D. Deneux

Introduction to assembly features: an illustrated synthesis methodology

The article is an introduction to a new concept of assembly features able to support intelligent design and manufacturing of complex products. An assembly feature is defined as a generic solution referring to two groups of parts that need to be related by a relationship so as to solve a design problem. The concept of assembly feature encompasses the notions of design intent, technical function, technological solution and manufacturing process as well as it provides a justification for the use of part features. After a general introduction and a justification of the interest of assembly features, some guidelines are provided to show how assembly features can be characterized in any domain of application concerned with engineering design of assemblies. As an illustration of the proposed methodology, the concept is finally applied to the engineering phase of aeroplane design.

A knowledge model for functional re-design

Abstract Re-design is a complex activity involving a great amount of knowledge. In this paper, the general issues of re-design are described. Based on these requirements, an original knowledge model, characterised by its hybrid symbolic and connectionist nature, is introduced. This is used to represent expert knowledge and to support the decision-making process by suggesting solutions to design problems based on a fuzzy representation of design constraints. First, the knowledge representation is formally described. Then, the design process based on this knowledge model is detailed. A specific section is dedicated to demonstrating the knowledge-adjustment mechanisms that are proposed. The application of this model to a subset of the design of an assembly tooling system for the aerospace industry is then presented, and the evaluation of the approach is performed on this test case. Finally, the conclusion discusses the relevance and limits of the model.

Feature-based Interoperability between Design and Analysis Processes

Nowadays, not only the production but also the design of industrial products is subject to severe constraints in terms of time, quality and delay. In order to satisfy these constraints, it is necessary to efficiently integrate the most recurrent tasks of the design process. For a large majority of mechanical products, the integration of mechanical analysis into the design process is one of the most obvious and crucial requirements, particularly during the early stages of design. This article presents an original model of design and analysis process interoperability, based on the concept of mechanical analysis features and a semantically rich product model. It is intended to support a variety of typical analysis tasks that are frequently required during the mechanical design process. The authors firstly present a brief survey of CAD/analysis integration approaches in order to position their contribution within this domain. Then, a general structure of analysis features is justified by means of experimental results. In order to highlight the modes of interoperability between design and analysis, the authors detail the main characteristics of the product model upon which the design activity is based. This delineation is followed by a formal description of the analysis features, and a proposition for their organisation in feature catalogues. The authors then consider the implementation aspect for these models, and present a scenario illustrating the benefits and current limitations of their approach. The evaluation of the approach is discussed in the conclusion.

The Material Angle: a Part-Level Criterion for Tool-Feature Extraction

Process planning of a given mechanical component is dependent on the part itself (topology, geometry, technology), the context (availability, capacity of the means of production) and the planner (knowledge, experience). This chapter aims at showing that complete genericity of an automatic process planning system can be achieved by providing the facility to algorithmically extract low level, manufacturing knowledge free and part-only dependant features (the tool features). At first we give the scope of feature extraction in advanced CAD/CAM sytems. Then we propose an original feature hierarchy compatible with current practices in process planning and show that the automation of this process can be derived from the extraction of tool-features and the subsequent ordering of these atomic features into setup-features and machine-features, with respect to the technological relationships among features, inherited from the functional dimensioning of the component. In the following, we put the accent on the tool-feature extraction methodology, present the current status of our prototype system PLANET and introduce the future work.

DFKN: A Model to Assist in the Capture and Utilisation of Design Knowledge

Abstract The process of acquiring and representing the engineering design knowledge is very important for Re-design. To address this problem, a hybrid knowledge model - dynamic fuzzy knowledge networks (DFKN) - is proposed. The DFKN is a structured networks composed of knowledge blocks. In a knowledge block, fuzzy concepts can be described based on the fuzzy theory; The experiential relationships can be represented in a meaningful way at the attribute level and achieved by way of connectionist computing at the value level. Through adjusting the weight of linkage in value level with artificial neural networks training algorithm, the experiential knowledge can be efficiently captured and reused.

A Prospective Scenario for Integrated CAD & CAPP

Abstract The aim of this paper is to introduce an intelligent manufacturing oriented design system kernel, intended to be customised for several design applications, which has been called the Meta Model for CAD (Computer Aided design) and CAPP (Computer Aided Process Planning). In a first section, the set of problems and experimented solutions of two aspects of the integrated design and manufacturing planning process are shortly described. In a second section, the models and functions of the meta model are introduced and detained. In a third section, the manufacturing planning aspects is addressed.

Function-based Design for Manufacturability

Abstract Our CAD/CAM approach concerns the integration of design and manufacturing of mechanical products. We replace the sequential product life cycle, adopted by the actual CAD/CAM systems, by a cyclic one which reflects the real practices in trade Design offices. We allow the designer to realize the products with both functional and geometrical points of view, by using predefined and user-defined features. Features of the first category represent the product functions. The link between functions and geometry and its attributes expresses “the design intent” which is captured in order to facilitate the reuse of products designs. Each feature provides not only its functions but also its manufacturing process, the second aspect is very useful for reliability estimations, especially when it is done in the early design stage. A validation mock-up was developed using, among others, the non-manifold geometry and the AI reasonings. After a summary description of the mock-up, we end this paper for illustration by a detailed design study of a sharpening device.