Geometry Modeling Reference Manual Part 2-Introduction to Geometry Modeling

Overview of Capabilities
A powerful and important feature of Patran is its geometry capabilities. Geometry can be:
? Created.
? Directly accessed from an external CAD part file.
? Imported from an IGES file or a PATRAN 2 Neutral file.
Complete Accuracy of Original Geometry
Patran maintains complete accuracy of the original geometry, regardless of where it came from. The
exact mathematical representation of the geometry (e.g., Arc, Rational B-Spline, B-rep, Parametric
Cubic, etc.) is consistently maintained throughout the modeling process, without any approximations or
conversions.
This means different versions of the geometry model are avoided. Only one copy of the geometry design
needs to be maintained by the engineer, whether the geometry is in a separate CAD part file or IGES file
or the geometry is part of the Patran database.
Below are highlights of the geometry capabilities:
Direct Application of Loads/BCs and Element Properties to Geometry
All loads, boundary conditions (BC) and element property assignments can be applied directly to the
geometry. When the geometry is meshed with a set of nodes and elements, Patran will automatically
assign the loads/BC or element property to the appropriate nodes or elements.
Although you can apply the loads/BCs or element properties directly to the finite element mesh, the
advantage of applying them to the geometry is if you remesh the geometry, they remain associated with
the model. Once a new mesh is created, the loads/BC and element properties are automatically
reassigned.
For more information, see Introduction to Functional Assignment Tasks (Ch. 1) in the Patran Reference
Manual.
Direct Geometry Access
Direct Geometry Access (DGA) is the capability to directly access (or read) geometry information from
an external CAD user file, without the use of an intermediate translator. Currently, DGA supports the
following CAD systems:
? EDS/Unigraphics
? Pro/ENGINEER by Parametric Technology
? CATIA by Dassault Systemes
With DGA, the CAD geometry and its topology that are contained in the CAD user file can be accessed.
Once the geometry is accessed, you can build upon or modify the accessed geometry in Patran, mesh the
geometry, and assign the loads/BC and the element properties directly to the geometry.

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