Fastener Threaded Shear Area Equation and Calculator ISO 898

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The following equations and calculator will determine the Shear Area For External Thread Screw or Fastener per. ISO 898.

Thread Shear Area:

A_th = 0.5 Π d_p L_e = 0.5 Π L_e ( D - 0.64952 P)

Where:

A_th= Total thread shear area (mm²)
L_e = Thread Engagement Length (mm)
d_p = Pitch circle diameter of thread (mm)
D = Major Diameter (mm)
P = 1 / Number of threads per mm (n)

Per. ISO 898, Calculation of the tensile strength, R_m is based on the nominal stress area A_{s, nom} (single full thread) and the ultimate tensile load F_m.

Equation:

R_m = F_m/A_{s, nom}

Where

A_{s, nom} = [π/4] [(d₂ + d₃)/2]²

Where:

F_m = Tensile Load (Measured or Design Load)
d₂ = d_p Basic Pitch Diameter External Thread per. ISO 724
d₃ = Basic Minor Diameter External Thread = d₁ - H/6
π = 3.14157
P = Pitch of threads, number per mm
H = Height of Thread Triangle Feature according to ISO 68-1