1 of 67

Destructive Test

2 of 67

Destructive Test

  • In Destructive Test we break the specimen and find out the mechanical properties of specimen.
  • Types of destructive Tests:
    1. Tensile test
    2. Compression test
    3. Hardness test
    4. Impact test
    5. Cupping test

3 of 67

Tensile test

  • Tensile test perform on UTM ( Universal testing machine)
  • In this test tensile force is applied on specimen by using UTM.

​

4 of 67

Universal testing machine

5 of 67

Selection of Specimen

  • Shape of specimen Circular Cross-section, Square Cross-section , Rectangular Cross-section
  • It should have Uniform Cross-section.
  • Avoid the sharp corner on specimen.

6 of 67

Gauge Length

  • It is the fix length and its length 5 times to diameter of specimen.

7 of 67

Stress vs Strain Graph

8 of 67

The following material property can find out by using tensile test

  • Strength
  • Ductility
  • Elasticity
  • Stiffness
  • Malleability
  • Modules of toughness
  • Modules of resileness

9 of 67

Application

  • In aerospace industry.( adhesive bonds, carpets, cables, gaskets, hoses, seat belts, wiring looms)
  • In Automotive Industry ( seat belt, handbrake levers, bumper moldings )
  • In Electrical and Electronics Industry (electrical wires , PCB)
  • Medical Equipment and Materials Industry (surgical tubes , surgical gloves, silicone rubbers)
  • Metals and Construction Industry (adhesives, sealants, mastics, and between layers of brick and foam)

10 of 67

Engineering Stress

  • It is define as load applied on material to its original cross-section area.

​

Load Applied

  • Engg. Stress= -----------------------------
        • Original Cross- Section Area

P

σ = ---------------------------

A0

11 of 67

Engineering Strain

  • Change in length to original length of specimen.

Change in length

  • Strain = ……………………….

Original length of specimen

​

​

dl

e = ------------------------------------------

l

12 of 67

True Stress

  • It is define as instantaneous load to the actual cross section area of specimen at that instant.

​

Instantaneous value of load ( Pi)

  • True Stress(σT) = ----------------------------------------------------

Actual cross section area of specimen at that instant (Ai)

13 of 67

True Strain

  • It is the summation of all engineering strain from instant to instant.

14 of 67

Stress vs. Strain curve

15 of 67

Elastic limit

  • The deformation of material is elastic beyond the elastic limit the deformation is permanent.

​

16 of 67

Proportional stress

  • Proportional stress is also called as proportional limit. It is the maximum value of stress up to which stress is directly proportional to strain.

17 of 67

Yield stress

  • The point at which material starting yielding that point is called as yield point

18 of 67

Ultimate tensile stress ( UTS)

  • It is the maximum value of stress that material can sustain without failure

19 of 67

Breaking stress( failure stress)

  • The value of stress at which material get break . It is always lower than ultimate tensile stress.

20 of 67

Toughness

  • Toughness is the total amount of energy absorb by the material before the fracture.

21 of 67

Toughness

22 of 67

Resilience

  • Its define as total amount of energy absorb by the material during its elastic deformation.

23 of 67

Ductility

  • It is ability of material to undergoes plastic deformation at ease under applied load.

​

  • Ductility expressed by

1. Percentage of elongation

2. Percentage of reduction in area

Change in length

Percentage of elongation=---------------------------- * 100

Original length

Change in CA

Percentage of RA = ---------------------------- * 100

Original CA

​

24 of 67

Malleability

  • It is the capacity of material to withstand deformation under compression without failure.
  • It is associated with compression force.

25 of 67

26 of 67

Compression Test

  • Compression test is exactly opposite to tensile test.
  • In this test compressive force applied on the specimen.

27 of 67

Selection of Specimen

  • Shape of specimen Circular Cross-section, Square Cross-section , Rectangular Cross-section
  • It should have Uniform Cross-section.
  • Avoid the sharp corner on specimen.
  • L/ D = ( 1.5 to 10) =2

28 of 67

Limitation of Compression Test

  • Top and bottom face should be flat and parallel.
  • Accurate measurement of strain is impossible.
  • A machine higher capacity can not used for testing small sample and machine of lower capacity can not be used for testing large sample.
  • During loading careful attention is required.
  • Not useful for ductile metals.

29 of 67

Hardness

  • It is the ability of material which is the resist the plastic deformation.

​

  1. Poldi Hardness test
  2. Brinell Hardness test
  3. Vicker Hardness test
  4. Rockwell Hardness test

30 of 67

Brinell Hardness test

31 of 67

Brinell Hardness test

32 of 67

Ball indentor and specimen

33 of 67

BHN

34 of 67

Pilling up and Sinking Effect

35 of 67

Vicker Hardness Test

36 of 67

Vicker Hardness Test

37 of 67

Indentor

38 of 67

Vicker formula ( VHN)

39 of 67

Advantages

  • More accurate than brinnel.
  • Indentor made by diamond so it doesn’t deform.
  • Thin material can easily test.
  • It use for hard material.

40 of 67

Disadvantages

  • Specimen should be free form dust and greese.
  • Material high surface finish is required.
  • Impression size is so small as compared brinnel.
  • Cost of indentor is high.

41 of 67

Rockwell Hardness Test

42 of 67

Rockwell Hardness Test

43 of 67

Scale

Indenter

Minor Load

Major Load

Total Load

Application 

A

​

Diamond cone

10

50

60

Cemented carbides, thin steel and shallow case hardened steel

B

1/16"(1.588 mm) steel ball

10

90

100

Copper alloys, soft steels, aluminum alloys, malleable irons, etc

C

Diamond cone

10

140

150

Steel, hard cast irons, case hardened steel

D

Diamond cone

10

90

100

Thin steel and medium case hardened steel and pearlitic malleable iron

E

1/8" steel ball

10

90

100

Cast iron, aluminum and magnesium alloys, bearing metals

44 of 67

F

1/16" steel ball

10

50

60

Annealed copper alloys, thin soft sheet metals

G

1/16" steel ball

10

140

150

Phosphor bronze, beryllium copper, malleable irons HRH . . . . Aluminum, zinc, lead

H

1/8" steel ball

10

50

60

aluminium alloys,Mg alloy

K

1/8" steel ball

10

140

150

Soft bearing metals, plastics and other very soft materials

L

1/4" steel ball

10

50

60

M

1/4" steel ball

10

90

100

P

1/4" steel ball

10

140

150

R

1/2" steel ball

10

50

60

S

1/2" steel ball

10

90

100

V

1/2" steel ball

10

140

150

45 of 67

Formula

  • For brale indenter: 100 - Depth of penetration

---------------------------------------

0.002

​

​

  • For ball indenter: 130 - Depth of penetration

---------------------------------------

0.002

​

46 of 67

Advantages

  • In this test both type of indentor is used which combine advantages of brinell and vickers test.
  • Thick as well as thin material can test.
  • no specimen preparation required (separation, grinding, embedding)
  • Hardness value directly readable, no optical evaluation required (measurement of diagonals as in the optical methods)

​

47 of 67

Limitations

  • It is not always the most accurate hardness testing method, as even a slight error in measuring the depth difference can result in a significant error in the calculated hardness value.
  • Required Skill operator.
  • Not suitable for elastic material.
  • Periodic calibration of indenter is necessary.

48 of 67

Impact test

  • This test is use to find out toughness.
  • Toughness is the total amount of energy absorb by the material before the fracture.
  • Type of Impact Test:

1. Charpy Impact Test

2. Izod Impact Test

49 of 67

Toughness

50 of 67

Charpy Impact Test

51 of 67

Charpy Impact Test

52 of 67

Specimen with different notches

53 of 67

Specimen Mounting

54 of 67

Height h1 and H2

55 of 67

Izod Impact Test

56 of 67

Specimen

57 of 67

Specimen Mounting

58 of 67

How to calculate the toughness value

  • Toughness: W( h1 – h2)

​

W: Weight of pendulum

h1: Original height of pendulum

h2 : Swinging height of pendulum

59 of 67

BEND TEST

To evaluate the

  1. Bending Modulus
  2. Flexural stress
  3. Flexural Strain
  4. Deflection under loading condition

60 of 67

61 of 67

62 of 67

DOUBLE SHEAR TEST

63 of 67

Fatigue test

64 of 67

65 of 67

66 of 67

Creep Test

67 of 67