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典型高速列车车体材料的动态拉伸破坏行为研究
Alternative TitleThe analysis of typical high speed train body materials in dynamic tensile failure behavior
刘子尚
Thesis Advisor魏延鹏
2019-05-26
Degree Grantor中国科学院大学
Place of Conferral北京
Subtype硕士
Degree Discipline材料工程
Keyword本构模型,数字图像相关技术,动态失效应变,动态力学性能,高速列车
Abstract

在高速列车车体材料的选择工作中,要综合多种因素,做出最优的选择。采用高比强度的材料,可以在同等质量条件下获得更高强度的高铁车体结构。同时,在确定了材料的基础上,借助于DYNAANSYS/LS-DYNA 软件)等数值仿真软件进行辅助设计,可以在优化工作中起到事半功倍的效果。

本文以典型车体材料的动态拉伸破坏行为为研究内容,针对碳钢、A6N01S-T5铝合金、单向玻璃纤维增强复合材料及双向玻璃纤维增强复合材料分别进行了研究,利用一整套静/动态拉伸装置以及高速摄影与DIC(数字图像相关)技术相结合的技术,获得了材料拉伸过程中的全场应变随时间变化信息。其中的动态拉伸装置主要包含中应变率材料拉伸试验机、霍普金森杆。试验中采用力传感器获得了材料拉伸过程的应力信息。结合应力及应变的随时间变化的信号,获得了碳钢、A6N01S-T5铝合金不同应变率的静/动态应力-应变曲线以及单向玻璃纤维增强复合材料、双向玻璃纤维增强复合材料不同方向、不同应变率的静/动态应力-应变曲线。利用高速摄影装置及DIC分析技术,获得了材料的动态失效应变,更加精确的描述了四种典型车体材料的动态失效行为。针对A6N01S-T5铝合金夹层结构进行了侵彻试验,并将实验结果与数值仿真结果对比验证,用以保证试验获得的本构参数及动态失效参数的有效性。针对双向玻璃纤维增强复合材料也利用冲击三点弯实验同样进行了试验,用以验证试验获得的本构参数及动态失效参数的有效性。通过本文的研究工作,得到以下结果:

1、在金属材料动态力学研究工作中,提出了霍普金森杆和DIC技术相结合的方法。通过对金属材料开展一系列静/动态试验,并配合DIC技术进行应变场分析,得到了Johnson-Cook本构模型参数和动态失效应变参数。

2、在参数验证过程中,采用实际高速列车上A6N01S-T5铝合金材料构造的夹层结构进行侵彻试验,并利用DYNA软件进行同样工况的数值模拟实验。将实验结果与仿真结果进行了比较:通过对结构破坏形貌和子弹的速度时间曲线,验证了参数的准确性。

3、针对金属材料的一系列实验及分析得到了可用于数值模拟工作的本构模型参数,实验结果为高速列车碰撞仿真模型提供了数据基础,提高了结构设计和优化的效率。

4、在玻璃纤维增强复合材料动态力学研究工作中,利用中应变率材料拉伸试验机和DIC技术相结合的方法。通过对玻璃纤维增强复合材料开展一系列不同方向、不同应变率的静/动态试验,并配合DIC技术进行应变场分析,得到了材料的动态失效应变。

5、玻璃纤维增强复合材料的不同方向拉伸应力应变曲线上都有一个刚度变化点NN点之后材料的刚度降低。将工程失效应变和DIC技术分析得到的动态失效应变作对比,不同方向的工程破坏应变均小于动态破坏应变。

6、对双向增强玻璃纤维复合材料利用落锤试验机开展冲击三点弯实验,并利用拟合得到的本构模型参数和动态失效应变进行同样工况的数值模拟。通过两者结果的一致性验证了材料本构参数和动态失效应变参数的准确性。从而为高速列车车体中的玻璃纤维增强复合材料的仿真工作提供了数据基础。

Other Abstract

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:

1In 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.

2In 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.

3According 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.

4In 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.

5There 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.

6The 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.

Language中文
Document Type学位论文
Identifierhttp://dspace.imech.ac.cn/handle/311007/78634
Collection流固耦合系统力学重点实验室
Recommended Citation
GB/T 7714
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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