共查询到19条相似文献,搜索用时 181 毫秒
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摩擦提升机的主轴以及卷筒的疲劳损坏是摩擦提升机最为重要的故障方式,因此摩擦提升机的主轴以及卷筒的疲劳设计是其重要的设计内容之一.传统的采用常幅对主轴和卷筒进行疲劳分析同其在实际工况中的情况有较大的的出入,实用性受到一定的限制.利用虚拟样机建模技术,综合利用了模态柔性体和有限元柔性体两种建模方法,构造摩擦提升机虚拟样机计... 相似文献
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采用有限元计算和应力疲劳分析相结合的方法,对某发动机连杆进行结构应力和高周疲劳计算,得到其疲劳安全因数分布情况.结果表明该连杆满足安全运转要求. 相似文献
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基于有限元分析和应力疲劳理论,通过Abaqus和FEMFAT软件,对某发动机缸体曲轴箱进行结构强度分析,得到其应力分布、接触情况和高周疲劳安全因数分布.结果表明此曲轴箱结构满足设计要求. 相似文献
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受电弓滑板与接触网导线是一对比较特殊的摩擦副,其工况条件有其显著的特点,摩擦磨损的形成机理较复杂,是机械作用、电气作用以及化学或电化学作用的综合结果。文章根据接触网与受电弓的物理模型建立了受电弓与接触网系统的动力学模型,然后分别建立了接触网和受电弓的运动方程,并确定了接触力的计算公式,从而得到了受电弓滑板与接触网导线之间的相互作用规律。 相似文献
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针对高速铁路弹性链型接触网进行接触线疲劳寿命预测分析.利用ANSYS,采用直接积分法对弓网耦合系统进行动态仿真,得到接触线的应力时程;运用雨流计数法得到离散的应力循环,采用应力修正算法得到平均应力为零的疲劳应力谱;通过简化方法估算获得材料S-N曲线,从而计算得到疲劳破坏次数;最终运用线性累积损伤理论预测接触线的疲劳寿命.对比分析接触线不同位置的疲劳寿命值,结果表明:接触线每跨疲劳寿命趋势一致;每跨在吊弦处和定位点处疲劳寿命较低,其中寿命最低值出现在左侧第一根吊弦处,疲劳寿命最低值为20 a左右.结果可为高速铁路弹性链型接触网接触线的实际施工维护和更换周期的确定提供参考. 相似文献
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为研究轮轨滚动接触疲劳(Rolling Contact Fatigue,RCF)载荷对铁轨表面裂纹应力强度因子的影响,以UIC60铁轨轮廓尺寸为依据建立轮轨接触的三维有限元模型,通过改变RCF载荷大小、轮轨表面摩擦因数和接触中心位置等轮轨接触的输入参数,计算铁轨表面接触裂纹尖端的应力强度因子,分析RCF载荷对铁轨表面接触疲劳裂纹的影响. 结果表明RCF载荷作为控制铁轨表面接触裂纹的重要因素,其变化直接导致裂纹尖端应力强度因子的变化,从而改变裂纹的扩展状况;为减缓铁轨表面裂纹的扩展,可以针对载荷采取均匀分布载重量、使用润滑剂降低轮轨摩擦因数等相应措施. 相似文献
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橡胶材料疲劳断裂特性研究进展 总被引:3,自引:0,他引:3
由于橡胶材料的动态疲劳特性对保证橡胶制品使用时的安全性和可靠性具有重要意义,综述机械载荷、环境和橡胶配方等因素对橡胶材料疲劳寿命的影响,总结用疲劳裂纹萌生寿命法和基于断裂力学的疲劳裂纹扩展法预测橡胶材料动态疲劳寿命方法的优缺点,并展望这2种方法的发展趋势. 相似文献
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为研究轮轨滚动接触疲劳(Rolling Contact Fatigue,RCF)载荷对铁轨表面裂纹应力强度系数的影响,以UIC60铁轨轮廓尺寸为依据建立轮轨接触的三维有限元模型,通过改变RCF载荷大小、轮轨表面摩擦因数和接触中心位置等轮轨接触的输入参数,计算铁轨表面接触裂纹尖端的应力强度系数,分析RCF载荷对铁轨表面接触疲劳裂纹的影响.结果表明RCF载荷作为控制铁轨表面接触裂纹的重要因素,其变化直接导致裂纹尖端应力强度系数的变化,从而改变裂纹的扩展状况.为减缓铁轨表面裂纹的扩展,可以针对载荷采取均匀分布载重量、使用润滑剂降低轮轨摩擦因数等相应措施. 相似文献
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《Ergonomics》2012,55(6):710-716
Current research on slipperiness of footwear has mainly focused on floors and lubricated floors. Slips and falls on icy and snowy surfaces involve not only outdoor workers, but also pedestrians and the general public; and occur in cold regions and in winter season in many parts of the world. However, in comparison with the size of the problem, research on slips and falls on icy and snowy surfaces has been scarce. The objective of this paper is to explore the slip resistant properties of footwear (soling materials, roughness and hardness) on ice. The coefficients of kinetic friction of four different soling materials (synthetic rubber, nitrile rubber, natural rubber and polyurethane) were measured on ice (? 12°C). The outsole roughness and hardness were also measured. Results showed that the polyurethane soling did not perform better than synthetic rubber, nitrile rubber and natural rubber on pure hard ice (? 12°C). Soling roughness was positively correlated with the coefficient of kinetic friction. The most slip resistant soling material (polyurethane) on floors and lubricated floors may not provide sufficient slip resistance on ice. 相似文献
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Damage tolerance based design optimisation of a fuel flow vent hole in an aircraft structure 总被引:2,自引:0,他引:2
This paper investigates the design optimisation of a fuel flow vent hole (FFVH) located in the wing pivot fitting (WPF) of
an F-111 aircraft assuming a damage tolerance design philosophy. The design of the vent hole shape is undertaken considering
the basic durability based design objectives of stress, residual (fracture) strength, and fatigue life. Initially, a stress
based optimised shape is determined. Damage tolerance based design optimisation is then undertaken to determine the shape
of the cutout so as to maximise its residual strength and fatigue life. For stress optimisation, the problem is analysed using
the gradient-less biological algorithm and the gradient-based nonlinear programming methods. The optimum designs predicted
by the two fundamentally different optimisation algorithms agree well. The optimum shapes of the vent hole are subsequently
determined considering residual strength and fatigue life as the distinct design objectives in the presence of numerous 3D
cracks located along the vent hole boundary. A number of crack cases are considered to investigate how the crack size affects
the optimal shapes. A semi-analytical method is employed for computation of the stress intensity factors (SIF), and an analytical
crack closure model is subsequently used to evaluate the fatigue life. The 3D biological algorithm is used for designing the
cutout profiles that optimise residual strength and fatigue life of the component. An improved residual strength/fatigue life
(depending on the optimisation objective) is achieved for the optimal designs. The variability in SIF/fatigue life around
the cutout boundary is reduced, thereby making the shape more evenly fracture/fatigue critical. The vent hole shapes optimised
for stress, residual strength, and fatigue life are different from each other for a given nature and size of the flaws. This
emphasises the need to consider residual strength and/or fatigue life as the explicit design objective. The durability based
optimal vent hole shapes depend on the initial and final crack sizes. It is also shown that a damage tolerance optimisation
additionally produces a reduced weight WPF component, which is highly desirable for aerospace industries. The design space
near the ‘optimal’ region is found to be flat. This allows us to achieve a considerable enhancement in fatigue performance
without precisely identifying the local/global optimum solution, and also enables us to select a reduced weight ‘near optimal’
design rather than the precise optimal shape. 相似文献
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This paper deals with a numerical and experimental investigation on the influence of residual stresses on fatigue crack growth in AA2024-T3 friction stir welded butt joints. The computational approach is based on the sequential usage of the Finite Element Method (FEM) and the Dual Boundary Element Method (DBEM). Linear elastic FE simulations are performed to evaluate the process induced residual stresses, by means of the contour method. The computed stress field is transferred to a DBEM environment and superimposed to the stress field produced by a remote fatigue traction load applied on a friction stir welded cracked specimen; the crack propagation is then simulated according to a two-parameter growth model. Numerical results have been compared with experimental data showing good agreement and evidencing the predictive capability of the proposed method. The obtained results highlight the influence of the residual stress distribution on crack growth. 相似文献
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针对汽车车轮径向疲劳仿真中传统径向载荷加载方式导致仿真结果误差明显的问题,本文进行了胎唇对钢制车轮胎圈座作用力分布的研究。首先通过径向载荷作用下轮胎变形实验,确定了用于计算胎唇与胎圈座之间作用力的橡胶轮胎材料模型;然后,考虑轮胎变形对轮辋应力分布的影响,进行了车轮径向载荷下的有限元分析;最后,对径向载荷作用下的实验测试数据与装配轮胎模型的车轮径向强度仿真结果、传统加载方式的仿真结果进行了对比分析。研究结果表明,汽车车轮径向疲劳仿真中传统的径向载荷加载分布确实存在明显误差;为获得准确的径向载荷作用下的仿真结果,应使用装配有轮胎的车轮模型。 相似文献
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正交异性钢桥的肋-桥面板焊缝处的疲劳裂纹是典型的三维裂纹问题,但是现在普遍采用平面应变二维裂纹模型对其进行断裂力学分析.基于Schwartz-Neuman交替法建立正交异性钢桥肋-桥面板焊缝裂纹的局部三维断裂力学分析模型;评估焊缝处表面裂纹的形状和深度对应力强度因子的影响;采用Paris公式估算等应力幅下焊缝的疲劳寿命.计算结果表明:用平面应变二维裂纹模型进行正交异性钢桥的肋-面板焊缝的断裂力学分析会严重低估其疲劳寿命;采用三维断裂力学模型进行肋-桥面板焊缝裂纹的疲劳寿命分析十分必要. 相似文献