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

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

Element Type

The formulation is based on Breitenberger et al. ^[1]. The element allows to

• coupling trimmed NURBS surfaces for geometrically linear and nonlinear analysis.

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
BREP_TYPE	COUPLING_DISP, COUPLING_ROT, COUPLING_DISP_ROT	Type of coupling. COUPLING_DISP: only displacements are coupled COUPLING_ROT: only rotations are coupled COUPLING_DISP_ROT: displacements and rotations are coupled
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_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 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 (cmake option extensive benchmarks is

• '../examples/benchmark_examples/isogeometric/x_ibra_oilsump_8mm/xcbm_oilsump_8mm.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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