1. MECHANICAL ENGINEERING FUNDAMENTALS Course Code : ME-2112
By:
Engr. Hassaan Bin Younis

2. Classification of Materials
Materials used in the design and manufacture of products
Plastics
Wood
Composites
Ceramics
Metals
Fabrics
Layers of polycarbonate, aluminium & acrylic
Tungsten carbide tool bit
Linen, cotton, nylon, Kevlar
Steel, aluminium
Balsa wood model
Acrylic lens

3. Mechanical Properties
Strength:
The ability of a material to resist externally applied force
Stiffness:
The ability of a material to resist deformation under stress. The modulus of elasticity is the measure of stiffness
Elasticity:
It is the property of a material to regain its original shape after deformation when the external forces are removed
Steel is more elastic than rubber.
Plasticity:
It is property of a material which retains the deformation produced under load permanently.

4. Mechanical Properties
Ductility:
Ability to deform under tensile stress
It is the property of a material enabling it to be drawn into wire with the application of a tensile force
The ductility is usually measured by the terms, percentage elongation and percentage reduction in area.
Brittleness:
It is the property of a material opposite to ductility
It is the property of breaking of a material with little permanent distortion
Toughness:
It is the property of a material to resist fracture due to high impact loads like hammer blows.
This property is desirable in parts subjected to shock and impact loads.

5. Mechanical Properties
Resiliance:
It is the property of a material to absorb energy and to resist shock and impact loads.
This property is essential for spring materials.
Creep:
When a part is subjected to a constant stress at high temperature for a long period of time, it will undergo a slow and permanent deformation called creep
Fatigue:
When a material is subjected to repeated stresses, it fails at stresses below the yield point stresses
The failure is caused by means of a progressive crack formation which are usually fine and of microscopic size
Hardness:
It is the ability of a metal to cut another metal.

6. Backelite, durite, plaskon
Plastics
1.Synthetic materials
2. Mould into desired shape under pressure and heat 3.Can be cast, rolled, laminate, machined
Thermosetting
Backelite, durite, plaskon
Plastics
Thermoplastic
PVC, Celluloid

7. Classification of Materials (Plastics)
Plastics can be further classified as;
Thermoplastic
Thermoset
Elastomers
Thermoplastics
Thermosets
Elastomers
Acrylics
Epoxy resins
Rubbers
Nylons
Phenolic
Silicones
PVC
Polyesters
Polyurethanes
Polyethylene
Phenol formaldehyde
Urea formaldehyde
PVC gutters
Polyethylene
Rubber
Rubber

8. Classification of Materials (Composites)
A composite is a combination of two or more chemically distinct materials whose physical characteristics are superior to its constituents acting independently.
Because of their high strength/stiffness to weight ratio they are widely used in the;
Aerospace industry
Offshore structures
Boats
Sporting goods

9. Classification of Materials (Composites)
Examples of composites include;
Reinforced Plastics
Ceramic-matrix
Metal-Matrix
Cylinder linings
Outer skin panels & fuselage A380
Kevlar, taffeta polyester sails
Cylinder linings
Carbon reinforced plastic
Combustion chamber of jet engine
Glass reinforced plastic hull
Thrust chamber for rocket

10. Classification of Materials (Ceramics)
Oxides (alumina – insulation and abrasives, zirconia – dies for metal extrusion and abrasives)
Carbides (tungsten-carbide tools)
Nitrides (cubic boron nitride, 2nd in hardness to diamond)

11. Classification of Materials (Metals)
Metals can be further classified as Ferrous & Non-Ferrous, some examples include;
Ferrous
Non-Ferrous
Steels
Aluminium
Stainless Steels
Copper
High Speed Steels
Brass
Cast Irons
Titanium
High Speed steel
Stainless Steel
Aluminium
Copper
Brass

12. Cast Iron Carbon ------ 1.7 per cent to 4.5 percent
small amounts of silicon, manganese, phosphorous and sulphur
Brittle (can’t be used for machine parts subjected to shocks)
Low cost
Good casting Valuable material for
Excellent machinability engineering purpose
High compressive strength

13. Purest form of iron (contains up to 99.9%) Tough Malleable Ductile
Wrought Iron
Purest form of iron (contains up to 99.9%)
Tough
Malleable
Ductile

14. Steel Alloy of iron and carbon (Carbon up to 1.5%)
Carbon has the ability to increase hardness and strength
1. Dead mild steel — up to 0.15% carbon
2. Low carbon or mild steel — 0.15% to 0.45% carbon
3. Medium carbon steel — 0.45% to 0.8% carbon
4. High carbon steel — 0.8% to 1.5% carbon

15. Stainless Steel Correctly heat treated Finished
Resist corrosive attack from corrosive media

16. Non-Ferrous metals
Ease of fabrication (casting, rolling, welding, machining)
Resistance to corrosion
Electrical and thermal conductivity
Weight

17. Aluminium Melting point 658 o C Weak and soft in pure form
Good thermal conductivity (widely used in overhead cables)
High resistance to corrosion and non toxic (Cooking utensils, thin coil used for wrapping food items)
Light weight (used in aircraft and automobiles)

18. Copper Melting point 1083 o C One of the most widely used in industry
Soft , malleable, ductile
Good conductor of electricity (Electric Cables)
Used in making coins, house hold utensils, electroplating

19. Lead Melting point 326 o C Bluish grey metal
Soft enough to be cut by knife
Extensively used for making solders
Coting of electric cables

20. Tin Brightly shining white metal Soft, Malleable, Ductile
Used for protective coating of iron and steel sheets
Foil used as moisture proof packing

21. Low density Low cost Flexible Resistance to heat and electricity
Non-Metallic
Low density
Low cost
Flexible
Resistance to heat and electricity

22. Rubber 1.Natural materials 2. Soft rubber is used for insulation
3.Used for Power transmission belts

23. Leather 1.It is very much flexible
2.Can withstand considerable wear under suitable conditions
3.Used in power transmission belts , washers, packing