机动车疲劳驾驶行为分析研究

机动车辆与日俱增，交通安全越来越受到世人的关注。随着经济的发展，疲劳驾驶现象更是频繁出现，疲劳影响驾驶员的警觉性和安全驾驶能力，驾驶疲劳导致了许多交通事故的发生。     

基于城市轿车循环行驶工况的汽车轮毂疲劳寿命预测

以16×7J铝合金轮毂为研究对象,依据国内城市轿车循环行驶工况,分析轮毂行驶载荷谱,此种编谱方法可以真实反映轮毂所受载荷大小和作用位置。通过有限元分析得到轮毂受力危险点的应力-时间曲线,提取每一循环修正后的应力幅值编制应力谱。依据疲劳分析理论结合轮毂的S-N曲线,把应力幅值作为疲劳分析的基本参数,将改进的Miner公式用于轮毂的疲劳寿命预测,最终以"循环公里数"度量轮毂疲劳寿命。     

基于磁记忆检测的钻杆疲劳寿命评估

传统的疲劳寿命评估方法用于钻杆评估存在诸多困难。依据磁记忆检测技术的特点,提出了应力集中水平定量计算及评估方法;通过疲劳实验,得出了表面磁场强度法向分量变化梯度、应力集中磁效应系数与循环周次之间的关系曲线,实现了对钻杆疲劳寿命的初步评估。     

穴位埋线对运动性疲劳大鼠能量代谢水平的影响

本试验旨在探讨埋线疗法对运动疲劳的改善作用。以运动性疲劳大鼠为研究对象,将36只SD大鼠随机分为空白组、跑台组、埋线组,每组12只,埋线组进行相应穴位埋线,研究其对骨骼肌能量代谢水平的影响。采用7周递增跑台训练法构建运动疲劳模型。7周训练结束后,除空白组外,跑台组、埋线组进行大速度力竭运动,记录力竭时间,测定能量代谢相关指标及疲劳相关生物标志物,制作骨骼肌切片。研究结果表明,与空白组相比,跑台组、埋线组血糖、糖原含量均显著降低（P<0.05）,乳酸、尿素氮、丙二醛含量均显著升高（P<0.05）,骨骼肌切片光镜下均观察到病理损伤现象。埋线组ATP含量、ATP酶活性均显著高于跑台组（P<0.05）,肌酸激酶含量上升幅度低于跑台组。综上所述,穴位埋线可以使机体具有更多的能源物质、更少的代谢产物,并可能通过改善氧化应激、提高能量供应等调节机体能量代谢水平,延缓运动疲劳的产生。     

Study on Influence of Fiber to Stability of Asphalt Concrete Pavement

The effect of fiber in asphalt mixtures has attracted general concern. For study of this problem, four kinds of fibers are chosen in this test. Asphalt and modified asphalt are adopted in asphalt mixtures AC-16I. The road performance influenced by additional fiber was analyzed impersonally,i, e. the stability of asphalt concrete under high temperature condition, anti-crack ability under low temperature condition, the water resistance and fatigue performance. It was shown through the research that the optimum asphalt content, air void rate, clearance rate of the mineral powder, saturation degree, and the flow value were increased and the density was decreased after adding the fiber. The road performance, such as the stability of asphalt concrete under high temperature condition, anti-crack ability under low temperature condition, water resistance and fatigue performance, was obviously improved,and the high temperature stability and fatigue performance improved most evidently. The fiber asphalt mixture performance reached and even exceeded the modified asphalt mixture performance. The modified asphalt performance after adding fiber would be improved more greatly.     

农机链链板与套筒最优过盈量有限元分析及试验研究

正确选择链板与套筒的配合过盈量，可以有效降低链板应力幅和应力集中系数，提高疲劳强度。针对传统计算过盈应力方法不适合链板非轴对称结构，文中根据配合表面位移连续条件拟合过盈量，并利用配合表面上力的等值条件建立有限元模型，推导有限元程序。通过与厚壁筒理论值应力场计算比较，证实了该程序具有很高的可靠性和精度。对16A链板应力场有限元理论分析和疲劳试验的结果表明：随着过盈量增加，应力幅不断减小，当过盈量数值继续增加而应力幅保持不变时，此数值即为最优过盈量。而合理的过盈量应为最优过盈量开始的某一范围。16A链板合理过盈量为0.06～0.08 mm，相对无过盈时其疲劳强度可提高40%～50%。     

30CrNiMo8钢的低周疲劳试验

试验研究了30CrNiMo8钢材料的常规机械性能和断裂性能及低周疲劳特性，并提供了相应的试验方法和试验数据。给出了30CrNiMo8钢钢材料的循环应力应变关系和寿命应变关系。首次介绍了该钢材抗疲劳、抗断裂的力学性能。     

Experimental Analysis of Bending Fatigue Behavior of Prestressed Concrete Girders with Complex Box-type Section Used in High-speed Railway

Based on a prestressed concrete girder with complex box-type section of 36m span, four models of 1/6 scale are made, and one of them is mixed with a kind of polymer latex. Experiments with monotonically and cyclically loading are carried out on the models to study bending fatigue behavior of the girder in service and under cyclic load exceeding the designed value, as well as the impact of polymer on fatigue performance of the girder. The results show that, under the cyclic load of value determined by the maximum and minimum stress at the key part of the girder in service, the fatigue performance is satisfactory and the fatigue behavior under a subsequent larger cyclic load is similar with that one under the same big cyclic load. Besides, the polymer has no negative effect on fatigue behavior of the model.     

板簧疲劳试验机设计参数分析

汽车钢板弹簧把车架与车轴弹性地联接起来,其主要作用是传递车轮和车架间的力和力矩,同时缓和由不平路面传给车架的冲击载荷,以减弱由冲击载荷引起的承载系统的振动,保证汽车平稳地正常行驶。为此,运用机构运动学的基本原理进行板簧疲劳试验机的特性参数分析,得出了机构结构参数变化对试验机特性的影响,同时得到功率匹配的基本计算方法,并进行了飞轮质量和位置对试验机性能的影响分析。     

齿轮弯曲疲劳寿命有限元计算方法研究

以材料弯曲疲劳特性为基础，采用有限元技术对齿轮的齿根应力进行分析，运用多轴疲劳设计准则对齿轮的疲劳寿命进行了计算。这一方法克服了传统的齿轮疲劳寿命计算中齿轮材料疲劳特性数据不足，应力计算不准的缺点。将计算结果与试验数据进行了对比分析，疲劳寿命计算值在试验值的0．3倍至3倍以内。