-PROP 1 : CORD_3D_NURBS
  MAT= EL-MAT 1  
  AREA=1.0000e-001
  PRESTRESS = 100
  PRESTRESS_CURVE = 0
  INT_TYPE_CORD_3D_NURBS = FULL
  !or:
  INT_TYPE_CORD_3D_NURBS = USER
  GAUSS_U = 3
</pre>

== Element Loading ==

The Cord_3D_NURBS element is able to carry the following loads:
* dead load
* snow load
* pressure load
* temperature load (not tested)

== Benchmarks ==

Currently, no main benchmark file in the ''Carat++''-repository is available.

== References ==

<references/>