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

Contents 1 General Description 1.1 Element Type 1.2 Degrees of Freedom 1.3 Parameter Description 1.4 Example of a Complete Input Block 2 Element Loading 3 Benchmarks 4 References

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

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. ↑ 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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