| With the development of science and technology, in view of the in situ mechanicstest, scanning probe microscopy, three coordinates measuring instrument and otherprecision monitoring instruments, tiny load of force signal precision testing is veryimportant.Therefore, research and development a miniature, high-precision andhigh-integrated micro-force sensor has a very urgent subject of great practicalsignificance. Based on the advantages of Piezoelectric element as well as thecharacteristic of flexible hinge, this paper will put the key work for small signaldetection unit load power design and experiment analysis.The sensor relates tomechanics, testing technology, piezoelectric, electrical, mechanical and other relatedknowledge. Integrating displacement amplification platform and self-sensing function,the uint takes advantages of high accuracy, wide testing range and light weightstructure.First, the tiny force measurement methods of the domestic and foreign researchprogress are introduced and the advantages and disadvantages of each measurementmethod are given. There are some shortcomings during methods, such as singledimension measurement, a higher of deviation with series other sensors and so on. Sothey are not suitable to carry out tiny force measurement in a limited space. And a kindof high-precision and high-integrated sensor which can test force load anddisplacement load at the same time has the vital significance.Then, the one measurement principle and the one key technology of uint areintroduced. The flexible hinge technology is introduced. The advantages of Straightcircular flexure hinge is analyzed. Mechanics analysis model of Straight circularflexure hinge is established and the formula of theoretical flexibility is deduced whichprovides reference for the design and optimize of flexible hinge. The output voltage indifferent ways of measuring circuit is deduced. The relationship among State strain, load and the structure size in the stress is established.Then, main components of the sensor mainly including self-detection unit of loadand head unit are designed and analyzed. Static analysis and modal analysis is carriedout for these components by finite element analysis software ANSYS10.0. And resultsof deformation and stress distribution as well as the first six order frequencies andmode shapes are obtained under different loading conditions. Through these resultsintensity and frequency response of these key parts are analyzed and the conclusion isthat self-detection unit of load and head unit have good strength and stability for lowfrequency work. Finally a sensor based on Piezoelectric stack as power source, flexiblehinge as precision transmission structure, strain gauge as the detection signal of strainis designed and its CATIA model is also established.Finally, the experimental researches contain magnification, displacement of theload, force of the load, stiffness, resolution, and test range in open loop. Experimentalresults indicate that magnification and stiffness of self-detection unit of load meet thedesign requirements, displacement of the load and force of the load in workingcondition have a good output characteristics, the resolution of indentation unit is20nm,the biggest displacement load is196.24μm, the biggest force load is69.39N, thestiffness of self-detection unit of load is44.28KN/m, the resolution is1mN. The curveshas a good reproducibility during loading and unloading with no load of the test uint.The thesis analyzes the experimental error of testing uint and puts forward somemeasures to reduce the error. The results show that the sensor presented in this papercan be able to reached a certain degree of accuracy but the error influence of its largerneed to be improved. |
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