Users:General FEM Analysis/Elements Reference/Shell9

The element formulation is based on the Shell8.

Contents 1 Input Parameters 1.1 Parameter Description 1.2 Example of a Complete Input Block 2 Benchmarks 3 Known issues

Input Parameters

Parameter Description

Compulsory Parameters
Parameter	Values, Default(*)	Description
MAT	EL-MAT int	Linking to a material input block
INT_TYPE_SHELL9	FULL	Control of integration type
ANS	NONE, Q, T, QT, TQ	Assumed Natural Strains (ANS) method: NONE: ANS is not activated Q: ANS against shear locking is activated. It works for 4-noded and 9-noded elements. It causes a constant-linear (linear-quadratic, respectively) interpolation of the transverse shear strains and thus avoids transverse shear locking. The approach for the 4-noded element represents the well-known Bathe-Dvorkin-Element (MITC-4). T: ANS against curvature thickness locking
EAS	M,B,T,Q,S	Enhances Assumed Strains (EAS) method M: Number of enhanced membrane modes. M = {1,(2),4,5,7} for 4-noded Elements, M = {(7),9,11} for 8- or 9-noded Elements B: Number of enhanced bending modes. B = {4,5,(6),7} for 4-noded Elements, B = {9,11} for 8- or 9-noded Elements T: Number of enhanced modes in thickness direction. T = {1,3,4,6,8,9} for all Elements. Recommended: 1 (3-noded), 4 (4-, 8- and 9-noded), 3 (6-nonded) Q: Number of const. transverse shear modes. Q = {2,4} for 4-noded Elements, Q = {2,4,6} for 8- or 9-noded Elements S: Number of lin. transverse shear modes. S = {2,4} for 4-noded Elements, S = {2,4,6} for 8- or 9-noded Elements
FORCE	XYZ, RST_ORTHO, RST	Output control for stress constraints XYZ: RST_ORTHO: RST:
SDC	real	condition factor for director length, recommended value: 1.0
ROTATORIC_DOFS	DIR_DIFF, GLOB_6	Switch between director and rotational degrees of freedom.
STRESS_OUTPUT	PRIN_VM, SIG_EPS	Stress output type PRIN_VM: Von Mises Stresses SIG_EPS: Stress and strains
STRESS_EVAL	GP, SURF	Stress evaluation location. Gauss Point Surface
Optional Parameters
Parameter	Values, Default(*)	Description
THICKNESS	real	Element thickness. This parameter is not compulsory, as the thickness can also be described via nodal values.

Example of a Complete Input Block

EL-PROP 1: SHELL9
MAT=EL-MAT 1 
THICKNESS = 0.1
INT_TYPE_SHELL9 = FULL
SDC = 1.0
EAS = 4,4,4,4,4
ANS = NONE
FORCE = XYZ
MATERIAL_ANGLE = 0

ROTATORIC_DOFS = DIR_DIFF
STRESS_OUTPUT = PRIN_VM 
STRESS_EVAL   = SURF   

Benchmarks

The main benchmark files in the Carat++-repository are

'../examples/benchmark_examples/elements/shell9_4_temperature_nln/cbm_SHELL_4NODED.dat'

'../examples/benchmark_examples/elements/shell9_8_temperature_nln/cbm_SHELL_8NODED.dat'

Known issues

Eigenvalue analysis with DIR_DIFF gives wrong results (AE, SSH;2017)

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