Classification of mechanical tests, Calculations, Limitations

1. Mechanical tests of metals
Destructive tests

2. Classification of mechanical tests
• Destructive test
• Non – Destructive test

3. Tensile test
destructive test – ductile material

4. We find

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A

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11. CALCULATION

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15. COMPRESSION TEST
• Brittle material used ( cast iron, brick, concrete)
• Same UTM Machine used

16. measurement
• Compression load is gradually applied on the
specimen and the reduction in length is
recorded

17. Shear test
Pure shear force applied
To measure shear strength

18. Pure Shear force
• A pure shear force
applied top and bottom
parallel to its faces
• Double shear system
used to measure the
shear stress and shear
strain.

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20. Limitations of shear test
• Need attachment with UTM machine .
• Material at last gets bend
• So we will get the bending stress also, not the
pure shear type.
• Very difficult in processing

21. Torsion test
• Rotational force given to material about longitudinal
axis.

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23. HARDNESS TEST
Brinell Hardness
Vickers Hardness
Rockwell Hardness

24. Definition

25. Types
• Brinell Hardness
• Vickers Hardness
• Rockwell Hardness

26. Brinell hardness test

27. Hardness test is performed by pressing a steel ball also known as
indenter, into the specimen

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30. Vickers hardness test
High accuracy than brinell due to
square based diamond pyramid
indenter

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35. Rockwell hardness test
Industries used due to its high
accuracy, simplicity and rapidity

36. Highlights
• In this test , the dial gives the direct reading of
hardness; no need of measuring indentation
diameter or diagonal length using the microscope

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40. advantages
• Simple
• Reading taken directly
• Time consuming process
• Suitable for mass production
• We can measure any range of value with
various indenters.
• Metallic and also plastics used

41. limitations
• Its not accurate than vickers test

43. IMPACT TEST-
TO STUDY THE BEHAVIOUR OF THE MATERIAL UNDER SUDDEN LOAD
IZOD TEST
CHARPY TEST

44. IMPACT STRENGTH
• The ability of the material withstand a
blow(force) without fracture

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46. IZOD TEST
Izod test uses cantilever specimen of
size 75mm×10mm×10mm.
The V-notch angle is450 and depth of
the notch is 2mm.
The Izod specimen is placed in the vise
such that it is a cantilever.

47. Charpy test

49. FATIGUE TESTS
• The capacity of material to withstand repeatedly
applied stresses is known as fatigue

50. FATIGUE TESTS

52. Creep test
• The continuous deformation of a metal under
a steady load is known as creep.
• The purpose of creep tests is to determine the
creep limit.
• The creep limit or the limiting creep stress is
defined as the stress that will not break the
specimen when applied for an infinite period
at a specific constant temperature.

55. BASIC REQUIREMENTS FOR CREEP TEST
• It must posses means for applying and
maintaining a constant load
• There must be a furnace capable of keeping
the temperature of the test- piece at the
desired value to within very close limits.
• There should be means for the measurement
of test- piece extension.