Users:General FEM Analysis/Elements Reference/Cord 3D NURBS

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Contents

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.[1]. 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

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
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

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

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

  1. 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




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