fedoo.weakform.StressEquilibriumFbar

class StressEquilibriumFbar(constitutivelaw, name='', nlgeom=None, space=None)

Weak formulation of the mechanical equilibrium equation for solids.

This method is still experimental ! Use with caution. The fbar method can be used with the the standard StressEquilibrium weak form.

The main point to consider are:

• This weak form is the same as the standard StressEquilibrium but allow to use the consistant tangent matrix with the Fbar method.

• This weak form can be used for solid in 3D or using a 2D plane assumption (plane strain or plane stress).

• Include initial stress for non linear problems or if defined in the associated assembly.

• This weak form accepts geometrical non linearities if simcoon is installed. (nlgeom should be in {True, ‘UL’, ‘TL’}. In this case the initial displacement is also considered.

Parameters:

• constitutivelaw (ConstitutiveLaw name (str) or ConstitutiveLaw object) – Material Constitutive Law (fedoo.constitutivelaw)

• name (str) – name of the WeakForm

• nlgeom (bool, 'UL' or 'TL', optional) – If True, the geometrical non linearities are activate based on the updated lagrangian method. This parameters is used only in the context of NonLinearProblems such as fedoo.problem.NonLinearStatic or fedoo.problem.NonLinearNewmark. If nlgeom == ‘UL’ the updated lagrangian method is used (same as True). If nlgeom == ‘TL’ the total lagrangian method is used. If not defined, the problem.nlgeom parameter is used instead.

• space (ModelingSpace) – Modeling space associated to the weakform. If None is specified, the active ModelingSpace is considered.

__init__(constitutivelaw, name='', nlgeom=None, space=None)

Methods

StressEquilibriumFbar.get_all()	Return the list of all weak forms.
StressEquilibriumFbar.get_weak_equation(...)	Get the weak equation related to the current problem state.
StressEquilibriumFbar.initialize(assembly, pb)	Initialize the weakform at the begining of a problem.
StressEquilibriumFbar.nvar(self)	Return the number of variables used in the modeling space associated to the WeakForm.
StressEquilibriumFbar.reset()
StressEquilibriumFbar.set_start(assembly, pb)	Start a new time increment.
StressEquilibriumFbar.sum(wf1, wf2)
StressEquilibriumFbar.to_start(assembly, pb)	Reset the current time increment.
StressEquilibriumFbar.update(assembly, pb)	Update the weakform to the current state.
StressEquilibriumFbar.update_2(assembly, pb)	Update the weakform to the current state.

StressEquilibriumFbar.corate	Corotational strain mesure for strain.
StressEquilibriumFbar.fbar	Set to True to use the F-bar method.
StressEquilibriumFbar.geometric_stiffness	Set to True to add the geometric effects to the stiffness matrix.
StressEquilibriumFbar.name	Return the name of the WeakForm.
StressEquilibriumFbar.space	Return the ModelingSpace associated to the WeakForm if defined.
StressEquilibriumFbar.nlgeom	Method used to treat the geometric non linearities. * Set to False if geometric non linarities are ignored. * Set to True or 'UL' to use the updated lagrangian method (update the mesh) * Set to 'TL' to use the total lagrangian method (base on the initial mesh with initial displacement effet).