Paper Title
Bolt Force Measurement For Applied Torque On Latch Release Bolts

Fasteners form an integral part of any aerospace structure. Design of a fastener chiefly aims at determining the diameter, strength class, thread pitch, thread length and pre-tightening load. The knowledge to calculate the pre-tightening load experienced by standard fasteners due to a known torque is available in the form of emperical relations. In aerospace applications, there sometimes exists a need for the usage of non-conventional fasteners or bolts. The separation of used stage or opening of panels for release of payload demands the use of non-conventional fasteners like latch bolts. These latch bolts on receiving a command shall help in the separation or opening as required. As the latch release bolts are not standard fasteners, it is necessary to establish a method of estimating the force experienced by the bolt due to an applied torque in other words the nut factor. In this paper, an experimental method using strain gages has been proposed to achieve this. A calibrated chart of Load vs Strain shall be utilized to estimate the load from the measured strains during the torque application. The details of the methodology to estimate bolt force and the experimental results obtained are discussed in this paper. Keywords— Bolt force, Strain gage, Wheatstone bridge, Latch bolt.