Parametric Solid Modeling

2006 ◽  
Author(s):  
Horea T. Ilies¸
Keyword(s):  
Heuristic Algorithms ◽  
Solid Modeling ◽  
Parametric Modeling ◽  
Geometric Constraints ◽  
Parametric Models ◽  
Open Problems ◽  
Solid Models ◽  
Modeling Systems ◽  
Alternative Approaches ◽  
And Performance

Parametric modeling systems are fundamentally changing the design process practiced in the industry today. Practically all commercial CAD systems combine established solid modeling techniques with constraint solving and heuristic algorithms to create, edit and manipulate solid models, while enforcing the requirement that every such solid model must maintain the validity of the prescribed geometric constraints. However, a number of fundamental (open) problems limit the functionality and performance of these parametric modeling systems. For example, the allowable parametric changes are history dependent; the number of parameters describing even relatively simple parts can quickly become prohibitively large, and commercial constraint solvers are limited today to 2-dimensional geometric constraints. Consequently, current parametric modeling systems do not support many practical design situations due to the associated theoretical and computational difficulties, as well as to the considerable organizational obstacles generated by the need to handle large parametric models. This paper investigates the current practices and limitations of parametric solid modeling systems, and explores some alternative approaches that could complement the identified limitations.

Motion-Based Shape Deformation of Solid Models

2007 ◽  
Author(s):  
Nier Wu ◽  
Horea T. Ilies¸
Keyword(s):  
Parametric Modeling ◽  
Parametric Models ◽  
Shape Deformation ◽  
Cross Sectional ◽  
New Approach ◽  
Geometric Invariants ◽  
Solid Models ◽  
Modeling Systems ◽  
Geometric Changes ◽  
Near Future

Mechanical designs undergo numerous geometric changes throughout the design process. Performing these changes relies, whenever possible, on the parametric models used to create the initial geometry. However, a number of open issues prevent the current parametric modeling systems to support many practical design situations, which, in turn, forces the geometry to evolve independently of the original parametric model. The fact that every parametric update can be expressed in terms of a sequence of shape deformations implies that the same geometric updates could be obtained, at least in principle, via shape deformation procedures that parameterize the deformation itself. In this paper we propose a new approach to create and edit solid models by introducing a geometric deformation procedure that relies on motion interpolation. We show that the proposed approach induces a parametrization of the deformation that allows direct control and editing of the deformation, is capable of preserving important geometric invariants such as constant cross-sectional properties of the deformed models, and maintains the ability to perform parametric optimization of the associated solid models. We conclude by discussing advantages and limitations of this approach as well as a number of important research directions that we will pursue in the near future.

Automatic Parametric Modeling From Non-Feature Based Designs for Additive Manufacturing

2021 ◽  
Author(s):  
Xinyi Xiao ◽  
Byeong-Min Roh
Keyword(s):  
Additive Manufacturing ◽  
3D Models ◽  
Parametric Modeling ◽  
Parametric Models ◽  
Performance Simulation ◽  
Cad Modeling ◽  
3D Cad ◽  
Feature Based ◽  
And Performance ◽  
The Given

Abstract The integration of Topology optimization (TO) and Generative Design (GD) with additive manufacturing (AM) is becoming advent methods to lightweight parts while maintaining performance under the same loading conditions. However, these models from TO or GD are not in a form that they can be easily edited in a 3D CAD modeling system. These geometries are generally in a form with no surface/plane information, thus having non-editable features. Direct fabricate these non-feature-based designs and their inherent characteristics would lead to non-desired part qualities in terms of shape, GD&T, and mechanical properties. Current commercial software always requires a significant amount of manual work by experienced CAD users to generate a feature-based CAD model from non-feature-based designs for AM and performance simulation. This paper presents fully automated shaping algorithms for building parametric feature-based 3D models from non-feature-based designs for AM. Starting from automatically decomposing the given geometry into “formable” volumes, which is defined as a sweeping feature in the CAD modeling system, each decomposed volume will be described with 2D profiles and sweeping directions for modeling. The Boolean of modeled components will be the final parametric shape. The volumetric difference between the final parametric form and the original geometry is also provided to prove the effectiveness and efficiency of this automatic shaping methodology. Besides, the performance of the parametric models is being simulated to testify the functionality.

Solution Selectors: A User-Oriented Answer to the Geometric Constraint Multiple Solution Problem

2001 ◽  
Author(s):  
Bernhard Bettig ◽  
Jami Shah
Keyword(s):  
Linear Equations ◽  
Independent Solution ◽  
Solid Modeling ◽  
Multiple Solution ◽  
Parametric Modeling ◽  
Geometric Constraints ◽  
Geometric Constraint ◽  
Basic Solution ◽  
Solution Selection ◽  
Solution Problem

Abstract The development of solid modeling to represent the geometry of designed parts and the development of parametric modeling to control the size and shape have had significant impacts on the efficiency and speed of the design process. Designers now rely on parametric solid modeling, but surprisingly often are frustrated by a problem that unpredictably causes their sketches to become twisted and contorted. This problem, known as the “multiple solution problem” occurs because the dimensions and geometric constraints yield a set of non-linear equations with many roots. This situation occurs because the dimensioning and geometric constraint information given in a CAD model is not sufficient to unambiguously and flexibly specify which configuration the user desires. This paper first establishes that only explicit, independent solution selection declarations can provide a flexible mechanism that is sufficient for all situations of solution selection. The paper then describes the systematic derivation of a set of “solution selector” types by considering the occurrences of multiple solutions in combinations of mutually constrained geometric entities. The result is a set of eleven basic solution selector types and two derived types that incorporate topological information. In particular, one derived type “concave/convex” is user-oriented and thought to be very useful.

A performance-based optimization approach for diffusive surface topology design

2020 ◽  
pp. 1351010X2096782
Author(s):  
Louena Shtrepi ◽  
Tomás Mendéz Echenagucia ◽  
Elena Badino ◽  
Arianna Astolfi
Keyword(s):  
Design Process ◽  
Performance Optimization ◽  
Parametric Modeling ◽  
Point Of View ◽  
Parametric Models ◽  
Topology Design ◽  
Surface Topology ◽  
Optimization Approach ◽  
Suitable Alternative ◽  
And Performance

Different numerical techniques have been used in the last decades for the acoustic characterization and performance optimization of sound diffusive surfaces. However, these methods require very long calculation times and do not provide a rapid feedback. As a result, these methods can hardly be applied by designers at early stages of the design process, when successive design iterations are necessary from an aesthetic point of view. A suitable alternative could be the use of parametric modeling in combination with performance investigations during the design process of sound diffusive surfaces. To this aim, this study presents a design process for diffusive surfaces topology optimization based on the combination of parametric models and geometrical acoustic simulations. It aims to provide architects and designers with rapid visual feedback on acoustic performances at a preliminary stage of the design process. The method has been tested on different case studies, which have been modelled based on geometric guidelines for diffusive surface optimization. The sensitivity of the method showed that it could be a very useful tool for comparisons among surface design alternatives. Finally, the advantages and limitations of the integrated optimization in comparison with conventional optimizations are discussed.

Solution Selectors: A User-Oriented Answer to the Multiple Solution Problem in Constraint Solving

2003 ◽  
Vol 125 (3) ◽  
pp. 443-451 ◽  
Author(s):  
Bernhard Bettig ◽  
Jami Shah
Keyword(s):  
Linear Equations ◽  
Independent Solution ◽  
Solid Modeling ◽  
Multiple Solution ◽  
Parametric Modeling ◽  
Geometric Constraints ◽  
Basic Solution ◽  
Solution Selection ◽  
Systematic Derivation ◽  
Solution Problem

The development of solid modeling to represent the geometry of designed parts and the development of parametric modeling to control the size and shape have had significant impacts on the efficiency and speed of the design process. Designers now rely on parametric solid modeling, but often are frustrated by a problem that unpredictably causes their sketches to become twisted, contorted, or take an unexpected shape. Mathematically, this problem, known as the “multiple solution problem” occurs because the dimensions and geometric constraints yield a set of non-linear equations with many roots. In practice, this situation occurs because the dimensioning and geometric constraint information given in a CAD model is not sufficient to unambiguously and flexibly specify which configuration the user desires. This paper first establishes that only explicit, independent solution selection declarations can provide a flexible mechanism that is sufficient for all situations. The paper then describes the systematic derivation of a set of “solution selector” types by considering the occurrences of multiple solutions in combinations of mutually constrained geometric entities. The result is a set of eleven basic solution selector types and two derived types that incorporate topological information. In particular, one derived type “concave/convex” is user-oriented and may prove to be particularly useful.

scholarly journals Comparison of Computer Extended Descriptive Geometry (CeDG) with CAD in the Modeling of Sheet Metal Patterns

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 685
Author(s):  
Manuel Prado-Velasco ◽  
Rafael Ortiz-Marín
Keyword(s):  
Sheet Metal ◽  
Computer Aided Design ◽  
Parametric Modeling ◽  
Descriptive Geometry ◽  
The Novel ◽  
Forming Process ◽  
Solid Models ◽  
Design Software ◽  
Solid Edge ◽  
Aided Design

The emergence of computer-aided design (CAD) has propelled the evolution of the sheet metal engineering field. Sheet metal design software tools include parameters associated to the part’s forming process during the pattern drawing calculation. Current methods avoid the calculation of a first pattern drawing of the flattened part’s neutral surface, independent of the forming process, leading to several methodological limitations. The study evaluates the reliability of the Computer Extended Descriptive Geometry (CeDG) approach to surpass those limitations. Three study cases that cover a significative range of sheet metal systems are defined and the associated solid models and patterns’ drawings are computed through Geogebra-based CeDG and two selected CAD tools (Solid Edge 2020, LogiTRACE v14), with the aim of comparing their reliability and accuracy. Our results pointed to several methodological lacks in LogiTRACE and Solid Edge that prevented to solve properly several study cases. In opposition, the novel CeDG approach for the computer parametric modeling of 3D geometric systems overcame those limitations so that all models could be built and flattened with accuracy and without methodological limitations. As additional conclusion, the success of CeDG suggests the necessity to recover the relevance of descriptive geometry as a key core in graphic engineering.

Geometric Reasoning Based on Graph Grammar Parsing

1994 ◽  
Vol 116 (3) ◽  
pp. 763-769 ◽  
Author(s):  
Z. Fu ◽  
A. de Pennington
Keyword(s):  
Intelligent Design ◽  
Feature Recognition ◽  
Geometric Reasoning ◽  
Geometric Constraints ◽  
Graph Grammar ◽  
Feature Interaction ◽  
Knowledge Based ◽  
Feature Based ◽  
Feature Information ◽  
And Performance

It has been recognized that future intelligent design support environments need to reason about the geometry of products and to evaluate product functionality and performance against given constraints. A first step towards this goal is to provide a more robust information model which directly relates to design functionality or manufacturing characteristics, on which reasoning can be carried out. This has motivated research on feature-based modelling and reasoning. In this paper, an approach is presented to geometric reasoning based on graph grammar parsing. Our approach is presented to geometric reasoning based on graph grammar parsing. Our work combines methodologies from both design by features and feature recognition. A graph grammar is used to represent and manipulate features and geometric constraints. Geometric constraints are used within symbolical definitions of features constraints. Geometric constraints are used within symbolical definitions of features and also to define relative position and orientation of features. The graph grammar parsing is incorporated with knowledge-based inference to derive feature information and propagate constraints. This approach can be used for the transformation of feature information and to deal with feature interaction.

scholarly journals ECLB: Edge-Computing-Based Lightweight Blockchain Framework for Mobile Systems

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Qingqing Xie ◽  
Fan Dong ◽  
Xia Feng
Keyword(s):  
Mobile Devices ◽  
Security Analysis ◽  
Edge Computing ◽  
Mobile Systems ◽  
Superior Performance ◽  
Consensus Protocol ◽  
Open Problems ◽  
Blockchain Technology ◽  
Natural Solution ◽  
And Performance

The blockchain technology achieves security by sacrificing prohibitive storage and computation resources. However, in mobile systems, the mobile devices usually offer weak computation and storage resources. It prohibits the wide application of the blockchain technology. Edge computing appears with strong resources and inherent decentralization, which can provide a natural solution to overcoming the resource-insufficiency problem. However, applying edge computing directly can only relieve some storage and computation pressure. There are some other open problems, such as improving confirmation latency, throughput, and regulation. To this end, we propose an edge-computing-based lightweight blockchain framework (ECLB) for mobile systems. This paper introduces a novel set of ledger structures and designs a transaction consensus protocol to achieve superior performance. Moreover, considering the permissioned blockchain setting, we specifically utilize some cryptographic methods to design a pluggable transaction regulation module. Finally, our security analysis and performance evaluation show that ECLB can retain the security of Bitcoin-like blockchain and better performance of ledger storage cost in mobile devices, block mining computation cost, throughput, transaction confirmation latency, and transaction regulation cost.

scholarly journals FREE LUNCH OR NO FREE LUNCH: THAT IS NOT JUST A QUESTION?

2012 ◽  
Vol 21 (03) ◽  
pp. 1240010 ◽  
Author(s):  
XIN-SHE YANG
Keyword(s):  
Convergence Analysis ◽  
Practical Importance ◽  
Metaheuristic Algorithms ◽  
Performance Evaluations ◽  
Algorithm Analysis ◽  
Free Lunch ◽  
Open Problems ◽  
No Free Lunch Theorems ◽  
And Performance ◽  
No Free Lunch

The increasing popularity of metaheuristic algorithms has attracted a great deal of attention in algorithm analysis and performance evaluations. No-free-lunch theorems are of both theoretical and practical importance, while many important studies on convergence analysis of various metaheuristic algorithms have proven to be fruitful. This paper discusses the recent results on no-free-lunch theorems and algorithm convergence, as well as their important implications for algorithm development in practice. Free lunches may exist for certain types of problem. In addition, we will highlight some open problems for further research.

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