Stress of Fracture of Crack

 , where:

 = Stress required for fracture at crack (Pa)

E = Young's Modulus (Pa)

G = Energy Dissipated at Fracture (J/m^2)

a = Length of crack (m)

Stretch Ratio

Also known as the extension ratio:

 = Stretch Radio

 = Final Length (m)

L = Original Length (m)

Torsional Stress

 , where:

 = Torsional Stress (Pa)

T = Torque (N*m)

r = Distance from rotational axis (m)

J = Polar Moment of Inertia (m^4)

Velocity of a Shear Wave

 , where:

vs = Velocity (m/s)

G = Shear Modulus (Pa)

 = Density (kg/m^3)

Von Mises Stress

Also known as Equivalent Tensile Stress

 , where:

The stresses in three dimensions represent numbers 1, 2, and 3.