Papers by Author: Li Shen

Abstract: Based on the electrostatic comb drive structure, the comb will do relative motion when it is driven up, and the space between them will be less than 1μm. Considering the micro-scale effect, the Van der Waals force and the Casimir force is used to analyze the influence on the micro-structure, compared with the electrostatic force. The van der Waals force and the Casimir force is almost equivalent to the electrostatic force when the initial gap of the micro-structure and the relative displacement between the micro-structure is relatively small. Therefore the van der Waals force and the Casimir force play an important role in the micro-structure and cannot be ignored.

Abstract: Casimir had measured the Casimir force through experimental methods, and fitted the empirical formula between the plates. On its basis we analyse that when the gap of two separating surfaces achieves submicron in micro devices, the effect of the Casimir force to the micro-devices is great and this Casimir effect can not be ignored. The results show that: Considering the Casimir force or not, the extreme value of acceleration which can be detected by micro-accelerometer is different, and we have got the specific numerical fitting figure by Matlab .

Abstract: Based on the calculation and analysis of three kinds of elastic beam’s stiffness coefficient in micro machined gyroscope, the results show: in the condition of small displacement，forces and displacement are linear relationship in clamped-clamped beam, crab-foot beam and bow beam; but as the displacement increases, the relationship between forces and displacement are obvious non-linear in clamped-clamped beam. When the displacement is three times the length of beam’s width, the bow beam’s force and displacement are linear relationship. By ANSYS crab-foot beam and bow beam’s stiffness is obtained, the simulation results and the polynomial fitting coefficient are all credible.

Abstract: A detailed analysis of the concept of strain energy density and strain gradient on the material microscale effect in a micro-machined gyroscope is carried out. By analysis, the material microscale effect mainly influences its elastic modulus. The analytical expression of the valid elastic modulus on the micro elastic beam structure of the micro-machined gyroscope is deduced. When considering the valid elastic modulus and not, respectively compare the natural frequency of the elastic beam with the actual measurement results. The error of former is far less than the latter. By the theoretical derivation and experiment test, the influence of the material microscale effect on the micro-machined gyroscope is analyzed.