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Sahithyan's S1
Sahithyan's S1 — Properties of Materials

Mechanical Properties

Tensile Force

Pulls out of the cross-sectional area.

In the direction of force, length increases. Cross-sectional area decreases.

Compressive Force

Pushes into the cross-sectional area.

In the direction of force, length decreases. Cross-sectional area increases.

Stress

Force per unit area.

Stress σ=ForceArea=FA\text{Stress }\sigma=\frac{\text{Force}}{\text{Area}}=\frac{F}{A}

Engineering stress

Engineering stress σ=ForceInitial Area=FA0\text{Engineering stress }\sigma=\frac{\text{Force}}{\text{Initial Area}}=\frac{F}{A_0}

True stress

True stress σT=ForceInstantaneous Area=FAi\text{True stress }\sigma_T=\frac{\text{Force}}{\text{Instantaneous Area}}=\frac{F}{A_i}

Strain

Dimensional change with respect to the original dimensions.

Engineering strain

Engineering strain ϵ=ExtensionInitial Length=l−l0l0\text{Engineering strain }\epsilon=\frac{\text{Extension}}{\text{Initial Length}}=\frac{l-l_0}{l_0}

True strain

True strain ϵT=lnlil0\text{True strain }\epsilon_T=ln\frac{l_i}{l_0}