1. NIST 1-kilonewton Dynamic Force Calibration Facility Ako Chijioke, Rick. L. Seifarth, Zeina J. Kubarych Mass and Force Group Quantum Metrology Division Physical Measurement Laboratory National Institute of Standards and Technology NCSLI Workshop and Symposium, July 2013

2. Objectives  Present the need for dynamic force calibration  Give a sense of the application areas that could benefit from dynamic force calibration  Explain the design of the NIST 1 kN facility

3. Why dynamic force calibration? Many force measurements are highly dynamic, but established S.I.-traceable calibration procedures are static. This leads to difficulty in assigning uncertainty to the results of such measurements, as: The information required to relate the measurement system’s dynamic output to its static calibration is often unknown. Where data values for such information are available the associated uncertainties are often larger than desired or unknown (traceability gap). F = 124.7 ± ??? N  This situation can be addressed by S.I.-traceable dynamic calibration

4.  Interchangeability and standardization: e.g. interchangeability of components in a manufacturing system e.g. application of measurement results to processes using different types of equipment  Measurement results to be compared to theory, results obtained by other measurements  Measurement results to be combined with other quantities to derive additional information (e.g. use of force measurement results to calculate expended energy) Why dynamic force calibration? S.I.-force-traceability: “a documented unbroken chain of calibrations, each contributing to the measurement uncertainty”, relating the force measurement result to the S.I. definition of the Newton Allows: [International Vocabulary of Basic and General Terms in Metrology, 3rd edition, JCGM 200:2008]

5. Frequency (Hz) Force (N) Why dynamic force calibration? 1 - Machining 2 - Robotics control 3 - Fatigue testing 4 - Auto crash testing 5 - Biomechanical 6 - Wire/wedge bonding Aerodynamics Charpy testing Forming Brake forces Blast protection Civil structure testing … staticdynamic 1 43 6 5 2 NIST 1 kN facility

6. Why dynamic force calibration? Robotic control Y. L. Yao and S.M. Wu, Trans. ASME, 115 (1993), 352-8. [Permission ASME] T. Olsson et al, Robotics and Comp.-Int. Manufacturing, 26 (2010) 24-38. [Permission Elsevier] Machining

7. Why dynamic force calibration? It is often assumed that the dynamic response of force transducers is traceably calibrated … T. J. Mackin and D. F. Tognarelli, “Design and Evaluation of a Verification System for Force Measurement Using Instrumented Impact Testing Machines”, Pendulum Impact Machines: Procedures and Specimens for Verification, ASTM STP 1248, ASTM, (1995), 268-282. “The guiding principle is as follows: If a NIST-traceable dynamic load cell is impacted by a service load cell, a comparison of the signals can be used to verify the performance of the service load cell.” "An experimental method has been developed to determine the transmissibilities between a reference force transducer and the sensors of a piezoelectric dynamometer." L. R. Castro et al, “Correction of Dynamic Effects on Force Measurements Made with Piezoelectric Dynamometers”, Int. J. Mach. Tools and Manufacture, 46 (2006) 1707-1715. “For the purposes of this verification, the dynamometer’s indicated forces will be considered the true forces” … “Calibration of the dynamometer instrumentation must be current and traceable to the National Institute of Standards and Technology (NIST) or some other recognized national standards organization” ASTM E467-08e1: Standard Practice for the Verification of Constant-Amplitude Dynamic Forces in an Axial Fatigue Testing System

9. NIST dynamic force calibration facility F = m a Shaker

10. NIST dynamic force calibration facility

11. Traceability NIST dynamic force calibration facility U.S. national prototype K20 NIST working reference masses J.J. represent. of the Volt

12. Voltage uncertainty: 5 V signal, 5 kS/s 20 mV signal, 5 kS/s 3.5 x 10 -5 8 x 10 -4 Sample timing uncertainty (5 kS/s)2.5 x 10 -4 Maximum sampling rate100 kS/s Interferometer: DVM: NIST dynamic force calibration facility Component Specifications Velocity range  0.65 m/s Displacement resolution0.15 nm Displacement accuracy*1 nm Sample timing uncertainty (5 kS/s)2 x 10 -5 Maximum sampling rate100 kS/s Maximum force2 kN Max. displacement± 19 mm Max. velocity2 m/s Max. acceleration800 m/s 2 Max. load mass100 kg Bare table res. frequency 3.8 kHz Shaker:

13. NIST dynamic force calibration facility Operating Region

14. Program initiated in 2012 Harmonic force excitation system using electrodynamic shaker and load mass is operational Vibrometer I (custom) is assembled and undergoing characterization DVM is operational NIST dynamic force calibration facility Status

15. NIST dynamic force calibration facility Current work Complete system integration (vibration isolation, environmental monitoring) Evaluation of achieved uncertainty High-speed vibrometer Air-bearing guide

16. Thank You !

17. NIST dynamic force calibration facility Uncertainty contributions  DVM voltage accuracy  Electronic phase error (displacement)  Frequency mixing (displacement)  Thermal expansion (displacement)