Here are the **top 50** commonly asked questions in **Strength of Materials** interviews. Whether you’re just starting your preparation or need a quick refresher, these questions and answers will help you tackle your interview with confidence.

## Basic Strength of Materials Interview Questions with Answers

### 1. What is Strength of Materials?

The study of strength of materials deals with solid bodies and its behavior when it is subjected to various types of loading.

### 2. What kind of bodies are analyzed in the Strength of Materials?

Unlike other studies, the strength of materials deals with practical applications. Thus, bodies in the strength of materials are deformable bodies, that change in shape or size.

### 3. How Engineering Mechanics differs from Strength of Materials?

In Engineering mechanics, external forces and reactions are considered. Whereas in strength of materials, only internal resistance and deformations are considered.

### 4. Which law plays an important role in the Strength of Materials?

Hooke’s law plays an important role in the strength of materials, as it directly relates to the stress induced and the strain developed in the body.

### 5. What are the conditions for a member to be analyzed in the Strength of Materials?

The member under consideration should be deformable, prismatic, homogenous, and isentropic.

### 6. What are different structural members studied in the Strength of Materials?

Bars, beams, columns, struts, shafts, thin shells, thick shells, frames, trusses, dams, rivets, weld joints, and so on are different structural members studied in strength of materials.

### 7. How stress differs from Strength of Materials?

Stress is defined as the resistance per unit area of the material under load. Whereas strength of material is the maximum stress, material can withstand without yielding.

### 8. What are the different strengths of a Material?

A material has different strengths depending on the direction of loading. Tensile strength, compressive strength, shear strength, torsional strength, and bending strength, and so on.

### 9. What is a deformable body in Strength of Materials?

A deformable body is one, which changes shape or size when subjected to an external force. All bodies in practical are deformable.

### 10. What are the three elastic constants in the Strength of Materials?

The three elastic constants in the strength of materials are Young’s modulus, rigidity modulus, and bulk modulus.

### 11. How the Strength of Materials is used in the design?

Under the given loading conditions, the design stress is always kept lower than the strength of the material to prevent failure.

### 12. How Strength of Materials differ from the Kinematics of Materials?

Both strength of materials and kinematics of materials do not consider the external load. However, the strength of materials considers stress and deformation, whereas kinematics of materials consider only motion.

### 13. How to determine the strength of a material?

The strength of a material can be determined by a simple tension test in a Universal Testing Machine.

### 14. What are the advantages of Strength of Materials?

Studying the strength of materials gives a basic understanding of materials under stress. Thus, with the help of the strength of materials, a suitable material can be selected for a certain application.

### 15. Can we alter the strength of a material?

Strength is a property of a given material. However, impurities, temperature change, voids, and cracks can alter the strength of the material.

### 16. How Strength of Materials differs from Fluid Mechanics?

Fluid mechanics deals with the behavior of fluids under force. The force can be externally applied or gravitational force. Whereas strength of materials deals with the study of properties of a solid body under load.

### 17. What are the types of load in Strength of Materials?

Depending on the direction, the loads are classified as tensile load, compressive load, torsional load, and transverse load.

### 18. Why do we need to study Strength of Materials?

Practically, the members in the structural applications are solid and deformable. As strength of materials deals with solid deformable bodies, it is necessary to have some knowledge of the strength of materials.

### 19. What is the unit of strength of the material?

As strength is the maximum permissible stress a material can withstand, its unit is the same as the stress. The unit of strength is given as N/mm^{2}.

### 20. What are the two types of materials in the Strength of Materials?

The two types of materials are ductile and brittle materials. Ductile materials are strong in tension and weak in shear, whereas brittle materials are weak in tensile and strong in compression.

## Intermediate Strength of Materials Interview Questions with Answers

### 21. What is stress?

Stress is the force of resistance to deformation by a body under load. Stress is defined as the ratio of load to the area under loading. Stress= P/A.

### 22. What is load?

Load is a collection of forces that acts on a body. The load on a body can result in either deformation or displacement.

### 23. What is strain?

Strain is defined as the ratio of change in length to the original length of the body under stress. Strain = \(\frac{change \, in \, length}{original \,length}\)

### 24. What is Hooke’s law?

Hooke’s law states, “When a material is loaded within the elastic limit, the stress induced is directly proportional to the strain developed in the material”.

Stress a Strain

### 25. What is elasticity?

The phenomenon of a material regaining its original shape when unloaded is called Elasticity. Elasticity is a constant for a given material.

### 26. What is the limit of proportionality?

The limit of proportionality is the point beyond which Hooke’s law becomes invalid for material under tension.

### 27. What is factor of safety?

Factor of safety is defined as the ratio between ultimate strength of the material of the body and the working stress or permissible stress.

### 28. What is Poisson’s ratio?

When a material is loaded within the elastic limit, the ratio of lateral strain to the longitudinal strain is called Poisson’s ratio. It is denoted by m or 1/m.

### 29. What is Strain energy?

Whenever a body is strained within the elastic limit, the body absorbs a certain amount of energy. This energy absorbed due to the straining effect is called as the Strain energy.

### 30. What is Resilience?

The capacity of a strained body to do work, on the removal of the force applied on the body is called as Resilience of the body.

### 31. What is proof resilience?

The maximum strain energy that can be stored in the body within the elastic limit is called as proof resilience.

### 32. What is the relationship between three elastic constants?

The relationship between Young’s modulus (E), bulk modulus (K), and shear modulus (C) is given by

E=\(\frac{9KC}{3K+C}\)

### 33. What is the modulus of rigidity?

The modulus of rigidity is defined as the ratio of shear stress induced in the body to the shear strain developed due to the shear stress, within the elastic limit. It is denoted by C or G or N.

### 34. What is the principle of complementary shear stress?

The principle of complementary shear stress states that a set of shear stresses across a plane is always accompanied by a set of balancing shear stresses across the plane and balance it.

### 35. What is Area Moment of Inertia?

Area moment of inertia is defined as the product of the area of the section and the square of the distance of the CG of the area from a reference axis.

### 36. What is a shear force?

Shear force is given by the algebraic sum of total unbalanced force to the right or left of the section. It is a transverse force acting perpendicular to the axis of the beam.

### 37. When a beam is said to be a statically determinate beam?

A beam is said to be a statically determinate beam if the reactions at the support of the beam can be determined by the use of a static equilibrium equation.

ΣV=ΣH=ΣM=0

### 38. What is the sagging and hogging of beams?

Sagging represents the bending of beams with concavity upwards. And hogging represents the bending of the beam with concavity downwards. In general, sagging is considered as negative and hogging is considered as positive.

### 39. How do you identify the point of the maximum bending moment?

The maximum bending moment is identified as the point where the shear force changes sign in the bending moment diagram. In other words, the maximum bending moment occurs at the point where the shear force is zero.

### 40. What is the moment of resistance.

Moment of resistance is defined as the couple produced by the internal forces induced in a beam under bending. In addition, the stress induced due to the bending must be under the maximum permissible stress.

### 41. What is section modulus?

Section modulus is defined as the ratio of moment of inertia of a section about the neutral axis to the distance of the outermost layer from the neutral axis.

Z= I/y

### 42. What is a frame?

A frame is a structural member that is made up of both horizontal and vertical structural members rigidly fixed together to support and transfer load.

### 43. What is a truss?

A truss is a structural member that is made of rods to form one or more triangles to behave as a single unit. A truss is always loaded at the joints.

### 44. What is a conjugate beam?

A conjugate beam is an imaginary beam with imaginary support conditions and load. A conjugate beam is used to find slope and deflection in a real beam and the length of the conjugate beam will be same as that of a real beam.

### 45. When a beam is said to be a fixed beam?

If both ends of the beam are rigidly fixed such that the support provides zero degrees of freedom, then the beam is said to be a fixed beam. The slope and deflection are zero at the fixed ends.

### 46. What is propped cantilever beam?

A cantilever beam is said to be a propped cantilever beam when the free end is given support to prevent deflection at the free end.

### 47. What is a composite shaft?

When a shaft is made of two or more materials, then the shaft is called as a composite shaft. A composite shaft behaves as a single shaft under torsion.

### 48. What is slenderness ratio?

The ratio of the actual length of the column to the least radius of gyration is known as the slenderness ratio.

### 49. What is general moment bending equation?

Explain the terms.

The general moment equation is given by,

\(\frac{M}{I}=\frac{F}{y}=\frac{E}{R}\)

Where M is the moment, I is the moment of inertia, F is bending stress, y is the distance of the outermost fiber from the neutral axis, E is Young’s modulus, R is the radius of curvature.

### 50. What is the equation of torsional rigidity of a shaft?

The torsional rigidity of a shaft is given by,

k=\(\frac{CI}{l}=\frac{T}{Ө}\)

Where k is torsional rigidity, C is the modulus of rigidity, I is the polar moment of inertia, l is the length of the shaft, T is the torque and Ө is the angle of twist.

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