查询词典 fatigue

Base on the problem of large quantity fatigue loads on corroded R.C. structure and small quantity study of its mechanical property, bending resistance fatigue test of corroded R.C. beams is discussed in this paper. The influence of stress ratio and re-bar weight loss ratio on bending resistance fatigue performance of corroded R.C. beams are researched, and the relation between strains of corroded re-bars and fatigue life of beams are obtained. The main research contents and conclusions are as following: 1. Under the fatigue loads, the overstrain of concrete approximately coincidences three stages strain development and accumulation rule, and the mechanical property of concrete is deteriorated. The fatigue damage of concrete is accumulated. The overstrain of re-bars increases and the increase rate decreases.

鉴于实际工程中大量存在腐蚀钢筋混凝土结构承受反复荷载作用，但其力学性能研究不多的问题，本论文进行了锈蚀钢筋混凝土梁抗弯疲劳试验，研究了应力比和钢筋锈蚀率对锈蚀钢筋混凝土梁抗弯疲劳性能的影响，得出了锈蚀钢筋的应变与构件疲劳寿命之间的关系曲线，主要研究内容及结论如下：(1)在循环荷载下，混凝土残余变形基本符合三阶段变形规律，力学性能劣化，疲劳损伤积累。

In addition, some experience formulas for them are regressed. The third chapter establishes a unified S-N curve equation to calculate multi-axial fatigue ultimate strength of concrete considering both the effect of confinement and minimum/maximum stress ratio, based on the triaxial fatigue test data in this paper and the test results under uniaxial and biaxial fatigue loading in previous literatures. Moreover, the consistency of calculating condition fatigue ultimate strength with fatigue life distribution and initial ultimate strength distribution is analyzed.

第二章简要地介绍了本文三轴疲劳试验装置，进行了两向等侧压约束下混凝土立方体试件三轴受压等幅和变幅疲劳试验，分析了三轴受压疲劳破坏机理，给出了相应的疲劳破坏试验判断标准；得到了混凝土在两向侧压约束下单级和多级受压疲劳的变形发展规律，包括最大纵向应变、残余应变、最大纵向应变率和疲劳变形模量等随循环次数的发展规律以及疲劳损伤的演变规律，并给出了相应的经验公式。

The fatigue is analyzed for the SENT specimen of TA6V titanium alloy at different stress ratio and on different stress level by the general finite element analysis software ANSYS. The dangerous fatigue location is predicted by the nodal stress Y-direction of the hemicycle notch for TA6V titanium alloy SENT specimen. Based on the local stress-strain method and the material S-N graph, the nominal stress-strain of the specimen is converted to the local stress-strain of the dangerous location by the elastic and plastic finite element analysis, thus the fatigue life is estimated by Miner fatigue damage accumulation theory and compared with the fatigue test of small crack growth.

借助大型通用有限元分析软件ANSYS对TA6V钛合金SENT试样在不同应力比和不同应力水平下进行疲劳分析，根据SENT试样缺口处的应力状态分布预测疲劳危险部位，采用局部应力应变法，结合材料循环的S-N曲线，通过弹塑性有限元法将构件上的名义应力谱转换成危险部位的局部应力应变谱，从而根据危险部位的局部应力应变历程采用Miner累积损伤理论对构件的疲劳寿命进行估算，并与疲劳小裂纹试验数据进行比较分析。

Results of analysis show that Generalized Paris Law can consider the complex crack propagation in the material of the pavement structure. The fatigue life of the pavement increases with increasing thickness of surface layer in a power function. Use of a thicker surface layer may extend the service life of the asphalt pavement. The fatigue life increases with decreasing modulus of surface layer in a power function with a negative exponent. However, since reduced modulus would scarify the structural strength and might cause rutting-related distress, caution should be taken when using low modulus materials for improving fatigue performance of asphalt pavements. The fatigue life increases with increasing modulus of base material in a power function. However, the fatigue life can not infinitely increases with increasing modulus of the base.

计算与分析表明：广义Paris公式可以考虑沥青路面结构内材料复杂的裂缝扩展：沥青面层的疲劳寿命随着面层厚度的增加以幂函数的形式增加，适当增加沥青面层厚度可以提高路面的使用寿命；沥青面层的疲劳寿命随着面层材料模量的降低以负指数的幂函数形式增加；由于材料模量的降低将牺牲路面的整体强度并可能引起路面车辙类损坏，以此提高疲劳寿命的方法应慎重对待；沥青面层的疲劳寿命随着基层材料模量的增加呈幂函数的形式增加，但由疲劳方程可以看出，寿命并不是随基层材料模量的增加而无限的增加，疲劳曲线在经过一个上升段后，逐渐趋于一个常数值，这说明，这时基层模量对寿命已不作关键性贡献；随着底基层厚度的增加，面层的疲劳寿命近似地呈线性函数增加，但效果并不很明显。

The results showed the maximum cyclic stress of CFRP bar should be under 70 percent of ultimate tensile stress; when the maximum cyclic stress decrease 5 percent of ultimate tensile stress, the fatigue life of CFRP bars increase generally 10 times; with the decrease of cyclic ratios, the fatigue life of CFRP bars decrease heavily; for the brittleness, CFRP bar should possess a higher reserve of strength, the margin of safety against failure is a necessity; according to experimental cyclic stress-fatigue life curve, the fatigue behavior of CFRP bar is much better than the fatigue behavior of Q235 steel.

将纤维复合材料用于土木工程结构的研究成果，已应用于实际工程【2j_国外对CFRP筋的一些短期性能以及CFRP筋构件的粘结性能、CFRP加筋混凝土结构的抗弯性能等都做了大量的研究，但对其长国家自然科学基金50278029，50538020和交通部西部交通科技200l431882021资助项目。2OO6年2月13日收到初稿；2006年9月4日收到修改稿。本文联系人：欧进萍，院士期性能如疲劳性能的研究还不够

Indoor flexural fatigue tests are carried out, the results are analyzed and two types of double logarithm fatigue equation under different stress level andequivalent stress level are got. Using the fatigue equation, the fatigue performance of porous concrete and common semi-rigid base materials and cement concrete are compared, the fatigue stress coefficient which is used in the load stress calculation for porous concrete as undersurface of cement concrete pavement and the tensile strength structure coefficient which is used in the flexural stress check for porous concrete as base of asphalt pavement are obtained.

进行室内小梁弯拉疲劳试验，对疲劳试验数据进行分析，得出多孔混凝土不同失效概率下两种形式的双对数疲劳方程，利用疲劳方程，将其疲劳性能与常用半刚性基层材料和水泥混凝土进行比较，还得出了多孔混凝土作为水泥混凝土路面下面层荷载应力计算的疲劳应力系数，和作为沥青路面基层层底弯拉应力验算的抗拉强度结构系数。

Wagon body is a complicated weld structure. While physical wagon can not used to do fatigue test, how to make anti-fatigue design has been discussed in this paper. One coal hopper wagon has been taken as an example to study about anti-fatigue design of the wagon. First of all, based on finite element technique and the theory about how to predict fatigue life of weld structure, the technology route and key technique are given as well, which is based on AAR standard about weld structure wagon fatigue life predicted.

论文认为货车车体是复杂的焊接结构，为了使货车车体焊接结构抗疲劳设计在产品的图纸上就能卓有成效地展开，论文以新型煤炭漏斗车为研究对象，对煤炭漏斗车车体抗疲劳设计开展了一系列研究：首先，基于有限元算法和焊接结构寿命预测的疲劳理论，给出了基于北美铁路协会AAR标准的货车车体焊接结构寿命预测的技术路线及关键技术。

It is clarified for the first time that the thermal fatigue failure of solder joint is actually a creep strain low cycle fatigue failure, and a physical model for creep fatigue crack propagation has been proposed. It was pointed out that creep strain increases in the high stress area ahead of the tip of thermal fatigue crack, results on one hand that the slide of crack tip increase, inactivation more serious and crack close length increases, the other hand, that intergranular crack exists, whose direction will affect the fatigue crack propagating.

本文首次阐明了焊点的热循环失效本质上是以焊点内循环蠕变为主要应变的低周疲劳失效，并在此基础上提出了蠕变疲劳裂纹扩展的物理模型，指出热循环裂纹前端的高应力区内，蠕变加剧，使裂纹前端滑移增加，裂纹钝化加剧，导致随后的裂纹闭合扩展长度增加；同时蠕变也使裂纹前端的高应力区出现晶间裂纹，蠕变沿晶裂纹对主裂纹扩展的影响取决于沿晶裂纹的连接方向。

It is widely concerned in fatigue of concrete structures. In this paper, concrete triaxial compression fatigue experiments and tension-compression fatigue experiments with constant confinements in two lateral directions have been carried out using a self-modified loading apparatus. Based on the analysis of the test data, the quantitative principles of concrete fatigue deformation and the calculation method of fatigue strength are determined.

混凝土结构的疲劳是一个广为关注的问题，本文针对这一问题结合国家自然科学基金项目——混凝土多轴变幅疲劳破坏准则(50078010)的研究，利用自制的试验加载装置完成了两向定侧压约束下混凝土三轴受压、三轴拉-压等幅和变幅疲劳试验，对试验结果进行了分析。

It was found that the low cycle fatigue character has close internal relations with the high cycle fatigue character. In the research of high cycle fatigue of concrete, the test means of cyclic loading between the set constant of force or stress has been extensively used. But this kind of test means can't be used in studying the behavior of concrete low cycle fatigue under large strain.

在研究中发现低周疲劳特征与高周疲劳特征有着密切的内在联系，但高周疲劳问题研究中使用的是在设定的力或应力的上下界限之间重复受力的试验方法，这种方法已无法用于混凝土高应变低周疲劳性能的试验研究。

More direct, directer ; most direct, directest

径直的，笔直的

Do you know how to use a chain saw?

你知道如何使用链锯吗？