RbCable::CableRM Class Reference

#include <Cable.h>

Inheritance diagram for RbCable::CableRM:

Collaboration diagram for RbCable::CableRM:

Classes
struct	element

Public Member Functions
	CableRM (const std::string &simObjectName, ISimObjectCreator *const creator)
	Reads parameters, registers states, input/output ports and shared resources.
void	OdeFcn (const double T, const double *const X, double *const XDot) const
	Computes object derivatives as a function of time, states and input ports.
void	InitialConditionSetup (const double T, const double *const currentIC, double *const updatedIC, ISimObjectCreator *const creator)
void	FinalSetup (const double T, const double *const X, ISimObjectCreator *const creator)
void	PreOdeFcn (const double T, const double *const X, IStateUpdater *const updater) override
	Takes the other objects' wakes at the centres of all elements for the step (MARE-0223).
const double *	forceA (const double T, const double *const X)
	Output port. Returns current force in endpoint A of cable.
const double *	forceB (const double T, const double *const X)
	Output port. Returns current force in endpoint B of cable.
void	calculations (const double T, const double *const X)
	Performs a series of computations within the cable object.
void	calculationsCommon (const double T, const double *const X) const

Protected Types
typedef Eigen::Matrix< double, 3, 3 >	mat3
typedef Eigen::Matrix< double, 3, 1 >	vec3

Protected Member Functions
void	DistributeCatenary (Eigen::Matrix< double, 3, 1 > P1, Eigen::Matrix< double, 3, 1 > P2, double L, double *states, int i1, int i2, ISimObjectCreator *creator)

Protected Attributes
PrintDuringExec *	m_print
environment::EnvironmentProvider *	m_environment
environment::wake::WakeReceiver	m_wakes
	The other objects' wakes at the element centres, per step (MARE-0223).
std::vector< double >	m_elementCentres
	The centres of all elements at the last take, 3 per element.
int	m_numElements
double	m_totalLength
double	m_radius
double	m_weight
double	m_alphaN
double	m_betaN
double	m_epsilonN
double	m_alphaM
double	m_betaM
double	m_epsilonM
double	m_alphaT
double	m_betaT
double	m_epsilonT
double	m_bending_epsilon [3]
double	m_length
double	m_mass
double	m_Ixy
double	m_Iz
bool	m_kelp
double	m_wKelp
element *	m_el
ISignalPort *	m_posA
ISignalPort *	m_posB
ISignalPort *	m_velA
ISignalPort *	m_velB
ISignalPort *	m_retractedLengthA
ISignalPort *	m_retractedLengthB
ISignalPort *	m_retractedSpeedA
ISignalPort *	m_retractedSpeedB
int	m_retractedNodesA
int	m_retractedNodesB
int	m_numFreeNodes
vec3	m_ka
vec3	m_kb
ICommonComputation *	m_calcDynamics
Eigen::Matrix< double, Eigen::Dynamic, 1 >	m_lambda
Eigen::Matrix< double, Eigen::Dynamic, 1 >	m_F_MDotV
Eigen::Matrix< double, Eigen::Dynamic, 1 >	m_B
double	m_forceA [3]
double	m_forceB [3]

Detailed Description

Author

Jørgen Haavind Jensen

Simobject name for use in input file: Cable.

Retains the same structural properties as the simObject CFlexibleBottomRing, but has a simpler interface where Young's and shear moduluses are provided rather than using the \(\alpha\), \(\beta\) and \(\epsilon\) values used in CFlexibleBottomRing.

Parameters

Parameter	Default	Comment
cableLength	-	total length of the cable [m]
numElements	-	number of rigid elements in the cable [#]
diameter	-	diameter of the cable. [m]
cableWeight	-	weight of the cable [kg/m]
E-modulus	-	Young's modulus for cable material [Pa] (used as given in the compliance formulas of the class description)
G-modulus	\(\frac{E-modulus}{2.6}\)	shear modulus for cable material [Pa]
damping	1	structural damping in the cable [-]
updateFreq	-	parameter which preserves simulation stability [-]
stabilityFactor	-	parameter which preserves simulation stability [-]
ExternalWakeUpdate	Step<td>Step takes the other objects' wakes at the element centres once per integrator step (in PreOdeFcn) and holds them for the step; Evaluation composes them live in every evaluation (MARE-0223)

Input ports

Tag	Size	Comment
PositionA	3	position of end-connection point A
PositionB	3	position of end-connection point B
VelocityA	3	velocity of end-connection point A
VelocityB	3	velocity of end-connection point B
RetractedLengthA	1	length of cable retracted on side A
RetractedLengthB	1	length of cable retracted on side B
RetractedSpeedA	1	retraction rate of cable retracted on side A
RetractedSpeedB	1	retraction rate of cable retracted on side B

Output ports

Tag	Size	Comment
ForceA	3	Reaction force on side A
ForceB	3	Reaction force on side B

States

Tag	Size	Comment
pos<i>	3	Position (x,y,z) of element with index <i>
vel<i>	3	Velocity of element with index <i>
theta<i>	4	Quaternion of element with index <i>
omega<i>	3	Angular derivatives of element (?) <i>

Note

The hydrodynamic load model does not currently support the effect of added mass (MARE-0314). Above the seabed each element's load is that of water for its wet fraction f against the wave surface (a cylinder between its ends, gated by MaxWaveElevation) and that of air for 1 - f, and in waves it takes the Froude-Krylov force rho f V a_n normal to its axis (owner ruling R104, CableRMWaterLoad.h). It was all water or all air by its centre's side of the surface. The other objects' wakes are taken once per integrator step, in PreOdeFcn, at the centres of all elements and held for the step; the current and the waves stay live (MARE-0223).

Revision history:

Q3 2011 JHJ: Initial version.

Constructor & Destructor Documentation

CableRM()

RbCable::CableRM::CableRM	(	const std::string &	simObjectName,
		ISimObjectCreator *const	creator
	)

The constructor performs all initial setup for a cable simobject. Reading in parameters, setting up communication interface i.e. output ports, input ports, and states, plus additional 'one time only' resource setup.

Parameters

[in]	simObjectName	-> The name of the simobject
[in]	creator	-> Retrieve parameters. Register states, ports and shared resources reads parameters, registers states, output and intput ports.

Member Function Documentation

calculations()

void RbCable::CableRM::calculations	(	const double	T,
		const double *const	X
	)

Computations that are important for the cable object dynamics, but only should be called once during each time step when simulating. Results are stored in member variables in the object.

Parameters

[in]	T	-> Current simulation time
[in]	X	-> Current simulation state

forceA()

const double * RbCable::CableRM::forceA	(	const double	T,
		const double *const	X
	)

See PortDefs.h

Parameters

[in]	T	-> Current simulation time
[in]	X	-> Current simulation state

Returns

-> Address of current force in endpoint A of cable

forceB()

const double * RbCable::CableRM::forceB	(	const double	T,
		const double *const	X
	)

See PortDefs.h

Parameters

[in]	T	-> Current simulation time
[in]	X	-> Current simulation state

Returns

-> Address of current force in endpoint B of cable

OdeFcn()

void RbCable::CableRM::OdeFcn	(	const double	T,
		const double *const	X,
		double *const	XDot
	)		const

Returns state derivatives.

Parameters

[in]	T	-> Current simulation time
[in]	X	-> Current simulation state
[out]	XDot	-> State derivatives

---

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

• webfhsim/reloadrepos/fhsim_marine_elements/src/RMCable/Cable.h