Untrimmed splines i: analysis suitable cad

Current CAD technologies describe geometry by means of the boundary representation or simply B-rep. Boolean operations, ubiquitous in computer aided design, use a process called trimming that leads to a non-conforming description of geometry that is un-editable and incompatible with all downstream applications, thereby inhibiting true interoperability across the design-through-analysis process. We propose a modeling paradigm in which designers are given the tools to create watertight, editable and conforming descriptions of geometry with interactive control over the boundary surface parameterization. The methodology is based on recent advances in topological vector field design and processing. First, a smooth frame field is computed, by minimizing an appropriate energy functional on a background mesh of the initial B-rep, that is compatible with sparse or dense input constraints on alignment and size [1]. Frame-field singularities, which together satisfy the topological invariant known as the Poincaré-Hopf theorem, are automatically placed and can be modified by the user. The frame field is used as a guide for the reparameterization [2] of the initial B-rep into a conforming watertight and editable spline description. In line with the main rationale of isogeometric analysis, the meshing and reparameterization techniques are applied within CAD as part of the design process, instead of as a post-processing step. The modeling tools actively support the design, analysis and manufacturing process as a whole, enabling true interoperability across these different disciplines and thereby support efficient product development. REFERENCES [1] Panozzo, D., Puppo, E., Tarini, M., and Sorkine-Hornung, O. Frame fields: Anisotropic and non-orthogonal cross fields. ACM Transactions on Graphics (TOG), 33(4), 2014. [2] F. Kälberer, M. Nieser and K. Polthier, QuadCover. Surface parameterization using branched coverings, Computer Graphics Forum, 26(3), 375-384, 2007. IGA 2018: Integrating Design and Analysis October 10-12, 2018, Austin, TX QUAD/HEX AUTO-PARTITIONING OF CAD FOR IGA Mark R. Gammon, Robin M. Fairey, Peter D. Beben and Shakeel Seebooa 1 ITI Ltd mark.gammon@iti-global.com 2 ITI Ltd robin.fairey@iti-global.com 3 ITI Ltd peter.beben@iti-global.com 4 ITI Ltd shakeel.seebooa@iti-global.com