Fundamental Research On Non-silicon High-g Micromechanical Acceleration Switch

Aimed at technical requirements of fuze power supply such as miniaturization,dexterity and real-time rapid accurate response,a passive non-silicon high-g micromechanical acceleration switch which can be used in combination with fuze power supply and recognize two typical circumstances(launch and drop)has been proposed.It has the following advantages such as small size,high energized reliability,excellent electrical performance and good anti-impact properties.Recognition mechanism of dual-threshold acceleration,energized reliability and electrical performance of switch were studied by combining numerical simulations with corresponding experiments.Firstly,based on working environments of the switch in its whole life,its performance requirements and working principle,A physical model which consists of recognition module and energized module was established and then its corresponding kinetic,system response and collision process analysis were taken to determine its curvilinear motion recognition method and structural parameters.Based on the analysis of spring and its combined layout with mass,a teeth-type recognition module which can recognize two load environments based on their amplitude and duration,an energized module with a pair of soft contact electrodes and corresponding auxiliary module have been designed by numerical analysis.Then,the optimized structure was determined by finishing the transient numerical analysis of overall structure of the switch.The multilayered UV-LIGA technology was chosen depends on processing period,difficulty and cost.To facilitate testing,the switch was packaged and the overall size is 11.43mm×11.43mm×2.05mm.Secondly,various factors were analyzed to evaluate the effects on the energized reliability and mechanical and electrical methods were proposed to improve the energized reliability of the switch.An RC debounce circuit was designed to remove the voltage bounce and momentarily interruption caused by the external unwanted mechanical impact based on charge and discharge principles of c the apacitor.Three related tests were taken to evaluate its performance under three simulated environments of the switch by using the flight simulation turntable and Mushet hammer system.The results showed that the switch kept closed and the voltage bounce has been removed clearly by introducing a novel latching mechanism with a RC debounce circuit to make sure the subsequent circuit can operate stably.Also,the switch after switching on would not be broken when applying a load current of 1.8A and it can meet the current requirements of fuze circuit.Thirdly,contact resistance model was studied depends on the classical Hertz elastic theory,elastic-plastic and plastic theory.Simultaneously,shrink resistance model and thin-film resistance model were analyzed.After studying on the single micro contact,a rough surface contact resistance model which has engineering significance was deduced precisely by analyzing the surface topography and external load.Thus,contact resistance-load characteristic curve was derived by introducing the contact force between two electrodes.According to the measured surface topography and the corresponding tests,theoretical and experimental contact resistance-load characteristic curves were obtained,and the contact resistance model is accurate enough which can provide a theoretical reference for the switch based on UV-LIGA technology.Also,the experimental results show that the electrical performance of switch is excellent and its contact resistance is?2?.Finally,a series of static and dynamic tests were taken to evaluate performances such as recognition ability and anti-impact performance of the packaged non-silicon high-g micromechanical acceleration switch.The experimental results certified the accuracy of the design and showed that the switch can recognize the two typical circumstances,that is,it can be closed reliably under launch environment(acceleration amplitude:3682g,duration:4ms)and always keep off when meeting drop environment(acceleration amplitude:15300g,duration:133 ?s).After the switch was closed,it remained on state during the simulated flight test and simulated hit target test.Then,an impact test was taken by using the Mushet hammer to evaluate the anti-impact properties of the switch.The results showed that there is no failure such as plastic deformation,delamination,adhesion and fracture when the impact acceleration amplitude and duration were 30200g and 100?s respectively,and it is in good agreement with the design.