Vibration calibrator
Vibration calibrators (also calibration tables or structure-borne sound calibrators ) are electromechanical devices that are used for the traceable calibration of vibration sensors and vibration measuring devices. They generate a sinusoidal mechanical vibration signal with a known amplitude and frequency . The vibrating part is usually a round steel bolt with an internal thread for fastening the test item. Electrodynamic or piezo-actuator systems are used to generate vibrations . With older devices, the vibration amplitude had to be set manually depending on the mass of the test object. Modern vibration calibrators have a built-in reference vibration sensor and a control loop, whereby the amplitude is kept constant up to a certain test object mass. Older models allow the calibration of objects up to around 100 g, while current devices work stably up to over 500 g.
Vibration calibrators are often used for checking vibration sensors and vibration measuring devices on site and are therefore usually portable and battery-operated.
The vibration frequency most commonly encountered in calibrators is 159.2 Hz, which corresponds to an angular frequency of 1000 rad / s. With older devices, 79.6 Hz (500 rad / s) are sometimes also common. Since the oscillation path, the oscillation speed and the oscillation acceleration are linked to one another via the factor of the angular frequency in the case of sinusoidal signals, the same numerical values advantageously result for the amplitudes of the three oscillation quantities at this frequency. For example, a vibration acceleration of 10 m / s² at 159.2 Hz corresponds to a vibration speed of 10 mm / s and a vibration path of 10 µm.
Some devices allow you to choose between several frequencies or to fine-tune a certain frequency range. Frequencies between 16 Hz and 10 kHz are customary in the market.
Vibration calibrators occasionally have a measuring channel for connecting different types of vibration sensors and a display for reading the sensitivity .
Web links
- Vibration calibrators, Metra measurement and frequency technology
- Hand-held vibration calibrator from Brüel & Kjær
literature
- Werner Schirmer: Technical noise protection: Measures on machines and workplaces . Springer, 1997, ISBN 3-540-62128-8 .