====== Appendix 13: Displacement of a foundation to model a cylinder in generalized plane strain state ======
Sometimes, it is necessary to study contact in generalised plane strain state. In some cases, the foundation is not easy to model with the classical way to define it. \\ \\
For example, in rolling, the foundation is a cylinder, but one can want to model only a slice that goes through the rolling mill, as follows:
{{ :appendices:a13_1.png?600 |}} \\
In such a case, the foundation in the study plane is a segment that represent the intersect of the plane and the cylinder surface. \\ \\
One can define the displacement of this segment thanks to a *.CYL file: in this case, the position and the radius of the cylinder is defined and the position of the segment of foundation is computed according to time. \\ \\
To make this function available, parameter IPRES must be set at 9 (*ex.dat). \\ \\
==== Structure of the *.CYL file ====
^Global parameters (I5, G10.0)^^
|NCYL|Number of cylinders (or pairs of cylinders)|
|SPEED|Speed of the slice (plane) in the z direction|
^Geometry parameters: Repeat NCYL times (5I5/3G10.0)^^
|NOD1 |First node defining the segment of foundation|
|NOD2|Second node defining the segment of foundation|
|ISYM |= 1 if another foundation is used to define a second cylinder symmetrically to the first one (see figure 2) \\ = 0 otherwise|
|NOD3|First node of the symmetrical cylinder (useless if ISYM = 0)|
|NOD4|Second node of the symmetrical cylinder (useless if ISYM = 0)|
|YC|Y coordinate of the cylinder axis|
|ZC|Z coordinate of the cylinder axis|
|R |Radius of the cylinder|

==== Example ====
In the following case, there are 3 pairs of cylinders (NCYL = 3), and all of the cylinders have a “twin”-cylinder, so that each of them will be defined with ISYM = 1.
{{ :appendices:a13_2.png?400 |}}