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《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(10):1495-1514
Dither generated by rolling contact of wheel and rail smoothes dry friction damping provided by the primary suspension dampers of freight wagons and it should be taken into account in numerical simulations. But numerically the problem is non-smooth and this leads to long execution time during simulation, especially when the vehicle with friction dampers is modelled in the environment of an multi-body system simulation program, whose solver has to cope with many strong non-linearities. The other difficulty is the necessity of handling within the code a number of big volume files of recorded dither sampled with high frequency. To avoid these difficulties, a substitute model of two-dimensional dry friction exposed to dither is proposed that does not need application of dither during simulation, but it behaves as if dither were applied. Due to this property of the model, the excitation of the vehicle model by track irregularities may be supplied as low-frequency input, which allows fast execution and, the necessity of handling high-volume files of recorded dither is avoided. The substitute model is numerically effective. To identify parameters of the substitute model, a pre-processing employing a sample of the realistic dither is carried-out on a simple two-degrees-of-freedom system. The substitute model is anisotropic, describing anisotropic properties of the two-dimensional friction arising in the presence of one-dimensional dither. The model may be applied in other branches of engineering, for example, in mechatronics and robotics, where application of dither may improve the accuracy of positioning devices. 相似文献
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利用CATIA软件的知识工程进行道岔零部件的系列化设计,建立了企业的三维模型库,显著减少设计人员的重复工作量,提高设计的效率和质量。 相似文献
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Ananya CHAKRABORTY M. CHAKRABORTY 《Journal of Transportation Systems Engineering and Information Technology》2010,10(6):53-63
In real world applications the supply, the demand and the transportation cost per unit of the quantities in a transportation problem are hardly specified precisely because of the changing economic and environmental conditions. It is also important that the time required for transportation should be minimum. In this paper a method has been proposed for the minimization of transportation cost as well as time of transportation when the demand, supply and transportation cost per unit of the quantities are fuzzy. The problem is modeled as multi objective linear programming problem with imprecise parameters. Fuzzy parametric programming has been used to handle impreciseness and the resulting multi objective problem has been solved by prioritized goal programming approach. A case study has been made using the proposed approach. 相似文献
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应用分区产生网格的方法产生了K型节点的有限元模型,计算了在轴向荷载作用下K型节点焊缝周围的热点应力分布情况,并与相关试验结果进行对比分析,验证了所提出的有限元模型的可行性和准确性。通过对1152个K节点模型分析,研究了几何参数对K型节点焊缝周围热点应力分布的影响,发现在几何参数取不同值时热点应力的分布随几何参数的变化发生改变,而且热点应力的位置也随着几何参数的变化在冠点和鞍点之间移动。并在此几何参数分析的基础上,提出了K型节点焊缝周围应力集中系数分布的参数公式,并对参数公式进行了误差分析。对于绝大多数K节点模型,拟合得到的参数公式所计算的焊缝周围应力分布结果是精确可靠的,所以提出的参数公式为工程中K节点疲劳设计和分析提供了参考方法。 相似文献
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针对目前自升式钻井平台方案设计特点,引入知识工程的理念,建立面向对象的知识表达方法及基于实例和规则的混合推理机制,采用参数化设计方法进行特征驱动,在快速生成设计方案的同时对设计进行检验并提出建议,使设计人员的工作重点从数据处理转移到对设计对象的分析上来.开发了原型系统,证明了该方法的有效性和实用性. 相似文献
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A new approach that models lift and drag hydrodynamic force signals operating over cylindrical structures was developed and validated. This approach is based on stochastic auto regressive moving average with exogenous (ARMAX) input and its time-varying form, TARMAX. Model structure selection and parameter estimation were discussed while considering the validation stage. In this paper, the cylindrical structure was considered as a dynamic system with an incoming water wave and resulting forces as the input a... 相似文献