<!-- GENERATED by tools/generators/itemDocsEmitter.py from definitions/ - do not edit -->
```{raw} latex
\clearpage
```

(sec-item-markerbodybeamshape)=
# MarkerBodyBeamShape

A special Marker attached to a 3D beam finite element which provides at least position and tangent to the beam axis.

## Interface

- Provides: `Beam3DShape`

## Parameters

The parameters of the item; in a dictionary, its type is 'BodyBeamShape':

| name | type | size | default | description |
|---|---|---|---|---|
| **name** | String |  | '' | marker's unique name |
| **bodyNumber** | ObjectIndex |  | invalid (-1) | body number to which marker is attached to (beam type) |
| **visualization** | VMarkerBodyBeamShape |  |  | parameters for visualization of item |

## Visualization parameters

The parameters of `VMarkerBodyBeamShape`, given as `visualization`:

| name | type | size | default | description |
|---|---|---|---|---|
| **show** | Bool |  | True | set true, if item is shown in visualization and false if it is not shown |

## Drawing

Drawn as [all markers](#sec-drawing-markers); spheres at the points of the beam it acts on.
(description-markerbodybeamshape)=
## Detailed description

### Attached to

A spatial ANCF cable element, `ObjectANCFCable`; the marker is made for `ObjectJointSliding`, which
evaluates the shape functions itself, and it serves no other beam: the implementation evaluates the
shape functions of `ObjectANCFCable`. `Assemble()` refuses it on any other body.

### Marker quantities

The coordinates of the element - position and slope of both nodes, **including** their reference
values - and their velocities, and the length of the element.

### Jacobians

The unit matrix of the element's coordinates: the joint computes the action on each coordinate.

(miniexample-markerbodybeamshape)=
## Mini example


```python
#the shape of 3D ANCF cable elements for a sliding joint: a mass point slides along a clamped, stiff cable
from exudyn.beams import GenerateBeamElementsAlongLine
cable = ObjectANCFCable(massPerLength=1, bendingStiffness=1e4, axialStiffness=1e6)
beamInfo = GenerateBeamElementsAlongLine(mbs, positionStart=[0,0,0], positionEnd=[2,0,0],
                        numberOfElements=4, beamTemplate=cable,
                        groundConstraintsStart=[1,1,1, 1,1,1], groundConstraintsEnd=[1,1,1, 1,1,1])
nodes, elements = beamInfo['nodes'], beamInfo['elements']
nMass = mbs.AddNode(NodePoint(referenceCoordinates=[0.6,0,0]))
mbs.AddObject(ObjectMassPoint(nodeNumber=nMass, mass=1))
mMass = mbs.AddMarker(MarkerNodePosition(nodeNumber=nMass))
mbs.AddLoad(LoadForceVector(markerNumber=mMass, loadVector=[1,0,0]))

cableMarkers = [mbs.AddMarker(MarkerBodyBeamShape(bodyNumber=e)) for e in elements]
offsets = [0.5*i for i in range(4)] #the element length is 0.5
nData = mbs.AddNode(NodeGenericData(numberOfDataCoordinates=2, initialCoordinates=[1, 0.6])) #element 1, sliding coordinate
mbs.AddObject(ObjectJointSliding(markerNumbers=[mMass, cableMarkers[1]], slidingMarkerNumbers=cableMarkers,
                                 slidingMarkerOffsets=offsets, nodeNumber=nData, constrainRotations=[0,0,0]))

mbs.Assemble()
mbs.SolveDynamic()

#the mass slides: x = 0.6 + F/(2m)*t^2 at t=1, the stiff cable deflects little
exu.sys['testResult'] = mbs.GetNodeOutput(nMass, exu.OutputVariableType.Position)[0] #1.1
```


Relevant Examples (Ex) and TestModels (TM) with weblink to github: [`ANCFslidingJoint.py`](https://github.com/jgerstmayr/EXUDYN/blob/master/python/Examples/ANCFslidingJoint.py) (Ex), [`NGsolveFFRFSlidingJoint.py`](https://github.com/jgerstmayr/EXUDYN/blob/master/python/Examples/NGsolveFFRFSlidingJoint.py) (Ex)