The ability of a material to deform before it fractures. Threads on bolts, screws and studs. The ability of a fastener to resist repeated cyclic stresses, first in one direction, then another. The sloping surfaces joining crests and roots. Mechanical resistance to the relative movement of two bodies in contact.
Static friction is typically greater than dynamic friction.
A joint in which the fastener rotates less than 30 degrees after reaching snugness. The enlarged shape formed on one end of a fastener to provide a bearing surface and drive feature. Threads in nuts or tapped holes. The diameter at the external thread's crest. The diameter at the external thread's roots.