Stress, Strain, and Material Properties

These flashcards cover key concepts related to stress, strain, modulus of materials, and properties essential for understanding material behavior under different loads.

What is stress?

Stress (σ) is force per unit area within a material that arises in response to an externally applied force.

What is the unit of stress?

The unit of stress is N/m², also known as Pascal (Pa). 1 MPa = 10^6 Pa and 1 GPa = 10^9 Pa.

What is strain?

Strain (ε) is defined as the change in length divided by the initial length of the object.

What is the formula for calculating strain?

Strain (ε) = ΔL / L0, where ΔL is the change in length and L0 is the initial length.

What does Young's modulus measure?

Young's modulus (E) measures the stiffness or rigidity of a material.

What is the significance of Poisson's Ratio?

Poisson's Ratio (ν) describes the relative change in lateral dimensions when a material is stretched or compressed.

Define tensile stress. How is it calculated?

Tensile stress is the stress experienced by a material when it is subjected to an axial load; it is calculated by dividing the force (F) by the area (A): σ = F/A.

Define compressive stress. How is it calculated?

Compressive stress is the stress experienced by a material under compression; it is calculated in the same way as tensile stress: σ = F/A, but the force (F) is negative.

What is a stress-strain curve?

A stress-strain curve is a graphical representation of the relationship between stress and strain for a material.

What distinguishes ductile materials in stress-strain curves?

Ductile materials display a distinct yield point and a plastic region where they can undergo significant deformation before fracture.

What features are shown in the stress-strain curve of brittle materials?

Brittle materials typically have a linear elastic region with no distinct yield point and fail without significant plastic deformation.

What is the maximum stress a material can withstand before necking occurs?

This point is known as the Ultimate Tensile Strength (UTS).

What does toughness refer to in materials?

Toughness is the ability of a material to absorb energy before fracturing, typically represented as the area under the stress-strain curve.

What information does Young's modulus provide?

Young's modulus provides a measure of the stiffness of a material and is calculated as the slope of the linear region of the stress-strain curve.

What happens when a material is in tension according to Poisson's ratio?

When a material is stretched in one direction, it generally contracts in the other two directions.

What is axial strain?

Axial strain is the change in length of a material in the direction of applied load, expressed as a fraction of its original length.

What is the formula for calculating axial strain?

Axial strain (ε) = (L - L0) / L0, where L is the final length and L0 is the initial length.

What is hydrostatic pressure?

Hydrostatic pressure is the pressure exerted by a fluid at rest due to the force of gravity acting on it.

What are the modes of loading for structural elements?

Modes of loading include axial tension, compression, bending, torsion, and hydrostatic pressure.