11O105 BASICS OF CIVIL AND MECHANICAL ENGINEERING

Prepared byMr. C. Ayyasamy

Assistant ProfessorDepartment of Mechanical EngineeringBannari Amman Institute of Technology

11O105 BASICS OF CIVIL AND MECHANICAL ENGINEERING

Objectives-basic knowledge in the field of Mechanical Engineering -focusing on generation of power from various natural resources -know about various types of Boilers and Turbines used for power generation

Unit IV

Engineering Materials and Manufacturing Processes• Classification of Engineering materials, Mechanical

properties and uses of cast iron, steel, and High Speed Steel.• Introduction to casting process, Green sand moulding -

Pattern, Melting furnaces - Cupola and Electric Furnace. • Metal Forming - Forging Process.• Introduction to Arc and Gas Welding. • Centre Lathe - Specifications - Principal parts - Operations -

Straight turning, Step turning, Taper turning methods, Knurling, Thread cutting methods, Facing, Boring, and Chamfering - Lathe tools and Materials.

• Drilling – Radial drilling machine - Specification and Operation.

Product- satisfy the functional requirementsProduct function is interdependent

Selection of Material

ManufacturingProcesses

Design Concepts

ProductFunction

MATERIALS

MATERIALS

MATERIALS

Vessels and Boiler

Metallic Non Metallic Composites

Materials

Inorganic

OrganicNon-ferrousFerrous

Selection of materialKnowledge about types of materials and their properties

Cast iron(>2%C) Gray White Ductile Malleable

Plastics, rubber Wood ,paper

Steel (<2%C) Plain carbon (Low,Medium,High) Alloy steel (Stainless steel, HSS)

Metals Copper Nickel Aluminium ChromiumAlloys Brass Bronze Duraluminium

Asbestos, GlassConcrete, Cement

Fiber matrix Metal matrix

10Based on data provided in Tables 9.1(b), 9.2(b), 9.3, and 9.4, Callister’s Materials Science and Engineering, Adapted Version.

Steels

Plain carbon Alloy

low carbon <0.25 wt% C

Med carbon0.25-0.6 wt% C

high carbon 0.6-1.4 wt% C

Uses auto structure. sheet

bridges towers press. vessels

crank shafts bolts hammers blades

pistons gears wear application.

wear application.

drills saws dies

high T application. turbines furnaces V. corros. resistant

increasing strength, cost, decreasing ductility

quantities that characterize the behavior of a material in response to physical phenomena other than mechanical forces. e.g. density, weight electric resistance (Electricity) thermal conductivity (Heat transfer) melting temperature

Mechanical properties

Physical properties

quantities that characterize the behavior of a material in response to external or applied forces.

Material properties

Mechanical properties 1 Strength – Resistance to deform

Mechanical properties

Ao

Balanced Rock, Arches National Park

Stress-Strain Diagram

Strain ( ) (DL/Lo)

41

2

3

5

Stre

ss (

F/A)

Elastic Region

PlasticRegion

StrainHardening Fracture

ultimatetensile strength

Slop

e=E

Elastic region slope =Young’s (elastic) modulus yield strengthPlastic region ultimate tensile strength strain hardening fracture

necking

yieldstrength

UTS

y

εEσ

ε

σE

12

y

ε ε

σE

16

Stress-Strain Test

specimen

machine

17

c07f25

18

F

bonds stretch

return to initial

1. Initial 2. Small load 3. Unload

Elastic means reversible.

F

Linear- elastic

Non-Linear-elastic

Elastic Deformation

19

1. Initial 2. Small load 3. Unload

Plastic means permanent.

F

linear elastic

linear elastic

plastic

planes still sheared

F

elastic + plastic

bonds stretch & planes shear

plastic

Plastic Deformation (Metals)

Mechanical properties

2 Stiffness – Resistance to bending

Mechanical properties

• 3 Elasticity – Ability of the metal to deform under load and return to its original shape and size when load is removed

Mechanical properties

4 Plasticity 5 Malleability – Plastic deformation under

compressive load

Mechanical properties

6 Ductility – Ability of the material to stretch under tensile load.

24

Malleability-property of a material to be deformed by compression without cracking or rupturing. -Load may be applied slowly or suddenly -determine whether the material will be suitable for forging or rolling into thin sheet.

High Malleability material : Silver Low Malleability material :Nickel

Mechanical properties

7 Hardness – Ability to withstand scratch

Mechanical properties

8 Fatigue – Failure when subjected to repeated load

Wind turbines are subject to fluctuating winds , and hence fluctuating forces. This is particularly the case if they are located in a very turbulent wind climate.

Mechanical properties

9 Toughness – Amount of energy absorbed before fracture

10 Creep – Slow and progressive deformation of metal with time under a constant stress. Creep become important at elevated temperature.

Tensile testArea

Load

F

F

LL L

A

EYoung's ModulusHook’s law (elastic limit)

yDuctile

0.002

L

L)(

brittle

Ultimate Tensile Strength: Highest value of stress on the stress-strain curve.

Modulus of Resilience: Stored energy per unit volume that the material can absorb without yielding. E

U yr 2

2

29

ANNEXURE II – MIND MAP

30

1. How the materials are classified?2. How cast iron differ from steel in carbon content?3. Define alloy and steel?4. Define the term heat treatment.5. How can you classify iron and steel?6. What are the factors affecting mechanical properties.7. What are the properties that can be determined by tensile test.8. How will you choose the material for industrial application?9. When the materials attain their required properties.10. What is the use of cast iron?11. What is the use of steel?

ANNEXURE IV - QUESTIONS

31

ANNEXURE V - QUESTIONS

Hidden Picture Puzzles

This is an optical illusion of a different type.

Find the seven hearts in this picture!!!!!!

Answer is!!!

1. In the water

2. In the mountain

3. Trees

4. Swans

5. Sky

6. On the balloon, and

7. Back in the grass with

water in it

Thank you