Toward Critical Thinking Mechanical Designers

The Mechanical Engineering Design curriculum at Santa Clara University has been reviewed using the principles of Total Quality Management. The review has led to a clear mission statement and the inclusion of an explicit component of Critical Thinking in our curriculum. We have begun to develop the educational process that will enable us to accomplish this mission.

Mathematical Resolution of MBTI Creativity Data Into Personality Type Components

A novel approach to the quantitative analysis of psychological issues in design is formulated. It treats any quadruple of Myers-Briggs Personality Index (MBTI) scores as a four-dimensional vector decomposable into components in the usual manner of vector analysis. To make the MBTI scores more understandable to the engineer untrained in psychology, new coordinate systems are proposed in which the component axes point toward human personality types such as “Strategist” rather than the usual idealized psychological concepts such as “Introvert”. Also presented as a semantic aid to understanding is a tentative matrix of oversimplified word labels serving as a bridge between terse psychological designators such as “INTJ” and their corresponding detailed personality type descriptions. The methods are used to analyze results from two American Society for Engineering Education (ASEE) faculty workshops on creativity in design education.

Wavelet Transforms in Fractal-Based Form Tolerancing

Tolerancing is a crucial problem for mechanical designers, as it has quality and cost implications on product design. Research in tolerancing has addressed specific areas of the problem. Building upon previous research, a unified approach for geometric tolerancing with fractal-based parameters has been recently proposed. This paper explores an alternative error profile analysis and synthesis method, based on wavelets, that maintains and extends the use of fractals for surface error abstraction. An overview of the theory of wavelets is provided, and the link between fractals and wavelets is established. Experimental data are used to illustrate the application of wavelet theory to surface profile reconstruction and synthesis. The synthesis methods are then implemented in the design of ball-bearing elements, demonstrating the utility of fractal-based tolerancing. Plans for further study and implementation conclude the paper.

Development of Design Skills Through Employment of Open-Ended Problems

With the recent increased concern about the design and problem solving needs of U.S. industry, and academia’s inability to address them, there has arisen a desire to incorporate open-ended problems in engineering education. In the initial stages most, if not all, real-world engineering problems are ill-defined, and have several acceptable solutions, i.e. they are open ended. Yet, our students get very little practice in finding solutions for this type of problem. Correcting this weakness in engineering curricula is hampered by misconceptions about, and inexperience with, these types of problems. As a consequence, educators often attempt to modify typical well defined example problems by expanding their scope, but still taking care to insure that the solution domains are closely circumscribed and well defined. The goal of this paper is to illustrate the main features of open-ended problems and their utility in design education. Such problems are characterized by incomplete or inconsistent information, no evident solution strategy, non-unique solutions, and often poorly understood goals. A real-world open ended design problem will be contrasted with its’ typical engineering education counterpart. This paper attempts to provide the necessary insights to aid in the formulation and selection of effective open ended problems for use in engineering education.

A Designer’s Spreadsheet

We have observed that many designers use spreadsheet programs for preliminary parametric design calculations. The primary reason for this appears to be the flexibility and ease of use of spreadsheets as compared to more advanced analysis tools. However, current commercially available spreadsheets were originally designed for finance and accounting and do not naturally support the analytical techniques used in design and engineering. Attempts to adapt spreadsheets for engineering have largely been limited to adding features such as support for trigonometric functions. In this paper, we propose a fundamentally different kind of spreadsheet for use in preliminary parametric design. We describe the features of this spreadsheet that make it especially suitable for preliminary parametric design, discuss the theoretical basis for implementing it and present the results of preliminary user tests.

Life-Cycle Clumping of Product Designs for Ownership and Retirement

This paper describes a design strategy for mechanical systems called clumping and its effect on product value during the ownership and retirement phases of its life-cycle. A “clump” is a collection of components and/or subassemblies that share a physical relationship and some common characteristic based upon user intent. Clumping for product ownership values, i.e. reliability and serviceability, aims to increase component accessibility. Clumping for product retirement issues, i.e. reuse, recycling, and disposal, seeks to form aggregations of components for material compatibility, thus decreasing disassembly cost. This paper gives a detailed description of life-cycle ownership and retirement assessment methods and how they can be adapted into an existing computer-based design aid. A refrigerator in-door ice dispenser serves as an illustrative example.

Computer-Assisted Catalog Selection With Multiple Objectives

In this paper, strategies appropriate for the computer support of engineering catalog selection are presented for selection problems involving multiple objectives. Problems with and without random and uncertain parameters are considered, and appropriate computer-assisted methods for their solution developed. Special attention is paid to the question of when the generation of a utility function using the methods of multi-attribute utility analysis is a useful part of the selection method. Motor catalog selection examples are used to clarify the concepts.

Recursive Annealing: A Computational Model for Machine Design

A recursive model of conceptual design occurring along an abstraction continuum is introduced. An algorithm based upon recursive simulated annealing is proposed for a computational implementation of the model. The mapping from function to form is accomplished using an abstraction grammar, a set of compatible string grammars for representing the function and form nature of machine components at various levels of abstraction. The promise of a recursive approach to machine design is demonstrated.

Development of a Machine Understandable Language for Design Process Representation

This paper describes the work in progress at Arizona State University to develop a design process description language. The intent is to go beyond decision making level in recording design activities, thus providing a basis for broad application of the proposed representation. At the same time the granularity is limited to a feasible level. The design language proposed in this paper currently is Prolog-based. It is able to relate the sequence of actions to attributes of the design artifacts, thus, providing reference to the product data. Specifics of the design process which are reflected in a natural way include iterations of the activities, versioning of the designs, as well as reasons, purpose, constraints, and method / knowledge / technique used for design decisions (although the latter is currently done in a somewhat unstructured manner). The association between rationale, actions, and artifacts is captured, so explanation of previous designs is adequately supported.

Consideration of Failure Diagnosis in Conceptual Design of Mechanical Systems

A methodology for improving quality and reducing life cycle costs of mechanical systems is described. The principle concept is that a system can be designed, in the conceptual stages, to be easier to diagnose for failures. To perform this, functional decomposition and form to function mapping are utilized both as a model of design and to demonstrate the relation of diagnosis to design. Design guidelines from other disciplines of engineering and concurrent engineering principles are applied to enhance the concept. The affects of the different elements of concurrent engineering on each other are explored. Of the elements of concurrent engineering, design for manufacturability affects the others the greatest. Design for manufacturability principles impact the size of field replaceable units and can improve the ease of failure diagnosis of a system. For a hypothetical case, form to function mapping that would create a difficult to diagnose system is redesigned to reduce the difficulty of failure diagnosis. Further, three diagnosability metrics are developed and four hypothetical conceptual designs are evaluated for diagnosability and compared The area of design for diagnosis offers promise in improving system quality and reducing life cycle cost; research is continuing to refine and integrate the procedures with other components of the concurrent engineering design process.