Abstract of project paper presented to the Senate of Universiti Putra Malaysia in fulfillment of the requirement for the degree of Master of Innovation & Engineering Design.

ABSTRACT

DESIGN OF AN AUTOMATED FOOD DISPENSING SYSTEM FOR GOATS' FEEDING

BY

MASJURI BIN MUSA @ OTHMAN

NOVEMBER 2006

Chairman: Lt. Col. (R) Ahmad Tarmizi bin Mohamed

Faculty: Engineering

"Auto feeder dispensing system" is a machine, which is designed to feed the

breeds automatically. In this case, goats breed sector has been selected as an

approach to implement this automated food dispensing system machine, due to meet

high local demand of goat's products.

Almost all the goat's breeders in this country, are still implementing the

traditional method and not economical. The farmers or breeders are still feeding the

goats by using an old technique, which is pouring the pallet (food) manually into

each container, which is located at the side of the barn. Farmers could not measure

the exactly amount of pallet needed for each goat if still implement this old

technique. Due to this improper distribution of feeding system, it will cause the

obvious food wastage and may effect badly to the monthly food operation cost. The

method will also take longer time to fill in all the containers and it needs more than

one person if involve with huge farm and huge amount of breeds.

The implementation of the auto feeder machine can avoid the food wastage

because this system is designed to reliably and correctly feed each goat individually.

This computerized feeding system has pre-setting of each goat's feed ration to

include the exact amount of concentrates as required. The machine provides a

comprehensive set of modules; control the feeding system automatically with the

aim of optimizing cost of production of goat products. The automated food

dispensing system is a modular design that provides a flexible and robust system

able to meet the requirements of goats feeding activities.

Abstrak kertas kerja yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi keperluan untuk ijazah Master Inovasi & Rekabentuk Kejuruteraan

ABSTRAK

REKABENTUK MESIN SISTEM PENGAGIHAN MAKANAN SECARA OTOMATIK UNTUK PEMAKANAN TERNAKAN KAMBING

Oleh

MASJURI BIN MUSA @ OTHMAN

NOVEMBER 2006

Pengerusi: Lt. Kol. (B) Ahmad Tarmizi bin Mohamed

Fakulti: Kejuruteraan

"Sistem pengagihan makanan otomatik", adalah merupakan sebuah mesin

yang direkabentuk khas untuk mengagihkan makanan kepada binatang ternakan

secara otomatik. Di dalam kes ini, sektor penternakan kambing telah dipilih

memandangkan permintaan tempatan yang tinggi untuk produk ternakan ini.

Hampir kesemua penternak kambing di negara ini, masih lagi mengamalkan

kaedah penternakan secara tradisional dan tidak ekonomi. Para penternak masih lagi

mengamalkan kaedah tradisional dalam proses pengagihan makanan kepada

kambing ternakan dengan mencurahkan makanan secara manual ke dalam setiap

bekas makanan ternakan yang terletak pada bahagian tepi setiap kandang. Para

penternak tidak akan dapat menyukat dengan betul makanan yang diperlukan bagi

setiap kambing sekiranya kaedah tradisional ini masih terus diaplikasikan. Akibat

daripada sistem pengagihan makanan yang tidak sempurna ini, maka pembaziran

makanan yang begitu ketara berlaku dan seterusnya memberi kesan buruk terhadap

kos operasi makanan setiap bulan. Kaedah ini juga memerlukan masa yang lama dan

lebih daripada seorang pekerja diperlukan untuk mengagih makanan sekiranya

melibatkan jumlah ternakan yang besar atau penternakan secara komersil.

Perlaksanaan mesin pengagihan makanan otomatik ini boleh mengelakkan

pembaziran makanan kerana sistem ini telah direkabentuk untuk mengagihkan

makanan kepada ternakan dengan betul. Sistem pengagihan makanan berkomputer

ini mempunyai suatu sistem kawalan bagi catuan makanan setiap kambing,

disesuaikan dengan jumlah sebenar makanan atau konsentrat yang diperlukan.

Mesin ini menyediakan suatu set modul yang komprehensif, mengawal sistem

pengagihan makanan secara otomatik dengan tujuan utama untuk mengoptimurnkan

kos pengeluaran produk berasaskan karnbing. Mesin ini terdiri daripada sistem

modul yang direkabentuk agar ianya fleksibel, bagi memenuhi keperluan harian di

dalam aktiviti pengagihan makanan kambing.

CHAPTER I

INTRODUCTION

1.1 Introduction

"Automated food dispensing system" or also known as "Auto feeder" is a

system, which is used to distribute foods and feed the breedings automatically by

using controlled mechanical hardware as well as the application of the electronic

programmable database. This system is suitable to implement for the huge capacity

of any kind of breeding sector. In this project, goats breeding sector has been

choosen as an approach to implement this automated food dispensing system due to

the aggressive encouragement from our government to enhance the development of

this sector, and in order to meet the local market demand of goat's product [I].

Goats as a species have a long history as domesticated animals used for

human consumption. Today it is estimated that there are more than 460 million goats

worldwide producing 4.5 million tons of milk and 1.2 million tons of meat annually

[I]. Recent increases in the demand for goat meat from ethnic and health conscious

groups has shifted some emphasis from fiber and milk production to meat

production. It is estimated that there are only 8% of meat goats currently raised in

our country, and most of these needs are imported from other countries such as

Indonesia and Thailand to overcome the local demand. Generally, the meat goat

industry is disorganized and not well defined [2].

Recent increases in immigration and the subsequent increase in ethnic

populations that are familiar with and prefer goat meat, have created an optimistic

and enthusiastic atmosphere among current and potential goat producers. While

interest and optimism have increased, a limited amount of formal work has occurred

toward assessing the feasibility of raising goats within our country. This work

represents a first known attempt at determining the feasibility of raising meat goats

within Malaysia. Understanding that this is a first attempt at determining the

feasibility of raising meat goats in Malaysia, producers or potential producers should

be aware that production costs and marketing niches in Malaysia meat goat industry

can and do differ among producers. Differences among producers can and will affect

the feasibility of producing meat goats. Potential producers should use caution and

careful analysis when deciding to enter the market.

Feed is, without doubt, the main cost incurred in goat production. By using

feed supplements that enhance production, this will not only improve the health of

the breeders, but also be able to offset costs and increase profits. Based from

MARDI's data, almost 80% of the monthly operating cost comes from food [I].

Commonly, in the existing feeding strategy, the farmer will feed the goats by

pouring the foods or required concentrates in the food containers and this may cause

ununiformity in the amount of quantity given. In order to optimize these food

quantities for each station in the barn, as well as to prevent from feed wastage, the

idea of using the automated food dispensing system has been taken placed. The

optimal approach is to feed the goats often with small individually adapted portions.

This method allows the goats to properly digest their feed, promotes good growth

and limits feed waste.

1.2 Background

The automated food dispensing system is one of the main systems, which

can be applied to the goat's breeding sector with huge amount of breeds. It is

designed to reliably and correctly feed each goat individually. This computerized

feeding system has pre-setting of each goat's feed ration to include the exact amount

of concentrates as required. The module provides a comprehensive set of control

system, to control the feeding activity automatically with the aim of optimizing cost

of production of goat products. The automated food dispensing system is a modular

design that provides a flexible and robust system, able to meet the requirements of

goats feeding activities.

However, the auto feeder dispensing system machine has not been applied

yet aggressively in our country. Most of Western and European countries such as the

United State of America, Denmark, Norway, United Kingdom as well as Australia

and New Zealand, the implementation of these auto-feeders dispensing system have

tremendously applied into their sheep farms, which involve thousands of breeds 131.

Since there are huge amounts of breeds, as a result, most of the farms involved many

workers to do all the related breeding process such as cleaning the barn as well as to

feed the breeds. Besides that, one of the most problems facing in the breeding

process is that, the distribution of the exact amount of nutrition food in a very

effective and proper way. The improper distribution of food can caused a lot of feed

wastage and directly it gives bad impact to the food operation cost. In order to

prevent the feed wastage, a proper and an efficient system of feed distribution

should be taken place where by, it will save the food distribution time without the

involvement of too many workers.

As a result, to overcome these critical phenomena, most of the farmers or

breeders have been shifted and focusing to other system, which is more efficient and

involve more cost saving in daily food operation cost. Starting from this point

onwards, the auto feeder dispensing system has been well known and has been used

widely among the breeders in Western and Europe.

Companies who producing and do marketing for the auto feeder dispensing

system is not only limited to the sheep or goat breeding. They also produce this

system to other kind of breeders such as cows, horses, fishes as well as pets.

1.3 Problem Statement

Food is one of the most important factors in any kind of breeding activities.

Food also contributed the most higest cost in the monthly operation cost compare to

others such as health and medication cost as well as contegencies cost. Goats need to

take care of from the quality of the food, the amount of food given, and those

diseases, which are caused by the foods. Non-quality food can effect the breeds

growth and health.

Almost all the goat's farmers in this country, are still implementing the

traditional breeding system and not economical. In other words, the "traditional

system which is not competence". In this traditional system, the goats are let free

during daytime to feed on leaves or grass and all will stay in the barn during

nighttime. The feed areas include rubber farms, coconut oil farms, and fruits farms

as well as around village areas. Due to the improper amount of food nutrition,

therefore the qualities of the food given to the goats are very low. Besides having

leaves and grass as one of the main food, goats also will be given with other special

nutrition food, which is the mixture of few ingredients, known as pallet. This quality

nutrition food will be fed to the goats twice a day and it is a very costly item.

Goat's farmers in our country are still feeding the goats by using an old

technique, which is pouring the pallet into each container, which is located at the

side of the barn as shown in Figure 1.1 [3]. By using this old method, the farmers

could not measure the exactly amount of pallet needed for each goat. They just

simply poured the pallet or nutrition food into the containers to make sure it full.

Due to this improper distribution of feeding system, it will cause the obvious food

wastage and may effect badly to the food operation cost. The method will also take

longer time to fill in all the containers and it needs more than one person if involve

with huge farm and huge amount of breeds and indirectly will increase the overhead

cost. This is the main reason why food operation cost is the highest cost in goats

breeding sector in Malaysia.

Figure 1.1 ; Traditional method of food distribution [3]

Q)

S S -is G S % 0 u

C M .- VY Q) a - cd 0

3 S i! a 5 !i 3 3 z Q)

S S .d

3 E Q)

2 3 X - C 0 - - 'is C 0 Q) -7

%

CHAPTER I1

LITERATURE REVIEW

2.1 Introduction

Intensive commercial goat's farm sector is one of the main sectors in our

country, which can gain a lot of profits and benefits. The demand for goat's products

such as pasteurize milk as well as its meat among the consumers, lead to the

increment of the goat's farms in Malaysia. Table 2.1 and Table 2.2 below [2], tells

us about the demand of goat's products and its market price in RM. Table 2.3, shows

us about the different of market price in Ringgit Malaysia (RM) per kg between

local live goats and combine gene live goats. According to the Agricultural

Department, presently, our country can only patch about 8% of the local demand on

the goat's products especially on meat and pasteurize milk. The remain of 92% of

the local demand, mostly are imported from other countries such as Australia, New

Zealand, Indonesia, Thailand and Myanmar.

Based on the Table 2.1, on the next page, which gain from the Agricultural

department [2], the demand of imported goats slightly increased from 1996 to year

2000. This data show us that the need is already there and will be succeeded if

manage properly and effectively.

Table 2.1 ; The demand of goat's products and its market price in RM from year 1996 to 2000 [2]

-

Year 2002 2003 2004 2010 (forecast)

Local Output 1.21 1.30 1.50 2.18

Demand 15.10 15.60 16.80 21.30

Percentage (%) 8.0 1 8.33 8.93 10.23

Table 2.2; The differences between market demand and local output

of goat's products [2]

From the table above, the demand are always increased, roughly we can see

the growth always maintained at the above 8%.

Year

1996

1997

1998

1999

2000

Meat

The data from Table 2.3, shows the price of combine gene live goats, where

the level is much better than the local goats (data from the Agricultural department

for the analysis been done from year of 1998 to 2000).

Goat

Weight

(metric ton)

13,804

12,508

1 1,840

12,239

13,956

Sheep

Weight

(metric ton)

25,759

43,773

25,6 17

42,6 16

45,325

Value RM

(000,000)

63.8

66.2

69.7

68.7

69.6

Weight

(metric ton)

10,309

9,233

2,892

8,62 1

3,987

Value RM

(000,000)

6.3

11.0

7.9

11.8

9.2

Value RM

(000,000)

3.3

3.3

1 .O

4.5

3.0

Table 2.3; The price (RM) of female and male genetic combination or local goat [2]

Year

1998

1999

2000

In order to overcome this short demand, the government through other

responsible and related agencies such as Malaysian Agricultural Research and

Development Institute (MARDI), Lembaga Kemajuan Ternakan Negara

(MAJUTERNAK), as well as State Agricultural Development Corporation (SADC),

has been put a lot of effort to encourage Malaysian to involve in this profitable

sector. Government through MARA agency, has been introduced a program to

encourage and attract unemployed graduates to dabble in this sector. Since our prime

minister, Y.A.B. Dato' Seri Abdullah bin Hj. Ahrnad Badawi, has been reintroduced

the idea of Green Book which stress on the importance of agriculture for the

country, more and more local individual has shown their interest in the goats breed

sector. This sector has bright hture and will be succeeded if focus seriously.

Information from Fortune Magazine stated that one of the three industries in

Malaysia, which definitely give a good prospect and gain a good income in 10 years

times, is in the breeding sector.

In order to design the automated food dispensing system, it is good to really

understand the system of the goat's feeding itself. The information such as, what is

the amount of food that needs to be taken everyday and how the distribution of the

Genetic Combination 1 Local Goat (RM pricekg live goat)

Female

Local

6.00

6.00

6.00

Male

Combine Gene 9.00

9.00

9.00

Local

10.00

14.00

14.00

Combine Gene 10.00

14.00

14.00

food to the food containers, which are located at the barn, need to be done. All the

information, later on will be used as a references to design an automated food

dispensing system, which is more efficient to replace and improve the existing

traditional method. With this automated system, hopefully it can contribute a

valuable value to our breeding sectors and meet our local demand in goat's products.

Through the search which done by the Veterinary Department, the amount of

food for each goat depend on its weight. Graph 2.1, shows us about the total amount

of food given for each goat per day.

1000

A 900 m - 800 '0

8 700 LL r 600 0 = 500 a

400

4 300 - g 200

+ 100

0 20 30 40 50 60

Goat's Weight (kg)

Graph 2.1 ; Total amount of food (g) given to each goat depend on the goat's weight (kg) [2]

Besides the weight of the goat, the factor of goat's age is also play an

important role in goats feeding. Table 2.4, tells us about the total amount of food

given based from the goat's age [2].

+I- 50 to 100 +I- 150 to 350 +I- 400 to 600

6 and above +I- 600 to 650

Table 2.4; The total amount of food given (g) based from the goat's age. [2]

The information from Graph 2.1 and Table 2.4, shows us that, the relation

between the goat's weight and age plays an important roles for the feeding amount.

In this particular case, we assume that all breeders are 5 to 6 months in age with the

weight is around 30kg for each goat. Therefore, the roughly amount of food given is

about 500g for each goat daily [2]. Base from this information, we can determine the

size of the food container of the automatic food dispensing system which going to

design later. The size of the food container is also depending on the quantity of the

goats in the barn to feed. If it involve with big quantity of goats, therefore the food

container need to replace with other size to cater with the goat's quantity, which

need to be fed.

2.2 Types of Auto feeder Dispensing System

There are two types of auto feeder dispensing system in the market, depend

on their application, design or shape and how the breeds are feed, the food area

location, as well as the size or capacity of the breeds.

The types are:

i) Static auto feeder dispensing system.

ii) Self-moveable auto feeder dispensing system.

2.2.1 Static Auto feeder Dispensing System

Static auto feeder dispensing system, normally applied to a small and

medium scale of breeding. This equipment is not limited to feed indoor-kept breeds.

The auto feeder system is equipped with lid and suitable seals to permit to be

operated outside. The programmable software is implemented to control all the

processes and activities done by the auto feeder system. There is an auto feeder

system, which only allows one goat to eat at one time as shown in Figure 2.1 on the

next page. This kind of auto feeder machine consists of two separate sections. One

of the sections is called control panel system that controls the auto feeder

automatically when feeding the goats. The control panel system will control the

amount of the food, which need to be given for each goat. The other section is a

place to feed the goats, which is also known as feeder section. Battery is used as a

power supply to generate the power. Once, when the goat is at the feeder section, the

control panel system will start to operate by allowing the feed to discharge from the

main food container into the other container with a certain amount of food that has

been set automatically. After the goat finish eating, the next goat will take place and

this process is a repeatable process. The disadvantage of this auto feeder system is

that only one goat can eat at one time.

There is an auto feeder system using the gravity concept as shown in the

Figure 2.2 [4]. The quantity of food can be set automatically and will discharge from

the main food container, which is located on the top of the machine to the bottom

food container through few chutes. The feeding period can also be set up

automatically. For this design, the control panel section is located inside the main

food container to prevent it from the weather conditions or to avoid from any outside

disturbances. This type of auto feeder system has simple design and the good thing

about this design is that it can feed about 16 to 18 goats in one time. The

disadvantage is that, goats have to share their food and possibility to quarrel to have

the food can be happened. Besides that, the food quantity of each goat taken cannot

be controlled and this may cause unbalance nutrition. Other static types of auto

feeder system are shown in Figure 2.3, Figure 2.4 and Figure 2.5 in Appendix

section [3], [5].

Control Panel Section

Feeder Section

Figure 2.1 ; Static Auto-feeder system [3]

Main Food Container

Bottom Food

Container

Chutes

Figure 2.2; Static Auto feeder system (Gravity type) [4]

2.2.2 Self-moveable Auto feeder Dispensing System

The other type of auto-feeder system is a self-moveable type. The application

of the self-moveable auto feeder dispensing system is more suitable for huge

capacity of breeding. This type of auto-feeder system handles group feeding from an

overhead, monorail mounted wagon and distributes food from the main station to

each barns as shown in Figure 2.6 and Figure 2.7 [ 5 ] . This method is much more

effective, save a lot of time, and not involved many workers. However, the first time

set-up cost will be much higher if compared to the static type due to the

implementation of more advanced technology. The machine itself is a dedicated auto

feeder machine where it is run by using patented feeding software. Every processes

or activities done by the machine are controlled automatically. Parameters such as

setting the feeding time (the auto feeder machine will start to move automatically to

distribute the food when reach the time which has been set), amount or quantity of

feeding, or even the speed of the machine can be set up with control panel attached

on the machine.

Top Monorail /

Control Panel.

Figure 2.6; DeLaval feed wagon R135 (Rail type) [5]

Control Panel

Top Monorail

Chutes

Figure 2.7; DeLaval feed wagon FCC380 (Rail type) [5]

Flow chart 2.1, on the next page, shows us roughly about the basic function

of the auto feeder dispensing system machine.

Flow-chart 2.1 ; General Process Flow of the Function of the Auto Feeder Dispensing System Machine

flective sensor v

:he presence of

7- the reflective tape

The re --------- sense t . * The reflective sensor

Auto-Feeder Machine will - - - - - - - - (at side panel) sense the stop moving presence of the

reflective tape (at food containers)

Auto-Feeder Machine start to move

+--------------------- Pallet flows out of the main food container through the chutes

The Auto-Feeder Machine will move backwards to the

starting point

+ The valve of the feeder's

system will close

After certain quantity 4 ------- of pallet has been

poured into the food container, the

Level sensor is on --------- b

actuator's sensor will give signal to the valve to close.

2.3 Design of the Auto feeder Dispensing system

First of all, the conceptual design need to be considered before proceed to the

detail and final design. To have the conceptual design, all the information regarding

to the auto feeder dispensing system will be collected. The information related to the

goat's breeding sector such as the types of barn which is normally built in our

country, methods used to feed the breeders as well as types of food given to the

breeders are also need to be concerned. To have a clear picture of the real situations

about the goat's breeding sector, a visit has been done to one of the well known

place, which is called KAPRIMA, located at Lendu, Melaka.

2.4 Technical Drawings and Design Analysis

One of the design's software, which is called Solidworks, will be used to

draw the technical drawings of the overall auto feeder dispensing system. The

drawings will include the 3D drawings as well as the 2D drawings. On the other

hand, the analysis of the structure of the auto feeder system will also be done. These

will involve Finite Element Analysis (FEA), an analysis software which is called

NASTRAN-PATRAN, where the purpose of using this software is to find out the

Von Mises of the structure.

2.5 Computer-Aided Engineering (CAE)

Computer-Aided Engineering (CAE) refers to computer software and

hardware systems used in the analysis of engineering designs to validate functional

performance. Computer-Aided Design (CAD) is sometimes used interchangeably

with CAE [6] .

CAE systems can be separated into four main categories which are:

i) Dynamic analysis.

ii) Finite element analysis (FEA).

iii) General purpose.

iv) Others.

2.5.1 Dynamic Analysis

Dynamics analysis include the kinematics and kinetics of bodies, that is, the

motion and the forces and moment that cause motion. Solid modeling packages, for

example, will mate parts into an assembly, and that we can manipulate various parts

to animate their relative motion. However, in the dynamics analysis package such as

Working Model, or ADAMS, we can apply specified loads to the parts and the

package will calculate their resultant motion using fundamental equations of physics

and a variety of numerical methods. These packages simulate behavior based on

physics, whereas CAD solid modeling packages illustrate motion. Since kinematics

and kinetic based packages are based on the physics of the problem, they can

analyze a number of behaviors including:

i) Positions, velocities as well as accelerations.

ii) Contacts and collisions.

iii) Joint forces, shaking forces.

iv) Relative motions.

2.5.2 Finite Element Analysis (FEA)

Finite Element Analysis (FEA) is a method that essentially divides a part into

smaller discrete elements to analyze the functional performance of a part. Used in

many engineering fields, the process begins with the creation of a geometric model

using CAD software. Solid modeling packages can export files to FEA and some

can communicate directly with FEA packages. The part is subdivided into a mesh of

smaller finite elements connected at nodes. Loads are then virtually applied to the

part. Using hndarnental equations from physics and engineering, an FEA package

can analyze a number of behaviors including:

i) Stresses and strains throughout the part.

ii) Factor of safety.

iii) Buckling of parts in compression.

iv) Temperature gradients and resulting heat transfer.

v) Fluids pressures and flows.

vi) Natural frequencies of vibration.

vii) Displacements of nodes.

2.5.3 General Purposes

General purpose software refers to computer applications covering word

processing, spreadsheets, mathematics, oral presentations, and project management

such as MSWord, Excel, MathCAD, Powerpoint as well as MSProject where by all

these software can help us to complete the daily tasks more efficient.

2.5.4 Others

Other computer-aided engineering application include:

i) Quality function deployment - applications that facilitate the

development of houses of quality such as QFDCapture.

ii) Material selection - specialized software that aids in screening materials

such as GRANTA design, which implements Ashby's methodology.

iii) DFMA - applications that facilitate design for assembly andlor design

for manufacturer analyses such as the Boothroyd-Dewhurst package.

iv) Systems simulation - such as MATLAB Simulink, which analyzes the

transient and steady state behavior of multicomponent electrical and

mechanical systems.

v) Variance analysis - applications that compute tolerances stacks in

assemblies.

2.6 Materials Selection

This section will describe about the basic concept of how to do the materials

selection. As we know that material has attributes: its density, strength, cost,

resistance to corrosion, and so forth [6] . A design demands a certain profile of these:

a low density, a high strength as well as a modest cost. The problem is that of

identifying the desired attribute profile and then comparing it with those of real

engineering materials to find the best match.

2.6.1 The Selection Strategy

There are two main steps, which called screening and ranking, and

supporting information, as shown in Flow chart 2.2.

2.6.1.1 Screening and Ranking

Unbiased selection requires that all materials are considered to be candidates

until shown to be otherwise, using the steps detailed in the boxes of Flow chart 2.2

[17]. Firstly, screening, eliminates candidates which cannot do the job at all because

one or more of their attributes lies outside the limits imposed by the design. For

example, the requirement that the component must function at 250°c, imposes

obvious limits on the attributes of maximum service temperature, which successful

candidates must meet. We refer this as property limits.

All Materials

Screening: apply property (Eliminate candidates which can't do the job)

I Ranking: apply material indices (Find candidates which can do the job well) I

Subset of Materials

I

w

Supporting Information (Handbooks, specialized software, expert systems,

CD-ROMs, website)

I Prime Candidates I

I Local Conditions I I (Does the choice match local needs, expertise?) I

* Final Material Choice

Flow-chart 2.2; The strategy for material selection. The main steps are enclosed in bold boxes [17].

However, the property limits do not help with ordering the candidates that

remain. To do this we need optimization criteria. They are found in the material

indices, which measure how well a candidate, which has passed the limits, can do

the job. Familiar examples of indices are the specific stiffness E I p and the specific

strength of l p (E is the Young's modulus, o, is the failure strength and p is the

density). The materials with the largest values of these indices are the best choice for

a light, stiff tie-rod, or a light, strong tie-rod respectively [17]. On the other hand, to

summarize this, we can say that the property limits isolate candidates which are

capable of doing the job, whereas material indices identify those among them which

can do the job well.

2.6.1.2 Supporting Information

The outcome of the screening step is a shortlist of candidates, which satisfl

the quantifiable requirements of the design. To proceed further we seek a detailed

profile of each, which is supporting information as shown in Flow chart 2.2.

Supporting information differs greatly from the property data used for

screening. Typically, it is descriptive, graphical or pictorial: as for example, the case

study, which involved with uses of the material, details of its corrosion behavior in

particular environments, information of availability and pricing, experience of its

environmental impact. Such information is found in the handbooks, supplier's data

sheets, CD-based data sources and the worldwide webs. Supporting information

helps narrow the shortlist to a final choice, allowing a definitive match to be made

between design requirements and material attributes.