Web design for the material selection for mechanical components

CONTENTS

Abstract

Nomenclature

List of figures

List of tables

CHAPTER - 1 INTRODUCTION
1.1 Importance of Material Selection System
1.2 Suitable material for product design and their development
1.3 Analysis of mechanical parts
1.4 Objective of the Present work
1.5 Thesis Layout

CHAPTER – 2LITERATURE REVIEW
2.1 Product Development and material selection
2.1.1 Physical factors
2.1.2 Mechanical factors
2.1.3 Processing and fabrication factors
2.1.4 Life of component factors
2.1.5 Cost and availability
2.2 Material Databases
2.3 Approaches to development of product design
2.4 Development of the web design
2.5 Development of software tools
2.6 Roles and Responsibilities

3 CHAPTER- MATERIALS DATA AND INFORMATION 23-
3.1 References for Sources of Data
3.2 Structure of Material Databases
3.3 Material Selection System
3.4 Properties of Engineering Materials
3.5 Material selection
3.6 Design Process
3.7 The art of selection
3.7.1. Example
3.7.2. The two key stages of selection
3.7.3. Relationships in selection

CHAPTER - 4 PRODUCT DESIGN
4.1 Introduction
4.2 Descriptive models
4.2.1 Concept design
4.2.2 Embodiment design
4.2.3 Detailed design
4.2.4 Breadth versus Precision
4.2.5 Areas of computer involvement
4.2.6 Database software in current use
4.5 The world of materials
4.6 Relation between Material Selection and Design process
4.7 Relation between Material Selection and Process Selection
4.8 Knowledge-Base Systems

CHAPTER-5 DEVELOPMENT OF THE DATA BASE
5.1 Introduction
5.2 Data Concept of the System
5.3 Engineering Materials Used in the Database
5.4 Broad Range of Applicability of the Database
5.5 Identification of the material database
5.6 General Information about Properties in the Database

CHAPTER-6 DATABASE DEVELOPMENT
6.1 Data Structure
6.2 Operations in the Database
6.3 Web Design development
6.3.1 Introduction
6.3.2 Modules in the Program
6.3.3 Property Displaying Module
6.3.4 Search Module
6.3.5 Selection Module
6.3.6 Update Module

CHAPTER-7RESULTS AND DISCUSSION
7.1. Minimum System Requirements
7.2. Main Window of the Program
7.2.1 Properties
7.2.2 About
7.3 Discussion

CHAPATE-

CONCLUSION AND RECOMMENDATIONS FOR FUTURE WORK

REFERENCES

APPENDIX A

APPENDIX B

Abstract

Material selection is one of the major points that should be taken into account seriously in the engineering design stage. Each material has various properties such as mechanical, thermal, electrical, physical, environmental, optical and biological properties. However, it is a well known fact that only a limited number of design engineers have a thorough knowledge on all these properties of a specific material, which is planned to be used in the manufacturing of the product. Therefore, the design engineer should be guided in selecting the most suitable material.

In the scope of this thesis, the aim was to develop” Web Design” and a software package for material selection to help the design engineer in his decision making process. Since some materials is a widely used material in industry, it was selected as a material class among whole engineering materials, and a database covering all the necessary properties was constructed. These properties include chemical, mechanical, thermal, electrical and physical properties for some of the materials. The database developed by using “Visual Basic .Net’ and also contains different material standards and can be updated if the user wants.3

It is expected that an information source such as the proposed database will provide all the necessary facts and figures to aid both designers and manufacturing engineers. Here in thesis we incorporated into the system are two main futures, browse and search. These allow the user to sift through information manually or enter multi-constraint criteria respectively. Retrieval of information is achieved by in-built queries and information is displayed.

The software package was developed for Windows environment by using Microsoft Visual Basic .Net in the program, materials can be searched for the list of suitable materials by entering application areas and properties such as chemical component, yield strength, heat capacity and electrical resistance. In addition to this, lists of materials can be created by selecting the appropriate material standards.

NOMENCLATURE

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CHAPTER 1 INTRODUCTION

Material selection plays a vital role in the recent product development process scenario. With the Manufacturing concepts keeping in fact, present day industry faces lot of problems in the selection of suitable material for particular design of a product. However a suitable design of software tool in concurrence with design and analysis of a product and selection of proper material is to be modeled. Present work proposes a method which is user friendly for the web design to the needs of present day design and manufacturing Engineers.

1.1 Importance of Material Selection System

Material data is the basic requirement in engineering design of a product. A material engineer should be aware of all possible alternative materials not to miss any opportunity in the design process. Tens of thousands of materials are available to engineers and the number is increasing faster at present than ever before. Each material has numerous mechanical, thermal, electrical, physical, environmental, optical, biological and other properties that are relevant to engineering design. No engineer can be familiar with more than a small subset of this information. Although is possible to narrow down these alternatives by using Past experiences or some global charts and tables, still tedious and time consuming task to select the materials from handbooks or supplier catalogs.

Materials information can be classified according to the material family, the properties, the source of the data, or the data format. Many types of property data are functions of one or more variables. Therefore, it is obvious that a single database cannot help in solving every problem related to all kinds of materials. In order to obtain practical result, the entire available material database is concerned with a certain group of materials. Grouping method changes due to the details of the information.

In the present work, taking into consideration the earlier experiences, problems and limitations encountered in engineering practice, a database and a data retrieval system is proposed for solving various problems in finding appropriate materials by searching through products of different applications.

1.2 Suitable material for product design and their development.

ANSYS is the one of the best Tool for the analysis .The Material data is available in the data base to analysis the mechanical parts, Basically Material information is needed to analyses, here Using ANSYS programs, ANSYS has three distinct steps to develop the results. Build the model, Apply loads and obtain the solution, Review the results, the results should incorporated in the Web Based Design to simply viewing the results.

1.3 Analysis of mechanical parts

The product design of the mechanical Components, materials should be taken by the data base to get the result, in the scope of this study a software package is developed to assist design engineer in selecting a suitable material for various applications. View results, the database contains general, mechanical, physical and thermal properties of materials. The user can view the properties of a specific material, which user may select among the material lists or search with its material designation or material UNS number. By the analysis, the parts by using ANSYS for getting the good results for the further extension of work

1.4 Objective of the Present work

The Present work describes mainly web based design by using a platform asp.Net basically work involves material selection system by finding material properties to apply on the product.

To find the material properties for a product, by material properties option or UNS Number option to get the result you need.

After finding the properties apply the results in the product design to analyses the component by using ANSYS Tool. By getting the perfect solution, the results displayed and saved in the Web based design.

Update module, according our work when get the new data base by other source just forwarded by using update module for further reference.

1.5 Thesis Layout

The work is presented in twelve chapters as follows

Chapter I deal how to select a material from system, and apply on the mechanical components, further to get product design issue for their development.

A detailed survey of literature is presented in Chapter II, in this discussed about development of product design, web design with their help of software tools.

Chapter III is the highlights the total layout to gather the information of data base, finding the structure of materials database for the source data, mainly inform about the engineering materials, design process and discusses the art of selection, two key stages of selection and relationships in selection.

Descriptive models, Breadth versus precision, areas of computer involvement, database soft ware in current use, world of materials presented here in Chapter IV

Database development, material used in the database and broad range of applicability of the database, and deals with content of the data base, in Chapter V

Chapter-VI deals with development of web design in this briefly discussed about program modules search module, selection module, update module.

Chapter-VII deals with the results and discussion.

Chapter- VIII discussed with the conclusions and scope for further work.

For more detailed about the material selection, product design and web based design with Ashby’s charts explained in Literature review in Chapter – II.

CHAPTER 2 LITERATURE REVIEW

2.1 Product Development and material selection

Product development (PD) is the term used to describe the complete process of bringing a new product to market. There are two parallel paths involved in the PD process: one involves the idea generation, product design and detail engineering, the other involves market research and analysis. Companies typically to using product development as the first stage in generating and commercializing new products within the overall strategic process of product life cycle management used to maintain or grow their market share.

Cebon and Ashby (1989) developed a computerized materials selection system called Cambridge Materials Selector (CMS). The system uses materials selection charts, which are a way of displaying material property data through the use of optimization procedures. The selection process depends on implementing performance indices, a combination of material properties and cooperation with any two entities.

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Fig 2.1 Plot using Ashby's (Young’s Modulus and density)

The charts are developed to present the materials, and the performance indices, so that the most suitable selection of materials and shape can be carried out (Ashby, 1999, 1989 and Cebon and Ashby, 1992, 1996).

The goal of design is “to create products that perform their function effectively, safely, at acceptable cost” (Prof. Ashby, Cambridge University, UK)

The performance of a typical engineering component is seldom limited by only one property. Quite often, the best choice of a material for a product, component, or structure is based not on specific properties but rather on a combination of properties.

EXAMPLE: in lightweight designs, it is not just strength that is important, but both strength and density. Therefore, we need to be able to compare materials based on several properties at once.

Materials do not exhibit single-valued properties. They show a range of properties, even within a single production run.

EXAMPLES:

(i) The elastic modulus of copper varies over a few percent depending on the purity, texture, grain size, etc.

(ii) The mechanical strength of a ceramic such as alumina (Al2O3) varies by more than a factor of 100 depending on its porosity, grain size, etc.

(iii) Metal alloys show large changes in their mechanical and electrical properties depending on the heat treatments and mechanical working they have experienced.

Ashby charts are to be used only at the conceptual stage of selection of materials. There is a tremendous amount of information as well as power in these charts, Data are plotted on a log-log scale to include the enormous range of properties of different groups or classes of materials Data for a given class of materials tend to cluster together on the charts. Data for a class are enclosed in a property envelope or property fiel d. The envelope encloses all members of the class. Thick lines bound envelopes. Within each envelope are bubbles that signify the variation of properties of specific materials within a given class. A bubble encloses a typical range for the property for a single material property. Light lines bound bubbles. Overlap of envelopes sometimes occurs, but each class of materials has its own distinct field in the chart. Overlapping does not destroy the identity of a field. Each chart contains a set of design guidelines. The materials that are intersected by a given design guideline will perform equally well under the condition being considered. Materials above the line will show superior performance, while those lying below will exhibit poorer performances (and will be rejected during the screening stage).

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Fig 2.2 factors influencing the material selection process

The selection of an appropriate material and its conversion into a useful product with the desired shape and properties is a complex process. Figure 2.2 shows the factors affecting the material selection process:

2.1.1 Physical factors:

The factors in this group are the size, and weight of the material needed and the shape pavailable for the component. Shape considerations greatly influence selection of the method of manufacture.

2.1.2 Mechanical factors:

The ability to withstand stress and strain is determined by these factors. Strength, ductility, modulus, fatigue strength, and creep, are some mechanical properties that influence what material needs to be used. The mechanical properties also are affected by the environment to which the materials are exposed.

2.1.3 Processing and fabrication factors:

The ability to form or shape a material falls under the processing and fabrication factors. Casting and deformation processing are commonly used.

2.1.4 Life of component factors:

These factors relate to the life of the materials to which they perform the intended function. The properties of this group are the external surface properties like oxidation, corrosion, and wear resistance and some internal properties like fatigue an creep. The performance of materials based on these properties is the hardest to predict during the design stage.

2.1.5 Cost and availability:

with reduced lead times from design to market, there is a tendency to jump to the first material that fits the selection profile. It is important to note that additional effort determining the correct material helps optimize the manufacturing costs. Also, standardization of parts and materials is related to the cost of the final product. Special processing requirements or rare materials with limited availability increase the final cost and affect the timely manufacture of the product.

The total design model states that in any product development, the steps to be carried out include market investigation, product design specification, conceptual design, detail design, manufacture and sale (Pugh, 1991).

2.2 Material Databases

According to Prasad (1997a), materials are the many reachearshes has contributed regarding material database generation and few of these works are highlighted in order to understand the influence of their product development. Nowadays, design engineers normally rely on the materials that they are familiar with. However, when design requirements exceed the constraints of such materials or exceed the constraints on material properties, concurrent engineering teams must consider alternative materials. With direct online access to the material database, the concurrent engineering teams could select proper materials that are lighter, stronger and lower in cost. Assuming that the impact of such substitutions can be analysed or simulated, the teams could easily make an optimum selection of materials for the available processes, conserve materials for each process and thus, reduce material waste. Therefore, the usage of the databases is very crucial in the design process. The use of computer-aided tools allows the engineer to minimize the material selection information overload. A computerized materials search can accomplish in minutes what may take hours or days by a manual search.

Reynard (1989) emphasized the importance of the materials database and has criticized the attitude of some people who said that materials selection is not required by engineers or as a service from a computerized database. The author suggested that the materials database should be presented ‘in the best form suited to the needs of the users’ such as by on line systems, mainframe systems, disc for desktop use and CD-ROMS.

Much materials information is structured in the material databases. It typically consists of databases or spread sheets with typical or allowable properties of materials. Other information is unstructured. It consists of electronic text, pdf or html files, photographs, tables, and/or graphs. The information may originate from reference or in-house sources. Reference data is provided by organizations such as ASM International, standards bodies (ISO, ASTM, and AISI), Mil-Handbooks, material producers and others. In-house data is data derived from corporate materials tests or data collections built by company personal using other sources. Examples of structured reference data are databases provided by ASM in its Alloy Center; by Granta Design Ltd in its Material Universe database, Matweb and others. Structured in-house data typically resides in the databases developed by materials engineers within a company. They often contain design (or “allowable”) values of the properties of a list of preferred materials. The most comprehensive source of unstructured reference information is probably the ASM Handbooks, both print and online. Unstructured in-house information consists of reports, failure analyses, personal notebooks and filling cabinets full of information collected over the years by material specialists in a corporation (Cebon and Ashby, 2003).

All materials property databases allow the user to search for a material match by comparing four or more property parameters, each of which can be specified as below, above, or within a stated range of values. Some databases have the ability to weigh the significance of the various properties. The most advanced databases allow the materials property data to be transmitted directly to a design software package, such as finite element analysis, so that the effect of changing material properties on the geometry and dimensions of a part design can be directly observed on the computer monitor. However, this capability is generally limited to a narrow homogeneous group of material (Cebon, 1996).

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Table 2.1 Examples of material databases and data centers according to their field

The development of material databases has been reported by Harmer (1997), Baur (1994), Ashby (1989) and Cebon (1992). Material information sources are listed in Table 2.1 to indicate current, authoritative and important databases. In selecting sources, emphasis was placed on sources containing substantial amounts of quantitative information on engineering properties of materials.

CAMPUS and FUNDUS have features, which allow the user to view all properties for any listed product, print the data for any products, search the database for products satisfying specific property requirements, select and view properties for comparison, and sort according to specific requirement in ascending or descending order.

Waterman et. al. (1992) studied the computerized materials property data systems for meeting the requirements of design, production and materials engineers. Computerized data and information on material are available in two forms. Firstly, there are on-line systems where the subscriber to the system could contact a central computer through a local terminal-modem telephone link and secondly, personal computer-based systems where the subscriber receives data on discs and accesses these through a compatible personal computer.

Since each materials database has a complicated data structure and specific search functions, construction of a database needs much money, manpower and expertise of skilled researchers. Therefore many of these databases are constructed by governmental organizations or national research institutes, sometimes by their cooperation, in financial support of national funds. In addition, a great deal of effort is necessary for compilation and evaluation of different types and levels of data, which are diversified widely. Therefore it has been recognized that interlinking of databases in various organizations, international cooperation and standardization are very important for establishing and distributing databases.

In recent years, growing cooperation between information institutions and their integration makes the future development of databases and their usage more efficient. Since the beginning of 1998, Elsevier Science, which offers databases and electronic library products and publishes approximately 1200 scientific journals in all major scientific technical and medical disciplines? Cooperative activities frequently take place within the framework of such organizations as the International Council of Scientific Unions and its Committee on Data for Science and Technology (CODATA) to improve the quality, reliability, processing, management and accessibility of data of importance to science ( Fiala and Sestak, 2000 ).

Printed documents include several drawbacks as they are often outdated before reaching the bookshelves and are very difficult to index them to find answers or to sort data in the manner of your choice. A computerized system, which provides access to materials data, is not necessarily a materials selection system, although access to data is essential to facilitate selection (White, 1995).

2.3 Approaches to development of product design

Product design approaches to assume a core function of a three basics are Marketing, Design and Manufacturing. Product design can be defined as the idea generation, concept development, testing and manufacturing or implementation of a physical object or service. 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 term is sometimes confused with industrial design, which defines the field of a broader spectrum of design activities, such as service design, systems design, interaction design as well as product design. 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. ( )

The relationship between design and product is one of planning and executing. In theory, the plan should anticipate and compensate for potential problems in the execution process. Design involves problem-solving and creativity. In contrast, product involves a routine or pre-planned process. A design may also be a mere plan that does not include a production or engineering process, although a working knowledge of such processes is usually expected of designers. In some cases, it may be unnecessary and/or impractical to expect a designer with a broad multidisciplinary knowledge required for such designs to also have a detailed specialized knowledge of how to produce the product.

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Fig 2.3 Product Design sheet

2.4 Development of the web design

Web design is the skill of creating presentations of content (usually hypertext or hypermedia) that is delivered to an end-user through the World Wide Web, by way of a Web browser or other Web-enabled software like Internet television clients, microblogging clients and RSS readers.

The intent of web design is to create a web site a collection of electronic files that reside on a web server/servers and present content and interactive features/interfaces to the end user in form of Web pages once requested. Such elements as text, bit-mapped images (GIFs, JPEGs), and forms can be placed on the page using HTML (Hyper Text Markup Language) / XHTML (Extensible Hypertext Markup Language.) / XML (Extensible Markup Language) tags. Displaying more complex media (vector graphics, animations, videos, sounds) requires plug-ins such as Flash, QuickTime, Java run-time environment, etc. Plug-ins are also embedded into web page by using HTML/XHTML tags.

Typically web pages are classified as static or dynamic:

- Static pages don’t change content and layout with every request unless a human (web master/programmer) manually updates the page. A simple HTML page is an example of static content.
- Dynamic pages adapt their content and/or appearance depending on end-user’s input/interaction or changes in the computing environment (user, time, database modifications, etc.) Content can be changed on the client side (end-user's computer) by using client-side scripting languages (JavaScript, JScript, Action script, etc.) to alter DOM elements DHTML( Dynamic Hypertext Markup Language ). Dynamic content is often compiled on the server utilizing server-side scripting languages ( Perl [ Perl is a high-level, general-purpose, interpreted, dynamic programming language ], PHP [Hypertext Preprocessor],JSP[ Jackson Structured Programming ], etc.). Both approaches are usually used in complex applications.

With growing specialization in the information technology field there is a strong tendency to draw a clear line between web design and web development.

Web design is a kind of graphic design intended for development and styling of objects of the Internet's information environment to provide them with high-end consumer features and aesthetic qualities. The offered definition separates web design from web programming, emphasizing the functional features of a web site, as well as positioning web design as a kind of graphic design.

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Fig 2.2 Basic Flow chart of web design

2.5 Development of software tools

A programming tool or software development tool is a program or application that software developers use to create, debug, maintain, or otherwise support other programs and applications. The term usually refers to relatively simple programs that can be combined together to accomplish a task, much as one might use multiple hand tools to fix a physical object.

Certain organizations are established to provide material information sources to engineers dealing with design process. They supply bibliographic material information sources as well as numeric or factual one. In addition to the organizations, the Internet is rapidly developing as a source of information on a vast array of topics. Clement (1995) and Renehan (1996) developed two general guides to science and technology on the Internet. Thomas (1996) and Meltsner (1995) were introduced databases to the Internet for materials scientists and engineers. PC software and mathematical routines are typical examples of available general- interest applications on the Internet. Newsgroups such as “sci. engr. metallurgy” and “sci. materials” can provide free information on the existence of material information sources covering particular materials topics. Because such a vast quantity of information is available on the Internet, considerable time or specialized browsing software is needed to deal with it.

The software development document contains all preparations pertaining to the development of each unit or module, including the software, test cases, test results, approvals, and any other items that will help to explain the functionality of the software. The document is dynamic and is maintained by the system development team and should he constantly update as the system’s development progresses. The software development folder should include the following information for each unit:

a) Description of the unit’s functionality in narrative format.
b) Description of development methodologies used.
c) Requirements in the functional requirements document allocated to this unit or module.
d) Completed trace ability matrix displaying the unit’s test cases satisfying the functional requirements in the test plan.
e) Source code listing.
f) Controlled libraries/directories/tables.
g) All data necessary to conduct unit testing.
h) Unit test results and analysis.
i) System Technical Lead sign off for design walk-through. approval of code, and completion of each unit
j) Completed Software Development Document Check-Off sheet.

2.6 Roles and Responsibilities

The team members have the following roles and responsibilities:

- The application developer assigned the primary responsibility for the module or unit creates a file folder for the unit, labels it according to the name of the unit, and places it in the appropriate place in the project team file cabinet.
- The application developer(s) add copies of the indicated documentation to the folder as they are created.
- The project QA representative reviews the contents of the folder for completeness, and points out discrepancies to the developer assigned primary responsibility for tile module or unit.
- The developer assigned primary responsibility for the module or unit completes the Software Development Document Check-Off sheet and arranges for the System Technical Lead review and approval when needed.
- The folder is available to all project team member for review, but if removed from the file cabinet, it must be replaced with a cheek-out card indicating who checked it out, when, and where it will he located.

For more detail information about the material data, source data and performance characteristic discussed Chapter – III.

CHAPTER-3 MATERIALS DATA AND INFORMATION

Materials data is a critical resource for manufacturing organizations seeking to enhance products, processes and, ultimately, profitability. Data describes the properties and processing of the materials. Metals, alloys, plastics, composite materials, ceramics, etc. This data may come from a wide range of sources - e.g., materials testing, quality assurance, or measurement of product performance. One project that has looked at this issue in-depth is the Material Data Management Consortium (MDMC), a collaboration of leading aerospace, defense, and energy enterprises - organizations such as NASA, Boeing, Rolls-Royce plc, Honeywell, and GE Aviation.

Only few decades ago the information needs of a materials engineer were rather simply served. Because there was little inter substitution among the major classes of materials and because the engineer was, most likely, a metallurgist with little concern for materials other than metals. There are over 100,000 different commercially available materials in today’s industry. Increasingly, in many applications, plastics, ceramics, Composites and glasses compete directly with metals; Processing techniques once regarded as unique to a certain materials class are being adapted to other quite different classes. Although there are many scientific approaches to narrow down these alternative materials during selection, it is still a tedious task to choose the materials from printed documents for a specific application (Farag, 1989). Thus, the scope of materials for which information is required has been greatly broadened.

In addition, the shear volume of material information has increased exponentially. There has been a general explosion in the primary journal publications, and another exponentially growing collection has developed in the report literature. Furthermore, an increasing proportion of materials data is not in hard-copy print form but in electronic formats, available on compact disks, tapes, CD-ROMs, or on-line. Moreover, health, safety, and environmental issues require types of information unheard of a few decades ago for the application, storage, and disposal of materials. Worldwide sourcing of materials, multinational operations of many companies, and development of the use of the SI (the “metric system”) place new demands on the searcher, compiler and disseminator of materials information.

Emphasize has to be made about the materials information, needs of engineers in industry are more demanding and difficult to satisfy than those of the materials scientists. Engineers must not only possess the best existing value for the certain property, but they must also know the limits of uncertainty for the value in order to estimate the reliability of design. While material scientists works with metals or individual chemical compounds, engineers in industry are frequently interested in complex alloys, clads, and other composites whose properties and behavior must also be known or reliably estimated. Furthermore, many properties of commercial materials are not fixed values, as they depend on processing history, resulting structure and effect of external variables. In addition, engineers frequently require data that cannot be expressed in terms of a single property or combination of properties, but must be related to a performance test or service application.

Fewer sources of compiled and evaluated data supply the needs of industry as compared to scientists. Engineers in industry have less time available to search for answers to their questions or to compare their answers with other diverse sources. Furthermore, existing materials data compilations, both print and electronic, display a confusing variety of terminologies, test methods, property unit. The available data compilations may be from a publisher, from a materials supplier, or result from an in-house testing program. Approval of reliability of the information may be keyed to the individual editor, a professional association, or the data generator.

Property data and information are needed at each stage of the design process. The needs for materials data changes as the design stages proceed. At the start of the design process, low-precision but all inclusive data are needed. At the end of the design process, data are needed for only a single material, but very precise data are required. These data are best found in the data sheets issued by material producers. There is a very wide range of properties that may be needed, but in addition to these properties information including manufacturability, cost, experience base in use in other applications, and issues of quality assurance must be included. The material information in detail design is listed in Table 3.1

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Table 3.1 Material information required during detail design (National Materials Advisory Board, 1995).

In recent years, attention is given 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.

3.1 References for Sources of Data

A persistent problem for seekers of materials information is the lack of adequate guides and directories. The insufficiencies of existing directories are composed of poor currency, narrowness of focus (by country, by material class, by format, etc.), and poor characterization of the reliability of the information contained.

Westbrook (1986), Westbrook and Reynard (1993) developed a guide for overviews of materials information sources. It covers technical information sources: encyclopedias; dictionaries; numeric, graphical and pictorial data sources, auxiliary information sources, the primary literature; reviews; and special topics. Moreover, Wawrousek et.al. (1989) presented a comprehensive materials information directory. An indexed catalogue of 1250 different sources of data on the mechanical and physical properties of engineering materials. Each identified source was categorized by type such as computer readable, data center, printed handbook, etc. Many other useful guides to materials information sources are developed in various types of surveys.

3.2 Structure of Material Databases

Original source data in materials databases have many items, and they often can be represented in complicated data structure. In construction of database, these source data items are structured to a record, which is the information unit of a data file. Typical data items of materials databases are presented in Table 3.2 (Eriguchi and Shimura, 1990).

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Table 3.2 Main data items of data in materials databases

The materials database must store a large number of data items, which represent both property data and various auxiliary information, thus a unit record should be very large. Furthermore, each data item is correlated with the other items, so it is necessary to select an appropriate database structure among simple linear structure, multi dimensional relational structure, and network structure. Spectrum databases and chemical substance databases have relatively simple data structures, but databases for physical properties and mechanical properties have complex data structures corresponding to the relations within each data items.

The validity of the data in a database is an important issue. In order to increase the reliability and accuracy of the data in a computerized database; used sources, statistical basis of the data, status of the material, evaluation status, validation status and certification status must be described. As the materials database includes standardized material specifications such as the material name, chemical composition and production method, as well as standardized material properties such as numerical data, unit, test method and measuring parameters; it can be considered as a validated database.

Data types of material databases are presented in simple textual data, numerical data, tables of data, or graphs. Textual data of character mode such as material names, key words, and author names are searchable with full-spelling, right- truncation and string search techniques. Numerical data can be searched with range searching, above below, or within the limits specified.

3.3 Material Selection System

Material selection is a complex process and it is very difficult to specialize in the selection sector. To choose the proper material for a specific process, the designer should avoid confinement of materials selection to materials that the designer is only familiar with. The designer utilizes also new materials and processes to enable innovation in design. The engineer improves product performance and eliminates material or service failure. Moreover, the designer solves processing difficulties and takes advantage of new processing techniques, reduces material and production costs, and anticipates or exploits a change in the availability of a material. The designer takes also the advantage of the introduction of a new product, or adjusts to a decline in the market. Furthermore, the designer accommodates a change in design for new and/or adverse environmental conditions.

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, material selection plays as important a role as other activities in the total design model such as market investigation, product design specification, component design, design analysis, manufacture and assembly.

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