Mechanical Computer-aided Design Research Articles

Integrated Intelligent System for Manufacturing Process

Abstract To face the challenge of the upcoming knowledge-intensive industries, the current state-of-the-art of mechanical CAD (Computer-Aided Design) technique, which is based on numerical calculation combined with a computer graphics function, cannot fully meet the need of decision-making automation. Any complex mechanical design generally consists of two different processes, i.e., qualitative reasoning and quantitative computation. The qualitative decision-making of design, such as conceptual design, is usually hard to depict with numerical models. It is becoming apparent that a new methodology is demanding the integration of numerical processing and symbolic reasoning, to integrate different domain knowledge as well as to integrate different objectives and functions into a complete software environment for more advanced design automation. This paper presents a parallel hierarchical structure of an integrated intelligent system and application in mechanical design.

Form-features for Mechanical Design and Manufacturing

SUMMARY The current status of research in computer-aided mechanical design is investigated. Much effort is currently being made towards the complete automation of the design process; in this context, a form-feature-based modelling system instead of a merely geometric one seems to provide the necessary tool to assist the designer during the product definition. A new feature-based model of representation for a CAD/CAM environment is proposed. This model combines the power of Predicate Logic (Prolog) with the flexibility of Contextual Logic to ensure that the most appropriate line of reasoning is chosen during any inferential stage of the design (form choice, dimensioning, process planning, etc.). The development of a prototype demonstrates the feasibility of this approach; an example with automatic geometry configuration and process plan generation is presented.

PHIIS: A parallel hierarchical integrated intelligent system for engineering design automation

To face the challenge of the upcoming knowledge-intensive industries, the current state-of-the-art of mechanical CAD (Computer-Aided Design) techniques, which are based on numerical calculation combined with a computer graphics function, cannot fully meet the need of decision-making automation. Any complex mechanical design generally consists of two different processes, i.e. qualitative reasoning and quantitative computation. The qualitative decision-making of design, such as conceptual design, is usually hard to depict with numerical models. It is becoming apparent that a new methodology is demanding the integration of numerical processing and symbolic reasoning, to integrate different domain knowledge as well as to integrate different objectives and functions into a complete software environment for more advanced design automation. This paper presents a parallel hierarchical structure of an integrated intelligent system, and its application in mechanical design.

Embodiment design: facilitating a simultaneous approach to mechanical CAD

The article focuses on the embodiment of product concepts, a formal design activity in which it is proposed that computer-aided design (CAD) techniques can be effectively deployed, hence facilitating a simultaneous approach to the mechanical engineering design of products. It also shows that simultaneous concept development, through systematic procedure, is significantly dependent on multidisciplinary cross-functional team working. >

Computer-aided modelling and simulation of mechanisms and manipulators

Some choices related to the design and implementation of computer programs for the kinematic modelling and simulation of mechanisms and manipulators are discussed, including global versus modular modelling features, numeric versus symbolic computation, and precompiler versus interpreter implementation. Within this framework, two original applications are presented: first, a program for modelling spatial single-loop robot arms that works as a precompiler of manipulators and reaches an automatic, symbolic, closed-form solution to the inverse position analysis; and second, an approach to friendly training in computer-aided mechanism design through hypertext. Various examples of implementations are given.

Product innovation and mechanical CAD: a strategic proposal for engineering manufacture

This paper attempts to give an appraisal of how current mechanical computer-aided design (CAD) technology may be best used within the product innovation strategies that have been identified and recorded (Refs. 1–5). In this connection, the paper focuses on and reviews the implications of CAD with respect to the interdependent issues of new product strategy, the product design spectrum, and product lifecycles. On the basis of the review, it is proposed that these issues must shape present and future CAD implementation and application policy within any manufacturing business attempting to be successful in competitive markets.

Capturing the design of mechanical components in VLSIs

This paper proposes an approach for implementing mechanical computer-aided design (CAD) systems with the aid of generic, multi-purpose VLSIs, as a partial substitute for software. Although software is not eliminated, a more equitable share of tasks is reached between software and hardware, providing for faster computer execution. Two approaches are presented; the first is based on “wired-in” design rules for every permissible solution, feasible but not practical; the second an approach which is based on a “solution-base” stored in ROMs and an imbedded search algorithm to retrieve the best solution. An appropriate search algorithm, called the virtual graphic method (VGM) has been developed. The VGM solves non-linear equations without performing arithmetic operations, and is therefore fast and easily implemented in hardware such as a VLSI. A flowchart and a conceptual diagram for VLSI implementation are presented.

Computer-aided design: limitations in automating design and drafting

The impact of CAD (computer-aided design) on employment and skill is examined. First, the relationship between the adoption of mechanical CAD systems and employment of drafters in the aerospace and automobile industries is assessed. Contrary to many employment projections, drafting employment in these industries increased with increases in the adoption of CAD systems. Second, the effects of design automation and skill transformation capacities of electronic CAD systems on printed circuit board designers are evaluated. Third, the limits to automation of design are explored, suggesting that there are trade-offs between automation of the design process and innovation in product design. The logical limits of software, flaws in programming, and the dynamic nature of product markets are evaluated as factors limiting automation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The implications of tolerancing for computer-aided mechanical design

This paper discusses the implications for current CAD systems of conveying tolerance information through examination of the re-use of geometric data. The concepts underlying this data re-use, notably data integrity and information flow, are also considered with respect to the overall design/manufacturing process. Tolerance application and analysis is considered within this context, and recent work carried out in this area is described. In addition, the implications of tolerance use within CAD systems are highlighted, and outline solutions to the problems raised are presented.

Considering cost effective computer-aided mechanism design

The following discussion considers computer-aided mechanism design in terms of the practical designer's concern — cost effectiveness. Applied design philosophy is reviewed to examine various types of software, both traditional and innovative. The situation of small/medium companies considering acquisition of such software is primarily addressed. The development of the ‘Subroutine Package’ approach is described and its merits compared to conventional general purpose software packages. A subroutine package approach to mechanism design, considers a system to be composed of a limited number of constituent elements. Each subroutine in a package models the behaviour of such an element. An example, which has been developed, is the Linkage Analysis Package (LAP), and an example of its use is given. The user writes a simple (Fortran) calling program to input/output data and call the appropriate subroutines. This represents a ‘self-customized’ interface that is inherently highly cost effective. As the design problem changes, the same interface may be used after limited modification and reselection of the necessary subroutines. Thus a flexible, user-friendly and low-cost computer-aided design tool is available to designers, solving all but the most specialized problems.

MECSYN-IMP-ANIMEC: Foundation for a new computer-aided spatial mechanism design system

The basis for a new computer-aided mechanism design system is described. It includes the programs MECSYN for synthesis. IMP for analysis, and a new program, ANIMEC, for automatic geometric modelling, assembly and animation of planar mechanisms. Key features of the system are effective graphical input, a common synthesis-analysis database and realistic automatic modelling and animation output for rapid evaluation of results. An example session showing synthesis, analysis, automatic modelling and animation is presented.

A device-independent graphics package for CAD applications

GSSP (Graphics Support Subroutine Package) is a device-independent two-dimensional graphics package developed by Engineering Design Systems (EDS) to support several major electronic and mechanical computer-aided design applications within IBM. Graphics systems supported range from interactive, highfunction, distributed-graphics workstations to passive graphic-output devices. GSSP provides many of the functions usually found in other device-independent graphics packages, with additional support for hierarchically structured display files and distributed graphics systems. The major functions provided by GSSP are described, and an overview of the implementation is presented to show how issues such as interactive performance and human factors are addressed.

Modification of geometric models through variational geometry

Systems for computer-aided mechanical design use geometric models for drafting, analysis and programming of NC machines. Because design is iterative in nature, the topology, geometry or dimensioning of a geometric model must be modified many times during the design cycle. The effectiveness of future CAD systems will depend in large part upon the ease with which geometric models can be created and modified. This paper presents the results of a research effort to develop flexible procedures for the definition and modification of geometric models. A central idea of this effort is that dimensions, such as appear on a mechanical drawing, are a natural descriptorr of geometry and provide the most appropriate means for altering a geometric model. A procedure is described by which geometry is determined from a set of dimensions. The geometry corresponding to an altered dimension is found through the simultaneous solution of the set of constraint equations. Presented in this paper are the basic approach to modifications of geometric models, a procedure for significant reduction of the number of constraint equations to be solved, and the effect of sparse matrix methods in reducing the time required to solve the equations.

Analysis of dimensions and tolerances in computer-aided mechanical design

The paper sets forth a theory to explain how dimensions and views combine to specify the shape of a mechanical component. It provides a method to determine whether a component is under, over, or exactly defined by a given dimensioning scheme. Measures for assessing the quality of a scheme are proposed. A solution is offered to a problem of tolerancing: given a toleranced dimensioning scheme, find the resulting tolerances between undimensioned parts of a component.