Acceleration data acquisition and processing system for structural health monitoring

A measurement system has been developed and investigated to acquire and process the acceleration data, from the array of MEMS sensors, for the structural health monitoring applications. The current solutions includes up to 20 analog sensor boards, each with ADXL326 and ADXL377 MEMS type sensors (from Analog Device, with range of ±16g or ±200g), the data acquisition box USB-6259 (from National Instruments) with the 16-bit aggregated 1Ms/s data throughput, and data acquisition and processing software, implemented as an LabView application for the PC. Accuracy, calibration and other metrological issues have been investigated, including noise parameters and its spectra in the system and non-linearity of the sensors. The estimation of the displacements from the acceleration has been investigated, to characterize the non-linearity of the sensors and also for possible special additional measurement feature of the system. It has found, that For calibration of the acceleration and further inclination calculation the use of the natural gravitation of the earth could be used. Accuracy of the retrieving of the inclination data from the 3D acceleration sensors is under research, as well as stability in the time and temperature. Also, an example of the practical usage of the proposed system has been investigated. A section of the real-life composite boat has been equipped with the array of the sensor boards and mechanical pulse excitation has been applied to the construction with sensors. Characteristic frequencies have been extracted in the experiments, for further analysis of the variations and deviations of the parameters of the structures, being under test.