Conceptual Design by a Topology Consistent Skeletal Modeler With Convolution Surfaces

2013 ◽  
Author(s):  
Guohua Ma ◽  
Richard H. Crawford
Keyword(s):  
Conceptual Design ◽  
Three Dimensional ◽  
Design Concept ◽  
Design Stage ◽  
Field Function ◽  
Design Engineers ◽  
Convolution Surfaces ◽  
Dimensional Object ◽  
Skeletal Model ◽  
Lower Dimensional

During the conceptual design stage, the design engineers usually sketch their design ideas. For those sketches, the skeleton of the design idea can be created with lower dimensional primitives like lines, arcs, etc. In this paper, we focus on skeletal modeling, which is an approach to creating solid models in which the engineer designs with lower dimensional primitives such as points, lines, and triangles. The skeleton is then “skinned over” to create the surfaces of the three dimensional object. Then the convolution surfaces are generated by convolving a kernel function with a geometric field function to create an implicit surface. We propose that skeleton, even it is simple, contains important design information, such as the geometric, topology that defines the design concept. It is very important to keep the topology of the skeleton and thus the important information that defines the design concept, i.e, the geometry of the product, the functionality of the product determined by the topology of the design. We assume that design engineers expect the topology of a skeletal model to be identical to that of the underlying skeleton. In this paper, the system is described and some examples are illustrated to use the skeletal based modeler.

Identifying the Critical Points of Skeleton-Based Convolution Surfaces for Conceptual Design

2007 ◽  
Author(s):  
Guohua Ma ◽  
Richard H. Crawford
Keyword(s):  
Critical Points ◽  
Three Dimensional ◽  
Analytic Solutions ◽  
Field Function ◽  
Solid Models ◽  
Convolution Surfaces ◽  
Will Force ◽  
Dimensional Object ◽  
Skeletal Model ◽  
Parameter Values

Skeletal modeling is an approach to creating solid models in which the engineer designs with lower dimensional primitives such as points, lines, and triangles. The skeleton is then “skinned over” to create the surfaces of the three dimensional object. Convolution surfaces are generated by convolving a kernel function with a geometric field function to create an implicit surface. Certain properties of convolution surfaces make them attractive for skeletal modeling, including: (1) providing analytic solutions for various geometry primitives (including points, line segments, and triangles); (2) generating smooth surfaces (3) and providing well-behaved blending. We assume that engineering designers expect the topology of a skeletal model to be identical to that of the underlying skeleton. However the topology of convolution surfaces can change arbitrarily, making it difficult to predict the topology of the generated surface from knowledge of the topology of the skeleton. To address this issue, we apply Morse theory to analyze the topology of convolution surfaces by detecting the critical points of the surface. We describe an efficient algorithm that we have developed to find the critical points by analyzing the skeleton. The intent is to couple this algorithm with appropriate heuristics for determining parameter values of the convolution surface that will force its topology to match that of the skeleton.

Multi-Objective Design Problem of Tire Wear and Visualization of Its Pareto Solutions2

2006 ◽  
Vol 34 (3) ◽  
pp. 170-194 ◽  
Author(s):  
M. Koishi ◽  
Z. Shida
Keyword(s):  
Inverse Problems ◽  
Conceptual Design ◽  
Dimensional Space ◽  
Design Stage ◽  
Objective Functions ◽  
Pareto Solutions ◽  
Design Problems ◽  
Multi Objective ◽  
Design Engineers ◽  
Design Variables

Abstract Since tires carry out many functions and many of them have tradeoffs, it is important to find the combination of design variables that satisfy well-balanced performance in conceptual design stage. To find a good design of tires is to solve the multi-objective design problems, i.e., inverse problems. However, due to the lack of suitable solution techniques, such problems are converted into a single-objective optimization problem before being solved. Therefore, it is difficult to find the Pareto solutions of multi-objective design problems of tires. Recently, multi-objective evolutionary algorithms have become popular in many fields to find the Pareto solutions. In this paper, we propose a design procedure to solve multi-objective design problems as the comprehensive solver of inverse problems. At first, a multi-objective genetic algorithm (MOGA) is employed to find the Pareto solutions of tire performance, which are in multi-dimensional space of objective functions. Response surface method is also used to evaluate objective functions in the optimization process and can reduce CPU time dramatically. In addition, a self-organizing map (SOM) proposed by Kohonen is used to map Pareto solutions from high-dimensional objective space onto two-dimensional space. Using SOM, design engineers see easily the Pareto solutions of tire performance and can find suitable design plans. The SOM can be considered as an inverse function that defines the relation between Pareto solutions and design variables. To demonstrate the procedure, tire tread design is conducted. The objective of design is to improve uneven wear and wear life for both the front tire and the rear tire of a passenger car. Wear performance is evaluated by finite element analysis (FEA). Response surface is obtained by the design of experiments and FEA. Using both MOGA and SOM, we obtain a map of Pareto solutions. We can find suitable design plans that satisfy well-balanced performance on the map called “multi-performance map.” It helps tire design engineers to make their decision in conceptual design stage.

A Collaborative Rapid Analysis Method for Decision-Making in Assembly Line Design

2004 ◽  
Author(s):  
Masataka Yoshimura ◽  
Satoshi Yoshida ◽  
Yoshinori Konishi ◽  
Kazuhiro Izui ◽  
Shinji Nishiwaki ◽  
...  
Keyword(s):  
Decision Making ◽  
Conceptual Design ◽  
Assembly Line ◽  
Rapid Analysis ◽  
Design Stage ◽  
Analysis Method ◽  
Design Engineers ◽  
Volume Flexibility ◽  
Conceptual Design Stage ◽  
Line Design

Many highly accurate computer simulation tools have been developed for assembly line design, such as for simulation of assembly processes, but these tools require much input information and are generally utilized only in detailed design stages. This paper proposes a rapid analysis method for manual assembly line design, which can be utilized in the conceptual design stage. This method is based on a layout tool where design engineers can construct assembly line models using 2- and 3-D views. This method provides design evaluation techniques for multiple important criteria such as volume flexibility, visibility, and so on, using the layout data. Spatial evaluation and quantitative efficiency analyses can be simultaneously performed, which enhance collaborative decision-making in the conceptual design stage.

Use of Analytical Hierarchy Process (AHP) for Selecting The Best Design Concept

2012 ◽  
Author(s):  
Hambali Ariff ◽  
Mohd. Sapuan Salit ◽  
Napsiah Ismail ◽  
Y. Nukman
Keyword(s):  
Product Development ◽  
Conceptual Design ◽  
Analytical Hierarchy Process ◽  
Development Process ◽  
Pairwise Comparison ◽  
Design Concept ◽  
Product Development Process ◽  
Design Stage ◽  
Conceptual Design Stage ◽  
Hierarchy Process

Pemilihan konsep reka bentuk yang sesuai di peringkat reka bentuk gagasan dalam proses pembangunan produk adalah merupakan keputusan yang genting. Keputusan yang tidak tepat boleh menyebabkan sesuatu produk itu perlu direka bentuk semula atau dikilang semula. Salah satu daripada keadah yang boleh digunakan dalam menentukan konsep reka bentuk yang paling sesuai adalah process hierarki beranalitis (AHP). AHP telah digunakan dalam hampir kesemua aplikasi yang berkaitan dengan membuat sesuatu keputusan. Dalam kertas kerja ini, hasil daripada kajian kes menunjukkan bahawa konsep AHP boleh membantu pereka bentuk untuk membuat penilaian secara berkesan daripada pelbagai konsep reka bentuk di peringkat reka bentuk gagasan. Kertas kerja ini memaparkan kaedah pemilihan konsep reka bentuk dengan menggunakan proses hierarki beranalitis. Kata kunci: Process hierarki beranalitis; reka bentuk gagasan; proses pembangunan produk; perbandingan pasangan; pembangunan kerusi roda Selecting the right design concept at conceptual design stage in product development process is a crucial decision. Inaccurate decision can cause the product to be redesigned or remanufactured. One of the useful tools that can be employed in determining the most appropriate design concept is Analytical Hierarchy Process (AHP). AHP has been employed in almost all applications related to decision–making problems. In this paper, the results of a case study illustrates that AHP concept can assist designers to effectively evaluate various conceptual design alternatives at the conceptual design stage. This paper presents the methodology of selecting design concepts using analytical hierarchy process. Key words: Analytical hierarchy process; conceptual design; product development process; pairwise comparison; wheelchair development

Determining Probability of Importance of Features in a Sketch

2017 ◽  
Vol 3 (4) ◽  
Author(s):  
Ricardo Cruz-Lozano ◽  
Fisseha M. Alemayehu ◽  
Stephen Ekwaro-Osire ◽  
Haileyesus B. Endeshaw
Keyword(s):  
Conceptual Design ◽  
Shape Matching ◽  
Three Dimensional ◽  
3D Models ◽  
User Preferences ◽  
Design Stage ◽  
Limited Experience ◽  
Expert Input

Sketches can be categorized as personal, shared, persuasive, and handover sketches. Depending on each category, their level of ambiguity also varies. The applications of sketches include conceptual design, eliciting user preferences, shape retrieval, and sketch-based modeling (SBM). There is a need for quantification of uncertainty in sketches in mapping of sketches to three-dimensional (3D) models in sketch-based modeling, in eliciting user preferences, and in tuning the level of uncertainty in sketches at the conceptual design stage. This paper investigates the role of probability of importance in quantifying the level of uncertainty in sketches by raising the following three research questions: How are the features in a sketch ranked? What is the probability of importance of features in a sketch? What is the level of uncertainty in a sketch? This paper presents an improved framework for uncertainty quantification in sketches. The framework is capable of identifying and ranking the features in the sketch, determining their probability of importance, and finally quantifying the level of uncertainty in the sketch. Ranking the features of a sketch is performed by a hierarchical approach, whereas probability of importance is determined by assessing the probability of likeliness using a shape matching approach and a probability transformation. Quantification of uncertainty is accomplished by using the principle of normalization of entropy. A case study of a bicycle sketch is used to demonstrate that the framework eliminates the need of expert input in assessment of uncertainty in sketches and, hence, can be used by design practitioners with limited experience.

Diagnosability Modeling and Diagnosability Evaluation of Mechanical System at Conceptual Design Stage

2006 ◽  
Author(s):  
M. F. Wani ◽  
Mohammad Ummar
Keyword(s):  
Mechanical System ◽  
Conceptual Design ◽  
Life Cycle Cost ◽  
Performance Monitoring ◽  
Mechanical Systems ◽  
Point Of View ◽  
Design Concept ◽  
Design Stage ◽  
Conceptual Design Stage ◽  
The Relationship

Reliability, availability and maintainability (RAM) of mechanical system plays a significant role in decreasing the life cycle cost of product. It is well known fact that reliability and maintainability of mechanical systems depends to a large extent on diagnosability of mechanical system, i.e., systems with higher diagnosability, not only helps in reducing the failure of the system at operational stage, but will also help in identification and isolation of faulty components of the system in quick possible time. However, to reap maximum benefits of it is inevitable to consider the design for diagnosability of mechanical systems right from conceptual design stage. For the implementation of the same, designer should be provided with suitable and efficient tool for carrying out diagnosability design and evaluation at conceptual design stage. In this paper, a methodology is developed for carrying out diagnosability of mechanical systems at conceptual design stage. At conceptual design stage designer is well versed with the functional and structural hierarchies of the product. The relationship between the components and functions are used to determine the relationship between the components/assemblies and their performance monitoring parameters (PMP). These are modeled in terms of fuzzy diagnosability bipartite graph (FDBG). FDBG is transformed into fuzzy diagnosability matrix (FDM). The FDM represents the fuzzy relationship between the components and PMP. Diagnosability of the system design concept is evaluated in terms of diagnosability index (IDN) which is obtained from the normalized matrix by using −plog2p. First of all the system which has lowest diagnosability is evaluated from normalized FDM (derived by considering relationship value of 1 between components and PMP). Then reference diagnosability value is obtained from this matrix by using −plog2p and this is represented by DP, ref. FDM for design concept is obtained from the relationship between the components and the PMP. DPN of the design concept is also obtained. Diagnosability index (IDN) of the design concept is then obtained by the ratio of (DP, ref − DPN)/ DP, ref. The higher value of IDN means higher diagnosability and its lower value means lower diagnosability. Component which has lowest diagnosability is also identified, i.e., which has highest functional relationship. This provides guidelines to designer not only for the improvement of design from diagnosability point of view, but also helps in evaluation of dignosability at system conceptual design stage.

Reconstruction of Objects from their Projections Using Orthogonal Functions

1973 ◽  
Vol 31 ◽  
pp. 268-269
Author(s):  
Elrnar Zeitler
Keyword(s):  
Unit Area ◽  
Three Dimensional ◽  
One Dimension ◽  
Spatial Density ◽  
Dimensional Representation ◽  
Orthogonal Functions ◽  
Object A ◽  
Plane Normal ◽  
Dimensional Object ◽  
Spatial Density Distribution

Considering any finite three-dimensional object, a “projection” is here defined as a two-dimensional representation of the object's mass per unit area on a plane normal to a given projection axis, here taken as they-axis. Since the object can be seen as being built from parallel, thin slices, the relation between object structure and its projection can be reduced by one dimension. It is assumed that an electron microscope equipped with a tilting stage records the projectionWhere the object has a spatial density distribution p(r,ϕ) within a limiting radius taken to be unity, and the stage is tilted by an angle 9 with respect to the x-axis of the recording plane.

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