Design and numerical performance analysis of a microgravity accelerometer with quasi-zero stiffness

We report a nonlinear electrothermal-loaded accelerometer for microgravity measurement, achieving quasi-zero stiffness nearby its static equilibrium position. The high mechanical sensitivity is attributed to the compression of the spring, in addition to the geometric parameters matched with quasi-zero stiffness characteristic. To make the spring compressed effectively, a V-shape electrothermal actuator was adopted in the design. The FEA results in multiphysics clearly show the different performance of the accelerometer when it is at applied voltage or not, verifying that the electrothermal-loaded mechanism has an effective influence on the sensitivity of accelerometer. At the applied voltage of 22.3 V, the natural frequency of the accelerometer decreases from 501.95 Hz to 8.24 Hz, while the other two higher mode frequencies remain above 500 Hz. In addition, this mechanism realizes a quasi-zero stiffness approximately of 0.007 N m(-1) within a linear working range of +/- 400 mu g and the stiffness becomes larger beyond this range protecting the device being overloaded.