18th International Meshing Roundtable
Salt Lake City, UT, USA.
October 25-28, 2009
Sandia National Laboratories, Albuquerque, New Mexico, U.S.A
We propose a method to automatically defeature a CAD model by
detecting irrelevant features using a geometry-based size field and a method to remove
the irrelevant features via facet-based operations on a discrete representation.
A discrete B-Rep model is first created by obtaining a faceted representation of the
CAD entities. The candidate facet entities are then marked for reduction by using
a geometry-based size field. This is accomplished by estimating local mesh sizes
based on geometric criteria. If the field value at a facet entity goes below a user
specified threshold value then it is identified as an irrelevant feature and is marked
for reduction. The reduction of marked facet entities is primarily performed using
an edge collapse operator. Care is taken to retain a valid geometry and topology of
the discrete model throughout the procedure. The original model is not altered as
the defeaturing is performed on a separate discrete model. Associativity between
the entities of the discrete model and that of original CAD model is maintained
in order to decode the attributes and boundary conditions applied on the original
CAD entities onto the mesh via the entities of the discrete model. Example models
are presented to illustrate the effectiveness of the proposed approach.
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