fedoo.problem.LinearBuckling

class LinearBuckling(assembly, reuse_assembled_matrix=True, name='MainProblem')

Compute linear buckling modes about a prestressed equilibrium state.

The problem solved is

\[\mathbf{K}_M\boldsymbol{\phi} = -\lambda\mathbf{K}_G\boldsymbol{\phi},\]

where \(\mathbf{K}_M\) is the material tangent stiffness and \(\mathbf{K}_G\) is the initial-stress stiffness. The supplied assembly must already contain the converged preload state.

Parameters:

• assembly (Assembly-like, Problem or str) – Prestressed assembly, a problem exposing it through assembly, or the name of a registered assembly.

• reuse_assembled_matrix (bool, default=True) – Reuse the cached preload matrix when all contributing weak forms agree on whether geometric stiffness was enabled. If False, independently assemble both required matrices.

• name (str, default="MainProblem") – Name of the problem.

Notes

Updated-Lagrangian preload states are not supported. Boundary conditions describe perturbations and must therefore be homogeneous.

__init__(assembly, reuse_assembled_matrix=True, name='MainProblem')

Methods

LinearBuckling.add_global_dof(variable_names)	Add global degrees of freedom to the problem.
LinearBuckling.add_output(filename, assembly)	Register an output for automatic saving managed by solve methods.
LinearBuckling.apply_boundary_conditions([...])
LinearBuckling.clear_outputs()	Stop automatic output by removing all registered requests.
LinearBuckling.get_A()
LinearBuckling.get_B()
LinearBuckling.get_D()
LinearBuckling.get_X()
LinearBuckling.get_active()	Return the active Problem.
LinearBuckling.get_all()	Return the list of all problems.
LinearBuckling.get_disp([name])	Return displacement components of the selected buckling mode.
LinearBuckling.get_dof_solution([name])
LinearBuckling.get_ext_forces([name, ...])	Return the nodal Forces in global coordinates system.
LinearBuckling.get_output_scalars()	Return metadata attached to the currently selected mode.
LinearBuckling.get_results(*args, **kargs)	Extract some results from the current problem.
LinearBuckling.get_rot([name])	Return rotation components of the selected buckling mode.
LinearBuckling.init_bc_start_value()
LinearBuckling.invalidate_factorization()	Invalidate any cached factorization.
LinearBuckling.make_active()	Define the problem instance as the active Problem.
LinearBuckling.save_modes([modes, scale])	Save selected modes through outputs registered with add_output.
LinearBuckling.save_results([iterOutput])	Write the current state to every registered output.
LinearBuckling.set_A(A)
LinearBuckling.set_B(B)
LinearBuckling.set_D(D)
LinearBuckling.set_X(value)
LinearBuckling.set_active(name)	Define the active Problem from its name.
LinearBuckling.set_dof(name, value)	Set values in the current degree-of-freedom vector.
LinearBuckling.set_mode(index[, scale])	Install one zero-based buckling mode as the current solution.
LinearBuckling.set_reuse_factorization([reuse])	Enable or disable factorization reuse for repeated solves.
LinearBuckling.set_solver([solver, which, ...])	Configure the symmetric generalized eigensolver.
LinearBuckling.solve([n_modes, sigma])	Solve for positive critical load factors and buckling modes.
LinearBuckling.update_boundary_conditions()

LinearBuckling.active
LinearBuckling.assembly	Prestressed source assembly.
LinearBuckling.current_mode	Zero-based index of the mode installed as the current solution.
LinearBuckling.geometric_stiffness_matrix	Full unconstrained initial-stress stiffness.
LinearBuckling.global_dof
LinearBuckling.material_assembly	Assembly built for material stiffness, or the reused source.
LinearBuckling.material_stiffness_matrix	Full unconstrained material tangent stiffness.
LinearBuckling.n_dof
LinearBuckling.n_global_dof
LinearBuckling.n_node_dof
LinearBuckling.name	Return the name of the Problem.
LinearBuckling.results
LinearBuckling.solver	Configured eigensolver function, or None in automatic mode.
LinearBuckling.space	Return the ModelingSpace associated to the Problem if defined.
LinearBuckling.total_assembly	Assembly built for total tangent stiffness, or the reused source.
LinearBuckling.total_stiffness_matrix	Full unconstrained material-plus-geometric tangent stiffness.
LinearBuckling.bc	Boundary conditions defined on the problem.