The parametric analysis of the centrifugal insurance mechanism in MEMS safety and arming device
In this paper, a MEMS S&A device has been proposed. The size of the device is φ 12×0.3mm. The role of the centrifugal insurance mechanism is to ensure the safety in handling transportation and storage, and reliable firing with the launch overload. Through establishing the three-dimensional model of the centrifugal insurance mechanism, establishing the force and the parameters of the centrifugal insurance mechanism, deriving the mathematical model according to the rigid dynamic mechanics theory and establishing the finite element model by using ANSYS/LS-DYNA, appropriate centrifugal insurance mechanism is designed to meet two items, one item is deformation of elastic beam can reliably release slider when the speed is more than 30000r/min and the centrifugal insurance mechanism can restrict the slider again when the speed is reduced; the other item is the centrifugal insurance mechanism can effectively restrict the slider to ensure the safety of the device when primary insurance accident arming in handling transportation.
Optimization of a Fuze MEMS Setback Arming Device Based on the EDM Process
This paper introduces the working principle of a MEMS safety and arming (S&A) device and measures and tests a setback arming device. To solve the problem of large fabrication errors in the UV-LIGA process, a MEMS S&A fuze device fabricated by low-speed wire electrical discharge machining (EDM) is proposed. Microsprings are susceptible to flexural deformation and secondary deformation in the EDM process, which is solved by setting the auxiliary support beam, using multiple cuts and destress annealing. The linewidth, thickness and elastic coefficient of the microspring fabricated using the EDM process are closer to the designed values than those fabricated using the UV-LIGA process under the same conditions. When comparing the MEMS S&A devices fabricated by the two processes, it is found that the EDM process has a the higher machining accuracy. In view of the plastic deformation of the upper end of the microspring, the structure of the microspring is optimized to incorporate a gradient linewidth, and the optimized setback arming device is tested. The results show that the device can ensure service process safety and launch reliability. The maximum overload that can be withstood in service processing is 17000 g, and the minimum overload for insurance release during launch is 1500 g.
Comparison of plasma generation behaviors between a single crystal semiconductor bridge (single-SCB) and a polysilicon semiconductor bridge (poly-SCB)
Abstract A single crystal semiconductor bridge (single-SCB) has been fabricated by a micro-electro-mechanical system (MEMS) technique based on anisotropic wet etching, where an air gap replaces the oxide layer (SiO 2 ) used as a thermal insulating barrier in the conventional polycrystalline semiconductor bridge (poly-SCB). Upon flowing current in the single-SCB and the poly-SCB, the single-SCB exhibits a second peak of plasma generation at 500 ns, whereas that of the poly-SCB is founded at 600 ns. The results of an electrical experiment are analyzed through a finite element analysis and a simple discrete-element modeling of the thermal structure. From these investigations, it is clear that more effective heat conduction related to the plasma discharge behaviors is achieved in the single-SCB with a simpler thermal structure.