Experimental Study On Tensile-Bending Mechanical Properties Of Typical Structural Materials

Tensile test and bending test have been widely used in the test of material mechanical properties. The elastic modulus, yield strength, fracture limit and other basic mechanical parameters of materials can be tested, which provides important basic data for materials preparation and optimization of mechanical structure design. With the development of science and technology, in situ tensile test and in situ bending test technologies characterized by scanning electron microscope, metallographic microscope and other material properties came into being. Under the help of the in situ test technologies, researchers can conduct in-depth study on micro deformation and damage mechanisms of materials under tensile and bending loads.As majority of existing researches focused on the test analysis of material mechanical properties under single load and the research of material mechanical properties under multiple loads has been rarely reported, this paper, based on the review and analysis of research status in related fields at home and abroad, focuses on the analysis and study of mechanical properties for the material sample with the cross-sectional area of square millimeter under tensile, bending and combined loads by means of combining theoretical analysis, simulation study and experimental test. Meanwhile, in situ test of the micro mechanical properties of materials was conducted by virtue of the test device developed by the project team and combining with the optical microscope. This paper focuses on the following aspects:(1) Basic theoretical analysis of tensile and bending mechanical propertiesIn this paper, relevant theories of tensile and bending load tests were introduced. Determination methods of material mechanical parameters were described according to the tensile and bending test curves.(2) Simulation analysis under combined tensile-bending loadsRelevant simulation analysis of single tensile and bending test was conducted by means of ABAQUS simulation software; the tensile stress-strain curves and load-displacement curves under different bending loads of 7075 aluminum alloy were obtained. In addition, bending mechanical response under pre-tensile load was analyzed. The simulation results showed that with the increase of pre-tensile displacement, the bending strength decreased significantly, and rebound property of the specimens decreased slightly.(3) Tests under combined tensile-bending loadsStudy on test analysis of material mechanical properties were conducted based on the simulation results. The tensile and bending tests of 7075 aluminum alloy under different loading rates were conducted. The test results showed that the loading rate of tensile test has no obvious effect on the elastic modulus of the material, but can improve its yield strength and tensile strength. Increase in loading rate of bending test can enhance bending plastic deformation. Subsequently, mechanical response under combined tensile-bending loads was studied. It found that the larger the pre-tensile load is, the smaller the bending strength of the specimen will be. Increase in bending preload may raise the tensile yield strength and tensile strength. Finally, in situ tests of microstructure of the specimen under typical loading condition were conducted using the metallographic microscope.