Mohammad Abolghasemzadeh - Department of Mechanical Engineering Amirkabir University of Technology (Tehran Polytechnic) Tehran, Iran
Hossein Afshari - Department of Mechanical Engineering Amirkabir University of Technology (Tehran Polytechnic) Tehran, Iran
Yasaman Hedayatnasab - Department of Mechanical Engineering Amirkabir University of Technology (Tehran Polytechnic) Tehran, Iran
Masoud Habibi - Faculty of Civil Engineering and Architecture University of Eyvanekey Tehran, Iran

Bolt/nut joints are widely used in machines and structures to enable easy assembly and disassembly. The estimation of the axial force (i.e. the fastening force) has been regarded as the main issue in the maintenance of such joints. In this paper, a simple and efficient method is presented for determining the parameters required in screw analysis, namely the fastening force and torque. For this purpose, a torque test machine equipped with an ultrasonic probe was designed and manufactured to measure the elongation of the bolt while tightening through capturing the changes in the ultrasonic wave propagation time. The elongation can then be used to estimate the axial force in the screw by knowing the geometrical and material properties of the screw. Furthermore, the tightening torque was also calculated through available relationships between the axial force created in the screw and the applied torque. To ensure the accuracy of the method, the resultant fastening force-torque diagram was compared with the data obtained from the traditional method, and a satisfactory agreement was found. Interestingly this research concentrated on alternative techniques for the bolts fastening force/torque real-time measurement aiming at approaching sustainable developments such as easy installation, less expensive, and high accuracy.

bolt; fastening force; ultrasonic; elongation; torque; real-time measurement