Preload Measurement in Sleeve Bolts Using an Ultrasonic Technique

摘要

Sleeve bolts, which can provide an interference fit in a cylindrical hole by expanding during assembly, were used on an aerospace structural joint. A nondestructive evaluation method that uses ultrasonic testing was used to take measurements during preload application and monitoring. Ultrasonic bolt gages have commonly been used on regular bolts and studs, but not sleeve bolts. Ultrasound preload measurement on a sleeve bolt is different in many ways from that on a regular bolt. The pressure and friction on the sleeve bolt shank are absent or insignificant for regular bolts. Pressure and friction change depending upon initial conditions and applied load. The two factors affect the stress distribution inside the bolt and the ultrasound measurements. The paper provides an experimental analysis to account for effects of pressure and friction in measuring preload using the ultrasonic bolt gage.