Caracterização de um sistema de medição de vibrações de baixo custo para aplicações gerais

Abstract

Measurement Systems should be calibrated before use. Relevant legislation and technical standards in effect determine the calibration procedures and reference transducer that should be used to ensure traceability of calibrations and tests made with these systems. The importance of evaluation of uncertainty at all levels of the traceability chain is emphasized. In the development phase of a measurement system, its calibration has a unique importance because it allows the determination of the metrological parameters that characterizes it, as well as it´s capability. However, the market requires low cost, efficient, automated and versatile measurement systems. Therefore, this study developed a measurement system based on capacitive accelerometer ADXL321 of low cost for general aplications. Two types of direct calibration by comparison, one at 160 Hz and the other in frequency range 2 Hz to 20 kHz, were planned and ten experiments made. The data collected were analyzed and compared with those obtained with a standard measurement system. In following the uncertainty associated with all calibrations was evaluated, applying the methodology proposed in ISO/TAG 4/WG 3 (2008). Resulting in a measurement system of low cost with good accuracy, resolution 0.0006 V, dynamic range 19 dB, precision ± 0.0183 V, stable over time and expanded uncertainty of 4.58% for all calibrations.