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Summary

Traditional calibration methods for force transducers are static, with a known constant force applied to the transducer and compared to the transducer indication. However, many force measurements are dynamic – in application areas such as automobile crashworthiness, aerodynamic measurements, materials testing and impact protection in sports – with the force changing rapidly compared to the measurement system settling time. This can lead to large errors in measurements based on static calibrations. Therefore, the Mass and Force Group has undertaken the development of SI-traceable dynamic force standards, calibration, and uncertainty evaluation.

Description

dynamic force

Photograph of 2 kHz – 2 kN dynamic force calibration system.

We have developed a system for calibration up to force bandwidths of 2 kilohertz and amplitudes of 2 kilonewtons, based on measuring the acceleration of a known load mass. We have demonstrated calibration at a k = 2 uncertainty level of 1.2 % using this system. We have also demonstrated calibration of a dynamic force transfer standard with a k = 2 uncertainty of 2.1 % up to a frequency of 5 kHz. We are working on applying these to force measurement applications, while reducing the uncertainty and extending the bandwidth.

 

dynamic calibration
Example dynamic calibration of a force transducer using several different load masses.

 

Selected Publications:

[1] N. Vlajic and A. Chijioke, “Traceable dynamic calibration of force transducers by primary means”, Metrologia 53, S136, 2016.

[2] N. Vlajic and A. Chijioke, “Traceable calibration and demonstration of a portable dynamic force transfer standard”, Metrologia 54, S83, 2017.

[3] N. Vlajic and A. Chijioke, “Impact mechanics parametric studies with applications to dynamic force calibration”, ASME 2017 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference, paper DETC2017-67893, 2017.

[4] A. Chijioke and N. Vlajic, “High-bandwidth Kibble-balance dynamic force standard”, submitted for publication.

Created June 30, 2015, Updated March 15, 2018