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纤维增强聚合物基复合材料的疲劳损伤模型

程光旭 , 李志军 , 戚东涛

材料研究学报

从微观离散分子力学出发,考虑力学化学的交互作用和材料微观组织的影响,建立了纤维增强聚合物基复合材料的力学化学分子链疲劳损伤模型。在模型中引入表示基体树脂和界面分子链断裂数占材料分子链总数的比例和以描述基体断裂主导和界面断裂主导的损伤,给出剩余强度与疲劳过程中微观断裂机理、结构参数、物理化学参数和力学性能变化之间的关系。与短玻璃纤维增强树脂基复合材料(SMC)的恒载荷疲劳实验结果比较,表明本模型预测的疲劳剩余强度与实验值吻合得比较好。

关键词: 复合材料 , fatigue damage , mechano-chemical effect , molecular chain model

纯铝双晶体交变形变损伤断裂过程中晶界的作用机制

王明章 , 林实 , 肖纪美

金属学报

从同一块纯铝双晶体截取试样,分别垂直或平行于其晶界面进行对称拉压疲劳实验.结果发现,在这两种加载方式下,晶界在晶体交变形变损伤断裂过程中的作用及机制有明显区别,横向晶界在变形过程中形成明显的不均匀形变带及多层次的影响区,比较容易萌生裂纹,而纵向晶界变形极小,只发现沿主滑移带的变形及微裂纹形核.相比之下,晶界结构(如∑值)对其自身损伤及裂纹萌生的作用则较弱.同时,对比试样实验结果还显示,相邻晶粒取向软硬相差较大的晶界,以及相对于应力轴的倾斜晶界,均能明显促进晶界疲劳裂纹的生长.

关键词: 晶界 , fatigue damage , crack initiation , bicrystal.

THE CHARACTERISTICS OF SHORT CRACKS AND EQUIVALENT PARAMETER OF FATIGUE DAMAGE

Z.X. Wu Engineering College , Yangzhou University , Yangzhou 225009 , China

金属学报(英文版)

In order to understand which parameters, such as the number of cracks and the total crack length is the useful indicators of fatigue damage, rotatory bending fatigue tests are carried out using smooth specimens of a medium-carbon steel. The behavior of short crock propagation and the evolution of surface cracks during fatigue are examined. The aim of this paper is to study how these damage parameters are correlated with the process of fatigue in order to evaluate the effectiveness of damage detection methods.

关键词: fatigue damage , null , null , null

SHORT FATIGUE CRACK PARAMETER BASED ON THE TOTAL CRACK AREA

Z.X.Wu , X.C.Wu

金属学报(英文版)

The progressive fatigue damage of a material is closely related to the whole populationof cracks on the surface of an un-notched specimen.In order to understand whichparameter is a more useful indicator of fatigue damage,rotatory bending fatigue testswere carried out using smooth specimens of medium-carbon steel.The behavior ofshort crack propagation during fatigue was examined and a new parameter "totalcrack area" was suggested.The aim of this paper is to extend the research on fatiguedamage in the already studied steel and to study how these damage parameters arecorrelated with the process of fatigue damage in order to evaluate the effectiveness ofdamage detection methods.

关键词: fatigue damage , null , null , null

微米尺寸不锈钢的形变与疲劳行为的尺寸效应

张广平 , 高岛和希 , 肥後矢吉

金属学报

采用聚焦离子束溅射蚀刻加工了微米尺寸304不锈钢悬臂梁试样。利用静态及动态弯曲加载研究了微米尺寸材料的形变与疲劳开裂行为。结果表明:随薄膜厚度的减小,材料的屈服强度升高,塑性下降。屈服强度随悬壁梁厚度的变化关系与Hall-Petch晶粒强化关系相似。微小悬壁梁屈服强度的升高来源于小尺度材料在非均匀变形下引起的应变梯度贡献的增加;而塑性下降则归因于较薄薄膜的晶粒内较少的可动位错。疲劳裂纹从尖缺口处萌生的门槛值接近块体材料。

关键词: 微米尺度 , deformation , fatigue damage

HEAT ENERGY DISSIPATION IN FATIGUE DAMAGE PROCESS

TUNG Xiaoyan Northwestern Polytechnical University , Xi'an , ChinaWANG Dejun XU Hao Northeast University of Technology , Shenyang , China

金属学报(英文版)

Using the dissipated energy as an essential parameter,the energy dissipative structure in pro- cess of fatigue damage of materials has been established.Through thermodynamic analysis for irreversible energy dissipation in fatigue damage process,the heat dissipative variations in cyclic loading process as well as in a cycle have been systematically studied on the basis of low cycle fatigue tests and infrared measurement of self-heating thermography.Meanwhile,the cyclic hysteresis energy and efficient energy dissipation (stored energy) have been proposed during fatigue damage process.

关键词: fatigue damage , null , null

Energetical Theories on Fatigue Life Prediction

TONG Xiaoyan ** Aircraft Engineering Department , Northwestern Polytechnical University , Xi'an , 710072 , China

材料科学技术(英文)

Current developments on fatigue life prediction methods have been systematically reviewed.In con- sideration of the irreversibility of energy dissipation during fatigue damage process,the main contents for fatigue damage estimation and localized equivalence as well as simulation models have been established.A frame of energy-based fatigue life prediction method has been proposed,meanwhile, the procedure in application to a practical structure component has been described.

关键词: energy dissipation , null , null , null

疲劳损伤过程的热能耗散分析

童小燕 , 王德俊 , 徐灏

金属学报

利用能量作疲劳损伤基本参量,建立了疲劳损伤的能耗结构,在试验的基础上,围绕着疲劳损伤过程中的不可逆能耗分析,系统地研究了循环过程及循环内的疲劳损伤热能耗散变化规律,并寻找出疲劳过程中循环滞回能与有效能耗(储能)之间联系。

关键词: 疲劳损伤 , energy dissipation , cycle loading process , null

持续滑移带的物理损伤效应对Al单晶体裂纹启裂的影响

翟同广 , 林实 , 潘祜 , 肖纪美

金属学报

本文研究了在纯Al单晶样品的两个特殊面(包含动作Burgers矢量的S面和与Burgers矢量成最小夹角的T面)上由循环形变引起的裂纹启裂过程,疲劳试验结果表明,在循环形变过程中,S面上没有形成表面持续滑移带,但有很多微裂纹产生,裂纹较短,平均长度约为10μm,近似沿一个方向分布,与动作Burgers矢量垂直,而T面上裂纹的形貌大致与以前的工作相同。通过扫描超声显微镜观察,发现在S面上的疲劳损伤要比T面上的深得多,为此,作者提出了裂纹启裂的孔洞模型及持续滑移带形成模型。

关键词: 疲劳损伤 , single crystal , crack initiation , persistent slip band , acoustic microscope

低周疲劳损伤过程的自热温升变化特征

童小燕 , 王德俊 , 徐灏

金属学报

通过对低周疲劳过程中试样的自热温升红外测试,讨论了不同控制应变下,试样的温升变化规律及其表面的温度分布与循环数、控制应变水平及加载频率的关系。探讨了循环疲劳损伤与温升变化的对应关系及其能量变化规律。

关键词: 疲劳损伤 , cyclic hysteresis energy , infrared thermometry , self-heating temperature increment

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