Dynamical Characterization Of Accelerometer Sensitive Elements Based On Composite Structure

With the rapid growth of MEMS field and wireless sensing industrial technology,people’s living standard of life has improved dramatically,and micro-accelerometer sensing element are extensive used in various sectors of life.Micro-accelerometer has turn into a hot issue in the research area of MEMS research because of its high performance and high sensitivity.With the continuous reduction of cost and volume,and good stability and high precision,they have been rapidly developed and applied in the fields of pressure sensors,industrial manipulators,and international space station.In MEMS accelerometers,the resonator is used as the core sensitive element of the structure,so it is crucial to have high vibration performance and good dynamic characteristics.Therefore,considering the influence of practical conditions on accelerometer performance,studying its vibration mechanics behavior will help the optimal design of the device and application expansion.The composite beam structure has excellent vibration performance and is often used in some microelectromechanical systems.However,a very small excitation can cause the vibration of the composite multi-beam structure,which can easily affect the stability of the whole structure.This paper mainly focuses on the study of microaccelerometer combined multi-beam structure,and it is of certain practical significance to analyze and study the vibration mechanical properties in order to ensure its better dynamic characteristics and stability.The main studying contents and achievements of this article are as follows:(1)In view of Euler Bernoulli beam model,the dynamic characteristics of composite multi-beam structure are studied.The displacement vector expression of the sensitive element is given,and the differential equation of motion and its boundary conditions of the composite multi-beam structure are established by Hamiltonian principle.The analytical vibration mode is studied theoretically,and the general calculation process of the numerical vibration mode of the sensitive element is obtained.The simulation results of ANSYS and finite element analysis of composite multi-beam structure are compared and analyzed,and the correctness of theoretical calculation is verified.The effects of the concentrated mass and the key structural parameters of the beam on its natural frequency vibration characteristics are studied.(2)The natural frequencies and modal shapes under different folding angles are obtained through simulation modal analysis.The results show that the first order frequency of the Z-beam structure increases with the increase of the included angle,and the second order frequency decreases with the increase of the included angle.When the angle reaches 80 °,the second frequency of the sensing element is twice the first frequency,and there is 1:2 internal resonance.The influence of different angles on the natural frequency of Z-beam structure is studied.Based on ANSYS,the model of composite multi-beam structure is modified,and the results of numerical analysis and analysis are compared in frequency error,which proving the validity of theoretical analysis.(3)Piezoelectric performance analysis of Z-beam structure sensing element.The axial vibration characteristics of Z-beam structure are studied,and the electromechanical coupling voltage dynamic equation is obtained.The effects of folding angle,beam structure size,excitation amplitude and external load amplitude on the piezoelectric performance of accelerometer are studied by COMSOL experiment.The influence of resistance on the output power of Z-beam structure with 30 ° and 90 °is studied,and the optimal resistance solution and maximum power at the first three natural frequencies are obtained.(4)The vibration test of Z-beam structure is carried out.The experimental samples were processed and a small experimental device was built.The vibration test is carried out by fixing one end of the composite beam structure with clamps and the other end free.The first five natural frequencies at different angles are obtained through experiments.The simulation results are contrast the test results,and the comparison curve is drawn to verify the correctness of the results.The first two vibration modes of the 120 ° Z-beam structure model are obtained through experiments,and the experimental results and the finite element results are drawn into curves.The correctness of the results is verified through comparative analysis.