From CAD to FEA : A Design Automation Perspective

Licentiate thesis, 2006

CAD-models of parts produced by injection moulding or die casting are often complex making the task of automated geometrical idealisation for finite element analysis difficult. Conventional tools for geometric idealisation are not ideal for the task as will be shown in the thesis. To address the idealisation problem this thesis proposes a novel method of creating geometric idealisations of CAD-models for finite element analysis. Knowledge about the production and design processes is used to support the idealisations. The key idea is simplify the idealisation problem by using the fact that die-cast and injection-moulded parts have a clearly defined tooling draft direction. It is primarily the mid-surfaces of the thin-walled geometry that are extracted for shell element meshing. The ideas have been tested by the creation of a CAD-integrated system which reads the construction history tree of the CAD-model and creates an idealised geometry in the same CAD-model automatically. It is also shown how the system can be used for idealising neutral format files by creating a virtual construction history tree in interaction with the user. The system is named CASTING (CAd Supported Tool for Idealisation of Geometry). The overall objective is to save time in the idealisation step freeing time for more creative work in the design process.