The thesis takes comb capacitance type micro-accelerometer as the research target and designs a new type of biaxial micro-accelerometer with variable cross-section beam. The biaxial accelerometer is mainly composed of proof mass, comb capacitation and cantilever beam. The design of cantilever beam is based on variable cross section. The section size increases linearly with the increase of the beam length so that the influence of stress concentration can be reduced and the detection rigidity in the y-axis and z-axis directions is the same. Therefore, dual-axis detection can be realized. Firstly, taking the regular quadrilateral as an example, derive the moment of inertia of any regular polygonal section, and construct the expression of the maximum deflection of a variable cross-section beam; then determine the deflection factors of the cantilever beam under pure bending, and verify the accuracy of the expression through finite element analysis; The beam is used in the micro-accelerometer, and the design rationality of the variable-section beam micro-accelerometer is verified by simulation analysis: modal analysis determined the working frequency of micro-accelerometer with variable cross-section beam. Harmonic load analysis proved that the micro-accelerometer has a larger range. According to thermal analysis, it has better adaptability to high-temperature environments. Furthermore, harmonic response analysis proved that resonance can be effectively avoided, and fatigue analysis proves that it is much safer and has longer life. The results show that the deflection expression established in this paper can be widely used in regular polygonal variable-section beam deflection calculation and stability analysis; compared with the constant-section beam micro-accelerometer, the new biaxial variable-section beam micro-accelerometer has better system performance.

本文以梳状电容式微加速度计为研究对象，设计了一种新型的变截面双轴微加速度计。双轴加速度计主要由检测质量，梳状电容和悬臂梁组成。悬臂梁的设计基于可变截面。截面尺寸随着光束长度的增加而线性增加，从而可以减小应力集中的影响，并且y轴和z轴方向的检测刚度相同。因此，可以实现双轴检测。首先，以正四边形为例，推导任意正多边形截面的惯性矩，并构造出可变截面梁的最大挠度表达式。然后确定悬臂梁在纯弯曲作用下的挠度因子，并通过有限元分析验证了表达式的准确性。该梁用于微加速度计，并通过仿真分析验证了变截面梁微加速度计的设计合理性：模态分析确定了变截面梁微加速度计的工作频率。谐波负载分析表明，微加速度计的量程更大。根据热分析，它对高温环境具有更好的适应性。此外，谐波响应分析证明可以有效避免共振，疲劳分析证明它更安全并且寿命更长。结果表明，本文建立的挠度表达式可广泛用于规则的多边形变截面梁的挠度计算和稳定性分析。与等截面光束微加速度计相比，新型双轴可变截面光束微加速度计具有更好的系统性能。