Fundamentals of Strength of Materials

What is the definition of stress in materials?

• Stress is always the force per unit area

• Stress is the internal resistance of a material to deformation

• Stress refers to the measure of deformation in a material.

• Stress is the weight of a material under load.

Answer explanation

The correct definition of stress in materials is that it is the internal resistance to deformation, measured as force per unit area. This distinguishes it from other concepts like energy, temperature, or weight.

How do you relate stress and strain.

• strain is proportional to stress until breaking stress is reached.

• Strain is independent of stress in all materials.

• Stress only occurs in plastic materials.

• strain is proportional to stress within the elastic limit of materials.

Answer explanation

Stress and strain are directly related through Hooke's Law, which states that strain is proportional to stress within the elastic limit of materials. This means that as stress increases, strain increases proportionally.

Which elastic constant is associated with shear phenomenon?

• Young's modulus

• Poisson's ratio.

• Flexural strength

• Rigidity modulus

Deflection in a beam is MOST influenced by

• depth along the direction of loading.

• length.

• breadth in a direction perpendicular to the direction of load.

• not influenced by any cross sectional parameters.

Where BENDING MOMENT will be maximum on a slender circular simply supported beam subjected to vertical point load at midspan?

• entire outer layers

• at the core

• at midspan

• at the supports

When particle idealisation is taken in mechanics?

• if moment exists

• For non coplanar force system alone

• coplanar force systems

• for concurrent force system

How many independent components are there in the state of stress at a point?

• 3

• 6

• 9

• 12

Answer explanation

The state of stress at a point is crucial as it indicates the internal forces acting on a material and helps identify potential failure modes, making it essential for assessing material integrity.

How do you calculate the shear stress in a beam?

• τ = VQ / Ib

• τ = P / L

• τ = M / I

• τ = F / A

Answer explanation

The correct formula for calculating shear stress in a beam is τ = VQ / Ib, where V is the shear force, Q is the first moment of area, I is the moment of inertia, and b is the width of the beam. This formula accounts for the distribution of shear stress.

Explain the concept of yield strength in materials.

• Yield strength is the point at which a material begins to melt.

• Yield strength is the amount of energy a material can absorb before breaking.

• Yield strength is the total load a material can carry before failure.

• Yield strength is the maximum stress a material can withstand without permanent deformation.

Answer explanation

Yield strength is defined as the maximum stress a material can withstand without undergoing permanent deformation. This means that beyond this point, the material will not return to its original shape.

What is the role of Poisson's ratio in material behavior?

• Poisson's ratio describes the electrical conductivity of a material.

• Poisson's ratio is the measure of a material's density.

• Poisson's ratio indicates the thermal expansion of a material.

• Poisson's ratio measures the ratio of lateral strain to axial strain in a material.

Answer explanation

Poisson's ratio is a key property in material science, measuring the ratio of lateral strain to axial strain when a material is deformed. This helps in understanding how materials respond under stress.