A knowledge-based system for materials selection in mechanical engineering design
Introduction
Materials selection is a task normally carried out by design and materials engineers. Gutteridge and Waterman [1] described the aim of materials selection as the identification of materials, which after appropriate manufacturing operations, will have the dimensions, shape and properties necessary for the product or component to demonstrate its required function at the lowest cost. For the purpose of material selection, thousands of data would be needed to characterize all the grades of materials. Many selection systems are available to help design engineers to choose the most suitable materials. At the most basic level, design engineers could use tables of material properties in data books. However, data sheets are incomplete and once published, they are difficult to update.
Dodd and Fairfull [2] described how information about engineering materials, can be divided into two main categories, i.e. data and knowledge. Data is defined as the results of measurements, whereas knowledge represents the connections between items of data, the source of this knowledge, which contributes to an understanding of the results. Both the computerized database and the KBS of material selection will be described in the following sections.
Section snippets
Supporting data and rigorous logic for the hypothesis and observation
In recent years, attention is being made to the use of computer systems to store and process data regarding the properties of materials. It enables the designers to achieve large capacity and rapid retrieval from a computer database to provide easy access to the materials data.
According to Prasad [3], materials are the common elements enumerating parts in a product realization process. Nowadays, design engineers normally rely on the materials that they are familiar with. However, when design
KBS: contribution towards advancing decision methods
In order to use a source of data effectively the user should have some knowledge base, which can be used to formulate an intelligent approach to the search and to provide a framework within which the data can be used. ‘Selection’ implies ‘decision’, and decisions can only be made against which would enable the data to be used in an intelligent way.
The KBS comprises expert knowledge capable of assisting the user in an interactive way to solve various problems or queries. KBS is a computer
The Contribution of KBS for materials selection towards concurrent engineering
According to Sharon [23], three bottlenecks are identified as being important in concurrent engineering. They are people, early decision making capability and feedback-facilitating technologies. Early decision making is seen as important because normally, engineering work begins without sufficient information. Current decisions have to be made in the early design stages. Therefore, computer systems play an important role in providing information to design engineers. KBS for material selection
The importance of KBS for materials selection in mechanical engineering design, design modification and development
Material selection is one of the most important activities for a product development process. In the modern design manufacturing environment such as newly-developed concurrent engineering methodology [27], [28], [29], [30], material selection plays as important a role as other activities in the total design model [31] such as market investigation, product design specification (PDS), component design, design analysis, manufacture and assembly as shown in Fig. 2.
Review of the knowledge sharing patterns developed by Prasad [3]
Decision making can be viewed as a process of creating an artifact that performs what is expected (specified as a set of requirements) in the presence of all sorts of constraints and operating environments that govern its behavior. Two types of situations exist.
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Cognitive type situations: a concurrent team identifies an outcome, a pattern, or an hypothesis from a finite set of possible outcomes that any team-member has experienced, which is close to the functions of the products.
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Progressive type
Conclusions
The study shows that the KBS is a very appropriate tool in material selection process. Some of the material databases could also be used as material selection systems, but as they are mainly developed for data storage, the material selection process using a material database is not very reliable. Therefore, attention should be given to the material selection process using a KBS.
Acknowledgements
The author wishes to thank Ms N. Zainal Abidin and Ms Qurratu Aini for their support in the preparation of this paper.
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