Main Objectives of Work Package 1
in the ViSiCADE Project
Analysis has become a major part in today product development cycle. The purpose of analysis is generally to predict the functional behaviour of the design, so that optimisation on the design can be carried out. However, attempts to derive a CAE model for analysis directly from CAD geometry sources have shown to be a
lengthy and tedious process.
Unsurprisingly, this labour intensive process is due to the difference background and requirements of theses two fields. When integrating CAD and CAE, there are significant differences between the representation content and representation format provided by the CAD models and that required by the analysis systems. Hence numerous problems preventing the true automation of a CAD-to-CAE process; these problems are:
- Inconsistent geometry, topology description and tolerance on difference system
- Over detailed models which hinder the meshing process
- Complex shape that not readily meshable by current meshing techniques
Most of the leading CAE packages, such as
CADfix, available on the market today can deal most of the geometry and topology problems.
The tasks set out in WP1 will mainly concentrate on solving problems in items 2 and 3 above. The following sections will highlight the main contribution from ViSiCADE project toward a better CAD-to-CAE integration.
Small Feature Identification
CAD models simplification needs are not only limited to meshing requirements, it is also essential for graphical manipulation and display and more efficient usage of simulation resources. Most simplification algorithms used or proposed involved a certain use of benchmarks to identify and validate features for suppression/simplification. There are no standard in how this is done, in fact much of the work in this field are still very much in research phase.
Narrow Regions
One of the most unfavourable side effects after Boolean operations and blending/filleting of a model is the appearance of a constriction area in the model surface. These narrow regions present a huge challenge to analysts as they do not have any distinctive characteristics nor clear boundaries defining their existence. And meshing operation either fall over because of the huge size different in a same surface or resulted in a very poor quality elements.
However, employing the
MAT techniques developed in the previous research carried out by FEMG showed that a narrow region can be identified. This involves evaluating and comparing the distance between opposite entities distance from a Delaunay triangulation.
The picture below shows one of the surfaces within a gearbox housing (model supplied by
ZF) with its narrow region identified and highlighted for further geometric operation.
