Wednesday, 17 June 2015

Publications


Publications are used in CATIA Assembly design and are particularly useful when it comes to contextual design with links.  Think of the primary function of a publication as an intermediate level between a source element and a contextually designed part.

Let me use an analogy I use with my students: imagine you were designing  a luxury motor yacht.  A large proportion of the interior fittings will be using the hull surface of the boat as a limit.  The hull is subsequently redesigned and the surface replaced.  If you have never had a situation like this, let me tell you what happens: when you open each contextually designed part, they will tell you that their contextual references cannot be synchronised.  You then have to manually replace the reference - replace boat hull surface one with surface two - a very long drawn out process.



So how does a publication help?  If the boat hull surface was published, because the contextually designed parts are looking at the publication not the actual reference, you only have to modify the link once by changing what the publication is pointing to in the source document, not each and every contextually designed part.

Other advantages include:
- The publication of an element can be easily recognised - they are in a separate folder in the spec tree - this also helps finding elements for constraining.
- Published elements can be swapped out with other elements with the same name - complete parts can be swapped with others and then update assemblies accordingly.


Desktop Engineering’s is a fully accredited Dassault Systèmes (www.3ds.com) software education partner and as such, the training courses have been developed over many years to provide concise and comprehensive training to users. The courses are progressive so that skills can be enhanced to the highest levels in a systematic way. The on-going evaluation of our courses show that we consistently achieve high levels of satisfaction from attendees and their companies for the training we provide. Visit www.dte.co.uk/training/ for more information on CATIA training courses. 
 




Monday, 13 April 2015

Isoparametric Curves



One of the great things about advanced CAD packages like CATIA is that not only can you specify tangent or curvature continuity between surfaces and wireframe, but there are some commands that also allow you to adjust the tension (how long the tangency or curvature is maintained) thus enabling you to properly 'style' the component with small changes to the wireframe or surface boundaries.

A parametric surface patch can be considered as an infinite union of curves - tangent and normal vectors from any given point.  As a mathematical model in a program such as CATIA, these infinite number of curves are called Isoparametric curves and can be thought of as the natural 'grain' direction(s) of a surface - much like wood or metal.


When creating support wireframe geometry for a new surface bordering an existing surface, it is important to use this internal grain structure for continuity in order that the new wireframe and therefore supported surface geometry benefits from existing mathematical flow.

The Isoparametric Curve tool can be found on the right hand end of the wireframe toolbar, hidden behind the 3D spline tool.  You simply select the surface, a reference point (existing or not) and the tangent or normal direction.  Use the endpoint for connection and the curve for tangent direction.


Desktop Engineering’s is a fully accredited Dassault Systèmes (www.3ds.com) software education partner and as such, the training courses have been developed over many years to provide concise and comprehensive training to users. The courses are progressive so that skills can be enhanced to the highest levels in a systematic way. The on-going evaluation of our courses show that we consistently achieve high levels of satisfaction from attendees and their companies for the training we provide. Visit www.dte.co.uk/training/ for more information on CATIA training courses.