Design Considerations to Improve Charpy Instrumented Strikers.

Instrumented impact testing allows the applicability of conventional Charpy tests to be extended toward assessing mechanical properties such as dynamic fracture toughness and dynamic tensile properties. In this work, we present design considerations for engineering instrumented strikers for Charpy V-notch impact testing. Specific attention is given to the mechanical and geometric features, as well as the placement of strain gauges and corresponding bridge circuits for instrumentation.

Traceable Calibration and Demonstration of a Portable Dynamic Force Transfer Standard.

In general, the dynamic sensitivity of a force transducer depends upon the mechanical system in which it is used. This dependence serves as motivation to develop a dynamic force transfer standard, which can be used to calibrate an application transducer . In this work, we SI-traceably calibrate a hand-held force transducer, namely an impact hammer, by using a mass suspended from a thin line which is cut to produce a known dynamic force in the form of a step function.

Nanometer Positional Control using Magnetic Suspension for Vacuum-to-Air Mass Metrology.

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Traceable Dynamic Calibration of Force Transducers by Primary Means.

We describe an apparatus for traceable, dynamic calibration of force transducers using harmonic excitation, and report calibration measurements of force transducers using this apparatus. In this system, the force applied to the transducer is produced by the acceleration of an attached mass, and is determined according to Newton's second law, = . The acceleration is measured by primary means, using laser interferometry.

Stress Analysis of Conical Contact Joints in the NIST 4.45 MN Deadweight Machine.

During the disassembly phase of the refurbishment of the National Institute of Standards and Technology 4.45 MN Deadweight Machine, workers confirmed previously suspected damage in certain conical contact joints within the apparatus. A finite element analysis of the contact joints is performed with the aim of understanding some of the potential origins of failure in order to prevent future damage in the machine.