Under varied loads such as cyclic and / or transient loading , soil structures or foundation will induce permanent and / or fluctuating plastic deformations . such plastic deformations are cumulative and / or alternating in nature with increase of time of loading during a sequence of cyclic loading . if the resulting accumulated deformations is limited within a given bound or the alternating deformations will be adapted to a given plastic state after a certain cycle numbers or a certain period of loading , the soils will be in shakedown state 在复杂变值荷载作用下，结构有可能出现两种状态：一种是在若干次载荷循环之后，塑性变形趋于稳定，在此后继的载荷循环中结构表现为纯弹性响应，这种状态称为安定状态( shakedown ) ；另一种则是塑性流动一直持续地发展或不断反复，直至结构破坏，结构的破坏有两种型式：一种是由塑性应变的累积引起的增量塑性破坏；一种是塑性变形多次反复引起的疲劳破坏，也称为交变塑性破坏。
It is briefly introduced the purpose and meaning of the paper , expatiate the reason of fatigue collapse in bridge , discuss the present condition of improvement of fatigue performance of concrete beam with gluing steel plate and gluing cfrp , pointing out merit and shortcoming of two kinds method , the application of cfrp in bridge reinforcement is discussed . and this paper point out the main investigations of cfrp in the aspects of bridge reinforcement in the future 深刻阐述了桥梁发生疲劳破坏的原因，细致探讨了粘贴钢板和粘贴碳纤维加固方法用于提高混凝土梁疲劳性能的研究现状及碳纤维材料在桥梁加固中的应用，深入地分析了两种加固方法的优缺点，明确的指出了今后碳纤维材料在桥梁加固方面的研究重点和广泛的应用前景。
With metal fatigue in material mechanics , this paper deduces the limestone fatigue curve of longmen grottoes by means of marble s one within the error permission . by the experiment elects the crucial factors of current vibration environment in longmen grottoes , the author contrasts the result of the experiment with its fatigue curve referred above and analyses the fatigue effect of longmen grottoes . finally , it is pointed out that after longmen grottoes have being suffered weathering and water - erosion more than 1500 years , the vibration environment is becoming an crucial factor leads to fatigue effect , especially in those weak surface carvings just like the crossings of several rifts , serious weathering places , etc 借鉴材料力学中金属疲劳破坏的研究手段，在误差允许范围内用大理岩疲劳曲线推导出门石窟石灰岩疲劳曲线。通过对石窟实际振动环境中典型要素的抽取和振动试验，将试验结果与疲劳曲线进行对比，分析了门石窟的疲劳破坏效应。文章指出，在经历了1500多年的风化和流水溶蚀后，振动环境已成为导致门石窟某些薄弱点如多条裂隙交叉点严重风化酥解的壁面雕刻品等产生疲劳破坏的重要诱发因素。
Through the research and analysis on the three aspects concerning the base interface of the pavement panel , crack accumulation , expansion in the pavement panel and interaction between spring plates on the road surface as well as its damage on the road fatigue , it is first brought forth that the process of fissures and breakage in the cement concrete pavement can be divided into three stages , i . e . stage of initial crack formation and damage in the bottom of the pavement slab , stage of accumulation , intensifying & expansion in ruptures from load during the time of use and stage of fissures & breakage in the pavement 通过对路面板底界面开裂、路面板中裂缝积聚、扩展和路面表面车板相互作用及其对路面疲劳破坏的影响等三个层面的研究和分析，首次提出水泥混凝土路面的开裂和破坏过程可以分为三个阶段，即路面板底初始损伤西南交通大学博士研究生学位论文第11页和早期裂缝的形成阶段、使用期间荷载作用对路面造成的开裂损伤累计、加剧和裂缝扩展阶段以及路面断裂破坏阶段。
Taking ti alloy tc11 electron beam welded work - piece as research object , which is the conventional material of aero engine compressor blisc , the fatigue damage evolution law of fatigue damage action in the area of welded joint based on damage mechanics theory is analysed , and fatigue damage model , which macro - parameter and micro - damage characteristics are related , with fractal geometry - a new conception of modern mathematics is set up in this paper . it tries to research the measuring method of fatigue fracture fractal dimension and the relationship of fractal damage variable with fatigue life . it also sets up the welded joint fatigue damage fractal evolution equation 本课题以航空发动机压气机叶盘常用材料钛合金( tc11 )电子束焊构件为研究对象，对焊接接头的疲劳破坏行为，基于损伤力学理论分析其疲劳损伤演化规律，应用现代数学的新概念? ?分形几何学理论，建立宏观参量与细观损伤特征相联系的疲劳损伤模型，研究疲劳断口分维数测量方法以及分形损伤变量与疲劳寿命之间的关系，建立焊接接头疲劳损伤分形演化方程。
