Influence of Geometric Features Associativity of CAD Class Models on the Process of Their Updating – Comparative Analysis
Grzegorz Świaczny
a:1:{s:5:"en_US";s:123:"Institute of Fundamentals of Machinery Design, Silesian University of Technology, Konarskiego 18a., 44-100 Gliwice, Poland";}Abstract
This article deals with the topic of one of the most important features of modern CAx class systems – associativity. The term refers to the ability to form relations (links) between two or more objects (in terms of their selected features), and with the consequence creating an associative (linked) three-dimensional model. The author pays special attention to the very process of creating relations between objects, as it has a key impact on the structural stability of CAD class models, and thus on their susceptibility to possible modifications. To show that not all associativity brings a positive effect, the author presents two examples of its implementation. In order to emphasize the influence of the method of linking individual elements, both examples are based on the same 3D model – a thin-walled part with a positioning pin. That means the geometric form of the default part is the same, whereas only relations of the individual objects of the 3D model change. In the first scenario, correctly defined relations between objects make that the positioning pin offset does not affect the initial design conditions. The second scenario shows an incorrect implementation of associativity, as a result of which the same operation of positioning pin offset gives non-compliance with the initial design conditions and with the consequence an undesirable change in its geometry.
The article is an attempt to draw attention to the fact that the associative structure of 3D models is not always equal to the optimal solution. Only the well-thought-out nature of associativity allows to use all its advantages.
Keywords:
associativity, parametrization, 3D model, CADReferences
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a:1:{s:5:"en_US";s:123:"Institute of Fundamentals of Machinery Design, Silesian University of Technology, Konarskiego 18a., 44-100 Gliwice, Poland";}
