考虑摩擦的材料界面裂纹疲劳特性分析

发布时间：2018-05-28 15:32

本文选题：界面裂纹 + 摩擦　；参考：《兰州理工大学》2017年硕士论文

【摘要】：本研究课题来源于甘肃省自然科学基金及教育部创新团队项目。因复合材料构件在工作过程中界面处会因外载荷的作用而产生相对滑动,出现摩擦接触。为提高复合材料构件的使用强度和延长工作寿命,对摩擦接触下的材料界面裂纹疲劳特性的研究是十分必要的。本文基于弹性理论,以材料界面断裂理论和摩擦理论为依据,以材料界面构件为具体的研究对象,采用有限元数值模拟计算方法,研究裂纹面摩擦对材料界面裂纹疲劳特性的影响。在材料界面裂纹建模的过程中,主要采用ANSYS有限元分析软件建立复合材料模型及界面裂纹模型,并在界面裂纹面设置摩擦接触。已有大量的实验证明,裂纹面摩擦系数f=0.2~0.6,本文取f=0.2、0.25、0.3、0.35、0.4。应用ANSYS软件APDL程序化语言进行编程对裂尖进行奇异化处理,计算裂纹尖端断裂控制参量,研究了不同裂纹面摩擦系数f及不同界面裂纹尺寸参数(a/w)下,裂纹尖端位移、等效应力和应力强度因子的变化趋势。还应用ABAQUS软件分析研究了材料界面裂纹在不同裂纹面摩擦系数f下,裂纹具体的扩展路径,并计算了f=0、0.2、0.4、0.6时的裂纹扩展长度。然后在单裂纹研究成果的基础上,以轮轨界面多裂纹为研究对象,预制界面裂纹与平面夹角呈45o,设置轮轨界面摩擦接触及钢轨裂纹面摩擦接触,拓展研究了材料界面多裂纹在考虑摩擦接触条件下裂纹间的相互影响情况,得到多裂纹对裂纹扩展的影响结果以及裂纹之间相互影响的结果。本文得到的主要成果有:(1)相同裂纹尺寸参数下,随着裂纹面摩擦系数的增大,裂纹尖端位移、等效应力和应力强度因子会减小;(2)裂纹面摩擦系数不变,裂纹尺寸参数变化时,裂纹尖端位移、等效应力和应力强度因子呈现波动的变化。(3)裂纹面摩擦对裂纹扩展行为具有阻碍作用,裂纹尖端应力分布会随着裂纹面摩擦系数的增加呈递减趋势;(4)裂纹面摩擦也可以被人为地利用来提高结构的承载能力,延长机械零部件的使用寿命,具有很大的工程实用价值。(5)考虑摩擦接触,多裂纹更具有阻碍轮轨界面疲劳裂纹扩展的作用;(6)轮轨界面裂纹尖端应力强度因子KI与KII的值随着裂纹数量的增加呈递减趋势;车轮接触斑接近裂纹时,应力强度因子K将取得最大值。
[Abstract]:This research project comes from Gansu Natural Science Foundation and Ministry of Education Innovation team Project. Because of the relative sliding and frictional contact at the interface of the composite member during the working process due to the effect of external load. In order to improve the service strength and prolong the working life of composite members, it is necessary to study the fatigue characteristics of interface crack in the friction contact. Based on the elastic theory, the material interface fracture theory and friction theory, and the material interface member as the specific research object, the finite element numerical simulation method is adopted. The effect of crack surface friction on the fatigue behavior of interfacial crack is studied. In the process of modeling the interface crack, the composite material model and the interface crack model are established by using the ANSYS finite element analysis software, and the friction contact is set up on the interface crack surface. A large number of experiments have proved that the friction coefficient of the crack surface is 0.2U 0.6. In this paper, the friction coefficient of the crack surface is 0.250.30.30.35N 0.4. Using the ANSYS software APDL programming language to program the crack tip singularity, calculate the crack tip fracture control parameter, study the crack tip displacement under the different crack surface friction coefficient f and the different interface crack size parameter (a / w). The change trend of equivalent stress and stress intensity factor. The crack propagation paths of interfacial cracks at different friction coefficients f are also analyzed by ABAQUS software, and the crack propagation length is calculated when the crack is 0.20.20.40.6.The results are as follows: 1. Then on the basis of the research results of single crack, taking multiple cracks in the wheel / rail interface as the research object, the angle between the precast interface crack and the plane is 45o. the wheel / rail interface friction contact and the rail crack surface friction contact are set up. In this paper, the influence of multi-cracks on crack propagation and the interaction between cracks at the interface of the material under the condition of frictional contact are studied. The main results obtained in this paper are as follows: under the same crack size parameters, the crack tip displacement, equivalent stress and stress intensity factor decrease with the increase of the friction coefficient of the crack surface. The crack tip displacement, equivalent stress and stress intensity factor fluctuate. The value of stress intensity factor (Ki) and KII at the crack tip of wheel / rail interface decreases with the increase of the number of cracks. The maximum stress intensity factor K will be obtained when the contact spot of the wheel is close to the crack.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB302.3

【参考文献】