NETAJI SUBHAS UNIVERSITY
OF TECHNOLOGY
Home Assignment On
Selection of Material
Made by :
Rishabh Mittal | 2017 UMP 3585 | Mpae Department
Achin Verma | 2017 UMP 3589 | Mpae Department
Mayank Kalshan | 2017 UMP 3571 | Mpae Department
Manvi Soni | 2017 UMP 3579 | Mpae Department
INTRODUCTION
Material selection is a step in the process of designing any physical object. In the context of
product design the main goal of material selection is to minimize cost while meeting product
performance goals. Systematic selection of the best material for a given application begins
with properties and costs of candidate materials. For example, a thermal blanket must have
poor thermal conductivity in order to minimize heat transfer for a given temperature
difference.Systematic selection for applications requiring multiple criteria is more complex.
For example, a rod which should be stiff and light requires a material with high Young
Modulus modulus and low density. If the rod will be pulled in tension, the specific modulus, or
modulus divided by density , will determine the best material. But because a plate; bending
stiffness scales as its thickness cubed, the best material for a stiff and light plate is
determined by the cube root of stiffness divided by density
INTRODUCTION TO ROLE AND RESPONSIBILITY OF MATERIAL
ENGINEER
1) Design Process :
a) Drawing the basic design
b) Proper selection of materials according to different parameters such as:
• Mechanical Loads
• Wear
• Electrical insulation
• Thermal properties
• Availability and cost
2) Proper choice of substitutive materials when needed.
3) Contributing and evaluating material tests results.
4) Study and composing materials data sheets before placing an order.
5) Enhancing the performance of the materials by carrying out research activities.
DEFINITION OF DESIGN PROCESS
Mechanical design refers to the mechanical components that have mass carry loads and
other functionalities such as thermal electromagnetic requirements and must be
manufactured.
DESIGN
refers to the selection of Engineering Materials based on the set of defined properties it is an
interactive process.
SELECTION OF MATERIAL
1. Availability of the material depending upon the price and money.
2. Depending on the group of Mechanical properties such as Density, Modulus
Stiffness, Damping and etc.
3. Thermal, Electrical, Optical and Magnetic.
4. Chemical environment change like oxidation, corrosion, friction, aberration
and wear.
5. Ease of manufacturing, joining and etc. which includes design for
manufacturing.
6. Aesthetics which includes appearance texture and fee.
Some of the common and analytical methods for material
selection are :
1. Cost versus performance
● Cost is the prime factor in selection of engineering materials so it is logical to
consider cost at the start of the material selection process.
● This is done by electing a target cost which is used to eliminate the materials
which are very expensive.
● The final choice is a tradeoff between cost and performance.
● Overall, cost is the most important factor in the selection of the material
● Cost is a most useful parameter when it can be related to a critical material
property that controls the performance of the design
● Such a cost versus performance index can be used for optimizing the
selection of a material.
● However the most common method of expressing cost of a material may not
be the most suitable criteria.
● The other factor participating in the criteria is also the function which the
material serves: whether it is used as load bearing or just as space filling.
There are various ways to compute costs.
● The most common method used in the industry is the TOTAL LIFE-CYCLE
COST.
● This cost consist of : The initial material cost +manufacturing costs+operation
costs+maintenance cost
● Consideration of these factors beyond just the initial materials cost leads to
various overall economic relations.
FACTORS AFFECTING THE SELECTION OF MATERIALS
(i) Component shape:
● The shape and size of a component has a great effect on the choice of the
processing units which finally affects the choice of the material.
● Example: let the best possible production method is selected, under given conditions,
it is die casting, obviously, now the choice of the material becomes limited, i.e. one
can only choose materials with lower melting points, e.g. aluminum, zinc,
magnesium and thermoplastics.
(ii) Dimensional tolerance:
● There are some materials which have the capability of being finished to close
tolerance while other does not.
● It is quite obvious that the required dimensional tolerance for finished components
will influence the choice of the materials.
(iii) Mechanical properties:
● To select a material which fulfills all the required mechanical properties required for
the industrial application
● Some mechanical properties are toughness, hardness, strength, fatigue, cyclic
loading, and creep.
(iv) Fabrication and manufacturing requirements :
● Methods used to process the materials also affect the properties of a component. For
e.g. forged materials are stronger than casted materials. Also investment casting
gives us the highest amount of accuracy and precision.
● Fabrication requirements are castability, weldability, machinability, formability,
hardenability etc.
(v) Service requirements:
● dimensional stability,
● strength,
● toughness,
● heat resistance,
● corrosion resistance,
● fatigue and creep resistance,
● Electrical and thermal conductivity etc.
PROCEDURE FOR MATERIAL SELECTION
DOUBLING TIME
● Period of time required for a quantity to double in size or volume.
● When the relative growth rate not the absolute growth rate is constant the quantity
undergoes exponential growth and has a constant doubling time or period
● Example apply to population growth inflation resources extraction consumption of
goods compound interest the volume of Merchant tumors.
IF Doubling time of a material is less therefore the cost of the material will be high
and vice versa.
RESOURCE AVAILABILITY
● Current Reserve i s the non deposit that can be extracted profitably at
today's price using today's Technology.
● Resource Based = Current Reserve + ( known and unknown deposit ).
Availability
● Copper, Silver, Tungsten, Tin and M
ercury are rarely available.
● Iron and Aluminium are the most widely available materials.
● Steel consumption is doubling in every 20 years.
● Aluminium consumption is doubling in every 09 years.
● Polymer in every 4 years.
HOW TO ENCOUNTER SHORTAGE OF MATERIALS
Material Efficient Design: Use less amount of material.
For example for a good surface property used substrate and good surface finish
Substitution: Substitute rare materials by the more available once
For example Copper and Aluminium
Recycling use recyclable material like Alluminium.
ECO EFFICIENCY
● Mergers ecological and economic goals.
● Improving the productivity of energy and material input to reduce resource
consumption and cut pollution for unit of output.
● A Win-Win approach that benefit both the bottom line and the environment.
● In a 1989 Procter and gamble introduce concentrate concentrated detergent
powder called Ultra detergent that took up half of the volume of traditional detergent
the product clean the same amount of floors but were more convenient for consumer
to have used 30% fewer raw material required 50% less packaging and
sustainable cut the energy needed and transport them to market.
Not only think of reducing a cost but also think of protecting environment. Not think
particular environment to only serve a particular operation but also think how the use
of that material will affect the environment.
ASHBY CHARTS
Material selection is a step in the process of designing any physical object. In the context of
product design, the main goal of material selection is to minimize cost while meeting product
performance goals.Systematic selection of the best material for a given application begins
with properties and costs of candidate materials. For example, a thermal blanket must have
poor thermal conductivity in order to minimize heat transfer for a given temperature
difference.
Families occupy different fields.
Systematic selection for applications requiring multiple criteria is more complex. For
example, a rod which should be stiff and light requires a material with high Young's modulus
and low density. If the rod will be pulled in tension, the specific modulus, or modulus divided
by density. will determine the best material. But because a plate's bending stiffness scales
as its thickness cubed, the best material for a stiff and light plate is determined by the cube
root of stiffness divided by density.
High density structures will be heavy in weight then we should go for low density structure
and with high strength that is CFRP as same strength level of metal but with low
density.
Aluminium is 2-½ times stronger than Steel so we can make lighter chassis from this.
● Car weighing 40% lighter
● Make it use 35% less energy over its life making its total life time energy use
much lower.
● Based on strength requirement we eliminate lot of material like polymer, foam.
● To optimise my choice remaining we can plot a guideline based on objective,
constraints and geometry. Minimum mass reference
● Material on the line perform better but the material on above the line perform
good. Al, Carbon Fiber, Titanium, Steel all good.
