Coordinate Systems - CAESAR II - Help

CAESAR II Users Guide

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CAESAR II
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CAESAR II Version
12

Many analytical models in engineering are based upon being able to define a real physical object mathematically. This is accomplished by mapping the dimensions of the physical object into a similar mathematical space. Mathematical space is usually assumed to be either two-dimensional or three-dimensional. For piping analysis, the three-dimensional space is necessary, because almost all piping systems are three dimensional in nature.

Two typical three-dimensional mathematical systems are shown in the following illustration. Both of these systems are Cartesian coordinate systems. Each axis in these systems is perpendicular to all other axes.

  • Each axis can be thought of as a number line, where the zero point is the point where all of the axes intersect. While only the positive side of each axis is shown in the illustration, each axis has a negative side as well.

  • The direction of the arrow heads indicates the positive direction of each axis.

  • The X-axis has one arrowhead, the Y-axis has two arrowheads, and the Z-axis has three arrowheads. The circular arcs labeled RX, RY, and RZ define the direction of positive rotation about each axis.

  • Any point in space can be mapped to these coordinate systems by using the point's position along the number lines. For example, a point 5 units down the X-axis has a coordinate of (5.0, 0.0, 0.0). A point 5 units down the X-axis and 6 units down the Y-axis has a coordinate of (5.0, 6.0, 0.0).

  • If the system on the right side of the illustration is rotated 90-degrees about the X-axis, the result is the system on the left side.

In addition, for these Cartesian coordinate systems the right hand rule defines positive rotation about each axis and the relationship, or ordering, between the axes.

The coordinate system on the left side is the default CAESAR II global coordinate system. In this system, the X-axis and Z-axis define the horizontal plane, and the Y-axis is vertical.

The coordinate system on the right side can be obtained in CAESAR II by selecting Z-axis Vertical.