ABSTRACT
The four critical areas which give the assembled threads their load carrying capability are: (1) the effective cross-sectional area through the thread, known as the tensile thread area, which resists bolt fracture in tension; (2) the shear area of the external thread which resists the stripping off of the bolt thread; (3) the shear area of the internal thread which resists the stripping of the thread out of the nut or tapped hole; and (4) the cross-sectional area through the thread which resists transverse shearing through the bolt. This area is also used when computing torsional stresses and the resistance of the externally threaded fastener to twist off during tightening.
