Mechanical Engineering: Materials Properties Quiz

Strain and Stress

• Strain is the deformation of a material from stress, and it's a ratio of the change in length to the original length.
• Deformations that are applied perpendicular to the cross section are normal strains, while deformations applied parallel to the cross section are shear strains.
• Strain is dimensionless.

Stress-Strain Diagram

• The stress-strain diagram is used to analyze the behavior of a material under different loads.
• The modulus of elasticity (E) is the slope of the linear part of the stress-strain diagram.

Modulus of Elasticity

• The modulus of elasticity (E) is the ratio of stress to strain within the proportional limit.
• It's also known as Young's Modulus.
• E is a constant of proportionality that describes the stiffness of a material.

Modulus of Elasticity in Shear

• The modulus of elasticity in shear (G) is a measure of a material's stiffness under shear loading.
• It's related to the modulus of elasticity (E) and Poisson's ratio (v) by the equation: G = E / 2(1 + v).

Poisson's Ratio

• Poisson's ratio (v) is the ratio of the lateral strain (contraction) to the longitudinal strain (extension) when a material is loaded with a longitudinal tensile force.
• It's a measure of a material's lateral deformation response to a longitudinal tensile loading.

Elastic Limit

• The elastic limit is the point beyond which a material will no longer return to its original shape when the load is removed.
• It's the point where permanent deformation occurs.

Yield Point

• The yield point is the stress value at which a material begins to deform plastically.
• It's the point where the material's stress-strain curve deviates from its linear elastic behavior.

Ultimate Stress or Tensile Strength

• The ultimate stress or tensile strength is the highest stress a material can withstand before breaking.
• It's the maximum stress a material can tolerate before failing.

Rupture Stress

• The rupture stress is the stress at which a material fails or breaks.
• It's also known as breaking strength.

Working Stress

• The working stress is the maximum safe axial stress used in design.
• It's the stress that a material can withstand without failing.

Ultimate Strength

• The ultimate strength is the maximum stress a material can withstand before breaking.
• It's also known as tensile strength or breaking strength.

Machinability

• Machinability is the relative ease with which a material can be cut or machined.
• It's an important factor in manufacturing and design.

Brittleness

• Brittleness is a material's tendency to fracture without appreciable deformation.
• It's the opposite of ductility.

Ductility

• Ductility is a measure of the degree of plastic deformation that a material can withstand before breaking.
• Ductile materials are more suitable for applications where repeated loads are expected.

Elasticity

• Elasticity is the ability of a material to return to its original shape after an external load is removed.
• It's a measure of a material's ability to withstand temporary deformation.

Plasticity / Creep

• Plasticity is the ability of a material to deform permanently under an external load.
• Creep is a slow process of plastic deformation that occurs when a material is subjected to a constant load below its normal yield point.

Resilience

• Resilience is the ability of a material to absorb energy when it's elastically deformed.
• The modulus of resilience is the amount of energy that a unit volume of material can absorb while in the elastic range.

Toughness

• Toughness is the ability of a material to withstand a shock load without breaking.
• It's a measure of a material's ability to absorb energy during plastic deformation up to rupture.