Engineering Design Methods

Strategies for Product Design

Nigel Cross

• Éditeur: Wiley
• Année: 2021
• ISBN:
  9781119724407
• Édition: 5
• Sujet: Technology & Engineering
• Sous-sujet: Technology & Engineering Research & Skills

A revised text that presents specific design methods within an overall strategy from concept to detail design

The fifth edition of Engineering Design Methods is an improved and updated version of this very successful, classic text on engineering product design. It provides an overview of design activities and processes, detailed descriptions and examples of how to use key design methods, and outlines design project strategies and management techniques. Written by a noted expert on the topic, the new edition contains an enriched variety of examples and case studies, and up to date material on design thinking and the development of design expertise.

This new edition opens with a compelling original case study of a revolutionary new city-car design by ex-Formula One designer Gordon Murray. The study illustrates the complete development of a novel design and brings to life the process of design, from concept through to prototype. The core of the book presents detailed instructions and examples for using design methods throughout the design process, ranging from identifying new product opportunities, through establishing functions and setting requirements, to generating, evaluating and improving alternative designs. This important book:

• Offers a revised and updated edition of an established, successful text on understanding the design process and using design methods
• Includes new material on design thinking and design ability and new examples of the use of design methods
• Presents clear, detailed and illustrated presentations of eight key design methods in engineering product design

Written for undergraduates and postgraduates across all fields of engineering and product design, the fifth edition of Engineering Design Methods offers an updated, substantial, and reliable text on product design and innovation.

Part One
Design Fundamentals

1
The Activity of Design

What Designers Say

Design is all around us, and the wish to design things is inherent in human beings. One of the most basic characteristics of human beings is that they make a wide range of tools and other artefacts to suit their own purposes. As those purposes change, and as people reflect on the currently‐available artefacts, so refinements are made to the artefacts, and sometimes completely new kinds of artefacts are conceived and made. The world is therefore full of tools, utensils, machines, buildings, furniture, clothes, and many other things that human beings apparently need or want in order to make their lives better. Everything that isn't a simple, untouched piece of Nature has been designed by someone.

In pre‐industrial societies, craftspeople made things according to long‐established traditions, following the patterns transmitted through apprenticeship. It was during the emergence and growth of industrial societies, with the shift from craftwork to manufacturing, that designing became regarded as a different kind of occupation. Although there is now so much designing going on in the world, how people perform this activity of design was rather poorly understood for a very long time. An ability in design has been regarded as something that many, probably most, people possess to some degree, but only a few people have a particular design ‘talent’. However, through decades of design research, there is now an established and growing body of knowledge about design activity and how to conduct it, about the design process and how to improve it, and about design ability and how to develop it.

When designers are asked to explain how they work, and to discuss their abilities, a few common themes emerge. One theme is the importance of creativity and ‘intuition’ in design – even in engineering design. For example, the engineering designer Jack Howe has said:

I believe in intuition. I think that's the difference between a designer and an engineer… I make a distinction between engineers and engineering designers… An engineering designer is just as creative as any other sort of designer.

Some rather similar comments have been made by the industrial designer Richard Stevens:

A lot of engineering design is intuitive, based on subjective thinking. But an engineer is unhappy doing this. An engineer wants to test; test and measure. He's been brought up this way and he's unhappy if he can't prove something. Whereas an industrial designer… is entirely happy making judgements that are intuitive.

Another theme that emerges from what designers say about their abilities is based on the recognition that problems and solutions in design are closely interwoven; that ‘the solution’ isn't always a straightforward answer to ‘the problem’. For example, the furniture designer Geoffrey Harcourt commented on one of his creative designs like this:

As a matter of fact, the solution that I came up with wasn't a solution to the problem at all. I never saw it as that… But when the chair was actually put together (it) in a way quite well solved the problem, but from a completely different angle, a completely different point of view.

A third common theme to emerge is the need to use sketches, drawings or models of various kinds as a way to explore the problem and solution together. The conceptual thinking processes of the designer seem to be based on the development of ideas through their external expression in sketches. As the engineer‐architect Santiago Calatrava said:

To start with you see the thing in your mind and it doesn't exist on paper and then you start making simple sketches and organising things and then you start doing layer after layer… it is very much a dialogue.

This ‘dialogue’ occurs through the designer's perception of the sketched concepts, and reflection on the ideas that they represent and their implications for the resolution of the problem. The designer responds to the perceptions, reflections and implications, and so the ‘dialogue’ between internal mental processes and external representations continues.

The quotations above are taken from interviews conducted with successful and eminent designers by design researchers Robert Davies and Bryan Lawson. The designers’ comments support some of the hypotheses that have emerged from more objective observational studies of designers at work, and other research that has been conducted into the nature of design. Some of this research reflects and supports the view that designers have particular, ‘designerly’ ways of thinking and working.

What Designers Do

People have always made things. In traditional, craft‐based societies the ‘designing’ of artefacts is not really separate from making them; that is to say, there is usually no prior activity of drawing or modelling before the activity of making the artefact. For example, a potter will make a pot by working directly with the clay, and without first making any sketches or drawings of the pot. In modern, industrial societies, however, the activities of designing and of making artefacts are usually quite separate. The process of manufacturing something cannot normally start before the process of designing it is complete. In some cases, for example in the electronics industry, the period of designing may take many months, whereas the average period of making each individual artefact might be measured only in hours or minutes.

Perhaps a way towards understanding design is to begin at the end; to work backwards from the point where designing is finished and making can start. If making cannot start before designing is finished, then at least it is clear what the design process has to achieve. It has to provide a description of the artefact that is to be made. In this description, almost nothing is left to the discretion of those involved in the process of making the artefact; it is specified down to the most detailed dimensions, to the kinds of surface finishes, to the materials, their colours, and so on.

In a sense, perhaps it does not matter how the designer works, so long as he or she produces that final description of the proposed artefact. When a client asks a designer for ‘a design’, that is what they want: the description. The focus of all design activities is that end‐point.

Communication of designs

The most essential design activity, therefore, is the production of a final description of the artefact. This has to be in a form that is understandable to those who will make the artefact. The most widely‐used form of communication is drawing. For a simple artefact, such as a door‐handle, one drawing would probably be enough, but for a larger, more complicated artefact such as a whole building the number of drawings may well run into hundreds, and for the most complex artefacts, such as aeroplanes or major bridges, then thousands of drawings will be necessary.

Thes...