Research On Structural Reliability Of MEMS Microaccelerometers Under Impact Load

The MEMS accelerometer is often combined with the micro gyroscope to form a micro inertial measurement unit(MIMU) to achieve the navigation function, which is installed in the civil aviation aircraft. Performance certification standards for aircraft navigation system in airworthiness regulations mainly contain the accuracy, integrity and continuity of function. MEMS accelerometers may often bear high impact load in the working environment and transport process, resulting in the failure. It's fatal for civil aviation. Therefore, it has important significance to research the structural reliability of MEMS accelerometer under impact laod for civil aviation safety and airworthiness.In this paper, the development history of MEMS devices and the impact resistance reliability of MEMS accelerometer are discussed in detail. Hopkinson technique is a kind of very good method to test impact reliability of MEMS accelerometer, which can produce similar half sine acceleration pulse, and adjust the width and amplitude of pulses. ANSYS/LS-DYNA is used in this paper to simulate MEMS accelerometer impact experiments. By change the velocity and length of the bullet, the impact loads used to test reliability of different MEMS accelerometers are gained, and the influence of strain gauge on impact waves is analyzed, providing guidance for Hopkinson technique.Working principle of MEMS accelerometers is discussed in this paper. The influence of the mass, the micro beam and the comb-finger on reliability is analyzed, which are in comb-finger capacitive accelerometer that is the research object of this paper. The failure modes are summed up as fracture, adhesion and the damage of anchors. Micro beams are the most common structure in MEMS accelerometers. The influence of structure parameters on modality is analyzed by changing the size of micro beams. A lot of impact simulations are conducted for comb-finger. The response characteristics of comb-finger are analyzed by changing the direction, amplitude and frequency of the impact load. The impact acceleration is applied to the MEMS accelerometer that consists of the anchor, micro beam and mass. The deformation process and the stress distribution are analyzed of the MEMS accelerometer under impact load. Finally, some suggestions for improving the impact reliability of MEMS accelerometers are given, and a good foundation is laid for the future research on the reliability of the same kind of MEMS accelerometer.