功能分析.ppt

1、功能分析,設計方法 朝陽科技大學工業設計系 林登立助理教授,designed to be made and used,we focus on design in the more limited sense of designing material products. For that purpose we define design as to conceive the idea for some artefact or system and/or to express the idea in an embodiable form. Products are designed to be

2、made and used. Making and using are actions.,fulfill one or more functions,A product is a material system, which is made by people for its properties. Because of these properties it can fulfill one or more functions. By fulfilling functions a product satisfies needs, and this gives people the possib

3、ility to realize one or more values. Figure 4.1 shows this state of affairs.,Function as the link,the opposite direction,In general the development of a new product proceeds in the opposite direction. The more to the right we start in figure 4.1, the more open-ended the product development process w

4、ill be. If several designers were to be instructed to develop a product - no matter what - that would contribute to the value of enjoying nature, one of them would come up with a rowboat, another with an easy chair and still another with a pair of binoculars.,product planning and strict development,

5、But usually product designers do not start entirely to the right in the diagram. In Chapter 2 we already noted that the product development process can be divided in two parts, namely product planning and strict development. In the product planning phase one seeks product ideas that fit with the com

6、pany and the market.,reasoning back,Reasoning back from the goals (values) of the company to statements on functions that are worth fulfilling forms the kernel of this part of the process of product development. The actual designing of products takes place in the strict development phase. The kernel

7、 of that phase is reasoning back from statements on functions to statements on the form of the product. What is the structure of that reasoning? To answer this question, we should first study what statements are made in the design process.,change the physicochemical form,In manufacturing processes a

8、n in-going material is transformed into an out-going material. In doing so, energy and information are transformed. What is usually immediately evident is that the geometrical form of the in-going material changes in the manufacturing process, for example when machining a part. There are, however, a

9、lso manufacturing processes that change the physicochemical form (the properties of the material) of an object. For example, by hardening a part one changes the physico-chemical form. Yet, it is inevitable that the dimensions of the part change a little as well. In manufacturing, changes of geometri

10、cal and physico-chemical form always go together, but usually these changes are not both wanted at the same time.,geometrical and physico-chemical form,The geometrical and physico-chemical form that a product must have after the manufacturing process, is the design of the product. It has been though

11、t up by a designer and laid down in a technical drawing. Thus, a technical drawing can be seen as the coding of two kinds of categorical statements which comprise a design: statements as to geometrical form (this product is so and so long) and statements as to the physico-chemical form (this product

12、 is of brass).,properties,Because of its form, a product has certain properties, such as weight, strength, hardness, colour etc. Each property tells us something about the reaction the object will show if we bring it into a certain environment and use it in a certain way. The total of all properties

13、 describes the behaviour to be expected under certain conditions.,intensive and extensive properties,We distinguish between intensive and extensive properties. Intensive properties depend on the physico-chemical form only, such as specific gravity. Extensive properties, or thing properties, are a re

14、sult of intensive properties plus the geometrical form; for example, the weight of an object. In designing, one is especially interested in the extensive properties, as these directly determine the functioning of the product.,The art of designing,By choosing a certain material, the designer immediat

15、ely sets many intensive properties for a product, both good and less desirable ones (steel is stiff, but it is heavy and rusts; aluminium is less heavy and does not corrode, but is more floppy). The art of designing is to give the product such a geometrical form that it has the desired extensive pro

16、perties, given the intensive ones.,The function of a product,The function of a product is the intended and deliberately caused ability to bring about a transformation of a part of the environment of the product. To realize a goal - a goal is a desired state - something must be changed in our environ

17、ment. The natural process of change that affects this environment - including ourselves - should be adjusted by the product in a desired direction. Some process should run differently than it would without the product; a coffee mill changes beans to ground coffee, a chair supports (prevents one from

18、 becoming tired), and a poster provides information (decreases uncertainty) .,intended behaviour of the product,Functions of products can be described in different ways, such as in normal language, in mathematical formulae, or as a black box (figure 4.2). Particularly the last form of representation

19、 is often used in design. Yet, whatever representation is chosen, actually statements are made on the intended behaviour of the product. Those statements have a hypothetical form, just like statements on properties.,functions are normative,Unlike statements on properties, statements on functions are

20、 normative. A product has certain properties or does not have them, irrespective of the purpose of a user. Functions, however, are imposed on products; they have to be fulfilled, otherwise the intended goal will not be reached.,design specification,Function is a general concept. It refers to the pur

21、pose of a product, which is usually many-sided. We can therefore talk about the technical, the ergonomic, the aesthetic, the semantic, the business economic, the social and other functions of a product. The detailed description of the function of a product in all its aspects leads to the design spec

22、ification; this is the list of all properties that the product should possess to achieve its purpose.,a possibility to function,One can think up all sorts of functions and try to design a product for them, but will that product really behave as intended? To begin with, this of course depends on its

23、form, for the form determines the extensive properties. Each product has many extensive properties, and each extensive property, or group of extensive properties, represents a possibility to function. But there is more: a product must also be used in a certain manner. Of the many properties that any

24、 product possesses, we usually only notice a few.,functions in the intended manner,Properties only become visible when we do something with the product. Properties are hypothetical statements, and even if such a statement is true, the consequence only becomes evident when we actualize the antecedent

25、. To do so, we actually have to bring the object into certain conditions (iron has the property that it rusts, but only when it meets water). A product with the required properties therefore functions in the intended manner, only if it is used in an environment and in a way that the designer has tho

26、ught up and prescribed The instructions for use are not given facts for the designer, like the function, but are thought up - together with the form of the product - and thus form an essential part of the design.,reason against the direction,Figure 4.3 shows how the functioning of a product depends

27、on its form and its use. The arrows indicate causal relations. The designer, however, should reason against the direction of the arrows. Given a desired function, he should think up the form and its use, and this in such a way that, if the user acts in accordance with the usage instructions, the int

28、ended function is realized. This is the kernel of the design problem. The descriptions - represented in whatever manner - of the form plus the use of the product form the design. The process of thinking, supported by all sorts of doing, which lead to these directions, is designing.,The functioning o

29、f a product,reason from function to form,However important the reasoning from form to function might be, the essential mode of reasoning in designing is to reason from function to form. The form of the product to be designed is then the unknown. The question arises whether we can infer the geometric

30、al and physico-chemical form from the function, by conclusive reasoning, given our knowledge of the laws of nature. The answer is no; in principle there are always different possibilities.,reductive reasoning,The indefiniteness of the transition function form goes even further, for a lever3 is not t

31、he only technical principle to enlarge force. This can also be accomplished with the help of pulleys and cables, gear-wheels and hydraulics, and new principles can be invented. In figure 4.3 the thinking process function form proceeds from right to left. It is based on reductive reasoning and is a c

32、reative process. This does not mean that scientific and technical knowledge do not play a part.,The number of solutions,Causal models indicate the direction in which main choices can be made (choice of material, choice of geometric shapes, choice of one or more key dimensions). Yet this never leads

33、to an unambiguous answer. The number of solutions is in principle even innumerable.,conceiving of the form,Here lies the great challenge for designers and for design methodology, for the most important step in designing is not to predict the properties of a product already thought up, but the preced

34、ing step of conceiving of the form of that product. In a rather poignant contrast to this stands the fact that for the transition form function much scientific knowledge and methods are available, while the transition function form depends largely on the creative abilities and insight of the designe

35、r.,the product design problem,In a broader sense, the product design problem can therefore be phrased as: to think up the form of the product (geometry and material), the usage, as well as the manufacturing, given a business economic and socioeconomic function, and given a certain size of the run.,F

36、unction analysis,We call these methods systematic, because the generation of solutions takes place by combining or varying subsolutions to parts of a problem. They are analytic because there is always first the structuring of the problem which is done by distinguishing aspects or subproblems thereof

37、 or by seeking the common characteristics of solutions to analogous problems.,function structure,Function analysis is a method for analysing, developing and describing a function structure. A function structure is a model of the product to be developed, which abstracts from material features such as

38、 shape, dimensions and materials of the parts. A function structure thus describes only the functions of the entire product and its parts and indicates the mutual relations,機能分析,機能分析是分析、發展和說明機能結構的方法。 機能結構是所要開發產品的模式，它是由產品零組件的造形、尺寸和材料等物質特點抽象化轉變而來的。 因此機能結構所描述的只是整個產品和零組件的機能和它們的相互關係,Functionalism,The def

39、inition of Functionalism is defined by Websters as “ The doctrine that the function of an object should determine its design and materials . Now, if the function of an object decides the type of design and materials used how does one integrate aesthetics into design,elementary functions,The great at

40、tention paid to function analysis is related to the idea of linking catalogues to a function structure. The underlying idea is that a function structure - in accordance with certain rules - may be built up from a limited number of elementary or general functions. These are functions on a high level

41、of abstraction, which cannot be further analysed in subfunctions in a meaningful way. The elementary functions may serve as entries to catalogues which hold collections of physical phenomena and technical principles. In this manner the technical design of products may be systematized and partially a

42、utomated.,subfunctions,In function analysis, the product is considered a technicalphysical system. The systems functions are described as a transformation process between a given initial state and a desired final state of its environment. This process may be characterized by means of three fundament

43、al variables: matter (M), energy (E) and information (I). The product - as a system - can function externally because it consists of a number of parts and components which fulfill subfunctions.,to reverse the process,All internal and external transformation processes - the functioning of the parts a

44、nd the whole - are based on physico-chemical or biological phenomena; by choosing the correct form and the proper material, a designer can utilize these phenomena to realize the purpose of a product. The mode of action - the functioning - of an existing product may be explained on the basis of the e

45、ffects of the parts on one another. The principle of function analysis is to reverse, so to speak, this process of explanation by first specifying what the product should do, and then to infer therefrom what the parts - which are yet to be developed - should do.,distance themselves from known produc

46、ts,Function analysis forces designers to distance themselves from known products and components in considering the question: what is the new product to do and how could it do that? The method is useful to bare the heart of a design problem and to accomplish a break-through in thinking in conventiona

47、l solutions. As the means (in the form of concepts and symbols) are provided to determine the essential characteristics of a new product in an abstract manner, this method also encourages the designer to consider as large a field as possible of conceivable solutions.,保持距離,機能分析強迫設計人員和已知的產品和零件保持距離。 他們

48、必須考慮此一間題:新產品能做什麼和它為什麼能那樣做? 這個方法對於了解設計間題和達成傳統解答案的突破方面很有幫助。 由於手段方法(以概念和象徵符號型式)以抽象方式用來決定新產品的重要屬性， 機能分析也鼓勵設計人員儘可能廣泛地考慮可能的解答方案。,Three steps1/3,The first step is describing the main function of the product in the form of a black box. The main function is the function that the product as a whole should ful

49、fill in its environment. The main function is defined in terms of transformations in flows of matter, energy and information. The input and output characteristics follow from the definition of the problem and from the requirements and constraints which the design should meet.,Three steps2/3,The seco

50、nd step is developing a simple function structure by describing the main technical processes in the product as a consistent whole of subfunctions. Two approaches can thereby be used. The first is analysing an already existing solution of the design problem (or a comparable problem); the components a

51、nd parts of which that solution consists are then studied and these are translated into functions. The second approach is synthesizing the function structure by means of elements from a collection of elementary, general, functions. Often the first step is the most important subfunction and other par

52、tial functions are added step by step. In practice, there is almost always an interaction between these approaches.,Three steps3/3,The third step is elaborating the result of step 2. Often a number of auxiliary functions which were left out in step 2, are to be fitted in. Part of the elaborating als

53、o is the varying of the function structure so as to find the best function structure. Variation possibilities include moving the system boundary, changing the sequence of subfunctions and splitting or combining functions.,Verb + noun,Functions are always recorded with a noun and a verb, for example

54、to separate leaves (from potatoes). In the second block diagram the function structure has been further elaborated by means of general functions; for the significance of the symbols, refer to figure 7.3. Figure 7.4 shows how to make the transition from a function structure to solution principles for

55、 the product to be developed, using a morphological chart. In the next section we will deal in depth with this matter.,coffee mill,Figure 7.5 shows the step-by-step development of the function structure for a coffee mill by means of general functions . Figure 7.6 explains the symbols used - in this

56、case the Roths symbols from whom we have taken this example. We have already mentioned that the general functions are defined differently by the various authors. With respect to the more informal application of function analysis, these differences are not of great importance. We therefore will not d

57、eal further with this and refer the interested reader to the authors mentioned.,step-by-step synthesis,In the step-by-step synthesis of the function structure, the functions required are added in order of importance: (a) coffee beans need to be ground (transforming matter), (b) adjust grinding coars

58、eness (connecting matter and information), (c) supply grinding energy (connecting matter and energy), (d) switch on and off (connecting energy and information), (e) turn electric energy into mechanical energy (transforming energy), (f) store fresh and ground beans (storing matter).,subfunctions,Then

59、 the function structure obtained may be varied by moving the system boundary (for example, place the source of energy within the mill) or by changing the connections of the subfunctions. Roth provides many examples of this as well.,beverage vending machine,In Example VI function analysis is applied to the development of a beverage vending machine. Build first a rough function structure from still complex subfunctions and then work it out step-by-step by splitting up the subfunctions. Often the analysis of a first design concept helps to find the essential subfunctions. 2. Start with the m