Chapter Two: Design
2.1 Chapter Overview
This chapter presents the review of literature regarding the subject of design and captures various aspects and thoughts on this. Various thoughts, process and research particularly related to the design process are explored. This chapter encompasses the definitions, characteristics, discussions and applications of design. It is intended that this chapter should give some clear background on the understanding of the design process and its development in today's world of design research.
While the literature review provides a useful background of current research in the material, process and RM systems, the literature available on the design aspect for RM products is severely limited. First a review of the literature for definition of the term ‘design' is presented. A discussion of the act of designing then follows. Next, the type of knowledge associated with design has been discussed. Finally, various thoughts of process of design have been reviewed. This introduction should provide the reader with a context for interpreting the remaining chapters of this report.
2.2. Definition of Design
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Design can be thought of as one of the earliest human activities. The early civilisation started sketching animals and various other forms of images with stones on the wall of their caves. The Egyptians made extensive use of coloured 2D images to record and illustrates various religious information and events that took place in their society. In this context design can be defined as a method of communication.
There exist several definitions of design, as well as design process models, design theories, and design methodologies (Cross 2006), (Lawson 2006), (Pugh 1991), (Ulrich, Eppinger 2004), (Eder, Hosnedl 2008). According to Cross (1990), the ability of humans to design is one of the several forms or fundamental aspects of human intelligence compared to animals and machine (Cross 1999). Human beings are a special kind of designer and their design philosophy influences their life and environment. Everything around us has been designed to fulfil our need. For example, clothes, furniture, machine, transportation, communication system and even food have been designed to meet our requirements. In general, design represents an answer to a problem that has visible form, shape and function. This statement is consistent with what Stoll (1999, p1) said that the primary objective of design is to make people's lives better, where design responds to technical, functional and cultural needs that communicate meaning and emotion with appropriate form, structure and manufacture.
According to Lawson (2006, p 3) the word “design” can be related to the end product or to the process. As a verb, "to design" refers to the process of originating and developing a plan for a product, structure, system, or component with intention. As a noun, "a design" is used for either the final (solution) plan (e.g. proposal, drawing, model, description) or the result of implementing that plan in the form of the final product of a design process. However, this research is concern with the understanding of the design process for Rapid Manufactured products. One of the objectives is to understand how the design process works and how it is learned and performed by professional and expert designers. The aim of the research is to support the design process with the aid of computers.
Design encompasses a wide range of discipline including industrial design, engineering design, architecture, graphics design, fashion design, furniture design etc. All these professions define design differently and all have their own unique views on design. However, many of these professions view design as communication process (Crilly et al. 2008). Design can be considered to be an information process or an information transformation process (Zha et al. 2008). The various design states each contain different extents of information; however, the process of transformation from one information state to another is the result of a decision process, driven by knowledge and information. Figure 2 demonstrates that both information and knowledge contribute significantly to the transformation and creation of the designed artefact, for all aspects but the inventive element of the creativity phases. Therefore, knowledge and information provide the basis of all possible decisions (Hicks et al. 2002).
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Design is also recognised as an art, rather than science. Science is ruled by laws written in formulas and constraints however art is the process or product of arranged in a way that appeals to the senses or emotions. Art encompasses a diverse range of human activities, creations, and modes of expression, including music and literature (Kemp 2009). In clarifying between art and design Eder (2008, p3) states that “design unlike art, requires practical justification in being societal, functional, meaning full and concrete”.
Schon (1983) work provided an important step when describing design as a process of “reflection in action” where through evaluation and reflection design problems are restructured and improved. This particular paradigm consider the importance of observing and doing in learning to design with the emphasis on the building of a rich experiential base.
This research is concern particularly with product design thus a specific definition is necessary. Product design can be defined as the idea generation, concept development, testing and manufacturing or implementation of a physical object or service (Ulrich, Eppinger 2004). Aesthetics is considered important in product design but designers also deal with other important aspects including technology, ergonomics, usability, stress analysis, materials engineering and environmental issues.
Whilst there may be some dispute about the precise definition of the term ‘design', it is recognized as a purposeful and creative activity. In summary, design seeks to create things with the purpose of satisfying certain requirements in new ways that improves the quality of lives. In product design, a variety of requirements must be considered ranging from functionality and usability to pleasure. However, design is more than just translating a set of requirements into a product. Also, and more importantly, it involves finding new requirements. Thus, design involves finding problems and solutions simultaneously, and this is where creativity is important.
2.3. The Act of Designing
Designing is something that all people do. We decide our own fashion style, we plan our daily schedules, we arrange the furniture of our rooms, among many other tasks that require processes similar to design. However, design activities are more visible in creative professions such as art, architecture, engineering, graphic design, and product design. The ability to design varies between people; some people have a better design ability than others.
Design is a complex activity, involving artefacts, people, tools, process, organisations and the environment in which this takes place. According to Eder (2008 p.12) , “Designing is a process of formulating a description for an anticipated process systems and/or an object systems that is intended to transform an existing situation into a future situation to satisfy needs”. Examples of process system in this definition are such as transportation, travel service; catering, maintenance and repair etc and examples of object systems are such as furniture, aircraft, food, machines etc. The definition of designing in this case involves continuous improvement of human needs by the anticipation of their future requirements and directs the activities toward the goals.
According to Ye at al. (2008), design is a purposeful involving creative thinking and problem solving. Design and knowledge have a very strong association: recollection and application of knowledge can be considered as a straightforward and practical design process (Baxter et al. 2008). Emerging new technique, devices and the globalisation of the product market are pushing creativity to its limits. Designers in every industry also are under a lot of pressure to quickly produce high-quality products (Brandt et al. 2008). These trends affect every industry, from the processes and end-products of manufacturing and engineering to the processes and end-products of educational instruction—teaching and learning.
Designing a product involves a constant decision making process that includes problem solving in a sequential fashion and analysis of constraints at each step. Product designers conceptualize and evaluate ideas, making them tangible through products in a more systematic approach. The role of a product designer encompasses many characteristics of the marketing manager, product manager, industrial designer and design engineer. The role of the product designer combines art, science and technology to create tangible three-dimensional goods. This evolving role has been facilitated by digital tools that allow designers to communicate, visualize and analyze ideas in a way that would have taken greater manpower in the past.
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In recent years a number of studies have taken place with the aim of identifying and understanding aspects of creativity in design (Liu 2000), (Gero 1996), (Carayannis, Coleman 2005), (Bonnardel, Marmèche 2005), (Howard, Culley & Dekoninck 2008). These studies suggest that creative designing involves movement from one ‘solution space' to another. There are many interpretations and definitions of the concept of creativity. A review of the literature provides four basic definitions of creativity. The first relates to output where a product is judged to be creative by being original and having appropriate value and use (Gero 1996). The second relates to the process to generate creative thought and action through a number of phases and techniques (Howard, Culley & Dekoninck 2008).
The third definition refers to characteristics and personality traits which are said to be exhibited by creative individuals (Carkett 2004). The final definition is that of environment which includes both social and physical factors (Eder, Hosnedl 2008). These aspects of creativity have been explored in a number of ways which include the study of the methods and models of designing and supporting technology that will be described in the next section.
Many types of knowledge are recognized in the literature; however, little work has been done on the research of knowledge in rapid manufactured product design, such as what knowledge is used in the design process (are you sure of this?). According to Qui at el. (2008), based on analysis of decision making and product design process, knowledge in product design is classified into four types as shown in Figure 3:
Market knowledge represents the knowledge interacting with the external interface like customers, partners, suppliers and other stakeholders. This knowledge consists of knowledge of marketing channels, customer relationships and the strength and loyalty of these. Market knowledge is important for designer to know the objective in product design.
Human knowledge represents the knowledge internalized in a person, such as skills, experience, creativity, etc. Within each designer resides the human knowledge the team seeks to utilize. Human knowledge is of vital importance because it is the source of innovation and knowledge generation.
Technology knowledge refers to knowledge about technologies. This form of knowledge includes inventions, publications, trademarks, patents, knowledge recipes, etc. Technology knowledge is part of the core competence of a design team.
Procedural knowledge refers to knowledge about how to accomplish an end. It deals with the mechanisms and structures. Procedural knowledge is the supportive infrastructure of human knowledge, technology knowledge and market knowledge.
Schön (1983) has studied work in five professions (engineering, architecture, management, psychotherapy and town planning), from which he has developed a view of expert problem solving which characterises two primary modes of activity. One he calls knowing-in-action, the other reflection-in-action. Knowing-in-action is described as follows:
“knowing-in-action refer to the sorts of knowledge we reveal in our intelligent action—publicly observable, physical performances like riding a bicycle and private operations like instant analysis of a balance sheet. In both cases, the knowing is in the action. We reveal it with our spontaneous, skilful execution of the performance; and we are characteristically unable to make it verbally explicit.
It is thus the cognitive state of an individual engaged in building the solution. It is
unselfconscious, non-reflective, non-rational in nature, controlling action in relation to
available artefacts. Schön also identifies a second kind of reflection which serves to shape activity, because it is embedded in it:
“In an action present—a period of time, variable with the context, during which we can still make a difference to the situation at hand—our thinking serves to reshape what we are doing while we are doing it. I shall say, in cases like this, that we reflect-in-action”. (p.49)
It is on reflecting-in-action which Schön mainly focuses, and its interplay with knowing in- action. He asserts that these are mutually exclusive states of being in design, although the smooth switching between them in skilled performance can make it hard to differentiate the two. Reflection-in-action is the designer's response to how he perceives the current problem state “talk back” to him through his “reflective conversation” with the external world with which he is working.
Design research aims at increasing on understanding of the phenomena of design in all its complexity and the development and validation of knowledge, methods and tools to improves the observed situation in design (Qui at el, 2008). The field of literature commonly known as design methodology is primarily concerned with the study of how designers work and think, the establishment of appropriate structure for the design process (Section 2.4), the development and application of new design methods, techniques and procedures and reflection on the nature and extent of design knowledge and its application to design problems (Cross 2006, pg 35). The methods used by Cross vary from report from designers themselves, through observation of designers at work, experimental studies base on protocol analysis and interviews with professional designers. However, there is no single model which is agreed to provide a satisfactory description of the design process. Instead most methods have a well defined and narrow focus ranging from the generation of mechanism concepts (Pahl, Beitz 1996), (Eder, Hosnedl 2008) through to the management of the project risk (Ulrich, Eppinger 2004). Even so, implementation and use of such methods is often problematic. However, there are tool to help designers to support change processes in design (Eckert et al. 2006). In their work, two ways of supporting designers are described: probabilistic prediction of the effects of change and visualisation of change propagation through product connectivity.
Research comparing how designers and scientists solved problem was made. The evidence from the study suggests that scientists solve problem by analysis whereas designers solve the same problem by synthesis; scientists use problem focused strategies and designers use solution focused strategies (Cross 1989 p.17). The designers' problem solving strategies is due to the nature of the problem they normally tackle. Some of the problem may not be able to be stated explicitly thus the designer has to figure out the starting point and suggest tentative solution areas. Solution and problem are then both developed in parallel and this leads to a creative solution. Thus, the solution focused strategies of designers are found the best way to tackle design problems which are, by nature, ill defined problems.
The construction of the Heathrow Airport Terminal 5 (T5) in London was approved by the Secretary of State on 20 November 2001. The project required an estimated investment of over £4.2 bn. The project consist various example of creative solution that the designers and engineers has to take to overcome the constraints. For example the aircraft control tower control tower has to be shifted and allocated to a new location due to the restriction of height of the building being constructed. This required the design and development of a transportation system to move the tower. The roof of the T5 was designed and build into a curve shape that also requires the design and development of a lifting system to lift the roof into the position. The taxiway and runaway have to use new concrete materials due to the heavy load of the new aircraft the Airbus A380. More information can be found from: http://www.airport-technology.com/projects/heathrow5/
2.4 Design Process
Design is a most ‘complex and intellectual human activity' which still needs further explanation and understanding (Gero 1996),(Gonnet, Henning & Leone 2007). Design is thus often quoted as ill structured because it is difficult to describe the process satisfactorily and it is an equally challenging task to describe the relationships between models concerned with its various aspect (Gonnet, Henning & Leone 2007) . Theory and research in design have moved along way from the 1960s positivist approaches where design was viewed as a logical search process to find a solution (Dorst, Dijkhuis 1995). This approach is reflected in various sequential linear models representing the design process (Pahl, Beitz 1996), (Eder, Hosnedl 2008)& (Ulrich, Eppinger 2004). Investigations into design practice have motivated design researchers whose main concern has been to capture patterns in the design process. These patterns, which assist in the development of design methodologies, suggest that the design process can be divided into various stages with different tasks in each one.
A number of formal structures and frameworks to better understand the design process have been suggested from many different disciplines. For example, engineering (Eder, Hosnedl 2008), (Pahl, Beitz 1996) and industrial design (Pugh, Clausing & Andrade 1996). Depending on the domain and on the problem being addressed, design methodologies can vary. Boyle (1989) proposes a classification that splits design into three broad methodologies: analytical, procedural, and experimental design (Boyle 1989). The concepts behind this classification are those of object, attributes, and operations as well as the different roles that are assigned to humans and machines in these classes of design methods. The three categories proposed by Boyle can be summarized as follows:
Analytical or attribute-centred design, in which the attributes of the objects are used to determine the appropriate design actions. A design solution is automatically synthesized from the object attributes and the design objectives.
Procedural or operation-centred design is based on using procedures to perform operations on an object with the aim of transforming it into one having the desired attributes.
Experimental search or object-centred design involves working through an available set of objects in order to find one whose attributes best match the design objectives.
Breaking down complex problems of design into smaller ones assists designers to tackle design problems in a logical way. Several authors have proposed different methods which divide the design process into stages. These methods are similar in that the phase where exploration of designs is performed with more intensity is located in the early stage of the process (Cross 2006). Models of the design process are often illustrated using a flow diagram with a sequence of stages. Cross (1994) proposed a four stage design model as shown in Figure 4 in which the designer first explores the ill defined problem space before generating a concept solution. This is then evaluated against the goals, constraint and criteria of the design brief. The final step is to communicate the design specification either for manufacture or integration into a more complex product. A feedback loop is included if the solution is not satisfactory.
Figure 5 illustrates a model suggested by French (1999). The process generally starts with an initial need or motivation, and ends with the necessary information, such as drawings or construction plans. Every stage is often repeated several times and sometimes feedback loops between stages are necessary in order to continue the process.
The first task of the design process is generally ‘analysis of the problem', or clarification of the task. To realize the clarification a requirement list should be defined and include the inputs and outputs of the required function of the design. In order to analyse a problem it is often necessary to go one step forward and generate design solutions. This indicates that designers learn about the problem as they generate designs. Often, as Lawson (2006) found, designers continue to search for alternative solutions through feedback loops even when they have already developed satisfactory design solutions.
In the second stage, namely the ‘conceptual design stage', designers generate broad solutions and, according to French (1999), it is at this point where many significant decisions are taken. This stage can be broken down into: (i) generate an idea, (ii) record the idea – e.g. through visual representations – and (iii) decide whether to continue to generate more ideas or explore the existing ones. The stage that follows conceptual design is the ‘embodiment of schemes' where selected design solutions are developed in greater detail. French points out that in most cases there is a great deal of feedback from this stage to the conceptual design stage making sometimes the boundaries between both stages not very clear (French M.J 1999). The last stage of the design process is the ‘detailing stage' in which subtle, but no less important, shape features as well as colours and textures of the product are laid down.
Pahl and Beitz (1996) outline a model of the design process for mechanical design that considers not only the sequence of stages, but also what the output of each stage should be as shown in Figure 6 as they consider this as a strategic guideline for design. They divided the design process into four phases that includes:
Planning and clarification of the task:
Collect information about the requirement to be embodied in the solution and also about the constraint.
Establishing the conceptual design by searching for working principles and selecting the suitable concept
Embodiment design through a fixed layout by means of a technical description
Physical realisations through detail drawing consist of form, dimension, material specification and bill of materials.
Although many more design focused models may be found in the literature, most have converged upon the general form proposed by Pahl and Beitz's and French (Cross N 1992). Other such example may be found in (Pugh 1991) and (Ulrich, Eppinger 2004). The German VDI 2221, Figure 7 states guidelines for systematic approach for the design of technical systems and products. The main phase includes clarification of task, conceptual design, embodiment design and detailed design. Whilst it is common ground that all these models and the current design support and CAD systems can help designers in many areas, what is not clear is the extent of assistance that can be provided in the support of product design for RM.
The VDI guideline follows a general systematic procedure of first analysing and understanding the problem as fully as possible then breaking this into sub problem finding suitable solution and combining these into an overall solution. This model has been criticised in the design world because it seems to be based on a problem focused rather than a solution focused approach. It therefore said to run counter to the designer's traditional ways of thinking (Cross 1989 p. 29). More radical model of design process has been suggested by March (1984) which recognise the solution focused nature of design. It is called the Production – Deduction- Induction model as shown in Figure 8. He argued that most commonly known form of reasoning such as inductive and deductive reasoning only suitable to the analytical type of design activity. However, design is mostly associated with synthesising for which there is no commonly accepted form of reasoning. In the model, he proposed the third type of reasoning the productive reasoning which is responsible for the creative activities of design.
Design integration was demonstrated by Pugh (1991), Ulrich (2004) who introduced integrative models of product design and development. The concept of Total Design was introduced by Pugh (1991) which is a systematic activity, from the identification of market/users need, to the selling of the product to satisfy that need that encompasses product, process, people organisation and also the emphasis of multi-disciplinary teamwork. Figure 9 shows the total design activity model which consist the design core such as the market or user need, the product design specification (PDS), conceptual design, detail design, manufacture and sales. From the statement of need the PDS has to be formulated to govern all the subsequent activities in the design core. Figure 10 shows 32 elements of PDS that can envelop the design core. To enable designers to practise design effectively, they have to use systematic tools and technique at each design core such as techniques of analysis, decision making, modelling etc that are applicable to any product or technology and are independent of discipline or technology. Pugh also believes that a successful product in the market requires the input from various personnel in an organisation that are familiar with other discipline in order to have common objective and ovoid misconception.
This chapter has explored and discussed the subject of design and captures various aspects and thoughts on this. Various thoughts, process and research particularly related to the design are explored. Conclusively, the design is seen as a possible but subjective. This leads to different sets of interpretation being used by different researchers. However, the assumption that there exists a set of universally accepted design process is an area that can be further explored. Finally, this chapter has given some background on the understanding of the design process and its development in today's world of design research.