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1.
In conjunction with the homogenization theory and the finite element method, the mathematical models for designing the corss-section
of composite shafts by maximizing the torsion rigidity are developed in this paper. To obtain the extremal torsion rigidity,
both the cross-section of the macro scale shaft and the representative microstructure of the composite material are optimized
using the new models. The micro scale computational model addresses the problem of finding the periodic microstructures with
extreme shear moduli. The optimal microstructure obtained with the new model and the homogenization method can be used to
improve and optimize natural or artificial materials. In order to be more practical for engineering applications, cellular
materials rather than ranked materials are used in the optimal process in the existence of optimal bounds for the elastic
properties. Moreover, the macro scale model is proposed to optimize the cross-section of the torsional shaft based on the
tailared composites. The validating optimal results show that the models are very effective in obtaining composites with extreme
elastic properties, and the cross-section of the composite shaft with the extremal torsion rigidity.
The project supported by the National Natural Science Foundation of China (10172078 and 10102018) 相似文献
2.
舰船推进轴系是舰船动力装置的重要组成部分,它的稳定性是舰船生命力的基本保证.本文以舰船主推进轴系为研究对象,考虑了非线性油膜力的作用,在推进轴的非线性油膜力模型中,考虑了油膜涡动效应和挤压效应以及多个轴承油膜力的耦合影响,并考虑了轴承结构本身的刚度.文中采用弹性体动力学方法对推进轴建模,考虑了在外冲击作用下转速和轴承油膜力对于转轴冲击响应的影响,考虑横向运动与转动耦合作用,导出以非线性偏微分方程描述的舰船主推进轴的动力学方程,并用经典理论对其进行离散,最后采用龙格-库塔法进行数值仿真.实例分析指出转速对于转轴冲击响应的影响不可忽略. 相似文献
3.
朱怀亮 《应用数学和力学(英文版)》2002,23(12):1413-1420
IntroductionRotatingshaftsarethemostvitalcomponentsofmodernindustrialandpowergenerationfacilities.DuetotheimportanceofthesecomponentstherewerewidelystudiesonthevibrationbehaviorofEuler_Bernoullirotatingshaftsusinganalyticalandnumericalmethods[1- 4 ].Howe… 相似文献
4.
Bifurcation and universal unfolding for a rotating shaft with unsymmetrical stiffness 总被引:1,自引:0,他引:1
The 1/2 subharmonic resonance bifurcation and universal unfolding are studied for a rotating shaft with unsymmetrical stiffness.
The bifurcation behavior of the response amplitude with respect to the detuning parameter was studied for this class of problems
by Xiao et al. Obviously, it is highly important to research the bifurcation behavior of the response amplitude with respect
to the unsymmetry of stiffness for this problem. Here, by means of the singularity theory, the bifurcation and universal unfolding
of amplitude with respect to the unsymmetrical stiffness parameter are discussed. The results indicate that it is a high codimensional
bifurcation problem with codimension 5, and the universal unfolding is given. From the mechanical background, we study four
forms of two parameter unfoldings contained in the universal unfolding. The transition sets in the parameter plane and the
bifurcation diagrams are plotted. The results obtained in this paper show rich bifurcation phenomena and provide some guidance
for the analysis and design of dynamic buckling experiments of this class of system, especially, for the choice of system
parameters.
The project supported by the National Natural Science Foundation of China (19990510), the National Key Basic Research Special
Foundation (G1998020316) and Liuhui Center for Applied Mathematics, Nankai University and Tianjin University 相似文献
5.
高速列车穿越有竖井隧道流场的特性研究 总被引:1,自引:0,他引:1
给出了高速列车穿越隧道压力波的三维粘性流场数值模拟过程,控制方程为三维粘性、可压缩、等熵和非定常流的Navier-Stokes方程,空间离散采用了中心有限体积法格式,时间采用预处理二阶精度多步后差分格式进行离散,对隧道壁面采用壁面函数处理。在模拟中考虑了竖井的位置、竖井的断面积、竖井的数目等因素对隧道内压力及压力梯度的影响。计算结果表明,竖井的存在改变了压缩波的波前形状,从而使得隧道内的压力变化的最大值降低,因而能够降低隧道内的压力梯度最大值,但它并不能延长压力上升的时间。 相似文献
6.
在网络的任意点求解绝对中心等特殊点是网络流研究的一个难点.在目前最小费用理论的基础上引入平面几何理论,把网络等效于几何图形,建立了数学模型.通过求解,得出了网络间的最佳连接点,从而确定出盲竖井的位置.最后以云南锡业集团个旧东区两个生产平台之间的连接为一算例,得出了理想的结果,验证了该方法的有效可行性. 相似文献
7.
基于小子样的思想,探讨扭力轴表面缺陷对其疲劳寿命的影响,有助于进一步找到降低扭力轴表面凹坑对扭力轴疲劳寿命影响的方法. 相似文献
8.
9.
A neural network predictor investigation is presented for analyzing vibration parameters of a rotating system. The vibration
parameters of the system, such as amplitude, velocity, and accelertion in the vertical direction, were measured at the bearing
points. The system's vibration and noise were analyzed for different working conditions. The designed neural predictor has
three layers, which are input, hidden, and output layers. In the hidden layer, 10 neurons were used for this approximation.
The results show that the network can be used as an analyzer of such systems in experimental applications. 相似文献
10.