| Abstract | Accelerometers are designed to measure vibration in one precisely defined principal axis, usually perpendicular to the mounting surface. Ideally, there should be no response to accelerations in the other directions. In practice, the accelerometer does produce a charge or voltage when it is vibrated in the axis at 90° to the principal axis of measurement. The resulting output is indistinguishable from the response to the acceleration in the principal axis. This leads to an increased measurement uncertainty if these transverse accelerations exist during the calibration of the accelerometer. For this reason, the international standard ISO 16063-11 specifies limits for the transverse motion of vibration shakers. This paper presents the development of a laser interferometric system, which is designed to measure the transverse motion of an air-bearing calibration-grade shaker for various loads. The use of a mounting fixture with integrated plane mirror reflectors allows the transverse motion to be measured during the calibration itself. The system is capable of simultaneously measuring transverse motions along two axes. The measured transverse motion of a low-frequency accelerometer mounted on a long-stroke shaker is presented for frequencies in the range from 2 Hz to 40 Hz. |
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