Description

Simple Rayleight damping of a Kirchhoff shell layer, where damping is proportional to stiffness via a beta coefficient.

In order to generalize it also in case of nonlinearity, the full element tangent stiffness matrix cannot be used (it may contain negative eigenvalues) and it can't be used to recover instant nodal caused by damping as F=beta*K*q_dt so it is generalized to the following implementation at the material stress level

  {n,m}=beta*[E]*{e',k'}

where

beta is the 2nd Rayleigh damping parameter
[E] is the 6x6 shell stiffness matrix at the undeformed unstressed case (hence assumed constant)
{e',k'} is the speed of deformation/curvature Note that the alpha mass-proportional parameter (the first of the alpha,beta parameters of the original Rayleigh model) is not supported.

#include <ChMaterialShellKirchhoff.h>

Inheritance diagram for chrono::fea::ChDampingKirchhoffRayleigh:

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Collaboration diagram for chrono::fea::ChDampingKirchhoffRayleigh:

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Public Member Functions
	ChDampingKirchhoffRayleigh (std::shared_ptr< ChElasticityKirchhoff > melasticity, const double &mbeta=0)
	Construct the Rayleigh damping model from the stiffness model used by the shell layer. More...

virtual void	ComputeStress (ChVector<> &n, ChVector<> &m, const ChVector<> &deps, const ChVector<> &dkur, const double z_inf, const double z_sup, const double angle)
	Compute the generalized cut force and cut torque, caused by structural damping, given actual deformation speed and curvature speed. More...

virtual void	ComputeDampingMatrix (ChMatrixRef R, const ChVector<> &deps, const ChVector<> &dkur, const double z_inf, const double z_sup, const double angle)
	Compute the 6x6 tangent material damping matrix, ie the jacobian [Rm]=dstress/dstrainspeed. More...

double	GetBeta ()
	Get the beta Rayleigh parameter (stiffness proportional damping)

void	SetBeta (const double mbeta)
	Set the beta Rayleigh parameter (stiffness proportional damping)

Additional Inherited Members
Public Attributes inherited from chrono::fea::ChDampingKirchhoff
ChMaterialShellKirchhoff *	section

Constructor & Destructor Documentation

◆ ChDampingKirchhoffRayleigh()

chrono::fea::ChDampingKirchhoffRayleigh::ChDampingKirchhoffRayleigh	(	std::shared_ptr< ChElasticityKirchhoff >	melasticity,
		const double &	mbeta = `0`
	)

Construct the Rayleigh damping model from the stiffness model used by the shell layer.

This is important because the Rayleigh damping is proportional to the stiffness, so the model must know which is the stiffness matrix of the material. Note: melasticity must be alreay set with proper values: its [E] stiffness matrix will be fetched just once for all.

Member Function Documentation

◆ ComputeDampingMatrix()

void chrono::fea::ChDampingKirchhoffRayleigh::ComputeDampingMatrix	(	ChMatrixRef	R,
		const ChVector<> &	deps,
		const ChVector<> &	dkur,
		const double	z_inf,
		const double	z_sup,
		const double	angle
	)

virtual

Compute the 6x6 tangent material damping matrix, ie the jacobian [Rm]=dstress/dstrainspeed.

In this model, it is beta*[E] where [E] is the 6x6 stiffness matrix at material level, assumed constant

Parameters

R	6x6 material damping matrix values here
deps	time derivative of strains de_11/dt, de_22/dt, de_12/dt
dkur	time derivative of curvature dk_11/dt, dk_22/dt, dk_12/dt
z_inf	layer lower z value (along thickness coord)
z_sup	layer upper z value (along thickness coord)
angle	layer angle respect to x (if needed) -not used in this, isotropic

Reimplemented from chrono::fea::ChDampingKirchhoff.

◆ ComputeStress()

void chrono::fea::ChDampingKirchhoffRayleigh::ComputeStress	(	ChVector<> &	n,
		ChVector<> &	m,
		const ChVector<> &	deps,
		const ChVector<> &	dkur,
		const double	z_inf,
		const double	z_sup,
		const double	angle
	)

virtual

Compute the generalized cut force and cut torque, caused by structural damping, given actual deformation speed and curvature speed.

Parameters

n	forces n_11, n_22, n_12 (per unit length)
m	torques m_11, m_22, m_12 (per unit length)
deps	time derivative of strains de_11/dt, de_22/dt, de_12/dt
dkur	time derivative of curvature dk_11/dt, dk_22/dt, dk_12/dt
z_inf	layer lower z value (along thickness coord)
z_sup	layer upper z value (along thickness coord)
angle	layer angle respect to x (if needed)

Implements chrono::fea::ChDampingKirchhoff.

The documentation for this class was generated from the following files:

/builds/uwsbel/chrono/src/chrono/fea/ChMaterialShellKirchhoff.h
/builds/uwsbel/chrono/src/chrono/fea/ChMaterialShellKirchhoff.cpp