查询词典 fatigue strength

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。

Test results show 1 the fatigue strength of peened joints under overloading, in spite of lower than the fatigue strength of the non-overloading peened joints, is still greatly higher than the fatigue strength of as-welded joints; 2 In the range of lower stress level and longer life, ultrasonic peening method exhibit better results than TIG dressing; 3 Fatigue strength of the welded joints with defects (such as undercut at the weld toe) can also be improved greatly after peening treatment.

结果表明，超声冲击处理过的焊接接头经过载后疲劳性能有所下降，但与原始焊态相比提高疲劳强度、延长疲劳寿命的效果仍然十分显著；在低中应力水平、中长寿命区域，使用超声冲击法提高焊接接头疲劳强度比TIG熔修法效果更好；超声冲击处理后，含咬边等缺陷的焊接接头，疲劳强度同样有较大的提高。

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。

The relationship between the ratio of Ca to Si with shrinkage value was needed to be studied further.The strength of M-AAS was comparatively high, but the flexural strength was regressed in the long term. The compressive and flexural strengthes of 3 days were able to surpass 8MPa and 78MPa, respectively, and compressive strength of 90 days were all around 100MPa, but compared to flexural strength of 28 days, the flexural strength of 90 days was regressed by 19.0%. The high strength property of M-AAS associated with its hydration products and Interfacial Transition Zoo. The main hydration products of M-AAS were microcline and CSH, no calcium hydroxide was found. The coexistence of microcline and CSH worked as micro-aggregate by each other, and no weak ITZ, both resulted in its high strength. The regression of its strength was related to its high shrinkage property, because the crazing caused by shrinkage would decrease the strength, especially the flexural strength.

M-AAS强度较高，但长期抗折强度倒缩。3天抗折和抗压强度分别可超过8MPa和78MPa，90天抗压强度在100MPa左右，但90天抗折强度比28天抗折强度相比低19.0％。M-AAS的高强特性与其水化产物和界面过渡区有关，M-AAS的水化产物主要为微斜长石和CSH凝胶，没有氢氧化钙，微斜长石与CSH凝胶相互填充和配合共同起到强度的作用，M-AAS砂浆中几乎没有发现界面过渡薄弱区。M-AAS的强度倒缩现象与其收缩值较大有关，收缩会引起M-AAS硬化体内部出现微裂缝，使强度下降。

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。

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。

Uses the biggest strength training method (80%～100% biggest strength) adding 30% biggest strength load training method; the load combination method to make the acclivity to lie pushes the barbell training, good in uses; the biggest strength training method to the upper limb shot fast strength training effect (80%～100% biggest strength) adding the unarmed quickest speed training method and the biggest strength training method (80%～100% biggest strength) adding 60% biggest strength shoulders the training method the load combination method.

用"最大力量训练(80％～100％最大力量)+30％最大力量负荷最快速度训练法"负荷组合方法做上斜卧推杠铃训练，对推铅球上肢快速力量的训练效果好于用"最大力量(训练80％～100％最大力量)+徒手最快速度训练法"与"最大力量训练(80％～1 00％最大力量)+60％最大力量负荷最快速度训练法"负荷组合方法。

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。

In the days of sailing vessels the crew were afraid they would be becalmed on the ocean.

在使用帆船的时代，船员们担心他们会因为无风而无法在海洋上航行。

As long as foreign donors pay the PA's salary bill, few expect a new intifada.

只要外国继续为巴权力机构的薪水买单，希望发动新暴动的人便寥寥无几。