Design Analysis And Experimental Research Of The Nano-indentation Device Based On Tension And Bending Load

Material is a basic staff in human life and production. The phenomenon often happens, such as the damage of the material during the usage, because of the lack of research on material deformation damage and failure mechanism.That will cause great losses on economy, life and property. It is difficult to avoid the loading effect on material; there still are few reports about the research on the test theory and method although the material mechanical performance testing technology develops so fast in recent years. Currently, some countries, including United States and Switzerland,already have commercial indentation test equipment products, these indentation testing is the single indentation testing which are aimed at sample materials, but nano-indentation testing and method under compound load are rarely reported.Therefore, nano-indentation testing study aiming at materials under compound load has already attracted broad attention in the world. Nano-indentation testing can make in-situ visualization of the mechanical behavior by using micro-imaging system; it is widely used in the fields of material mechanics, biomechanics and biomedicine. So it is very important to study the basic theory and the key technology of the composite load indentation testing. In the meantime, it is still need further studies on the composite load coupling and decoupling, and test equipment error correction.The paper meet the needs of national development, combining the progress and the existing problems of indentation testing under compound load both in China and other countries, and gives the basic research about nanometer testin gunder compound load. And on this basis, for the equipment design and manufacture, detecting control, commissioning and calibration, ain-depth study is launched. The typical micromechanical propertiestesting and analysis of material are carried out by using self-developed instrument. The main contents of this paper are as follows:Tension, bending and indentation test basic theory has been researched.On this basis, the deflection curve equation of four-point bending test is derived with both ends fixed. For the case of a composite load loading, the pre tension bending composite loading and precurved tensioned composite loading theoretical model has been established. And the correction algorithm of formulas elastic modulus was proposed. Using finite element simulation analysis verified that the formula has a good scientificity and accuracy. Meanwhile, analyzed the effect of stress analysis of the test sample from whether arc transition under tension – bending composite loading. The results were concluded: in sample designation, when increasing arc transition, the surface of the sample is smoother, which can effectively reduce the grip ends.Designation and analysis of nano-indentation test equipment are carried out under complex loading under preload. We focused on the structure and function of the mechanical test equipment designation and modular control systems building theory and technical issues. Key components and the whole finite element static and dynamic analysis were analyzed by ANSYS to ensure that each unit structure in the course of its operating frequency have kept away the natural frequency to ensure test equipment reliability.Tests and experiments Properties of nano composite under indentation load test equipment were carried out. We tested equipment of each module unit displacement sensor and force sensor calibration test. The tensile curve of self-developed test instrument and commercialized tensile tester tensile curves were compared. Results showed: Determination of the curve has a good consistency, and verified the reliability of the test equipment. We used steel Q235, aluminum, copper standard samples for tensile, bending and creasing module repeated tests. The results showed that each module has a very good test accuracy and repeatability accuracy.The specimen rack holding portion and the deformed portion tension module correction algorithm is proposed; we carried out research and experimental calibration correction. Test results showed that the elastic modulus of the test error was 2.6%; Frame compliance and bending modulus of elasticity of the bending test instrument module was modified and we carried out experimental research. The determination of alumina ceramic, the elastic modulus test error 6061 aluminum and copper were 4.78% and 1.52%, it verified that the correction algorithm was correct. Then, Bose's indenter was used for aluminum indentation to test different maximum load. The conclusion is: elastic modulus relatively reduced with greater press-fit load, but there was little change in hardness. Finally, a four-point bending test was carried with different bending radius indenter at the same time, test results show that under the same force bending load, the indenter radius is larger, the slope of the load-deflection curve bending is greater which means the smaller of the deformation of the sample.We carried out research using homemade stretch-bending preload nanoindentation testing equipment for aluminum, Q235, bones and etc. First, the 6061 aluminum alloy indentation test analysis was carried out under varying pre-stretched load conditions, indentation test under varying pre-bent load conditions and stretched-bent complex loading conditions. Test showed that: With respect to the pre-6061 aluminum alloy tensile load, pre-bending load, pre-load composite increasing, the elastic modulus and hardness increase significantly. We used typical material Q235 material to carry out pure tension, pure bending and microstructure tests under compound load. Metallographic microscope was used to test Q235 specimen of change in the morphology under tensile, bending and their complex process and in situ observations. The micro mechanics relationship of composite material under load performance characteristics and microstructure was found. Finally, bone biomaterial was carried out for in situ indentation test and simulation analysis. The change chart of two dimensional morphology and indentation depth of the bone surface were observed, finite element simulation was used to analyze the impact of internal defects on bone samples for nanoindentation. When the preset defect radius ‘r' is larger, elastic modulus and hardness value are significantly reduced with the increase of indentation depth. It indicates that internal defects affected the specimen elastic modulus and hardness to a certain extent.