You need to find out what file types CGNS, FIDAP, IDEAS, NASTRAN, PATRRAN, or Hypermesh can read.....ie IGES or StEp. Then know when you do file conversions you may run into geometry issues which depends on the complexity of the models.
Here is a clip from an article written about transfering MCAD Data from one program to another.
When Bad things Happen to Good CAD Users
Stephen Wolfe, P.E.
Publisher, Computer Aided Design Report
Feature-based Basics
In the days before dimension-driven solids became popular, three-D CAD systems employed lines and curves in space, analytic surfaces, such as planes and cylinders, and free-form surfaces, such as B-spline surfaces (NURBS). Creating models was a tedious process because users had to keep track of both the outer and inner surfaces of the model. Cutting a hole in a model with a curved surface involved drawing a curve in space, projecting it onto the surface, and then manually trimming the surface back to the curve.
Solids-based systems, such as Pro/Engineer and the systems that followed it, employ geometry for curves and surfaces that's conceptually similar to their wire-frame and surface predecessors. But they have automated the production of complete three-D models by keeping track of more information. Solid systems keep track of not only surfaces but edges of intersecting surfaces. Solid CAD systems also keep track of which side of a surface faces out of a part and which faces inside.
CAD operators are unaware of these details because solid-modeling programs let them create models using sophisticated features. To cut a hole, for example, a designer might sketch the hole profile and then cut it through the model. The CAD system automatically projects new edges onto the surface being cut, trims the opening back to the hole edges, and then creates new surfaces to line the insides of the hole. It's no wonder that this automation requires a lot of number-crunching power.
What many CAD users don't realize is that in many cases the edge curves of solid models only approximate the actual intersection of two surfaces. According to a paper from Sandia National Laboratories, the precise intersection of two NURBS surfaces must be described by a 54th-order polynomial. To reduce the computation to more manageable levels, most CAD systems settle for approximating the intersection by a cubic (third-order) polynomial. The edge curve so defined usually lies close to, but not precisely on, the two surfaces it bounds. Because of these approximations there are gaps between the edges and faces of boundary-representation solids (B-REPS). These gaps are the source of much mischief.
Heckler
Sr. Mechanical Engineer
SWx 2007 SP 2.0 & Pro/E 2001
XP Pro SP2.0 P4 3.6 GHz, 1GB RAM
NVIDIA Quadro FX 1400
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