|Alternative Title||The analysis of typical high speed train body materials in dynamic tensile failure behavior|
|Place of Conferral||北京|
In the selection of high-speed train body materials, it is necessary to synthesize various factors and make the best choice. High specific strength materials can be used to obtain higher strength of high-speed rail body structure under the same quality conditions. At the same time, on the basis of defining the material, the assistant design is carried out with the aid of numerical simulation software such as DYNA (ANSYS/LS-DYNA software). Better design results can be obtained on the basis of lower workload.
In this paper, the dynamic tensile failure behavior of typical high-speed train body materials is studied. Carbon steel, A6N01S-T5 aluminium alloy, unidirectional reinforced glass fiber composites and two directions reinforced glass fiber composites are studied respectively. By using a set of static/dynamic tensile devices and high-speed photography combined with DIC (digital image correlation) technology, the full-field strain of materials during tensile process is obtained. The dynamic stretching device mainly consists of an intermediate strain rate material testing machine and a SHTB (split Hopkinson tensile bar). In the experiment, the stress information of material during tension was obtained by force sensor. Combined with the signal of stress and strain changing with time, the static/dynamic stress-strain curves of carbon steel and A6N01S-T5 aluminum alloy at different strain rates, as well as the static/dynamic stress-strain curves of unidirectional reinforced glass fiber composites and two directions reinforced glass fiber composites at different directions and strain rates were obtained. The dynamic failure strain of four typical high-speed train body materials is obtained by using high-speed camera and DIC analysis technology, and the dynamic failure behavior of four typical high-speed train body materials is described more accurately. The penetration test of A6N01S-T5 aluminum alloy sandwich structure was carried out, and the experimental results were compared with the numerical simulation results to ensure the validity of the constitutive parameters and dynamic failure parameters obtained from the test. The two directions reinforced glass fiber composites were also tested by impact three-point bending test to verify the validity of the constitutive parameters and dynamic failure parameters. Through the research work of this paper, the following results are obtained:
1、In the research of dynamic mechanics of metal materials, a method combining Hopkinson bar and DIC technology is proposed. The Johnson-Cook constitutive model parameters and dynamic failure strain parameters were obtained through a series of static/dynamic tests of metal materials and strain field analysis with DIC technology.
2、In the process of parameter validation, the penetration test of the sandwich structure made of A6N01S-T5 aluminium alloy material on the actual high-speed train was carried out, and the numerical simulation experiment of the same working condition was carried out by using DYNA software. The experimental results are compared with the simulation results. The accuracy of the parameters is verified by the damage morphology of the structure and the velocity-time curve of the bullet.
3、According to a series of experiments and analysis of metal materials, the constitutive model parameters which can be used in numerical simulation are obtained. The experimental results provide data basis for the simulation model of high-speed train collision, which improve the efficiency of structural design and optimization.
4、In the research of dynamic mechanics of glass fiber reinforced composites, the method of combining intermediate strain rate material testing machine with DIC technology is proposed. A series of static/dynamic tests of glass fiber reinforced composites with different directions and strain rates were carried out. At the same time, the dynamic failure strain of the composites was obtained by using DIC technology.
5、There is a stiffness change point N on the tensile stress-strain curves of glass fiber reinforced composites in different directions. After N point, the stiffness of the composites decreases. Comparing the engineering failure strain with the dynamic failure strain obtained by DIC technology, the engineering failure strain in different directions is smaller than the dynamic failure strain.
6、The impact three-point bending test of two directions reinforced glass fiber composites was carried out by drop hammer tester, and the constitutive model parameters and dynamic failure strain were fitted to simulate the same working conditions. The accuracy of material constitutive parameters and dynamic failure strain parameters is verified by the consistency of the two results. This provides a data base for the simulation of glass fiber reinforced composites in the high-speed train body.
|刘子尚. 典型高速列车车体材料的动态拉伸破坏行为研究[D]. 北京. 中国科学院大学,2019.|
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|典型高速列车车体材料的动态拉伸破坏行为研（10021KB）||学位论文||开放获取||CC BY-NC-SA||Application Full Text|
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