Solid modeling (Panel Session)

Solid modeling for optimizing metal removal of three-dimensional NC end milling

The ACM Symposium on Solid and Physical Modeling and Applications is an annual international forum for the exchange of recent research results and applications of spatial modeling and computations in design, analysis and manufacturing, as well as in emerging biomedical, geophysical and other areas. Previous symposia in this series were held in Austin, Texas, 1991; Montreal, Canada, 1993; Salt Lake City, Utah, 1995; Atlanta, Georgia, 1997; Ann Arbor, Michigan in 1999 and 2001; Saarbrucken, Germany, 2002; and Seattle, Washington, 2003, and Genova, Italy, 2004. For additional information, visit www.solidmodeling.org, the home page of the Solid Modeling Association that oversees this symposia series.Since its inception in 1991, the ACM Symposium on Solid Modeling and Applications has been the primary venue for disseminating research results in the design, representation, analysis, visualization, and use of digital models of real or planned solid objects and of their bounding surfaces. At the same time, modeling solids entails not only handling their geometric shape, but also their physical properties and behaviors. To emphasize this broader mission, we have expanded the name of the 2005 Symposium to Solid and Physical Modeling (abbreviated SPM). SPM-05 was held on the MIT campus, in Cambridge, Massachusetts, in plenary sessions (no parallel tracks) from Monday June 13 to Wednesday June 15, and was followed by the <u>Shape Modeling International</u> (SMI) conference. Both SPM and SMI events are part of the <u>2005 Joint Convention on Solids and Shapes</u>, (S&S'05) hosted at MIT and chaired by Nick Patrikalakis. The <u>2004 Joint Convention on Shapes and Solids</u> took place in Genoa Italy.Some sixty technical papers have been submitted and were reviewed by the international program committee and expert reviewers from around the world. At least three to four external reviewers and members of the program committee reviewed and discussed each submission. A total of 22 refereed papers have been selected for plenary presentation and full paper publication in the proceedings. In addition, 6 more papers have been selected as technical sketches for shorter publication and presentation at the conference. The symposium program also includes two keynote presentations invited from leading authorities in their fields: Bruce Donald and James O'Brien. Another new feature in the symposium program was that we had three panel session where recent trends and challenges are discussed. The panel sessions were organized by Dimitris Metaxas (Biomedical Modeling), Michael Wang (Physical Modeling and Simulation), and Jan Vandenbrande (Design, Analysis, and Manufacturing).

Although curved-surface solid modeling systems achieve a higher level of accuracy than faceted systems, they also introduce a host of topological, geometric, and numerical complications. A method for calculating accurate boundary representations of solid models is introduced that reduces the impact of these complications. The method uses a pair of bounding polyhedral approximations to enclose the boundary of each object. A structural analysis automatically determines where to make adaptive refinements to the polyhedrons to assure the topological validity of the results. Potential singularities are localized. The implementation is an experimental extension to the Geometric Design Processor (GDP) solid modeling system. >

PLANT DESIGN ON MICROCOMPUTERS

Design changes are frequently encountered in the product development process. The complexity of the design changes is multiplied when the product design involves multiple engineering disciplines. Very often, a simple change in one part may propagate to its neighboring parts, therefore, affects the entire product assembly. Both parts and assembly must be regenerated for a physically valid product model, at the same time, the regenerated product model must meet designer’s expectations. When a product is being developed in a Concurrent Design and Manufacturing (CDM) environment, the design changes are usually implemented first by altering geometry of the product represented in computer-aided design (CAD) solid models. If the product solid model is not parameterized properly, the changes in geometry often lead to invalid parts or assembly. At the part level, the changes may yield a solid model with invalid geometric features if it is not properly parameterized. In this case, the entire product assembly is in vain. Even when individual parts of the product are regenerated correctly, parts may still penetrate to their neighboring parts or leave excessive gaps among them, if the solid model is not properly parameterized at the assembly level. In this paper, solid modeling and assembly techniques implemented in two major CAD tools, Pro/ENGINEER and SolidWorks, will be discussed. A set of guidelines will be proposed for the designers to parameterize the solid models in order to capture the design intents more effectively in the product virtual mockup. These guidelines at both part and assembly levels will support designers to successfully conduct product design in the CDM environment. A number of examples, including a slider-crank mechanism and its crankshaft, a single-piston airplane engine and its components, as well as a number of simpler parts are presented to illustrate and demonstrate the parameterization method and guidelines proposed for both Pro/ENGINEER and SolidWorks.

The ACM Symposium on Solid and Physical Modeling and Applications is an annual international forum for the exchange of recent research results and applications of spatial modeling and computations in design, analysis and manufacturing, as well as in emerging biomedical, geophysical and other areas. Previous symposia in this series were held in Austin, Texas, 1991; Montreal, Canada, 1993; Salt Lake City, Utah, 1995; Atlanta, Georgia, 1997; Ann Arbor, Michigan in 1999 and 2001; Saarbrucken, Germany, 2002; Seattle, Washington, 2003; Genova, Italy, 2004, Cambridge, Massachusetts, 2005; Cardiff, Wales, United Kingdom, 2006; and Beijing, China, 2007. For additional information, please visit www.solidmodeling.org, the home page of The Solid Modeling Association that oversees this symposium series. The SPM symposium series started initially with the name "ACM Symposium on Solid Modeling and Applications." To emphasize the fact that solid modeling entails not only handling their geometric shapes, but also their physical properties, behaviors and simulations, the name of the symposium was expanded to The ACM Symposium on Solid and Physical Modeling and Applications (abbreviated as SPM) in 2005. SPM'08 was held at Suny, Stony Brook from June 2 to June 4, as part of Stony Brook Modeling Week that also featured international joint convention on shapes and solids. SPM'08 was held as a single track conference, which also included two mini-symposia. In response to SPM'08 call for papers, 79 technical papers were submitted and reviewed by an international program committee with 96 expert reviewers from around the world. At least three external reviewers and members of the program committee reviewed and discussed each submission. A total of 25 refereed papers have been selected for plenary presentation and publication in the proceedings as full papers. Moreover, a total of 18 refereed papers have been selected for poster presentation and publication in the proceedings as short papers. The symposium program also includes three invited presentations, by Helmut Pottmann (Vienna University of Technology), Hugues Hoppe (Microsoft Research) and Kokichi Sugihara (University of Tokyo), all leading researchers in their fields.

This paper presents a new methodology for resolving visible surface images of solid models derived from Boolean combinations of volumetric building blocks. The algorithm introduced here is an extension of well-established scan-line hidden surface removal procedures, and it integrates knowledge of a Boolean construction tree in the surface resolution process. Several hidden surface coherence properties are discussed in terms of their possible exploitation in the intricate solid model visualization process. While many of the earlier coherence techniques depend on a polygon environment in which surfaces and volumes do not intersect, the Boolean process can not afford that luxury because it is inherently required to handle intersecting volumes and surfaces. Initial tests indicate that substantial performance improvements over previous methods can be achieved with the algorithm described in this paper, and that these improvements increase as model complexity increases.An underlying philosophy of a dual solid modeling system is proposed in this paper. It suggests that two solid modelers are necessary to successfully satisfy both analytical precision requirements and user interface visualization requirements. The visual solid modeling task addressed in this paper provides greatly improved response capabilities, as compared to other systems, by striving to optimize the constructive solid model (CSG) solid model computations specifically for display purposes.

The major objective of this paper is to develop a front-end scheme necessary for interfacing the tolerance module with the solid model. This includes the development of (i) an efficient user interfacing system for inputing tolerance information, (ii) a suitable tolerancing data module (to be attached to the solid model), and (iii) an information retrieval system from the stored database for future tolerance analysis. This work has been developed with the help of the Quick Turnaround Cell (QTC) Design System [7], [8] and TWIN Solid Model Package [4], developed at the Purdue Engineering Research Center (ERC).

NC machine tool path generation from CSG part representations

Design engineers create models of design artifacts with commercial Computer Aided Design (CAD) solid modeling systems and manage the data files through Product Data Management (PDM) systems. These systems stop short of providing support for querying and retrieving data from “within” the CAD data files. A true CAD query language that allows designers the flexibility to describe queries against single and multiple CAD files would be of great benefit for design engineers. This query language ought to be both datacentric and user-centric in nature. The design exemplar, a datastructure that provides a standard representation of design knowledge based upon a general constraint validation and satisfaction algorithm, is shown here to be a concept upon which a CAD query language may be developed. The first required extension of the design exemplar is the inclusion of logical connectives. Some insights into the different levels at which the extensions may be implemented are discussed. Also, some applications retrieving geometric data using this query language are demonstrated. The query language, as it evolves, is expected to support geometric retrieval across domains and offer an all-purpose approach to geometric retrieval.

A spatially-segmented solids database — justification and design

Parametric 3D finite-element mesh generation

This paper studies the numerical and geometric properties of interval B-splines, a newly developed geometric representation introduced for increased robustness in solid modeling systems and for uncertainty representation in data fitting problems. Interval B-spline curves and surfaces have some unique properties that are different from classical B-splines. The properties discussed in this paper include error propagation in the evaluation of B-spline basis functions using rounded interval arithmetic, width of an interval B-spline curve or surface, transformation of interval B-splines, hodograph of an interval B-spline curve, enveloping curves or surfaces of an interval B-spline curve or surface, variation diminishing property, and knot insertion for interval B-splines.

An approach for the fully automatic generation of three‐dimensional finite element meshes is presented. The method is specifically designed for use with solid modelling systems which provide a complete and unique definition of the geometry of a part. The method follows from the basic concepts of the octree encoding technique with specific modifications made to produce valid, user controllable finite element meshes. Example problems are included to demonstrate the technique.

In solid modeling systems, the stability of Boolean set operation algorithms is an important issue. The stability can be achieved by using the homogeneous processing, which is proposed by one of the authors, and the exact integer arithmetic. The variable integer data type can represent very large integers by changing the size of the date length. However, the increase of the data length of integers leads to the increase of the computation time. In geometric algorithms, the signs of determinants are necessary to modify the topological data structure. The previous method adaptively and repeatedly extracts 8 bits from variable integer data to detect the signs of 4×4 determinants. The previously proposed method detects the signs of determinants using an FPU. In this paper, a more efficient method is proposed for detecting the signs of 4×4 determinants by extracting 16 bits. The algorithm can detect the signs of 4×4 determinants faster than the previous algorithm.