Estimation of accuracy in ultrasonic preload measurements

Ajay M. Koshti

doi:10.1117/12.434186

24 July 2001 Estimation of accuracy in ultrasonic preload measurements

Ajay M. Koshti

Proceedings Volume 4335, Advanced Nondestructive Evaluation for Structural and Biological Health Monitoring; (2001) https://doi.org/10.1117/12.434186
Event: 6th Annual International Symposium on NDE for Health Monitoring and Diagnostics, 2001, Newport Beach, CA, United States

Abstract

An ultrasonic extensometer is used to measure tensile preload in fasteners such as bolts and studs. Raymond Boltgage and StressTel Boltmike are two of the most commonly used extensometers. It is necessary to know the accuracy of extensometer measurements. Many factors affect the accuracy of extensometers. Characteristics of the fasteners affect the accuracy. Moreover, the variability in transducer coupling also affects the accuracy. Variation in the grip length of fastener also affects the accuracy. Therefore, the extensometer doesn't have a fixed amount or percentage of measurement accuracy. A detailed procedure to estimate the accuracy is currently not available in the manufacturer's manuals. The paper discusses all sources of errors and provides a procedure to compute the preload measurement accuracy for the two instruments. The paper also provides relationships between the corresponding parameters of the two instruments. Moreover, it provides equations to program the two instruments so that the difference between preload measurements by the two instruments is minimized.

Citation Download Citation

Ajay M. Koshti "Estimation of accuracy in ultrasonic preload measurements", Proc. SPIE 4335, Advanced Nondestructive Evaluation for Structural and Biological Health Monitoring, (24 July 2001); https://doi.org/10.1117/12.434186

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