人车路系统三维耦合振动分析及舒适度评价

基于将车身视作三维弹性梁、车轮为刚性体的全车模型,人体采用坐姿并联动力模型,路面简化成Kelvin地基上的板,通过轮胎的刚性滚子接触模型将车辆与路面耦合在一起,建立起考虑人车、车路耦合作用的用于评价车辆乘坐舒适度的三维人车路耦合系统振动模型,并推导出其运动平衡方程;通过Galerkin法对路面方程进行离散,采用New-mark积分法对耦合系统方程组进行求解,对人车路系统振动响应进行了分析;采用人体加权振动加速度均方根值对车辆乘坐舒适度进行评价,并对系统各参数对车辆乘坐舒适度的影响进行探讨.数值分析表明:传统模型下车辆乘坐舒适度指标与本文模型的指标相差最高可达到约30％;在分析车辆振动响应及乘坐舒适度时,不能忽视车辆与路面、人体与车辆相互作用,系统各参数对车辆乘坐舒适度都有一定程度的影响.     

大跨度双层网壳的非线性动态响应

网壳结构在大跨度结构中得到广泛应用．在建立了双层网格扁球壳的非线性强迫振动微分方程的基础上,研究了在边缘滑动固定的边界条件下,双层网格扁球壳的非线性动态响应问题．用突变理论建立了该网壳的尖点突变模型,得出了突变的临界方程,并阐述了网壳参数对该结构动态屈曲的影响．     

车辆各轮相干桥面不平顺激励的车桥耦合振动

根据车辆左右轮的互功率谱密度和相干函数,推导了左右轮桥面不平顺特性中对应相位角的相干关系,提出了采用相位角相干生成车辆各轮相干桥面不平顺激励的方法,并通过数值算例验证了该生成方法的可靠性.工程应用结果表明,车辆各轮相干桥面不平顺激励增大了桥梁、车辆竖向和车辆俯仰角的振动响应,但降低了车辆侧倾角的振动响应;不同相干函数模型对桥梁振动响应影响较小,但对车辆振动响应影响较大;同一相干函数模型,桥梁振动响应随着相干强度的增大而增大,但车辆振动响应随着相干强度的增大而减小;研究桥面不平顺随机激励对车桥耦合系统振动响应的影响有必要考虑车辆各轮的相干关系.     

Complexity results in graph reconstruction

We investigate the relative complexity of the graph isomorphism problem (GI) and problems related to the reconstruction of a graph from its vertex-deleted or edge-deleted subgraphs (in particular, deck checking (DC) and legitimate deck (LD) problems). We show that these problems are closely related for all amounts c?1 of deletion:

(1)

, , , and .

(2)

For all k?2, and .

(3)

For all k?2, .

(4)

.

(5)

For all k?2, .

For many of these results, even the c=1 case was not previously known.Similar to the definition of reconstruction numbers vrn_∃(G) [F. Harary, M. Plantholt, The graph reconstruction number, J. Graph Theory 9 (1985) 451-454] and ern_∃(G) (see [J. Lauri, R. Scapellato Topics in Graph Automorphism and Reconstruction, London Mathematical Society, Cambridge University Press, Cambridge, 2003, p. 120]), we introduce two new graph parameters, vrn_∀(G) and ern_∀(G), and give an example of a family {G_n}_n?4 of graphs on n vertices for which vrn_∃(G_n)<vrn_∀(G_n). For every k?2 and n?1, we show that there exists a collection of k graphs on (2^k-1+1)n+k vertices with 2ⁿ 1-vertex-preimages, i.e., one has families of graph collections whose number of 1-vertex-preimages is huge relative to the size of the graphs involved.     

Dependence of the solution of a semi‐discrete von Mises equation with respect to the pressure for an inverse problem

We study precisely the solution of a semi‐discrete von Mises problem with known pressure to generalize a method for an inverse problem: the problem with known displacement. We prove the boundedness of the diffusive term, the uniqueness and the continuity of the solution with respect to the pressure and a coercivity property. However, the estimate of the diffusive term is not sharp enough for the inverse problem. We highlight a special behaviour of this term due to the combination of the nonlinearity with the degeneracy of the diffusion coefficient. Copyright © 2013 John Wiley & Sons, Ltd.     

民机驾驶舱布局流程设计及应用

为减少民机驾驶舱设计迭代次数,提高设计质量和效率,提出了一种民机驾驶舱布局的设计流程。结合适航要求和人机工效分析方法,对飞行员眼位、人体尺寸、内部视界和外部视界、飞行员坐姿、座椅和脚蹬调节行程、中控台尺寸及其它关键部件位置进行了分析和研究。最后,应用提出的民机驾驶舱布局流程进行了公务机驾驶舱布局设计。结果表明,设计的民机驾驶舱布局流程能够快速实现预期设计目标,提高了设计效率,对民机驾驶舱设计具有指导意义。     

拉压循环载荷下正交异性钢桥面板肋-面板焊缝裂纹扩展分析

采用四步法计算了考虑循环载荷中压应力影响的正交异性钢桥面板的肋-面板焊缝表面裂纹扩展。第一步是基于正交异性钢桥面板的疲劳分析模型,计算肋-面板焊缝处的应力,第二步是通过肋-面板焊缝的三维局部模型,用Schwartz-Neumann交替法计算焊缝表面裂纹的应力强度因子分布,第三步是用二维断裂力学模型和增量塑性损伤模型,计算循环载荷中的压应力对裂纹扩展的影响,第四步是用第二步中的三维裂纹分析结果和第三步中的二维断裂力学模型得到的裂纹扩展公式,计算钢桥面板的肋-面板焊缝表面裂纹扩展。计算结果表明,对应于正交异性钢桥面板肋-面板焊缝处的循环应力,本文所用模型的裂纹尖端反向塑性区导致裂纹扩展率增加50%以上。研究结果为正交异性钢桥面板肋-面板焊缝裂纹的疲劳寿命分析提供了研究基础。     

振动桥梁CFD数值模拟的网格运动算法

针对非流线型桥梁断面模型,采用Delaunay背景网格方法、棱边弹簧及线性弹簧网格方法,研究非结构网格与结构网格条件下,计算域网格运动的特点及算法优劣.研究表明,在正常的桥梁断面振动振幅内,三种网格运动方法均能保持网格变形时不会失效,其中Delaunay背景网格方法耗时最少,线性弹簧网格方法获得网格质量最高;在大振幅状态下,结构化网格容易失效,线性弹簧网格方法可最大限度保证网格有效.     

A linear theory for Ekman's boundary layer according to a triple deck

The problem of the interaction between Ekman's classical boundary layer and that induced by a thermally non-homogeneous site shows that the latter is strongly linked to the order of magnitude of the horizontal scale of the site. Our purpose is the analysis of the local interaction equations (Boussinesq equations) starting from a triple-deck model. This analysis yields a system of quasi-linear equations for the viscous lower deck. The linear theory of this system shows that the thermal non-homogeneity has a significant influence on the Ekman boundary layer flow owing to the interactive nature of the triple-deck structure. The numerical solution of the quasi-linear system confirms to a large extent this influence. The numerical results are given in graph form. © 1997 John Wiley & Sons, Ltd.     

正交异性钢桥面板轮载横向效应的解析分析方法

在分析正交异性钢桥面板构造特点的基础上,将轮载影响范围内的桥面板简化为弹性支撑的平面框架,建立了正交异性钢桥面轮载横向效应的解析分析模型,推导了纵肋弹性支撑刚度和车轮荷载集度等效计算方法,提出了桥面板与U肋交接位置处横向弯曲应力的解析公式,讨论并明确了影响桥面板横向弯曲应力峰值的关键敏感影响因素,并以某钢箱梁为例证明了本文算法的合理性。研究发现,本文方法计算得到桥面板与U肋相交位置的横向应力值与有限元结果相差不超过10%,证实了本文算法的正确性,也为正交异性钢桥面的初步设计提供了极大的方便;正交异性钢桥面板的横向轮载应力随U肋厚度和高度增加而增大,但随顶板厚度和横隔板间距增大而减小;相对而言,顶板内横向拉应力受顶板厚度的影响最为显著,对腹板倾角和U肋腹板厚度的变化并不敏感。