fedoo.problem.Modal

class Modal(assembly: Assembly, name: str = 'MainProblem')

Compute natural frequencies and mode shapes of a linear model.

The undamped free-vibration problem is

\[\mathbf{K}\boldsymbol{\phi} = \omega^2\mathbf{M}\boldsymbol{\phi}.\]

Modal obtains the stiffness and consistent mass matrices from the supplied assembly. Dirichlet and multi-point constraints are applied to both matrices before the generalized symmetric eigenproblem is solved.

Parameters:

• assembly (Assembly-like object or str) – Linear mechanical assembly. Its weak forms must provide second-order storage, normally through a material density or set_inertia.

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

Notes

Mode shapes are mass-normalized and stored by row in modes. Frequencies are expressed in cycles per unit of time; angular frequencies are expressed in radians per unit of time.

__init__(assembly: Assembly, name: str = 'MainProblem')

Methods

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

Modal.active
Modal.assembly	Mechanical assembly used by the modal problem.
Modal.current_mode	Zero-based index of the mode installed as the current solution.
Modal.global_dof
Modal.mass_assembly	Assembly used to construct the consistent mass matrix.
Modal.mass_matrix	Full unconstrained consistent mass matrix from the last solve.
Modal.n_dof
Modal.n_global_dof
Modal.n_node_dof
Modal.name	Return the name of the Problem.
Modal.results
Modal.solver	Configured eigensolver function, or None in automatic mode.
Modal.space	Return the ModelingSpace associated to the Problem if defined.
Modal.stiffness_matrix	Full unconstrained stiffness matrix from the last solve.
Modal.bc	Boundary conditions defined on the problem.