400+ TOP STRENGTH of MATERIALS LAB VIVA Questions and Answers


1. Define Hooke’s Law.
It states that when the material is loaded within the elastic limit the stress is directly proportional to strain.
i.e. Stress α strain. or Stress = constant x Strain

2. Define Strength of materials.
The strength of a material is its ability to withstand an applied stress without failure.

3. What is stress?
When load is applied on any object then a resisting force is induced, that resisting or reacting per unit area of cross-section is called stress.

4. What is strain?
Stress is change in dimensions upon original dimentions.

5. What is deformation?
Deformation is change in dimensions of any object due to applied load.

6. On which steel you have performed tension test. What is its carbon content?
On mild steel (0.3 to 0.6% carbon).

7. What kind of fracture has occurred in tensile specimen.
Ductile fracture.

8. Define temperature stress.
Stress introduced by uniform or nonuniform temperature change in a structure or material which is constrained against expansion or contraction.

9. What is hardness?
Hardness is the resistance of a material to localized deformation.
Hardness is the mechanical resistance which a material asserts against the mechanical penetration of a harder test body.

10. What is toughness?
Toughness is the amount of energy per volume that a material can absorb before rupturing.
It is also defined as the resistance to fracture of a material when stressed.

11. Types of stresses.
Normal stresses(tensile & compressive), shear stresses

12. Types of strains.
Longitudinal strain(tensile & compressive), shear strain, volumetric strain.

13. What is volumetric strain?
Volumetric strain is change in volume upon original volume.

14. What is poisson’s ratio?
It is the ratio of lateral(or transverse) strain to longitudinal strain.

15. Define longitudinal strain and lateral (transverse) strain.
Longitudinal strain is change in length upon original length.
Lateral strain is change in lateral dimensions (i.e. dimensions perpendicular to length) upon
original lateral dimensions.

16. Differentiate Shear Strain and Shear stress.
Stress is a measure of how much force is taken by an object of particular size. shear stress is therefore shear force divided by area under shear. Clearly, increasing the force and/or decreasing the size or cross sectional area will result in larger stresses.
Shear strain is a measure of the deflection caused by a shear stress, and is related via the shear modulus (or modulus of rigidity) G, where G= shear stress/shear strain.

17. What is factor of safety?
The ratio of the breaking stress of a structure to the estimated maximum stress.

18. What is Ultimate strength?
Absolute maximum compressive, shear, or tensile stress a material can bear without failure
is called ultimate strength.

19. Define elastic constants E,K & G.
Young’s modulus of elasticity(E) is the ratio of normal stress to normal strain.
Bulk modulus of elasticity(K) is the ratio of normal stress to volumetric strain.
Shear modulus of elasticity or modulus of rigidity(C or G) is the ratio of shear stress to shear

20. What is Yield Strength?
The ability of a metal to tolerate gradual progressive force without permanent
deformation. Yield strength is the stress at which a specified amount of permanent deformation
of a material occurs.

21. Define impact strength.
The ability of a material to withstand shock loading.

22. What is beam.
A beam is a horizontal structural element in which longitudinal dimensions are very large
in comparison of lateral dimensions and that is capable of withstanding load primarily by
resisting bending.

23. What is difference between force and load.
Force is a push or pull applied on a body to change its state.
Load is the combined effect of external applied forces at any point.

24. Types of Loads.
Point load, uniformly distributed load, uniformly varying load.

25. What is torque?
Torque is the tendency of a force to cause or change rotational motion of a body. A force applied at a right angle to a lever multiplied by its distance from the lever’s fulcrum (the length of the lever arm) is its torque.

26. What is Torsional force?
A force acting on a body that tends to twist the body.

27. What is torsional rigidity?
The applied torque needed to produce a unit angle of twist in a circular elastic material, it is a measure of a body’s resistance to torsion.

28. Types of beams.
Simply supported beam, over hanging beam, Cantelever beam, continuous beam, fixed

29. Define shear force and bending moment.
Shear force is the algebraic sum of all the vertical forces acting on either side of the section.
Bending moment is the algebraic sum of all the moments of the forces acting on either side of the

30. What is point of inflection.
The point on beam at which the moment is zero is called point of inflection or point of

31. What are sagging and hogging moments?
If clockwise bending moments are taken as negative, then a negative bending moment within an element will cause “sagging”, and a positive moment will cause “hogging”. It is therefore clear that a point of zero bending moment within a beam is a point of contraflexure that is the point of transition from hogging to sagging or vice versa.

32. When bending moment will be maximum?
Bending moment is maximum when shear force is zero.

33. What is Moment of inertia?
Moment of inertia is second moment of area or second moment of mass.

34. What is Polar moment of inertia?
The Polar Moment of Inertia is a geometric property of a cross section. Physically, it is a
measure of how difficult it is to turn a cross-section about an axis perpendicular to it.

35. Define slope and deflection.
The deflection at any point on the axis of the beam is the distance between its position before and after loading.
Slope at any section in a deflected beam is defined as the angle in radians which the tangent at
the section makes with the original position.

36. Explain about Principal plane.
The planes on which shearing stresses are zero are called principal planes.

37. Explain about Principal stresses.
The stresses normal to principal planes are known as principal stresses

38. Units of force, deflection, stress, strain, E, K, G.

  • SI Unit of force is Newton,
  • SI unit of deflection is meter,
  • SI unit of stress,E,K&G is N/m2,
  • Strain is unitless quantity.

39. Purpose of UTM.
UTM is used to test the tensile stress and compressive strength of materials.

40. What are lifting machines?
Lifting machines are devices which are used to lift heavy load by applying less effort.

41. What is torsion equation?
T/J = τ/R = Gθ/L

42. What is flexural rigidity?
The product EI is called flexural rigidity.

43. Define Mechanical Advantage,velocity ratio & efficiency.

  1. M.A. is the ratio of load lifted to effort applied.
  2. V.R. is the ratio of distance moved by effort to distance moved by load.
  3. Efficiency is the ratio of mechanical advantage to velocity ratio.

44. Define Section modulus.
The elastic section modulus is defined as S = I / y, where I is the second moment of area (or moment of inertia) and y is the distance from the neutral axis to any given fibre.

45. What is a composite beam?
A structural member composed of two or more dissimilar materials joined together to act as a unit in which the resulting system is stronger than the sum of its parts.

1. Define Hooke’s Law.
2. Define Strength of materials
3. What is stress?
4. What is strain?
5. What is deformation?
6. How is deformation calculated?
7. Say something on Rigid Body.
8. Say something on deformable solids.
9. Differentiate simple and compound stress.
10. What is stiffness?
11. Types of stresses.
12. Types of strains.
13. What is volumetric strain?
14. Differentiate Tensile Strain and Tensile stress.
15. Differentiate Compressive Strain and Compressive stress.
16. Differentiate Shear Strain and Shear stress.
17. What is factor of safety?
18. What is Ultimate strength?
19. What is working stress?
20. What is Yield Strength?
21. Define Stiffness of a helical spring.
22. Differentiate between closed and open coil helical spring.
23. Principle of Superposition in bars of varying cross section.
24. Types of Load.
25. Explain torque.
26. What is Torsional force?
27. What is torsional rigidity?
28. Define Centripetal force.
29. Define Centrifugal force.
30. Explain Radius of gyration.
31. What is calibration?
32. Tell About Moment of inertia.
33. What is Inertia?
34. Polar moment of inertia.
35. Say something on Traction.
36. Explain about Principal plane.
37. Explain about Principal axis.
38. Draw Shear force diagram for a cantilever beam with udl and point load.
39. Draw Shear force diagram for a SSB with udl and point load
40. What are SSB, Fixed Beams, Hinged Beams.
41. Explain the equilibrium condition for a body.
42. Differentiate between Bar and column
43. Types of beams.
44. What is Shear centre?
45. Tell something on elastic constants.
46. What is Poisson’s ratio?
47. Differentiate Longitudinal and Lateral Strain.
48. Relation between Bulk Modulus and Young’s modulus.
49. Explain about modulus of rigidity.
50. What is Strain energy?
51. What is Resilience?
52. Define proof of resilience.
53. Define modulus of resilience.
54. How is potential energy related to strain energy.
55. Explain Castigliano’s Theorem.
56. What is slenderness ratio?
57. When do we call the failure to be fatigue?
58. Explain sudden impact.
59. Explain about buckling in a beam.
60. Why is it necessary to check hardness?
61. Enumerate the advantages of Rockwell Hardness test over Brinell hardness test.
62. Differentiate between pneumatic and hydraulic pumps.
63. Unit of force, deflection, stress, strain, E, K, G.
64. Purpose of UTM. 65. Define a Hydraulic jack.
66. What is torsional bending?
67. What is axial load?
68. Say something on ageing factor.
69. Define Section modulus.
70. What is a composite beam.


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