疲劳曲线

The fatigue reliability analysis for the 16V240ZJB diesel engine crankshaft inserving DF4B internal-combustion locomotive were carried out in thisdissertation.Firstly,according to the fatigue loads of the crankshaft,the bendstress and torsion stress at danger zone in rated operation modes werecalculated respectively.The stress randomicity of the crankshaft was analyzedrelating operation modes of acceptance,and the probability distribution ofstresses were obtained with statistical analysis.

运用本文所提出的疲劳可靠性分析模型(干涉模型-Miner准则综合法及弯扭复合模型)和经分析简化得到的材料p-S-N曲线和p-Sa-Sm-N曲面，分别按一维、二维疲劳应力及弯扭复合应力三种情况对东风4B型内燃机车16V240ZJB柴油机曲轴进行了疲劳可靠性分析。

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。

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 fatigue test of CFRP bars was carried out at the different cyclic stress, choose the 70% ultimate tensile stress of CFRP bar as the maximum cyclic stress, under the cyclic ratios of R=0.5 （the minimum-to-maximum stress ratio） and R=0 and the fatigue behavior of CFRP bars was investigated.

进行了不同循环应力下CFRP筋的常温疲劳试验，选取CFRP筋70％的极限拉伸应力作为最大循环应力，在R=0.5（最小循环应力与最大循环应力的比）和R=0的应力率下，测量了CFRP筋的疲劳寿命曲线，研究了CFRP筋的疲劳性能。

While sustaining constant force, isometric muscular contraction, the initial past decreasing rate of medium frequency curve, the absolute value of the fitting straight line slope, was increased with the degree of the muscular fatigue. With this rate, it was possible to quantitatively judge the state of the muscular fatigue, reduce the physical consumption and muscular uncomfort of recipients.

在维持等长、恒力肌肉收缩时，f＿曲线初始段下降率（即拟合直线斜率的绝对值）随肌肉疲劳程度的增加而增加，因此希望能用f＿曲线初始段的下降率来定量判断局部肌肉疲劳的状态，以减少受试者的体力消耗和肌肉不适程度。

Tension-tension fatigue experiment was carried out at three different stress-level, the fatigue life and the S-N curve of the unnotched laminates were acquired.

进行了三种不同应力水平下的拉-拉疲劳试验，得到无孔试件的疲劳寿命及其S-N曲线；通过研究复合材料疲劳寿命预测的方法，建立了该无孔层合板剩余刚度疲劳累积损伤寿命预测模型。

The characteristics of fatigue cracking, in rib to crossbeam joints, rib to deck plate joints and rib to rib joints, are understood by the analysis of the test results. The regression line and 95% confidence lower limit of △σ-N curves are given for these joints. Their available fatigue strength is suggested for fatigue design.

通过对试验结果的分析，了解了纵肋与横梁连接、纵肋与盖板连接和纵肋与纵肋连接的疲劳开裂特点，给出了这些连接细节△σ—N曲线的回归线和95%置信下限，提出了疲劳设计时可采用的疲劳强度。

In engineering application, especially in the design stage, it is always using the material fatigue property curve and fatigue strength factors, ie.

在工程应用中，特别是在产品设计阶段，通常利用材料的疲劳性能曲线，再考虑零部件的尺寸系数、表面加工系数及应力集中系数等疲劳强度影响因素进行构件疲劳强度设计。

The characteristics of fatigue life curve of materials in three stages of fatigue life were analyzed and then a model with three parameters was presented to describe the fatigue life curve of materials in the whole region.

分析了材料疲劳寿命曲线在三个阶段内的变化特性，提出了一个描述材料全寿命区域内疲劳寿命曲线的三参数模型。

It's necessary to study probabilistic fatigue life curve and probabilistic crack growth curve of welded steel components in order to design fatigue reliability and to evaluate fatigue life in service of steel constructions.

焊接钢构件的概率疲劳寿命曲线和概率裂纹扩展速率曲线是进行钢结构疲劳可靠性设计和服役期间剩余疲劳寿命可靠性评估所必须的。

Chrysanthemum of 10 thousand birthday is lax to edaphic requirement, with the arenaceous qualitative loam with fecund, good drainage had better.

万寿菊对土壤要求不严，以肥沃。排水良好的砂质壤土为好。

He unstepped the mast and furled the sail and tied it.

他拔下桅杆，把帆卷起，系住。