Medium carbon steel is selected for the design because it has a high performance index and low cost. Polytetrafluoroethylene (PTFE) GF1 is selected, despite its high cost, for safety purposes. Wrought Ferritic Stainless Steel is selected because it has a good performance index and good thermal properties. Common hard brick is selected for its low cost, good thermal conduction, and ease of manufacture. Nodular (spheroidal, ductile) Cast Iron is selected for its good performance index and low cost. Low Carbon steel is suitable for designs requiring a material that is low cost, stiff, and strong.

1. MATERIAL SELECTION IN MECHANICAL ENGINEERING
01.
Performance index =
𝜎
ƥ
Figure 01: Material property table for question 1

2. Table 01: Material properties for selected materials for question 1
 Medium carbon steel is used to design because it had high performance index and low cost
Material Strength
(MPa)
Density
(Kg/m3
)
Performance index
(m2
/s2
)x106
Cost
SLR/Kg
Remarks
Wrought Precipitation Hardened Stainless
Steel
1007.5 7.8 129.17 243.7 good corrosive
resistence/expensive
Nodular (spheroidal, ductile) Cast Iron 502.5 7.15 70.28 40.6 low cost
Cast ferritic stainless steel, ASTM CC-50,
low nickel
447.5 7.525 59.47 139.3 low ductility
Medium Carbon Steel 1030 7.85 131.21 40.6 high strength/low cost
Wrought Ferritic Stainless Steel 435 7.65 56.86 208.9 expensive

3. 02.
Performance index =
𝜎
3
2
𝐸
Figure 02: Material property table for question 2

4. Table 02: Material properties for selected materials for question 2
Material Strength Youngs modulus Performance index Relative cost
Polypropylene (PP) - 20% CaCO3 23 2000 0.055 75.4
Polytetrafluoroethylene (PTFE) GF1 (PTFE+25% Glass Fibre) 20 1400 0.064 986.5
Chloro TriFluoro Ethylene (CTFE) 23 1600 0.069 3597
Ethylene TetraFluoro Ethylene (ETFE) 26 1400 0.095 1972.5
Polypropylene (PP) - 20% Talc 28.5 2300 0.066 86.6
 Polytetrafluoroethylene (PTFE) GF1 (PTFE+25% Glass Fibre) is selected for the designing though it had somewhat high cost because for
safety proposes
Material Strength
(MPa)
Young’s modulus
(GPa)
Performance index
(MPa0.5
)x10-3
cost
(SLR/Kg)
Remarks
Polypropylene (PP) - 20% CaCO3 23 2000 0.055 75.4 Use as coatings
Polytetrafluoroethylene (PTFE) GF1
(PTFE+25% Glass Fibre)
20 1400 0.064 986.5 Use for non-stick applications
Chloro TriFluoro Ethylene (CTFE) 23 1600 0.069 3597 High Chemical resistivity
Ethylene TetraFluoro Ethylene (ETFE) 26 1400 0.095 1972.5 Use as film
Polypropylene (PP) - 20% Talc 28.5 2300 0.066 86.6 Us for fiber reinforcement

5. 03.
Performance indices
M1 = 𝐾𝐼𝐶 M2 =
𝐾 𝐼𝐶
𝜎 𝑓
M3 =
𝐾𝐼𝐶
2
𝜎 𝑓
M4 = 𝜎𝑓

6. Figure 03: Material property chart for question 3
Table 03: Material properties for selected materials for question 3
 Wrought Ferritic Stainless Steel is selected for the design because it had good PI and good thermal properties

7. Material Fracture
thougness(PI1)
Strength(PI4) Performance index 2 Performan
Wrought Ferritic Stainless Steel 100.5 435 0.231 23.22
Low Carbon Steel 61.5 322.5 0.191 11.73
Cast Austenitic Stainless Steel 141.5 330.5 0.428 60.58
Wrought Precipitation Hardened Stainless Steel 102.5 1007.5 0.102 10.43
Cast Duplex Stainless Steel 100.5 510 0.197 19.80
Material Fracture
toughness(PI1)
(MPa.m0.5
)
Strength(PI4)
(MPa)
Performance
index 2
(m0.5
)
Performance
index 3
(MPa.m)
Cost
(SLR/Kg)
Remarks
Wrought Ferritic Stainless Steel 100.5 435 0.231 23.22 208.5 Good thermal
properties
Low Carbon Steel 61.5 322.5 0.191 11.73 40.5 Low PI
Cast Austenitic Stainless Steel 141.5 330.5 0.428 60.58 324.9 Expensive
Wrought Precipitation Hardened
Stainless Steel
102.5 1007.5 0.102 10.43 243.5 Expensive/Corrosive
resistance
Cast Duplex Stainless Steel 100.5 510 0.197 19.80 231.5 Good corrosive
resistance

8. 04.
Performance index =
𝛼
1
2
𝜆

9. Figure 04: Material property chart for question 4
Table 04: Material properties for selected materials for question 4
Material Thermal diffusivity Thermal conductivity Performance index Relative cost
Medium Density Wood (Transverse) (0.45-0.85) 0.0000001245 0.1395 0.002529 493
Common Hard Brick 0.0000006231 0.9 0.000877 63
Cement 0.0000003228 0.85 0.000668 8
Normal Density Concrete 0.0000006678 1.65 0.000495 4.5
Granite 0.0000012773 2.85 0.000397 203
 Common hard brick is selected for the design because it’s low cost and ,thermal conduction and easiness of manufacture
Material Thermal
diffusivity
(m2
s)
Thermal
conductivity
(W/m.k)
Performance
index
(s0.5
/W.k)
cost
(SLR/KG)
Remarks
Medium Density Wood (Transverse)
(0.45-0.85)
0.0000001245 0.1395 0.002529 493 Flammable/Expensive
Common Hard Brick 0.0000006231 0.9 0.000877 63 Low thermal conductivity
Cement 0.0000003228 0.85 0.000668 8 High thermal expansion
Normal Density Concrete 0.0000006678 1.65 0.000495 4.5 High thermal expansion
Granite 0.0000012773 2.85 0.000397 203 Expensive

10. 05.

11. Performance index =
σ2
E
Figure 05: Material property chart for question 5
Table 05: Material properties for selected materials for question5

12. Material Strength Youngs modulus Performance index Relative cost
Wrought Ferritic Stainless Steel 435 200 0.946 208.9
Nodular Graphite Cast Iron 205 117.5 0.358 59
Blackheart Malleable Cast Iron 224.5 170 0.296 43.1
Nodular (spheroidal, ductile) Cast Iron 502.5 172.5 1.464 40.6
Cast Ferritic Stainless Steel 430 200 0.925 139
 Nodular (spheroidal, ductile) Cast Iron is selected for the design because it had good PI and low cost.
Material Strength
(MPa)
Young’s modulus
(GPa)
Performance index
(MPa)
Cost
(SLR/Kg)
Remarks
Wrought Ferritic Stainless Steel 435 200 0.946 208.9 Chemical and corrosive
resistance
Nodular Graphite Cast Iron 205 117.5 0.358 59 use as gas manifolds
Blackheart Malleable Cast Iron 224.5 170 0.296 43.1 not good corrosive resistance
Nodular (spheroidal, ductile) Cast Iron 502.5 172.5 1.464 40.6 Low cost/ high PI
Cast Ferritic Stainless Steel 430 200 0.925 139 Excellent corrosive resistance

13. 6.1
Performance index =
E
1
2
Cv,R
Figure 06: Material property chart for question 6.1

14. Table 06: Material properties for selected materials for question6.1
Material Youngs Modulus Cost Performance index Remarks
Low Alloy White Cast Iron 185 34.8 0.3908 Good abration resis
Wrought Aluminium Alloy 75 168 0.0515 Light weight
Low Carbon Steel 210 40.5 0.3578 Used in engineering
applications
Wrought Ferritic Stainless Steel 200 208.5 0.0678 Expensive
Cast ferritic stainless steel, ASTM CC-50, low nickel 200 139 0.1017 Low nickle content
 Low Carbon steel is selected for design because of its High young’s modulus and low cost.
Material Young’s Modulus
(GPa)
Cost
(SLR/Kg)
Performance index
(GPa.Kg/SLR)
Remarks
Low Alloy White Cast Iron 185 34.8 0.3908 Good abrasion resistance
Wrought Aluminum Alloy 75 168 0.0515 Light weight
Low Carbon Steel 210 40.5 0.3578 Used in engineering
applications
Wrought Ferritic Stainless Steel 200 208.5 0.0678 Expensive
Cast ferritic stainless steel, ASTM CC-50, low nickel 200 139 0.1017 Low nickel content

15. 6.2

16. Performance index =
𝜎 𝑓
2
3
𝐶 𝑉,𝑅
Figure 07: Material property chart for question 6.2
Table 07: Material properties for selected materials for question6.2

17. Material Strength Cost Performance index Remarks
Low Alloy White Cast Iron 345 34.8 1.4135 Good abration re
Wrought Aluminium Alloy 270 168 0.2487 Light weight
Low Carbon Steel 322.5 40.5 1.1612 Used in engineer
applications
Wrought Ferritic Stainless Steel 435 208.5 0.2754 Low PI
Cast ferritic stainless steel, ASTM CC-50, low
nickel
447.5 139 0.4209 Low nickle conte
 Low Carbon steel is selected for the design because it had high PI and low cost
6.3
 According to the results in 6.1 and 6.2 Low Carbon steel is suitable for low cost, stiff and strong beam
Abbreviation
Material Strength Cost Performance index Remarks
Low Alloy White Cast Iron 345 34.8 1.4135 Good abrasion resistance
Wrought Aluminum Alloy 270 168 0.2487 Light weight
Low Carbon Steel 322.5 40.5 1.1612 Used in engineering
applications
Wrought Ferritic Stainless Steel 435 208.5 0.2754 Low PI
Cast ferritic stainless steel, ASTM CC-50, low
nickel
447.5 139 0.4209 Low nickel content

18.  SLR – Sri Lankan rupees