Establishing reliability in vibration measurement and its international equivalency

Abstract

earthquakes, the accelerometer used in inertial navigation of aircraft, and the acceleration sensor installed in smart phones are also vibrometers. On the other hand, as it can be projected from Fig. 1, while the mass can stay at a fixed point as long as the vibration amplitude is small enough, the mass will not be able to stay at the fixed point due to the restoring force of the spring when the vibration surpasses a certain level. Such a property is determined by the stiffness of the spring, the natural vibration when considered as a mass-spring model, and the viscous element (damping) that absorbs vibration though this is abbreviated in Fig. 1. The vibrometer manufacturers optimize the above parameters for specific uses such as measurement of earthquakes, vibration of structures such The metric system and primary national metrology standards are necessary, but not sufficient for obtaining measurement equivalency. Recently, national metrology institutes of various countries including NMIJ/AIST of Japan are participating in international comparisons to confirm equivalency of their measurement capabilities, under a mutual recognition of arrangement (MRA). In this report, we describe progress on improving vibration measurement at NMIJ/AIST, along with global activities for establishing MRA. We also discuss future issues for improving vibration measurement.