Cylindrical Guide Surfaces |
 
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Cylindrical Guide Surfaces |
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(i)Whether the cylindrical guide contact surface is external (the convex shape against the contacting body), or internal (the concave shape against the contacting body).
(i)The name of a set of elements that are to be monitored for contact with the guide surface. In most analyses, only a small section of the model is ever likely to come into contact with a particular guide surface, and for this reason it is, in general, unnecessary to check every node in the model for contact with a flat guide surface at every timestep. By associating a set of elements with each guide surface, the number of nodes that must be checked at each solution time is significantly reduced. This leads to faster analyses.
(ii)The location of the cylindrical guide surface at the start of the analysis. This is specified by inputting the coordinates of the origin of the contact surface at solution initiation. The origin is located at the centre of curvature, at the first end of the cylinder.
(iii)The orientation of the cylindrical guide surface at the start of the analysis. This is defined by specifying the components of axial and radial vectors.
(iv)The dimensions (length, radius and subtended angle) of the cylindrical surface.
(v)The elastic contact stiffness of the guide surface.
(vi)The axial and circumferential friction coefficients associated with the contact surface.
(vii)Whether the cylindrical guide contact surface is external (the convex shape against the contacting body), or internal (the concave shape against the contacting body).
The overall layout of the cylindrical guide surface is illustrated in the figure below.
Cylindrical Guide Surface
Each cylindrical surface has a local axis system associated with it, as shown above. The axial and radial vectors form two components of a right handed system. The length of these vectors is not significant – it is their orientation that is important. Naturally these two vectors should be orthogonal. A third vector is assembled internally using the right-hand rule.
The sign convention for both the Start Angle and the Subtended Angle is consistent with the right handed system. Specifically, positive angles represent rotations of the radial vector toward the third vector. If a Start Angle is not specified, its magnitude is half that of the Subtended Angle, and it differs in sign. In this case, the radial vector bisects the Subtended Angle, and represents an axis of symmetry for the cylindrical surface.
The thickness of the contact surface is used for display purposes only and does not affect the overall operation of the contact modelling algorithm. It is an optional entry and defaults to 0.1m or 0.328ft. For external contact it is measured from the external surface in. For internal contact it is measured from the internal surface out.
•*GUIDE is used to define guide (contact) surfaces. Specifically, the TYPE=CYLINDRICAL inputs are used to define cylindrical guide surfaces.