Pattern Repetition

A technique where different structural components can be linked together so as to produce similar topological layouts.

To achieve this goal, a main DSIZE card needs to be defined, followed by any number of secondary DSIZE cards which reference the main. The main and secondary components are related to each other through local coordinate systems, which are required, and through scaling factors, which are optional.

Other manufacturing constraints, such as minimum or maximum member size, can be applied to the main DSIZE card. These constraints will then automatically be applied to the secondary DSIZE card(s) as described in the sections below.

The following procedure should be followed to set up pattern repetition:

Create a main DTPG card.
Apply other manufacturing constraints as needed.
Define the local coordinate system associated to the main DTPG card.
Create a secondary DTPG card.
Define the local coordinate systems associated to the secondary DTPG card.
Apply scaling factors as needed.
Repeat steps 4-6 for any number of secondary DTPG cards.

Local Coordinates Systems

Local coordinates systems are generated by providing four points. These points can be defined either by entering explicit coordinates or by referencing existing grids, as follows:

CAID: Defines the anchor point for the local coordinates system.
CFID: Defines the direction of the X-axis.
CSID: Defines the XY plane and indicates the positive sense of the Y-axis.
CTID: Indicates the positive sense of the Z-axis.

The definition of the fourth point allows for both right-handed and left-handed coordinate systems, which facilitates the creation of reflected patterns.

Alternatively, local coordinate systems can be defined by referencing an existing rectangular coordinate system in the CID field, and by defining an anchor point in the CAID field.

Note: If the fields defining CFID, CSID, CTID, and CID are left blank, then the global coordinates system is used by default. The anchor point CAID, however, is always required.

Scaling Factors

Scaling factors in the X, Y, and Z directions can be defined for each secondary DSIZE card. These factors are always related to the local coordinate system. By playing with the local coordinate systems and the scaling factors, a wide range of effects can be obtained as illustrated in Figure 2.