Experimental Research On Tensile-bending Mechanical Properties Of Oxygen-free Copper

With the continuous development of materials science,the engineering community is increasingly demanding the testing and guarantee of mechanical properties of materials.Domestic and foreign scholars began to pay attention to the development and application of material performance testing machines,and the functions of various mechanical performance testing devices have become more and more perfect.In order to avoid accidents and improve product quality,it is particularly important to study materials through mechanical properties tests.In most service conditions,the load on the material is very complicated.The two types of tensile and bending loads are the most typical two types of loaded materials in the material service environment,so they are also widely used in the mechanical properties test of materials.Oxygen-free copper materials have stable processing properties and are often used in automotive parts,wires and cables.Therefore,research on the mechanical properties of oxygen-free copper materials is of great significance in the field of mechanical manufacturing and mechanical design.Based on the analysis of the mechanical properties of tensile,bending and tensile-bending composites,the paper analyzes the tensile,bending and tensile-bending composite loading test theory,and analyzes the ANSYS Workbench software for stretching-bending.The simulation of the composite loading is outlined.Based on the research progress at home and abroad and the theory of stretching and bending,the experimental part of this paper is carried out.The multi-load multi-physics coupled in-situ mechanical property testing instrument made by the research group is used to study the tensile test under different loading conditions.The research on bending test under different loading conditions is carried out in two aspects.The related mechanical properties of oxygen-free copper materials are studied through a large number of repetitive tests.In this paper,the tensile test of TU2 oxygen-free copper material under different conditions and different preloading conditions is carried out.In the simple tensile test,the samples are reproducible for different rolling directions and different loading speeds.test.A sample having a rolling direction of 0° in the direction of stretching was found,and the measured modulus of elasticity was slightly larger than 90°,and the peak stress of the 0° sample appeared earlier,while the sample of the 0° direction was The elongation is generally less than 90° sample;for samples with different loading speeds,it can be seen that within the speed range given in this paper,the tensile strength increases with the increase of the loading speed,but the elastic modulus is not Obvious regular changes.For the tensile test under preload,when the pre-expansion tensile load is applied to the sample,the sample is reloaded after being unloaded,and a significant bulge appears on the reloading curve,and the upper yield point is improved.As the number of pre-cycles increases,the unloading string modulus of the material during the unloading and unloading shows a downward trend;the pre-bending deflection is applied to the specimen,and the tensile strength is decreased relative to the pure tensile specimen,and The elongation of pre-bending increases,the elongation of the material shows a decreasing trend,but the influence of the pre-bending deflection on the tensile strength of the sample is not obvious.Combined with the scanning electron microscope,the tensile fracture under pre-bending deflection is observed and analyzed.In this paper,the fixed-point three-point bending test at both ends and the fixed three-point bending test at both ends under preload are carried out for the oxygen-free copper samples.For the three-point bending test of different rolling directions,it can be seen that the relative load of the 90° sample is increased with respect to the rolling direction of 0°,and the 90° sample corresponds to the 90° sample.The curve is relatively fluctuating slightly;for the bending test at different loading speeds,it can be seen that the load carrying capacity of the sample shows a slight increase with the increase of the velocity within the given rate range,but the difference is not large.For the bending test of different preloads,the pre-cycle bending load is applied to the specimen,and after each unloading and reloading,the load value is improved to some extent,and the yield strength is also improved;for the test of applying the pre-tension displacement The pre-tension displacement is applied in the elastic range.As the displacement increases,the bending resistance of the oxygen-free copper material can be improved.After the pre-tension displacement reaches a certain level,the bending resistance performance will decrease,but The pre-tension displacement applied by the material has no significant effect on the elastic modulus of the sample.