Showing papers in "Engineering With Computers in 2004"
TL;DR: This paper presents a procedure under development for the automatic generation of general curved element mesh modification procedures to correct any invalid elements created by the curving of mesh entities on the model boundary, which is required to ensure a properly geometric approximation of the domain.
Abstract: To achieve the exponential rates of convergence possible with the p-version finite element method requires properly constructed meshes In the case of piecewise smooth domains, these meshes are characterized by having large curved elements over smooth portions of the domain and geometrically graded curved elements to isolate the edge and vertex singularities that are of interest This paper presents a procedure under development for the automatic generation of such meshes for general three-dimensional domains defined in solid modeling systems Two key steps in the procedure are the determination of the singular model edges and vertices, and the creation of geometrically graded elements around those entities The other key step is the use of general curved element mesh modification procedures to correct any invalid elements created by the curving of mesh entities on the model boundary, which is required to ensure a properly geometric approximation of the domain Example meshes are included to demonstrate the features of the procedure
82 citations
TL;DR: In this paper, the authors present a method to compute compatible triangulations of planar polygons, sometimes requiring extra Steiner vertices, and show how to increase the quality by adding Steiner nodes in a compatible manner, using remeshing and mesh smoothing.
Abstract: Compatible meshes are isomorphic meshings of the interiors of two polygons having a correspondence between their vertices. Compatible meshing may be used for constructing sweeps, suitable for finite element analysis, between two base polygons. They may also be used for meshing a given sequence of polygons forming a sweep. We present a method to compute compatible triangulations of planar polygons, sometimes requiring extra (Steiner) vertices. Experimental results show that for typical real-life inputs, the number of Steiner vertices introduced is very small. However, having a small number of Steiner vertices, these compatible triangulations are usually not of high quality, i.e. they do not have well-shaped triangles. We show how to increase the quality of these triangulations by adding Steiner vertices in a compatible manner, using remeshing and mesh smoothing techniques. The total scheme results in high-quality compatible meshes with a small number of triangles. These meshes may then be morphed to obtain the intermediate triangulated sections of a sweep, if needed.
53 citations
TL;DR: CCSweep is a new method to automatically decompose multi-sweepable volumes into many-to-one sweepable volumes that have only single target faces and are represented in the meshing system as real, solid geometry, enabling them to be automatically meshed using existing many- to-one hexahedral sweeping approaches.
Abstract: CCSweep is a new method to automatically decompose multi-sweepable volumes into many-to-one sweepable volumes. Multi-sweepable volumes contain both multiple source and multiple target faces. In hexahedral mesh generation, most sweeping techniques handle many-to-one sweepable volumes that contain multiple source faces, but they are limited to volumes with only a single target face. Recent proposals to solve the multi-sweep problem have several disadvantages, including: indeterminate edge sizing or interval matching constraints, over-dependence on input mesh discretization, loop Boolean restrictions on creating only loops with even numbers of nodes, and unstable loop imprinting when interior holes exist. These problems are overcome through CCSweep. CCSweep decomposes multi-sweep volumes into many-to-one sweepable sub-volumes by projecting the target faces through the volume onto corresponding source faces. The projected faces are imprinted with the source faces to determine the decomposition of the solid. Interior faces are created to decompose the volume into separate new volumes. The new volumes have only single target faces and are represented in the meshing system as real, solid geometry, enabling them to be automatically meshed using existing many-to-one hexahedral sweeping approaches. The results of successful application of CCSweep to a number of problems are shown in this paper.
50 citations
TL;DR: A set of tools that are sufficient to measure the geometric complexity of a solid are proposed that have been tested on many industrial models and can be extended to consider other non-geometric factors that influence the mesh size, such as physics, boundary conditions, etc.
Abstract: This paper focuses on the generation of a three-dimensional (3D) mesh sizing function for geometry-adaptive finite element (FE) meshing. The mesh size at a point in the domain of a solid depends on the geometric complexity of the solid. This paper proposes a set of tools that are sufficient to measure the geometric complexity of a solid. Discrete skeletons of the input solid and its surfaces are generated, which are used as tools to measure the proximity between geometric entities and feature size. The discrete skeleton and other tools, which are used to measure the geometric complexity, generate source points that determine the size and local sizing function at certain points in the domain of the solid. An octree lattice is used to store the sizing function as it reduces the meshing time. The size at every lattice-node is calculated by interpolating the size of the source points. The algorithm has been tested on many industrial models, and it can be extended to consider other non-geometric factors that influence the mesh size, such as physics, boundary conditions, etc.
45 citations
TL;DR: An algorithm based on tracing the neighbours of intersecting triangles (TNOIT) is proposed to determine the intersection lines, which will drastically reduce the time of geometrical checking for intersections between triangles, making the surface intersection and mesh generation a quasi-linear process with respect to the number of elements involved.
Abstract: The use of discrete data to represent engineering structures as derivatives from intersecting components requires algorithms to perform Boolean operations between groups of triangulated surfaces. In the intersection process, an accurate and efficient method for the determination of intersection lines is a crucial step for large scale and complex surface intersections. An algorithm based on tracing the neighbours of intersecting triangles (TNOIT) is proposed to determine the intersection lines. Given the node numbers at the vertices of the triangles, the neighbour relationship is first established. A background grid is employed to limit the scope of searching for candidate triangles that may intersect. This will drastically reduce the time of geometrical checking for intersections between triangles, making the surface intersection and mesh generation a quasi-linear process with respect to the number of elements involved. In the determination of intersection between two triangles, four fundamental cases are identified and treated systematically to enhance robustness and reliability. Tracing the neighbours for the determination of intersection lines not only greatly increases the efficiency of the process, it also improves the reliability as branching and degenerated cases can all be dealt with in a consistent manner on the intersecting surfaces concerned. Five examples on a great variety of surface and mesh characteristics are given to demonstrate the effectiveness and robustness of the algorithm.
39 citations
TL;DR: Two optimization approaches are described, one which improves the quality of elements as much as possible and the other which improves element quality but also keeps the new mesh as close as possible to the original mesh.
Abstract: A procedure has been developed to improve polygonal surface mesh quality while maintaining the essential characteristics of the discrete surface The surface characteristics are preserved by repositioning mesh vertices so that they remain on the original discrete surface The repositioning is performed in a series of triangular-facet-based local parametric spaces The movement of the mesh vertices is driven by a nonlinear numerical optimization process Two optimization approaches are described, one which improves the quality of elements as much as possible and the other which improves element quality but also keeps the new mesh as close as possible to the original mesh
36 citations
TL;DR: This paper will review several of the issues associated with accessing geometry for mesh generation and evaluate alternative techniques for accessing geometry and how these techniques address, or do not address, the issues related to geometry access forMesh generation.
Abstract: One of the major issues of mesh generation today is access to geometry in an accurate and efficient manner. This paper will review several of the issues associated with accessing geometry for mesh generation. This paper will also evaluate alternative techniques for accessing geometry and review how these techniques address, or do not address, the issues related to geometry access for mesh generation. The techniques for geometry access to be reviewed include: translation and healing, discrete representations, direct geometry access, and unified topology accessing geometry directly. The intent of this paper is to provide an overview to the alternative approaches and how they address the specific issues related to accessing geometry for mesh generation. It is not the intent of this paper to provide detailed algorithms related to accessing or repairing geometry data.
32 citations
TL;DR: A method for mapping between the parametric spaces of regions of structured and semi-structured mesh, and methods for representing these regions and interfaces between them are described, and a 57% reduction in mesh storage cost is demonstrated.
Abstract: Structured and semi-structured (a.k.a. swept or extruded) hexahedral meshes are used in many types of engineering analysis. In finite element analysis, regions of structured and semi-structured mesh are often connected in an unstructured manner, preventing the use of a globally consistent parametric space to represent these meshes. This paper describes a method for mapping between the parametric spaces of such regions, and methods for representing these regions and interfaces between them. Using these methods, a 57% reduction in mesh storage cost is demonstrated, without loss of any information. These methods have been implemented in the MOAB mesh database component, which provides access to these meshes from both structured and unstructured functions. The total cost for representing structured mesh in MOAB is less than 25 MB per million elements using double-precision vertex coordinates; this is only slightly larger than the space required to store vertex coordinates alone.
27 citations
TL;DR: A fully automatic surface mesh generation system is presented in this paper, achieved by an automatic determination of a consistent mesh size distribution, which is based on geometry rasterisation.
Abstract: A fully automatic surface mesh generation system is presented in this paper The automation is achieved by an automatic determination of a consistent mesh size distribution, which is based on geometry rasterisation The user specifies a minimal and maximal allowed mesh size, and a maximal allowed curvature angle for the complete geometry, or, rather, parts of it Now, these local curvature and local characteristic lengths of the geometry are computed, which determine the local mesh size These local mesh sizes are stored and smoothed in a Cartesian background mesh Afterwards, the triangulation is generated by an advancing front triangulator: the local resolution of the surface triangulation is determined by the mesh sizes stored in the Cartesian background mesh The object-oriented design and implementation is described The complete system is very fast due to an efficient parallelisation based on MPI for computer systems with distributed memory
27 citations
TL;DR: The paper presents a method of synthesising cam profiles based on the use of piecewise polynomials together with an optimisation technique, manipulating the variables in the linear system to select the ideal combination.
Abstract: The paper presents a method of synthesising cam profiles based on the use of piecewise polynomials together with an optimisation technique. Special cases and limitations are discussed and illustrated, making the procedure complete and systematic for any design requirements. Using piecewise polynomials, the complete cam profile can be designed as a combined linear system. The optimisation technique described goes even further, manipulating the variables in the linear system to select the ideal combination. In addition, a means to prove the validity of the results is explained.
25 citations
TL;DR: This paper presents the design, implementation, and evaluation of the etree, a database-oriented method for large out-of-core octree mesh generation.
Abstract: This paper presents the design, implementation, and evaluation of the etree, a database-oriented method for large out-of-core octree mesh generation. The main idea is to map an octree to a database structure and perform all octree operations by querying and updating the database. We apply two standard database techniques, the linear octree and the B-tree, to index and store the octants on disk. Then we introduce two new techniques, auto-navigation and local balancing, to address the special needs of mesh generation. Preliminary evaluation suggests that the etree method is an effective way of generating very large octree meshes on desktop machines.
TL;DR: In this paper, a simple anisotropic modification of Floater's shape-preserving parameterization scheme is presented, where the original scheme is formulated as a discrete energy minimization and the modification is performed by introducing an additional stretching term.
Abstract: We introduce a simple anisotropic modification of Floater’s shape-preserving parameterization scheme. The original scheme is formulated as a discrete energy minimization and the modification is performed by introducing an additional stretching term. Results and example applications to anisotropic regular surface meshing are presented.
TL;DR: A computing approach to the provision of best practice advice within a workflow-enabled engineering computing environment and the initial implementation and population of the BPA are described, and some early feedback from prototype trials are presented.
Abstract: Engineering design teams today are often widely distributed, and design authority is shared between collaborating companies. Technology is changing rapidly, and understanding of the most appropriate approach to the application of engineering assessment tools is developing accordingly. There is therefore a need to support coordination and auditing of engineering processes, and to provide best practice advice. This paper describes a computing approach to the provision of best practice advice within a workflow-enabled engineering computing environment. The engineering context is described using a formal information model for automotive engineering analysis processes, embedded in an object database. This same model is used to associate best practice advice documents with the engineering context. The best practice adviser (BPA) system assembles four types of information: general information that is pertinent to a particular activity, irrespective of the context in which it is taking place; context-specific information that is pertinent to the particular circumstance in which an activity is taking place; errors and warnings that may be encountered in the activity, especially when software is being used, and examples of previous application of the activity in related contexts. The BPA is implemented in a three-tier architecture using server pages technology. In the absence of any suitable matching information for a particular context in the BPA database, the BPA Server can execute a “close-match” algorithm which searches the database for information that is provided on contexts that are close to the user’s interest. The paper describes the initial implementation and population of the BPA, and presents some early feedback from prototype trials.
TL;DR: The approach solves the problem in a novel way that is close to the design convention, and is dealing with the developability problem of an arbitrarily trimmed NURBS patch.
Abstract: Developable surfaces are desired in designing products manufactured from planar sheets. Trimmed non-uniform rational B-spline (NURBS) surface patches are widely adopted to represent 3D products in CAD/CAM. This paper presents a new method to increase the developability of an arbitrarily trimmed NURBS surface patch. With this tool, designers can first create and modify the shape of a product without thinking about the developable constraint. When the design is finished, our approach is applied to increase the developability of the designed surface patches. Our method is an optimisation-based approach. After defining a function to identify the developability of a surface patch, the objective function for increasing the developability is derived. During the optimisation, the positions and weights of the free control points are adjusted. When increasing the developability of a given surface patch, its deformation is also minimised and the singular points are avoided. G0 continuity is reserved on the boundary curves during the optimisetion, and the method to reserve G1 continuity across the boundaries is also discussed in this paper. Compared to other existing methods, our approach solves the problem in a novel way that is close to the design convention, and we are dealing with the developability problem of an arbitrarily trimmed NURBS patch.
TL;DR: This paper proposes a method to identify, on a mesh, geometric primitives commonly used in mechanical parts (plane, sphere, cylinder, torus, cone) in order to improve the quality of the surface remeshing.
Abstract: In this paper, we propose a method to identify, on a mesh, geometric primitives commonly used in mechanical parts (plane, sphere, cylinder, torus, cone) in order to improve the quality of the surface remeshing. We have already presented techniques to adapt an existing surface mesh based on a mesh-free technique denoted as diffuse interpolation. In this approach, a secondary local geometrical model is built from the mesh. From this model, principal curvatures are calculated and the type of surface can be determined from the computation of the curvatures. Some of the concepts presented here are original while others have been adapted from techniques used in reverse engineering. Our approach is not limited to feature recognition on meshes but has been extended to a set of points.
TL;DR: An objective function for optimization-based smoothing is proposed that can be used to untangle and smooth a mesh in a single process and has higher order continuous derivatives that make it suitable for optimization techniques.
Abstract: An objective function for optimization-based smoothing is proposed for both linear and quadratic triangular and quadrilateral elements. Unlike currently published objective functions that are used to perform smoothing or untangling separately, this objective function can be used to untangle and smooth a mesh in a single process. The objective function is designed in such a way that it is easy and straightforward to be extended to higher order elements. The objective function has higher order continuous derivatives that make it suitable for optimization techniques. It has been shown empirically that the proposed function only has one minimum. With the integration of the proposed new objective function into our optimization-based smoothing algorithm, our combined Laplacian/optimization smoothing scheme provides us with satisfactory high quality meshes.
TL;DR: An a posteriori approach to unstructured mesh generation via a localized truncation error analysis is presented and applies to the western North Atlantic tidal (WNAT) model domain and focuses on the area surrounding the Bahamas.
Abstract: This paper presents an a posteriori approach to unstructured mesh generation via a localized truncation error analysis and applies it to the western North Atlantic tidal (WNAT) model domain. The WNAT model domain encompasses the Gulf of Mexico, the Caribbean Sea and the North Atlantic Ocean east to the 60°W meridian. In this paper, we focus on the area surrounding the Bahamas. A bathymetric data set with fine resolution is employed in separate linear, harmonic simulations of shallow water tidal flow for seven different tidal-forcing constituents. Each set of simulation results is used to perform a truncation error analysis of a linear, harmonic form of the depth-averaged momentum equations for each of the different tidal-forcing frequencies. The process has been built upon successful research aiming to produce unstructured grids for large-scale domains that can be used in the accurate and efficient modelling of shallow water flow. The methodology described herein can also be transferred to other modelling applications.
TL;DR: A new multi-loop-cascaded governor is proposed for hydro turbine controls that ensures that the overall system remains asymptotically stable for all norm-bounded uncertainties.
Abstract: In the present paper, a new multi-loop-cascaded governor is proposed for hydro turbine controls. A turbine model is obtained that covers the effects of the water hammer, travelling waves, inelastic water penstocks and head loss due to the friction. Plant parameter uncertainties are taken into account to investigate stability robustness. The polynomial H∞ robust control design method is used to design the multi-loop-cascaded governor. Water and load disturbance, and permanent oscillations in the power systems such as inter-area modes are included in the robust design procedure. Robust performance is achieved by using parameterised dynamic weighting functions of the design theory. The designed governor ensures that the overall system remains asymptotically stable for all norm-bounded uncertainties. Simulation results show that the system performance specifications and stability margins are improved significantly even in the presence of parameter uncertainties.
TL;DR: The numerical tests presented demonstrate the computational advantage of the proposed approach of ESs combined with functional networks (FNs) which become pronounced for fairly large scale optimisation problems involving about 700 degrees of freedom.
Abstract: In this work, the input for large space structures is created using the Formex algebra of the Formian software. The different search and optimisation algorithm known as evolution strategies (ESs) has been applied to find the optimal design of the space trusses considering the areas of the members of the space structures as discrete variables. The objective function is obtained for first few generations by using a structural analysis package such as Feast and for other generations by functional networks (FNs). Initially, to obtain the data for a functional network, a structural package such as Feast is used. The use of a functional network is motivated by time consuming repeated analyses required by evolution strategies during the optimisation process. In addition, a multilevel optimisation approach is implemented by reducing the size of the search space for individual design variables in each successive level of the optimisation process for the first example; for the remaining three examples, a functional network has been combined with evolution strategies to get away with the use of a structural analysis package and a multilevel optimisation technique. The numerical tests presented demonstrate the computational advantage of the proposed approach of ESs combined with functional networks (FNs) which become pronounced for fairly large scale optimisation problems involving about 700 degrees of freedom.
TL;DR: This paper outlines an algorithm for the continuous non-linear approximation of procedurally defined curves that uses the continuous L_2 form metric based on minimizing the integral of the least square error metric between the original and approximate curves.
Abstract: This paper outlines an algorithm for the continuous non-linear approximation of procedurally defined curves. Unlike conventional approximation methods using the discrete L_2 form metric with sampling points, this algorithm uses the continuous L_2 form metric based on minimizing the integral of the least square error metric between the original and approximate curves. Expressions for the optimality criteria are derived based on exact B-spline integration. Although numerical integration may be necessary for some complicated curves, the use of numerical integration is minimized by a priori explicit evaluations. Plane or space curves with high curvatures and/or discontinuities can also be handled by means of an adaptive knot placement strategy. It has been found that the proposed scheme is more efficient and accurate compared to currently existing interpolation and approximation methods.
TL;DR: An analytic characterization of quadrangular shape is provided, and existing concepts of stretching and skewness, earlier proposed for specific geometries, are generalized and extended to quadrilaterals and their respective extremal and asymptotic behaviors examined.
Abstract: This article examines the quality assessment of planar quadrilateral mesh elements in a comprehensive way. First, an analytic characterization of quadrangular shape is provided, and existing concepts of stretching and skewness, earlier proposed for specific geometries, are generalized. Then, two triangle quality measures are extended to quadrilaterals and their respective extremal and asymptotic behaviors examined, showing in particular that even if needed they cannot detect the triangular degeneracy of a quadrilateral. An existing quality measure is then discussed, which is able to handle this case. In particular, an unbalanced asymptotic behavior is demonstrated, justifying the need for a new approach. Toward this goal, the triangle quality measure based on Frobenius norm is modified in order to replace equilateral reference element by right isosceles triangles, with control on the specific right angle. Finally, two new quadrilateral quality measures are designed and examined using these results. Numerical results illustrate the matter.
TL;DR: An adaptive quadrilateral refinement process with a goal-oriented error estimation, in which a posteriori error is estimated with respect to the specified quantity of interest.
Abstract: A posteriori error estimation in finite element analysis serves as an important guide to the meshing tool in an adaptive refinement process. However, the traditional posteriori error estimates, which are often defined in the energy or energy-type norms over the entire domain, provide users insufficient information regarding the accuracy of specific quantities in the solution. This paper describes an adaptive quadrilateral refinement process with a goal-oriented error estimation, in which a posteriori error is estimated with respect to the specified quantity of interest. A highlight of this paper is the demonstration of tools described in the paper used in a practical industrial environment. The performance of this process is demonstrated on several practical problems where the comparison is with the adaptive process based on the traditional error estimation.
TL;DR: This paper concerns the simplification of composite parametric surface meshes which conform to the boundary of each constituting patch, and the goal is to eliminate the small edges which result from this boundary patch preserving constraint.
Abstract: This paper concerns the simplification of composite parametric surface meshes which conform to the boundary of each constituting patch. The goal is to eliminate the small edges which result from this boundary patch preserving constraint, provided that these small edges belong to an almost flat area. To this end, two tolerance areas with respect to the initial reference mesh are introduced to keep close to the surface. The reference mesh is then simplified and optimized (in terms of shape quality) so that the resulting mesh belongs to these tolerance areas. Several examples of surface meshes are provided in order to assess the efficiency of the simplification method.
TL;DR: An optimizer was developed to adjust virtually the forming process of a linear cylindrical vase by determining the optimal forming parameters and the numerical tools were validated during trial campaigns carried out in crystal glass-makers.
Abstract: To answer an increasing need for glass product manufacturing in both small and medium series, the first glass-blower robot was recently developed. In the face of this new technology, which particularly interests crystal glass-makers, expertise remains the main decision-making element which intervenes in the choices of the design and implementation of these new processes. Finite element models of this new blowing process were developed. After the analysis of the process and of these stages, an initial sensibility study allowed us to find the essential parameters for the success of the operation. With the results of these sensitivity analyses, an optimizer was developed to adjust virtually the forming process of a linear cylindrical vase by determining the optimal forming parameters. A second optimization allowed us to determine the initial shape of the parison, an essential parameter in the successful forming of a convex cylindrical vase. Finally, the numerical tools were validated during trial campaigns carried out in crystal glass-makers.
TL;DR: A systematic method for representing and analysing coupled integrated engineering systems by means of general discrete mathematical models, called Combinatorial Representations, that can be conveniently implemented in computers are introduced.
Abstract: The current paper introduces a systematic method for representing and analysing coupled integrated engineering systems by means of general discrete mathematical models, called Combinatorial Representations, that can be conveniently implemented in computers. The combinatorial representation of this paper, which is based on graph theory, was previously shown to be useful in representing engineering systems from different engineering domains. Once all of the subsystems of an integrated multidisciplinary system are brought up to the common level of the combinatorial representation, they cease to be separated from one another and the analysis process is applied to all of the engineering elements disregarding the domain to which they belong.During the development of the representation and study of its inherent properties, special attention was dedicated to developing an efficient analysis method. A vectorial extension of the mixed variable method known from electrical network theory was found to be the most suitable choice for this purpose.In the paper, the approach is implemented by representing and analysing two systems: one that is a macro system comprised of truss, dynamic and electric elements, and another that is a comb-driven micro-resonator. The techniques presented in the paper are not limited to analysis only, but can be applied to many other aspects of engineering research. Among them is a systematic derivation of new ways of presenting engineering elements, one of which – the process of derivation of a new type of force representation entitled “face force” – is described in the paper.
TL;DR: The paper demonstrates the transformation of the known method in planetary gear trains—the Willis method—to two other engineering systems: linkages and trusses, and enables a systematic derivation of engineering knowledge through knowledge transformations between the graph representations.
Abstract: The paper introduces an approach for transforming methods and knowledge between different engineering fields through general discrete mathematical models, called graph representations, which carry engineering knowledge of specific systems. The idea is demonstrated by showing the transformation of the known method in planetary gear trains—the Willis method—to two other engineering systems: linkages and trusses. In doing so, two efficient methods were derived: one for analysing compound linkages, such as those containing tetrads, and another for compound trusses. These new methods were derived from two relations characterising graph representations: a representation that is common to two engineering fields and the duality relation between representations. The new approach underlying these transformations is shown to open new ways of conducting engineering research by enabling a systematic derivation of engineering knowledge through knowledge transformations between the graph representations.
TL;DR: This paper develops a fast and efficient method for creating the facetted approximations of the medial surfaces of extrusions generated by sweeping along the normal direction to the generating cross-section.
Abstract: Generating the medial surface for a general boundary representation model raises several difficulties. Problems might emerge from the complexity of the resulting equations, singularities caused by unforeseen relative boundary element positions and orientations, etc. The majority of the current algorithms are based on the topology of the boundary representation model and produce wireframes composed of straight lines regardless of the real medial surfaces. Many of the solids used in engineering can be represented by extrusions, delimited by a cross-section and an extrusion distance. This paper develops a fast and efficient method for creating the facetted approximations of the medial surfaces of extrusions generated by sweeping along the normal direction to the generating cross-section.
TL;DR: A new modelling approach is presented that supports the designer during the transformation of a concept to an embodied solution and its capabilities and potential for supporting the embodiment of systems and the important task of design synthesis are demonstrated.
Abstract: In today’s global markets the commercial success of a product, however defined, is highly dependent upon the rapid and efficient transformation of an engineering system from a design schema to a fully embodied optimal solution. The ability of the designer to achieve this is severely frustrated by the analytically intensive and time-consuming aspects of embodying a concept. This is particularly the case where standard components have to be considered. This paper presents a new modelling approach that supports the designer during the transformation of a concept to an embodied solution. This modelling approach provides for the representation of conceptual schemas and their subsequent embodiment with standard components from third-party electronic representations. The modelling strategies and associated software issues for representing a mechanical system, handling the interactions between components and incorporating the governing representations for the design and selection of individual components are discussed. The process of constructing a system model, specifying the desired performance characteristics and the process of system resolution are also described. The paper concludes with an industrial case study which is used to demonstrate the capabilities and potential of the new approach for supporting the embodiment of systems and the important task of design synthesis.
TL;DR: This paper presents an approach designed to support convenient management and analysis of multiple design configurations, and to provide a high degree of spatial and temporal congruence for model visualization, thereby allowing more direct comparisons to be made.
Abstract: Current methods of analyzing multiple design configurations can be labor intensive and typically require engineers to make relatively indirect comparisons between structural models This paper presents an approach designed to support convenient management and analysis of multiple design configurations, and to provide a high degree of spatial and temporal congruence for model visualization, thereby allowing more direct comparisons to be made This ultimately can allow for a more thorough evaluation of design alternatives, while decreasing the workload needed to perform these analyses
TL;DR: Examples are given in the paper to show the feature line extraction, the influence of the feature lines extracted under different resolutions, and the final reconstructed B-spline surfaces based on these feature lines.
Abstract: In this paper, multiresolution models are employed in the context of reverse engineering for feature line extraction Starting with a proper triangulation of the cloud point data as a priori, our feature line extraction algorithm has three steps: (1) establishing a Gauss normal sphere and creating multiresolution models for the Gauss sphere based on different levels of subdivisions for the sphere regions; (2) mapping the unit normal vectors of triangular faces in the multiresolution Gauss sphere and merging those connected triangular faces whose unit normal vectors fallen on the same Gauss sphere region with a given resolution to form super-faces (the collection of triangular facets with similar normal); and (3) extracting the boundaries from the super-faces and generating the feature lines from the extracted boundaries We then use these feature lines as a base for tracing boundary curves for B-spline surface construction Since feature lines maintain the characteristics of the original product models, in this way, we have a good chance to reconstruct B-spline surfaces with high quality Examples are given in the paper to show the feature line extraction, the influence of the feature lines extracted under different resolutions, and the final reconstructed B-spline surfaces based on these feature lines