Simulation Analysis And Experimental Research On The Error Factors Of Three Point Bending Mechanical Property Test

With the development of material test instrument to the direction of miniaturization, integration, in-situ, under the promotion of new materials and test technology, especially, the rapid development of some sensitive element, conversion element and other new equipment and computer science, material science, microelectronics and automatic control technology. New test technologies are constantly emerging and gradually shifting from the traditional mechanical properties of structural materials to test biomaterials, micro and nano materials, functional materials, thin film materials, composite materials and other new materials, changing from original single load to composite load, transiting from in-situ observation to out-of-position observation and transforming from general environmental conditions to extreme environment. Especially, under the high temperature creep, influence of the friction coefficient between specimen and support rollers on the test results is more obvious in three point bending test.Based on the points above, the main research of this paper is to study the influence of various error factors in the test process of the mechanical properties of the material in three point bending test, including the relative distance between the punch and specimen, friction coefficient between specimen and support rollers, and punch deviation angle. By the study of these factors, that specific impact on the three point bending test technology to provide some theoretical basis for the accuracy of the instrument development and test results can be understood.In this paper, the research status of measurement and test of mechanical properties of materials at home and abroad, three-point bending and finite element application in practical engineering was described in detail. At the same time, this paper introduces the basic principle, error factors source and the finite element theory of the three point bending mechanical property test, and analyzes specifically the error theory.The test platform was built, and the finite element analysis of the punch and support rollers was carried out to eliminate the influence of the deformation from the punch and support rollers on the test results, the elastic modulus was measured by the standard test machine of 6061 aluminum to modify the instrument frame flexibility coefficient, 4C2.041 10?? ? mm/N, In turn, verify the accuracy and reliability of the modified method frame flexibility coefficient by using 45 steel standard results from the standard test machine. Sensor calibration was carried out. Research on the effects of relative distance between the punch and specimen, friction coefficient between specimen and support rollers, and punch deviation angle was done through three different kinds of test respectively, to explore specific effects derived from these error factors.In this paper, the stress-strain relationships of 45 steel and Q235 steel were extracted by the tensile test established simulation model and parameter setting, the finite element simulation analysis was carried out on the relative distance between the punch and specimen, friction coefficient between specimen and support rollers, and punch deviation angle, extracted the load-deflection curve, maximum principal stress and its relative error of the maximum principal stress, get the change law, and determine the influence factor value of the safe allowable value of the error within the allowable error range of the project.