`DAVE.scene`¶

Module Contents¶

class DAVE.scene.Node(scene)¶

ABSTRACT CLASS - Properties defined here are applicable to all derived classes Master class for all nodes

_scene :Scene¶: reference to the scene that the node lives is

_name :str = no name¶: Unique name of the node

_manager :Node or None¶: Reference to a node that controls this node

__repr__(self)¶

__str__(self)¶

depends_on(self)¶: Returns a list of nodes that need to be available before the node can be created

give_python_code(self)¶: Returns the python code that can be executed to re-create this node

_verify_change_allowed(self)¶: Changing the state of a node is only allowed if either: 1. the node is not manages (node._manager is None) 2. the manager of the node is identical to scene.current_manager

_delete_vfc(self)¶

update(self)¶: Performs internal updates relevant for physics. Called before solving statics or getting results

class DAVE.scene.CoreConnectedNode(scene, vfNode)¶

Bases: DAVE.scene.Node

ABSTRACT CLASS - Properties defined here are applicable to all derived classes Master class for all nodes with a connected eqCore element

_delete_vfc(self)¶

class DAVE.scene.NodeWithParent(scene, vfNode)¶

Bases: DAVE.scene.CoreConnectedNode

NodeWithParent

Do not use this class directly. This is a base-class for all nodes that have a “parent” property.

depends_on(self)¶

change_parent_to(self, new_parent)¶

Assigns a new parent to the node but keeps the global position and rotation the same.

See Also: nodes_depending_on

delete(self, node)¶: Deletes the given node from the scene as well as all nodes depending on it.

See also

dissolve

dissolve(self, node)¶

Attempts to delete the given node without affecting the rest of the model.

Look for nodes that have this node as parent
Attach those nodes to the parent of this node.
Delete this node.

There are many situations in which this will fail because an it is impossible to dissolve the element. For example a poi can only be dissolved when nothing is attached to it.

For now this function only works on AXIS

savepoint_make(self)¶

savepoint_restore(self)¶

update(self)¶: Updates the interface between the nodes and the core. This includes the re-calculation of all forces, buoyancy positions, ballast-system cogs etc.

solve_statics(self, silent=False, timeout=None)¶

Solves statics

Parameters:: silent – Do not print if successfully solved
Returns:: True if successful, False otherwise.
Return type:: bool

verify_equilibrium(self, tol=0.01)¶

Checks if the current state is an equilibrium

Returns:: True if successful, False if not an equilibrium.
Return type:: bool

goal_seek(self, evaluate, target, change_node, change_property, bracket=None, tol=0.001)¶

goal_seek

Goal seek is the classic goal-seek. It changes a single property of a single node in order to get some property of some node to a specified value. Just like excel.

Parameters:

evaluate – code to be evaluated to yield the value that is solved for. Eg: s[‘poi’].fx Scene is abbiviated as “s”
target (number) – target value for that property
change_node (Node or str) – node to be adjusted
change_property (str) – property of that node to be adjusted
range (optional) – specify the possible search-interval

Returns:

True if successful, False otherwise.

Return type:

bool

Examples

Change the y-position of the cog of a rigid body (‘Barge’) in order to obtain zero roll (rx) >>> s.goal_seek(“s[‘Barge’].fx”,0,’Barge’,’cogy’)

plot_effect(self, evaluate, change_node, change_property, start, to, steps)¶

Produces a 2D plot with the relation between two properties of the scene. For example the length of a cable versus the force in another cable.

The evaluate argument is processed using “eval” and may contain python code. This may be used to combine multiple properties to one value. For example calculate the diagonal load distribution from four independent loads.

The plot is produced using matplotlob. The plot is produced in the current figure (if any) and plt.show is not executed.

Parameters:

evaluate (str) – code to be evaluated to yield the value on the y-axis. Eg: s[‘poi’].fx Scene is abbiviated as “s”
change_node (Node or str) – node to be adjusted
change_property (str) – property of that node to be adjusted
start – left side of the interval
to – right side of the interval
steps – number of steps in the interval

Returns:

Tuple (x,y) with x and y coordinates

Examples

>>> s.plot_effect("s['cable'].tension", "cable", "length", 11, 14, 10)
>>> import matplotlib.pyplot as plt
>>> plt.show()

new_axis(self, name, parent=None, position=None, rotation=None, inertia=None, inertia_radii=None, fixed=True)¶

Creates a new axis node and adds it to the scene.

Parameters:

name – Name for the node, should be unique
parent – optional, name of the parent of the node
position – optional, position for the node (x,y,z)
rotation – optional, rotation for the node (rx,ry,rz)
[True] (fixed) – optional, determines whether the axis is fixed [True] or free [False]. May also be a sequence of 6 booleans.

Returns:

Reference to newly created axis

new_geometriccontact(self, name, slave_item, master_item, inside=False, swivel=None, master_rotation=None, slave_rotation=None, swivel_fixed=True, master_fixed=False, slave_fixed=False)¶

Creates a new new_geometriccontact node and adds it to the scene.

Geometric contact connects two circular elements and can be used to model bar-bar connections or pin-in-hole connections.

By default a bar-bar connection is created between item1 and item2.

Parameters:

name – Name for the node, should be unique
slave_item – [Sheave] will be the master of the connection
master_item – [Sheave] will be the slave of the connection
inside – [False] False creates a pinpin connection. True creates a pin-hole type of connection
swivel – Rotation angle between the two items. Defaults to 90 for pinpin and 0 for pin-hole
master_rotation – Angle of the connecting hinge relative to master or None for default
slave_rotation – Angle of the slave relative to the connecting hinge or None for default
swivel_fixed – Fix swivel [True]
master_fixed – Fix connecting hinge to master [False]
slave_fixed – Fix slave to connecting hinge [False]

Note

For pin-hole connections there is no geometrical difference between the pin and the hole. Therefore it is not needed to specify which is the pin and which is the hole

Returns:: Reference to newly created new_geometriccontact

new_waveinteraction(self, name, path, parent=None, offset=None)¶

Creates a new wave interaction node and adds it to the scene.

Parameters:

name – Name for the node, should be unique
path – Path to the hydrodynamic database
parent – optional, name of the parent of the node
offset – optional, position for the node (x,y,z)

Returns:

Reference to newly created wave-interaction object

new_visual(self, name, path, parent=None, offset=None, rotation=None, scale=None)¶

Creates a new Visual node and adds it to the scene.

Parameters:

name – Name for the node, should be unique
path – Path to the resource
parent – optional, name of the parent of the node
offset – optional, position for the node (x,y,z)
rotation – optional, rotation for the node (rx,ry,rz)
scale – optional, scale of the visual (x,y,z).

Returns:

Reference to newly created visual

new_poi(self, name, parent=None, position=None)¶

Creates a new poi node and adds it to the scene.

Parameters:

name – Name for the node, should be unique
parent – optional, name of the parent of the node
position – optional, position for the node (x,y,z)

Returns:

Reference to newly created poi

new_rigidbody(self, name, mass=0, cog=(0, 0, 0), parent=None, position=None, rotation=None, inertia_radii=None, fixed=True)¶

Creates a new rigidbody node and adds it to the scene.

Parameters:

name – Name for the node, should be unique
mass – optional, [0] mass in mT
cog – optional, (0,0,0) cog-position in (m,m,m)
parent – optional, name of the parent of the node
position – optional, position for the node (x,y,z)
rotation – optional, rotation for the node (rx,ry,rz)
inertia_radii – optional, radii of gyration (rxx,ryy,rzz); only used for dynamics
[True] (fixed) – optional, determines whether the axis is fixed [True] or free [False]. May also be a sequence of 6 booleans.

Examples

scene.new_rigidbody(“heavy_thing”, mass = 10000, cog = (1.45, 0, -0.7))

Returns:: Reference to newly created RigidBody

new_cable(self, name, endA, endB, length=-1, EA=0, diameter=0, sheaves=None)¶

Creates a new cable node and adds it to the scene.

Parameters:

name – Name for the node, should be unique
endA – A Poi element to connect the first end of the cable to
endB – A Poi element to connect the other end of the cable to
[-1] (length) – un-stretched length of the cable in m; default [-1] create a cable with the current distance between the endpoints A and B
[0] (EA) – stiffness of the cable in kN/m; default
sheaves – [optional] A list of pois, these are sheaves that the cable runs over. Defined from endA to endB

Examples

scene.new_cable(‘cable_name’ endA=’poi_start’, endB = ‘poi_end’) # minimal use

scene.new_cable(‘cable_name’, length=50, EA=1000, endA=poi_start, endB = poi_end, sheaves=[sheave1, sheave2])

scene.new_cable(‘cable_name’, length=50, EA=1000, endA=’poi_start’, endB = ‘poi_end’, sheaves=[‘single_sheave’]) # also a single sheave needs to be provided as a list

Notes

The default options for length and EA can be used to measure distances between points

Returns:: Reference to newly created Cable

new_force(self, name, parent=None, force=None, moment=None)¶

Creates a new force node and adds it to the scene.

Parameters:

name – Name for the node, should be unique
parent – name of the parent of the node [Poi]
force – optional, global force on the node (x,y,z)
moment – optional, global force on the node (x,y,z)

Returns:

Reference to newly created force

new_sheave(self, name, parent, axis, radius=0.0)¶

Creates a new sheave node and adds it to the scene.

Parameters:

name – Name for the node, should be unique
parent – name of the parent of the node [Poi]
axis – direction of the axis of rotation (x,y,z)
radius – optional, radius of the sheave

Returns:

Reference to newly created sheave

new_hydspring(self, name, parent, cob, BMT, BML, COFX, COFY, kHeave, waterline, displacement_kN)¶

Creates a new hydspring node and adds it to the scene.

Parameters:

name – Name for the node, should be unique
parent – name of the parent of the node [Axis]
cob – position of the CoB (x,y,z) in the parent axis system
BMT – Vertical distance between CoB and meta-center for roll
BML – Vertical distance between CoB and meta-center for pitch
COFX – X-location of center of flotation (center of waterplane) relative to CoB
COFY – Y-location of center of flotation (center of waterplane) relative to CoB
kHeave – heave stiffness (typically Awl * rho * g)
waterline – Z-position (elevation) of the waterline relative to CoB
displacement_kN – displacement (typically volume * rho * g)

Returns:

Reference to newly created hydrostatic spring

new_linear_connector_6d(self, name, slave, master, stiffness=None)¶

Creates a new linear connector 6d node and adds it to the scene.

Parameters:

name – Name for the node, should be unique
slave – Slaved axis system [Axis]
master – Master axis system [Axis]
stiffness – optional, connection stiffness (x,y,z, rx,ry,rz)

See LC6d for details

Returns:: Reference to newly created connector

new_connector2d(self, name, master, slave, k_linear=0, k_angular=0)¶

Creates a new new_connector2d node and adds it to the scene.

Parameters:

name – Name for the node, should be unique
slave – Slaved axis system [Axis]
master – Master axis system [Axis]
k_linear – linear stiffness in kN/m
k_angular – angular stiffness in kN*m / rad

Returns:

Reference to newly created connector2d

new_linear_beam(self, name, master, slave, EIy=0, EIz=0, GIp=0, EA=0, L=None)¶

Creates a new linear beam node and adds it to the scene.

Parameters:

name – Name for the node, should be unique
slave (The length defaults to the distance between master and) – Slaved axis system [Axis]
master – Master axis system [Axis]
0 (All stiffness terms default to) –
slave –

See LinearBeam for details

Returns:: Reference to newly created beam

new_buoyancy(self, name, parent=None)¶

Creates a new buoyancy node and adds it to the scene.

Parameters:

name – Name for the node, should be unique
parent – optional, name of the parent of the node

Returns:

Reference to newly created buoyancy

new_contactmesh(self, name, parent=None)¶

Creates a new contactmesh node and adds it to the scene.

Parameters:

name – Name for the node, should be unique
parent – optional, name of the parent of the node

Returns:

Reference to newly created contact mesh

new_contactball(self, name, parent=None, radius=1, k=9999, meshes=None)¶

Creates a new force node and adds it to the scene.

Parameters:

name – Name for the node, should be unique
parent – name of the parent of the node [Poi]
force – optional, global force on the node (x,y,z)
moment – optional, global force on the node (x,y,z)

Returns:

Reference to newly created force

new_ballastsystem(self, name, parent=None, position=None)¶

Creates a new rigidbody node and adds it to the scene.

Parameters:

name – Name for the node, should be unique
parent – name of the parent of the ballast system (ie: the vessel axis system)
position – the reference system in which the tanks are defined [0,0,0]

Examples

scene.new_ballastsystem(“cheetah_ballast”, parent=”Cheetah”)

Returns:: Reference to newly created BallastSystem

new_sling(self, name, length=-1, EA=1.0, mass=0.1, endA=None, endB=None, LeyeA=None, LeyeB=None, LspliceA=None, LspliceB=None, diameter=0.1, sheaves=None)¶

Creates a new sling, adds it to the scene and returns a reference to the newly created object.

`DAVE.scene`¶

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DAVE.scene¶

Module Contents¶

`DAVE.scene`¶