Variable Section Guide Blade for High Acceleration MEMS Proof Mass
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Solution Overview
Problem
Conventional guide blades in micro-machined electromechanical systems, particularly those with a substantially parallelepiped shape, are unsuitable for high accelerations due to low critical buckling loads, leading to buckling and deformation under significant acceleration conditions.
Innovation Solution
A guide blade with a variable section inertia along the Oz axis, featuring a central zone with increased width and thickness, and shorter hinge sections, allowing for higher critical buckling loads while maintaining flexibility along the sensitive axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional guide blade with substantially parallelepiped shape is used, then the structure is simple to manufacture, but the critical buckling load is low causing buckling under high acceleration
Solution Approach 1:
The guide blade employs variable cross-sectional dimensions along its length, with the section being thickest at the center and tapering towards the ends. This local variation in geometry concentrates structural reinforcement where it is most needed to prevent buckling under compression while maintaining flexibility at the hinge regions, thereby resolving the contradiction between manufacturing simplicity and buckling resistance.
Solution Approach 2:
The invention changes the geometric parameters of the guide blade by defining variable width and thickness along its length rather than maintaining constant dimensions. This parameter variation optimizes the moment of inertia distribution, allowing the blade to withstand high acceleration forces without buckling while remaining compatible with standard micromachining processes.
2Strength
If the guide blade width along Oy axis is increased to提高 buckling load, then the critical buckling load increases, but the stiffness along sensitive axis Oy increases and flexibility decreases
Solution Approach 1:
The guide blade features a non-uniform cross-section with maximum dimensions at the center and reduced dimensions towards the ends. This local quality variation allows the central region to provide high buckling resistance while the end regions maintain low stiffness for flexibility, effectively resolving the contradiction between strength and operational flexibility.
Solution Approach 2:
The invention addresses the stiffness-f flexibility contradiction by varying the blade properties along its length (adding a dimensional gradient) rather than uniformly increasing width. This dimensional variation allows different sections to serve different functions: the thick central section resists buckling while the thin end sections allow flexibility, eliminating the need to uniformly increase width.
3Ease of operation
If the guide blade length is increased to reduce stiffness along sensitive axis, then the flexibility improves, but the critical buckling load decreases
Solution Approach 1:
By concentrating the maximum cross-sectional dimensions at the center of the blade and reducing them towards the ends, the invention creates a local quality distribution that optimizes both flexibility and buckling resistance. The variable section allows the blade to achieve the required flexibility for sensitive axis movement while maintaining sufficient buckling load capacity.
Data Source
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AI summary
The invention pertains to the field of micro-machined electromechanical systems including a proof mass capable of displacement. The invention relates to a guiding blade for a mobile proof mass in a monolithic electromechanical system which is micro-machined in a plate having a thickness H and defining a plane O,x,y, wherein the electromechanical system includes a base and at least one measurement cell including the proof mass connected to the base by the guiding blade and capable of translation displacement along the axis Oy, said blade extending along an axis Ox and being connected to a fixed portion of the base, and said blade limiting the movement of the proof mass (1) along the axis Ox, characterised in that said blade is monolithic and in that it sequentially comprises: a first hinge section in the shape of a parallelepiped having a thickness h long the axis Oz, a length I1 along the axis Ox and a width L along the axis Oy; a central section essentially in the shape of a parallelepiped having a thickness h long the axis Oz, a length lt along the axis Ox and a width Lt along the axis Oy; and a second hinge section essentially in the shape of a parallelepiped having a thickness h long the axis Oz, a length I2 along the axis Ox and a width L along the axis Oy.