Thread engagement check
Minimum thread engagement so the bolt fails before the tapped threads strip. NASA RP-1228 pullout relation, common bolt grades and tapped materials.
Thread engagement check
How deep does a tapped hole need to be so the bolt breaks before the threads strip? Uses the NASA RP-1228 pullout relation with the bolt's full tensile strength as the load.
Tensile stress area: A_t = 0.7854 · (d − 0.9743/n)². Bolt capacity: P = A_t · UTS.
Internal thread shear area per length, NASA RP-1228 simplified: A_s ≈ π · d_m · L / 3 with pitch diameter d_m = d − 0.6495·p.
Required engagement so the threads outlast the bolt: L = 3·P / (π · d_m · F_s), where F_s is the tapped material shear strength.
This is a sizing check, not a certified analysis. Shear strengths are typical values. Add depth for chamfers, incomplete threads at the bottom of a blind hole, and any plating or coating.
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