Reliability Evaluation of Bolt Fastening Force Based on Ultrasonic Measurement Method

摘要

Bolts are important fasteners indispensable in the manufacturing industry and are widely used in national defense industry and important facilities such as aerospace, vehicle, ship, railway, and bridge. The precise control and verification of bolt fastening force is closely related to the safety and reliability of the bolt-assembled equipment and structures. Although there are many conventional methods for controlling the fastening force applied to a bolt, poor control accuracy and low detection efficiency remain issues in evaluating the safety of bolted assemblies. Additionally, these conventional methods all have limited application to the detection of changes in the residual fastening force in in-serve bolts. As a nondestructive testing technology, ultrasonic measurement can be applied to successfully address these issues. To help researchers understand the theoretical basis and technological development in this field and equip them to conduct further in-depth research, the theoretical models of the ultrasonic fastening force measurement proposed domestically and abroad in recent years are reviewed. Then, two main influencing factors, temperature and effective stressed length, are analyzed and proposed methods of calibration and compensation are reviewed. Finally, aiming at the issue that the axial stress inside the bolt is not uniformly distributed within the effective stressed length, some newly proposed theories and methods are discussed.