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ULiege - Aerospace & Mechanical Engineering

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doc:user:conditions:rotations

# Prescribed Rotations

Displacements and rotations imposed with respect to an axis are extensions of imposed displacements (translations) and are used to rotate/move a set of nodes around an axis, which can be moving. As for displacements, this is done with LoadingSet. The motion of the axis is defined in the LoadingSet.

## Translation of rotation axis

(axis defined by points p1 and p2):

loadingset.define(p1, Field1D(TX,RE), dx1, fctX1)
loadingset.define(p2, Field1D(TZ,RE), dz2, fctZ2)
 p1 reference of the origin of the axis dx1, dy1, dz1 displacements of p1 fctX1, fctY1, fctZ1 Functions y=f(t) of the displacement of p1 p2 reference of the end of the axis dx2, dy2, dz2 displacements of p1 fctX2, fctY2, fctZ2 Functions y=f(t) of the displacement of p2

## Case #1: Radial displacement imposed with respect to the axis

loadingset.defineRad(gObject, Field1D(TX,RE), p1, p2, ampl, fct)
 gObject Geometric entity field name of the variable which is concerned by the motion ampl amplitude fct Functions y=f(t) (temporal dependency) p1 reference of the origin of the axis p2 reference of the end of the axis

## Case #2: Rotation imposed around the axis

loadingset.defineRot(gObject, field, p1, p2, option, ampl, fct)
 gObject Geometric entity field name of the variable which is concerned by the motion (only Field3D(TXTYTZ,RE) allowed) ampl amplitude fct Functions y=f(t) (can depend on time and position) p1 reference of the origin of the axis p2 reference of the end of the axis option = False : the boundary condition is a given angle, in degrees = True : the boundary condition is a given angular speed, in degrees/second

## Case #3: 2 successives Rotations imposed around 2 axis

loadingset.defineRot2(gObject, field, axe1, ampl1, fct1, axe2, ampl2, fct2, option)
 gObject Geometric entity field name of the variable which is concerned by the motion (only Field3D(TXTYTZ,RE) allowed) axe1 first axe of rotation (mtGeoAxe object) ampl1 amplitude first rotation fct1 Functions y=f(t) of the first rotation (can only depend on time) axe1 second axe of rotation (mtGeoAxe object) ampl1 amplitude second rotation fct1 Functions y=f(t) of the second rotation (can only depend on time) option = False : the boundary condition is a given angle, in degrees = True : the boundary condition is a given angular speed, in degrees/second