# ZY Card

This card defines a surface mesh in the form of a cylindrical segment.

On the Construct tab, in the Surfaces group, click the  Cylinder icon. From the drop-down list, click the  Cylinder (ZY) icon.

## Parameters:

S1
The start point of the axis.
S2
The end point of the axis.
S3
A point on the corner of the cylindrical segment.
Normal vector directed
The triangles can be created so that the normal vector is points Outward or Inward.
The angle $\phi$ (degrees)
The angle in degrees, which is subtended by the cylindrical arc.
Maximum edge length on arc
Maximum edge length of the triangles along the curved side in m (is scaled by the SF card). If this parameter is left empty, the value specified with the IP card is used.
Scale second half axis with
If this parameter is empty or is set to 1 , a circular cylinder is created. If set to $\frac{b}{a}$ , an elliptical cylinder is created. Here $\frac{b}{a}$ gives the ratio of the two half axes, where a is the distance S1–S3. It is not recommended to generate elliptical cylinders with extremely small or extremely large axial ratios with a CAD system as the distortion formulation used in PREFEKO may fail in these cases.
For an orthogonal cylinder (that is the lines S1–S2 and S1–S3 are perpendicular), the segmented area (shaded in the figure of the cylinder) is obtained by rotating the point S3 around the axis S1–S2 through $\phi$ . For $\phi =360°$ a full cylinder is created.

An oblique cylinder (that is the circular or elliptical rim is not perpendicular to the axis) can also be created. Then S1–S2 still represents the axis, but the top and bottom planes of the rims are defined by planes perpendicular to the plane defined by the three points S1, S2, S3, and parallel to the line S1–S3.

## Examples of ZY card usage:

The cylindrical section below was created with a single ZY card.
**
IP:  :  :  :  :  :  : 0.4
DP: A :  :  :  :  : 0.0 : 0.0 : 0.0
DP: B :  :  :  :  : 0.0 : 0.0 : 2.0
DP: C :  :  :  :  : 1.0 : 0.0 : 0.0
ZY: A : B : C :  :  : 180.0 : 0.35
EG: 1 : 0 : 0 :  :  :  :  :  :  :  :  :  : 1
EN

The elliptical cylinder below was created with a single ZY card.

** Example for an elliptical cylinder

** General parameters
#a=1.5  ** first half axis of the elliptical cylinder
#b=2.5  ** second half axis of the elliptical cylinder
#h=4  ** height of the cylinder

** Segmentation
#kanl=0.4
IP:  :  :  :  :  :  : #kanl

** Define points
DP: A :  :  :  :  : 0 : 0 : 0
DP: B :  :  :  :  : 0 : 0 : #h/2
DP: C :  :  :  :  : #a : 0 : 0

** Define the geometry
ZY: A : B : C :  :  : 90 : #kanl : #b/#a

** End
EG: 1 : 0 : 0 :  :  :  :  :  :  :  :  :  : 1
EN

The non-orthogonal cylinder below was created with a single ZY card.

** Example for a non-orthogonal elliptical cylinder
IP:  :  :  :  :  :  : 0.3
DP: A :  :  :  :  : 0.0 : 0.0 : 0.0
DP: B :  :  :  :  : 0.7 : 0.0 : 1.0
DP: C :  :  :  :  : 1.0 : 0.0 : 0.0
ZY: A : B : C :  :  : 360.0 :  : 1.5
EG: 1 : 0 : 0 :  :  :  :  :  :  :  :  :  : 1
EN