Design And Experimental Research Of An In Situ Shear Device For Characterizing Micro-mechanics Of Materials

With the development of science and technology, new materials, technologiesand new processes constantly emerging in the field of material science. Micro andnano materials, organic polymer composite materials, inorganic non-metalliccomposite materials are widely used in many different fields, especially in theaerospace field. Many parameters of the mechanical properties of the materialmechanical testing, the elastic modulus, yield strength, ultimate strength, elongationand shear modulus and other parameters of the test object is the most important testobject, there are many methods for testing the performance parameters of thesematerials, such as tension/compression, torsion, bending, nano-indentation andtympanic membrane method, in which in-situ tensile/compression cancomprehensively reflect the mechanical properties of materials,can be through thereal-time stress-strain curves more intuitive analysis of material mechanical propertiessuch as fracture limit, elastic modulus. As for the research and development of shearmechanical testing equipment, materials subject to pure shear and simple shear arelittle studied. During the use of material, the shear stress is almost can appear in anykind of machinery, Such as using the bolt connect two pieces of materials, the shafthole with key connection, etc, the bolt and the key play a critical role in efforts totransfer, so it is necessary to develop a device for the mechanical properties of theshear test. By experiment, the shear mechanics performance test on some newmaterials, to study the shear mechanics properties, choose the more suitable materialin the application of the shear stress, not only can make full use of the advantages ofmaterial, can save more cost and prevent the material in the application of damagecaused by some accident or unnecessary loss. The paper on the material mechanicalproperties of in-situ testing technology development present situation has carried onthe comprehensive analysis, on the basis of the design material shear mechanicalproperties of testing device.Papers on mechanical properties of testing technology at home and abroad werereviewed analysis, on the basis of this puts forward the overall design scheme ofmaterial shear mechanics performance test device. Analyses the working principle oftest equipment, the working module mainly includes the precision of the drive unit, the transmission unit, the signal detection unit, the execution unit, execution unit andthe observation of the experimental process, analyses the working principle of eachexecution unit, whole machine for the finite element simulation analysis and structureoptimization. This test device is using the Art data acquisition card, model forUSB2817, analog acquisition use the single-ended analog input connection way,through this connection to the amplified signal displacement sensor and force sensorprocessing after collection, use the software which support the Art USB2817dataacquisition card to achieve real-time display of the signal acquisition, the deformationof the specimen and load values are obtained during the test. Send code by a computervia a serial port for motor drive, through the definition of code can achieve motoracceleration and deceleration and uniform operation, get the needed test variousloading modes.Through the application and analysis of microscopic imaging technology, for themechanical properties of the material in situ testing, can make use of scanningelectron microscope (SEM), transmission electron microscopy (TEM), scanningprobe microscopy (SPM), etc. using certain observation equipment can be real-timeobserved material failure mechanism, compared with conventional observationmethod, in situ test can further determine the performance of the material and strength.The test device by using microscopic imaging instrument microscope, the specimenscontinuous to be observation, recording and analysis in real-time by the process oftesting, by this way it can be more intuitive analysis of the failure mechanism of thematerial. Therefore, the mechanical properties of the shear testing device can beachieved under the load of the material in real time observation of the microstructureand mechanical properties of a shear test, combine the change of the material in theprocess of testing and the mechanical properties of the shear curve, analysis theresults, and it can help for the further study of the microscopic mechanism of material.This set of equipment selected specimens of different materials for multiple sheartest, compared with the experimental results and the parameters of the material itself,appraisal reliability and usability of this test device. The experimental results showthat the test device can undertake material shear mechanics performance test, andstable performance, also can make use of microscopic imaging instrument microscopeto study the microstructure of the shearing process changes, can provide a referencefor the analysis of shear mechanical properties of materials.