Significance of Nut Factor in Fastening of Joints in Engineering Structures

Threaded fasteners are category of bolts used in the joint assembling of aerospace structure. Torque is the process of applying a force that works at a circular distance and rotates the threaded fasteners at the bolted joints of these structures. With the aid of this torqueing force the two different parts are clamped together to form the joints. Due to torqueing there arises an opposing force which is known as the frictional force. The frictional force in threaded portion of the bolt transforms the applied Torque into stress. Due to this stress there is a chance of joint loosening or bolt fracture which is considered to be critical. Hence, selection of torqueing force for a desired preload is a major issue in joint deployment. The friction coefficient is a key factor for estimating the torque that is required for the fasteners to be deployed in the aerospace structures. There are many features which influence the friction coefficient for example size, pitch, thread tolerance. Till date only experimental methods and theoretical formulae has been used to estimate the friction coefficient, torque and preload. This paper identified the key features which are most correlated to coefficient of friction using the fisher score filtering technique and ca boost algorithm for both numerical and categorical datatypes. Along with that gives the insight on the torque, preload and coefficient of friction which are associated in fastening of the bolted joint in different non-permanent aerospace structures.