Optimization design for medium-high frequency FBG accelerometer with different eigenfrequency and sensitivity

• For FBG accelerometer based on flexible gemels, a higher eigenfrequency and a higher sensitivity cannot be achieved simultaneously. It is necessary to design and optimize the parameters about the accelerometer in order to increase the sensitivity but keep eigenfrequency unchanged. In this paper, sequential quadratic programming (SQP) method have been used to optimize the sensor. So, we can design expectant FBG accelerometer with the best response sensitivity, according to required frequency range of use.
• In this paper, a simple empirical equation of rotational stiffness for single-notch circular flexible gemel is proposed. It shows that the eigenfrequency of this prototype accelerometer can reach a broad range from 600 to 3050 Hz. And the sensitivity can be obtained from dozen to hundreds pm per gravitational acceleration.
• Finally, two prototype accelerometers with eigenfrequency of 650 Hz and 3050 Hz have been designed and fabricated. The shake table test results exhibits that, the sensors can be worked in a broad flat range.

A simple empirical equation of rotational stiffness for single-notch circular flexible gemel is proposed. Based on the parameter optimization, we have discussed how to choose the structural parameters to achieve the balance between the sensitivity and the eigenfrequency. By using sequential quadratic programming (SQP) method, two prototypes of FBG accelerometers with eigenfrequency of 650 Hz and 3050 Hz are designed. Furthermore, we also perform the shaking table test for the fabricated prototype sensors. The experimental results show that the measured eigenfrequency and sensitivity are approximately identical to design values. Also, the FBG accelerometers show great anti-interference capacity in flat range which may be applied to the structural–health monitoring.