A novel ultra-simplified flexure-based spring-mass device for relative gravimeter

Abstract

This study presents the design and test of a novel ultra-simplified flexure-based spring-mass device (NUFSMD) with high sensitivity for relative gravimeters. The NUFSMD is mainly composed of a highly sensitive spring based on flexure hinges (SFH) and a cantilever beam. When the change of gravity causes SFH to rotate, an amplified displacement can be obtained on the tail of the cantilever beam. The displacement is measured by a capacitive displacement sensor. The change of gravitational acceleration can be calculated based on the output of the sensor. A theoretical analysis of the working principle of the NUFSMD is established. A prototype NUFSMD is machined from 304 stainless steel and a series of experiments are carried out. The effectiveness of gravity measurement is demonstrated by finite element simulations and experiments. The experimental results show that the sensitivity of the NUFSMD is about 15.27 μGal nm−1, and the resolution is about 1.83 μGal. The designed NUFSMD shows outstanding performance. And the sensitivity and resolution of the NUFSMD can be further improved by increasing the number of flexible hinges connected in series. Compared with the existing spring-mass devices in high-precision relative gravimeters, the significant advantage of the NUFSMD is that it is simple in structure and easy to machine, which helps to greatly improve performance. Firstly, it is simple in structure, so it can be machined in one piece, which considerately contributes to stability and precision. Secondly, it is easy to machine, so it can be machined from high-performance but difficult-to-machine materials to improve its performance. Thirdly, there are a few parameters that need to be traded off for miniaturization because of the simple structure, so it is easy to be miniaturized to adapt to narrow measurement space. Therefore, it is expected to greatly improve the performance of the existing spring-mass device in relative gravimeters.