================
Ball screw drive
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Ball screw drive link properties implement a ball screw drive. Only the linear elastic behaviour is modelled, non-linearities are neglected. The simplifications are:

- any kind of backlash is neglected
- local deformation of the nut is not modelled

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Definition
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Source and target interfaces should be chosen as shown in following figure:

   .. image:: media/lp_screw.png
      :alt: Ball screw drive link definition
      :scale: 100 %


^^^^^^^^^^^^^^^^^^^^
Source interface
^^^^^^^^^^^^^^^^^^^^

==============  ===========================================================================================
Type            Moving interface (Fourier)
Topologies      Peripheral face of the screw
Location        Along the screw axis
u direction     Axial, along the screw axis
v direction     Radial
w direction     Radial
==============  ===========================================================================================

^^^^^^^^^^^^^^^^^^^^
Target interface
^^^^^^^^^^^^^^^^^^^^

==============  ===========================================================================================
Type            Stationary interface (6dof)
Topologies      Mounting face of the nut
Location        Center of the screw axis
u direction     Axial, along the screw axis
v direction     Radial
w direction     Radial
==============  ===========================================================================================

^^^^^^^^^^^^^^^^^^^^^^^^^
Recommended link settings
^^^^^^^^^^^^^^^^^^^^^^^^^

==========================  ==========================
Use ground for source       unchecked
Location master             target
Orientation master          either source or target
==========================  ==========================

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Parameters
----------

===================  =========  =======================================================================
Parameter            Unit       Description
===================  =========  =======================================================================
Screw pitch          m          Pitch of the ball screw
Axial stiffness      N/m        Axial stiffness of the nut-to-screw coupling
Radial stiffness     N/m        Radial stiffness of the  nut-to-screw coupling
Tilting stiffness    Nm/rad     Tilting stiffness of the  nut-to-screw coupling
Axial damping        Ns/m       Axial damping of the nut-to-screw coupling
Radial damping       Ns/m       Radial damping of the  nut-to-screw coupling
Tilting damping      Nms/rad    Tilting damping of the  nut-to-screw coupling
Rotational damping   Nms/rad    Rotational damping when rotating the screw relative to the nut
===================  =========  =======================================================================