Design And Experimental Research On Torsion Mechanical Testing Instrument

The ultimate purpose of material research is to application,in order to ensure the use of materials and their products stable and reliable,Material performance testing technology is particularly important.With the development of materials science,material applications tend to diversify,the actual work is often subject to a variety of loads,physical fields and even corrosive environment and other complex factors,and the current test technology mainly aiming at single mechanical,physical or chemical properties of the material,can`t meet the study the damage mechanism of the material under the actual complex operating conditions.With the progress of science and technology,the mechanics of in situ measurement technology has come into being.This technology can dynamically monitor the micro-mechanical behavior and deformation damage mechanism of material performance via the organization representation methods.In addition,compared to other test methods,the torsion test technology is more convenient to study the plastic deformation behavior of materials,widely used in the field of evaluation of materials testing.In order to solve this problem,this paper designed an in-situ torsional testing device which can be compatible with equipment that can provide force,physical field and corrosive environment.The whole machine debugging and performance test have been carried out,and an error correction algorithm is proposed for the original test results.A number of different conditions torsion tests on the typical silicon manganese steel and aluminum alloy were conducted.Based on the analysis of the present situation of the development of mechanical properties of materials,the structural and functional compatibility requirements of the multi-load multi-field loading device and in situ imaging have been analyzed in this paper.And then from the drive,transmission,clamping,testing and other aspects of the torsion test instrument for a comprehensive design analysis,and carried out the design of components.And the finite element analysis software ANSYS Workbench was used to analyze the key components.The modal analysis of the drive and the fixed end of the torsion device was carried out to verify the rationality of the design.In this paper,the integration of the torsion test device and other loading equipment,such as physical force,physical field and corrosive environment,and the in situ observation equipment are introduced.The calibration of the force sensor and the circular grating was carried out.After the whole machine assembly,the repeatability of the torsion test results and the effect of the reverse stress reduction were tested by using typical steel and aluminum alloy specimen.An error analysis of the device and the correction algorithm for the cylindrical and rectangular specimen are proposed.By comparing the shear modulus and the standard value after the test of a number of typical materials,the error of the modified test results is less than 5%,which verifies the applicability of the algorithm to the device.Based on the torsion curve,the specimen section and the shape of the test,the characteristics of the torsion performance of the typical silicon manganese steel and aluminum alloy have been analyzed based on the test of the different loading conditions of the torsion load.The torsion test of 60Si2 Mn steel shows that under the condition of regular torsion,the fracture mode of 60Si2 Mn steel is cut off.The torsion performance of the 60Si2 Mn steel isn`t changed obviously after a certain cycle angle and cycle times torsion tests.In a certain temperature range,with the rise of temperature,shear modulus,yield and torsional strength of 60Si2 Mn steel are gradually reduced.The results of the torsion tests on 7050 and 7075 aluminum alloys show that both the shear modulus didn`t change significantly and the torsional strength was reduced when the pre-tension of the specimen was increased within a certain range.The yield strength of 7050 aluminum almost didn`t change and that of 7075 aluminum showed a clear downward trend.Finally,the Nikon and Olympus microscopes were used during in situ torsion test,and the variation of the morphology and microstructure of the material during the process of torsion was analyzed.