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241.
242.
三体船侧体位置优化设计研究 总被引:1,自引:0,他引:1
基于二维半理论的计算软件TRIMARAN研究了侧体纵向、横向位置的变化对三体船运动响应的影响,同时研究了船体横摇惯性半径对三体船横摇性能的影响,从而提出一套三体船侧体位置优化方案。通过在低速和高速两种情况下,对三体船侧体纵向、横向位置的变化对三体船的运动响应分析,可以看出:低航速下侧体应布置于靠近主体船艏的位置,有利于三体船运动性能的提升,高航速下则应将侧体放置于主体船尾。同时,根据横摇惯性半径对三体船横摇性能的影响研究表明:三体船的横摇半径越小越能增加三体船的横摇稳定性。 相似文献
243.
详细介绍了黄骅港扩容完善工程6 000 t/h斗轮悬臂取料机的安装调试技术。根据现场条件和设备到货的实际情况,确定安装工艺流程,计算吊装性能参数,合理选择吊装起重机和索具,制定合理有效的质量控制措施,保证了安装调试的质量和安全,提高了施工效率,达到了预期的施工效果。 相似文献
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G. Xie S. D. Iwnicki 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2008,46(1):117-128
A new model for simulating rail roughness growth on tangent track is presented in this paper. The model consists of three relatively independent components: (1) a time-domain vehicle/track interaction model; (2) a 2D non-Hertzian and non-steady wheel/rail contact model; and (3) a wear model. Wheel/rail contact forces for a given initial roughness obtained from the vehicle/track interaction model are used by the contact model to calculate the contact patch size, normal pressure and tangential stresses with material removal assumed to be linearly proportional to the friction work in the contact patch. The roughness profile is updated and fed back into vehicle/track interaction model. The 2D contact model is initially compared with a 3D model for various wavelength of initial sinusoidal roughness. Long term roughness growth is then simulated with the 2D contact model. Simulation shows that all initial sinusoidal roughness of wavelengths between 20-100 mm are levelled out. The wavelength-fixing mechanism, that has previously been used to explain the cause of corrugation, is not found in the present investigations. 相似文献
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248.
《铁道标准设计通讯》2013,(9)
城市轨道交通的车辆段和停车场需要占用大量的城市土地,合理分配场段规模可以优化占地面积,提高运营效率。基于一场一段情况下,总结出不同接轨方案的场段规模分配计算方法,提出场段分布位置在线路中接近对称时,场段规模大致相等的研究结论。同时,提出地铁收发车空跑距离计算模型,并对不同场段分布对运营成本的影响因素进行分析,提出降低运营期间场段收发车空跑运营成本的途径。 相似文献
249.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(9):1453-1471
A method is described which is an extension of rolling contact models with respect to plasticity. This new method, which is an extension of the STRIPES semi-Hertzian (SH) model, has been implemented in a multi-body-system (MBS) package and does not result in a longer execution time than the STRIPES SH model [J.B. Ayasse and H. Chollet, Determination of the wheel–rail contact patch in semi-Hertzian conditions, Veh. Syst. Dyn. 43(3) (2005), pp. 161–172]. High speed of computation is obtained by some hypotheses about the plastic law, the shape of stresses, the locus of the maximum stress and the slip. Plasticity does not change the vehicle behaviour but there is a need for an extension of rolling contact models with respect to plasticity as far as fatigue analysis of rail is concerned: rolling contact fatigue may be addressed via the finite element method (FEM) including material non-linearities, where loads are the contact stresses provided by the post-processing of MBS results [K. Dang Van, M.H. Maitournam, Z. Moumni, and F. Roger, A comprehensive approach for modeling fatigue and fracture of rails, Eng. Fract. Mech. 76 (2009), pp. 2626–2636]. In STRIPES, like in other MBS models, contact stresses may exceed the plastic yield criterion, leading to wrong results in the subsequent FEM analysis. With the proposed method, contact stresses are kept consistent with a perfect plastic law, avoiding these problems. The method is benchmarked versus non-linear FEM in Hertzian geometries. As a consequence of taking plasticity into account, contact patch area is bigger than the elastic one. In accordance with FEM results, a different ellipse aspect ratio than the one predicted by Hertz theory was also found and finally pressure does not exceed the threshold prescribed by the plastic law. The method also provides more exact results with non-Hertzian geometries. The new approach is finally compared with non-linear FEM in a tangent case with a unidirectional load and a complete slip: when plasticity is taken into account, and for large adhesion values, friction forces have an influence on the size of the contact patch. The proposed approach enables also to assess extensively the level of plasticity along a track through an indicator associated with a given yield stress. 相似文献
250.
邱满根 《减速顶与调速技术》2013,(3):1-8
驼峰溜放车辆的走行阻力包括车辆本身的阻力、线路阻力、空气阻力,以及调速设备的残余阻力等,它们在溜放车辆的走行过程中,参与了调速设备对车辆的速度控制,而且它们对速度的“控制”是人们无法干预的,是复杂而多变的,故对车辆的正常调速起到了干扰作用,使调车作业的效果受到一定影响.文中重点阐述了车辆走行阻力的基本情况,同时对车辆溜行速度控制产生偏差进行了分析. 相似文献