Recyclability-Cost

1
Selection of Materials
2
Game!
Aim To make as much money as possible! Make and
sell these shapes. All dimensions must be correct
or they will not be accepted.
5cm
100 r
6cm
45 r
20 r
10 r
5cm
3
Game!
Colour Material Cost per sheet (rupees)
Green Wood from hillside 50
Blue Cut treated wood from local craftsman 100
Yellow High quality wood from large manufacturer 200
Pink Very high quality synthetic material, global manufacturer 300
7cm
100 r
7cm
45 r
20r
10 r
7cm
4
Selection of Materials
5
Selection of Materials
6
Selection of Materials
What qualities are important in your final
product?

• Light
• Cheap
• Strong enough to withstand expected forces
• Rigid
• Durable

7
Selection of Materials
How can we measure and compare these qualities?

• Rupees per kilogram
• Kg per m3 (Density)
• Maximum Force (N) per m2
• Youngs Modulus
• Toughness

• Cost
• Light/Heavy?
• Strength
• Rigid
• Durable

8
How light is my material?

• Density is a measure of lightness
• Density is the mass per unit volume

wood
steel
Density (kg/m3)
Steel 7900
Wood 800
Water 1000
water
9
Density

• Density is the mass per unit volume
• Do polythene and PVC float or sink?

Density (kg/m3)
Polythene 960
PVC 1600
Water 1000
Polythene
PVC
water
10
Density

• Density is the mass per unit volume

1 m
2 m
Volume (m3) x x
0.004 m

• I have a mild steel sheet
• The density is 7900 kg/m3

0.008
Mass (kg) x
7900 kg/m3
0.008 m3

63
0.004 m thick
1m
2m
11
How rigid is my material?
The Youngs Modulus is how we measure stiffness

• Large Youngs Modulus
• High Stiffness

• Small Youngs Modulus
• Low Stiffness

12
How durable is my material?

• During manufacture, materials will get small
  cracks
• These cracks may get bigger very fast, or very
  slowly
• Fatigue crack video
• The tougher the material, the slower a small
  crack turns into a big crack

glass
steel
13
How environmentally friendly is my material?

• Energy used during manufacture
• Often extracting a material can use a lot of
  energy
• For example extracting aluminium requires a
  temperature of 2000 oC.
• This uses up fuel resources, and also large
  processes need constant supplies of electricity,
  diverting power away from places such as Pabal.

14
How environmentally friendly is my material?

• 2) CO2 produced during manufacture
• When we burn fuel/use electricity we release CO2
• CO2 contributes to global warming

15
How environmentally friendly is my material?

1. Recyclability

16
How strong must my material be?
Wind Load 8,9000N
Self Weight 1,4000N
10,3000N
6
Force on 1 column /
1,7000 N

17
How strong must my material be?

• Strength is measured in N per square metre
• Does this post have a cross section of 1 square
  metre?

Load 1,7000N
Estimate Area Cross Section
x
0.05m
0.05m
5cm

0.0025 m2

• How many 0.0025 m2s fit into 1 square metre?

5cm

• The force on 0.0025 m2 is 20,000 N
• How much force is on 1 m2 ?

/
1 m2
0.0025 m2

400

• 1m is 400 times bigger than 0.0025 m2

Force (N/m2) x
1,7000N
400

6,800,000
18
1
2
Strength - Cost
6.8 MPa
4
3
19
Material Strength-Cost
Cast iron 2
Low carbon steel 2
Medium carbon steel 2
High carbon steel 2
Stainless steel
Aluminium 3
Copper
Wood (along grain) 1
Wood (across grain)
Bamboo 1
PVC 1
Polythene 1
Cement
Concrete
Strength - Cost
20
1
2
4
3
Density - Cost
21
Material Strength-Cost Density-Cost
Cast iron 2 2
Low carbon steel 2 2
Medium carbon steel 2 2
High carbon steel 2 2
Aluminium 3 2
Wood (along grain) 1 1
Bamboo 1 2
PVC 1 1
Polythene 1 2
Density - Cost
22
1
2
Strength - Density
3
4
23
Material Strength-Cost Density-Cost Strength-Density
Cast iron 2 2 3
Low carbon steel 2 2 2
Medium carbon steel 2 2 2
High carbon steel 2 2 2
Aluminium 3 2 2
Wood (along grain) 1 1 1
Bamboo 1 2 1
PVC 1 1 1
Polythene 1 2 1
Strength - Density
24
1
2
Stiffness - Density
3
4
25
Material Strength-Cost Density-Cost Strength-Density Stiffness-Density
Cast iron 2 2 3 3
Low carbon steel 2 2 2 2
Medium carbon steel 2 2 2 2
High carbon steel 2 2 2 2
Aluminium 3 2 2 1
Wood (along grain) 1 1 1 2
Bamboo 1 2 1 3
PVC 1 1 1
Polythene 1 2 1
Stiffness - Density
26
1
2
Toughness - Density
4
3
27
Material Strength-Cost Density-Cost Strength-Density Stiffness-Density Toughness-Density
Cast iron 2 2 3 3 3
Low carbon steel 2 2 2 2 1
Medium carbon steel 2 2 2 2 2
High carbon steel 2 2 2 2 3
Aluminium 3 2 2 1 1
Wood (along grain) 1 1 1 2 2
Bamboo 3 2 1 3
Toughness - Density
28
2
1
Recycle - Cost
3
4
29
Material Strength-Cost Density-Cost Strength-Density Stiffness-Density Toughness-Density Recycle-Cost
Cast iron 2 2 3 3 3 1
Low carbon steel 2 2 2 2 1 1
Medium carbon steel 2 2 2 2 2 1
High carbon steel 2 2 2 2 3 1
Aluminium 3 2 2 1 1 1
Wood (along grain) 1 1 1 2 2
Recycle - Cost
30
1
2
4
3
Price - Energy
31
Material Strength-Cost Density-Cost Strength-Density Stiffness-Density Toughness-Density Recycle-Cost Energy-Cost Total
Cast iron 2 2 3 3 3 1 1 15
Low carbon steel 2 2 2 2 1 1 2 12
Medium carbon steel 2 2 2 2 2 1 2 13
High carbon steel 2 2 2 2 3 1 2 14
Aluminium 3 2 2 1 1 1 3 13
Price - Energy