Advanced Design Fatigue Resistant Rivetless Nut Plate System

This paper discusses an advanced design rivetless nut plate system which overcomes the inherent problems associated with typical riveted and rivetless nut plate configuration used in blind assembly of aerospace structures.

The ForceTec_™ (FtCx_™) rivetless nut plate system presented utilizes hole cold expansion technology to radially expand a nut retainer into the fastener hole. Torque and push-out resistance are achieved by the resultant high interference fit of the retainer. Residual compressive stresses induced in the metal surrounding the hole during cold expansion and the reduction in applied cyclic stress range, caused by the high interference fitted retainer, significantly improve resistance to fatigue cracking. This system significantly reduces the high stress concentration associated with other methods and has demonstrated superior nut plate qualities with fast, consistent and reliable installation.