Fiber Bragg grating-based accelerometer design based on multi-objective optimization

In this work, a Fiber Bragg grating-based accelerometer design is presented. Different geometries (Double-L Cantilever, Single Cantilever, Triangular Cantilever, Clamped–Clamped Cantilever, Capillary Steel Tube, and Flexible Hinges) are analyzed using analytical models to select the one that meets the project requirements: natural frequency of at least 500 Hz and acceleration sensitivity of at least 100 pm/g. After this step, a multi-objective optimization approach is used to provide a geometric parameter combination to generate a Pareto front to analyze different sets of natural frequencies and acceleration sensitivities. Through this procedure, four combinations of geometric parameters were selected to provide one accelerometer with the maximum natural frequency, one accelerometer with the maximum acceleration sensitivity, and two accelerometers that fulfilled the project requirements. These structures were numerically evaluated using modal finite element analysis. Finally, the experimental characterization of the manufactured sensors was carried out at three different excitation frequencies: 17 Hz, 35 Hz, and 50 Hz. For 17 Hz, the experimental sensitivities were 180 pm/g, 690 pm/g, 380 pm/g, and 400 pm/g, for accelerometers 1, 2, 3, and 4, respectively. For 35 Hz, the experimental sensitivities were 150 pm/g, 510 pm/g, 290 pm/g, and 230 pm/g, for accelerometers 1, 2, 3, and 4, respectively. For 50 Hz, the experimental sensitivities were 120 pm/g, 410 pm/g, 150 pm/g, and 160 pm/g, for accelerometers 1, 2, 3, and 4, respectively. The multi-objective optimization procedure proposed in this work is a versatile tool for accelerometer design, where different geometric parameter combinations can be studied to meet different project requirements. In the case of quasi-distributed mechanical vibration monitoring, where project requirements vary depending on the sensor’s location, this is an advantageous alternative.