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《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(3):361-386
Passive fluidically coupled suspensions have been considered to offer a promising alternative solution to the challenging design of a vehicle suspension system. A theoretical foundation, however, has not been established for fluidically coupled suspension to facilitate its broad applications to various vehicles. The first part of this study investigates the fundamental issues related to feasibility and properties of the passive, full-vehicle interconnected, hydro-pneumatic suspension configurations using both analytical and simulation techniques. Layouts of various interconnected suspension configurations are illustrated based on two novel hydro-pneumatic suspension strut designs, both of which provide a compact design with a considerably large effective working area. A simplified measure, vehicle property index, is proposed to permit a preliminary evaluation of different interconnected suspension configurations using qualitative scaling of the bounce-, roll-, pitch- and warp-mode stiffness properties. Analytical formulations for the properties of unconnected and three selected X-coupled suspension configurations are derived, and simulation results are obtained to illustrate their relative stiffness and damping properties in the bounce, roll, pitch and warp modes. The superior design flexibility feature of the interconnected hydro-pneumatic suspension is also discussed through sensitivity analysis of a design parameter, namely the annular piston area of the strut. The results demonstrate that a full-vehicle interconnected hydro-pneumatic suspension could provide enhanced roll- and pitch-mode stiffness and damping, while retaining the soft bounce- and warp-mode properties. Such an interconnected suspension thus offers considerable potential in realising enhanced decoupling among the different suspension modes. 相似文献
13.
Modeling capacity flexibility of transportation networks 总被引:1,自引:0,他引:1
Anthony Chen Panatda Kasikitwiwat 《Transportation Research Part A: Policy and Practice》2011,45(2):105-117
Flexibility of the transportation system is one of the important performance measures needed to deal with demand changes. In this paper, we provide a quantitative assessment of capacity flexibility for the passenger transportation network using bi-level network capacity models. Two approaches for assessing the value of capacity flexibility are proposed. One approach is based on the concept of reserve capacity, which reflects the flexibility with respect to changes in terms of demand volume only. The second approach allows for variations in the demand pattern in addition to changes in demand volume in order to more fully capture demand changes. Two models are developed in the second approach to consider two types of capacity flexibility. The total capacity flexibility allows all users to have both route choice and destination choice when estimating capacity flexibility. The limited capacity flexibility estimates how much more demand volume could be added to a fixed demand pattern by allowing the additional demand to deviate from the fixed demand pattern. Numerical examples are provided to demonstrate the different concepts of capacity flexibility for a passenger transportation system under demand changes. 相似文献
14.
采用裂缝率、车辙、横向力系数和功能性破损率四个指标衡量沥青路面是否达到预防性养护标准。结合选取的锦阜、锦朝高速公路代表性路段检测数据分析评价,负指数函数y=a.e-bx能够很好地表征路面单值指标性能变化规律。通过分析预测,得到了锦阜、锦朝高速公路最佳的预防性养护年限。 相似文献
15.
阐述了黄土的分布与性质,对黄土路堤沉降的机理及原因进行了分析.分析比较了基于实测资料预测黄土路堤工后沉降值的实用模型,包括指数模型,幂函数模型,双曲线模型.以指数模型为例,根据已建成某大坝实测数据,确定了预测模型的参数. 相似文献
16.
在土的应力应变关系中,柔度矩阵要求主对角线元素为正且主对角线元素占优,对主应力表示的柔度矩阵进行了研究,证明了这两个条件同时满足时柔度矩阵的行列式必大于0.因而,柔度矩阵的行列式是否大于0可以作为评价土的本构模型合理性的一个方法.通过对传统弹塑性模型塑性柔度矩阵的研究,发现传统弹塑性模型的塑性柔度矩阵行列式等于0,不能... 相似文献
17.
《铁道标准设计通讯》2017,(2):55-59
为了准确模拟桩基础对桥梁结构的空间约束,在总结常用桩基模拟方法的基础上,提出一种新的等效结构来模拟群桩基础的空间刚度,然后采用基于WinKler假定的"m法",根据"柔度相等"的原则,推导出这种等效结构的相关参数,最后通过与常用模拟方式比较验证的方式,验证这种等效结构的准确性。研究表明:该种虚拟结构构造简单、建模方便,能够模拟桩基础的空间刚度,满足工程设计要求。 相似文献
18.
《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(3):362-389
A vertical vehicle–track coupled dynamic model, consisting of a high-speed train on a continuously supported rail, is established in the frequency-domain. The solution is obtained efficiently by use of the Green's function method, which can determine the vibration response over a wide range of frequency without any limitations due to modal truncation. Moreover, real track irregularity spectra can be used conveniently as input. The effect of the flexibility of both track and car body on the entire vehicle–track coupled dynamic response is investigated. A multi-body model of a vehicle with either rigid or flexible car body is defined running on three kinds of track: a rigid rail, a track stiffness model and a Timoshenko beam model. The results show that neglecting the track flexibility leads to an overestimation of both the contact force and the whole vehicle vibration response. The car body flexibility affects the ride quality of the vehicle and the coupling through the track and can be significant in certain frequency ranges. Finally, the effect of railpad and ballast stiffness on the vehicle–track coupled vibration is analysed, indicating that the stiffness of the railpad has an influence on the system in a higher frequency range than the ballast. 相似文献
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In this paper, we take an initial look at the spatial and temporal flexibility in the activity patterns of the so-called “baby-boomer”
cohort (born 1947–1966) in comparison with younger and older adults. Using a unique longitudinal survey carried in Quebec
City from 2002 to 2005, we explore activity patterns and trip rates over a seven-day observation period during the first wave,
and take a first look at some aspects of their evolution over two subsequent waves at about one-year intervals. We model the
propensity to undertake activities within selected conventional non-work classifications such as “shopping” and “leisure”,
and also according to respondents’ own perceptions of the spatial and temporal flexibility of each out-of-home activity that
they had executed. While we cannot strictly separate cohort effects from age-related effects, after controlling for gender
and household structure, we infer that age and related lifestyle effects dominate in explaining these propensities. However,
the boomers were the only age stratum to increase their total out-of-home activity participation over the course of the panel,
an intriguing starting point for the future study of this cohort.
Luis F. Miranda-Moreno has been recently appointed as Assistant Professor in the Department of Civil Engineering and Applied Mechanics at McGill University. His research focuses on travel behaviour, transportation safety and evaluation of sustainable transport strategies. Martin Lee-Gosselin recently retired as Full Professor at the Graduate School of Planning and CRAD, Université Laval, Québec, and is Visiting Professor at Imperial College London. His research interests are transport and telecommunications behaviour, survey methods, energy efficiency and the impacts of transport on the environment and public health. 相似文献
Martin Lee-GosselinEmail: |
Luis F. Miranda-Moreno has been recently appointed as Assistant Professor in the Department of Civil Engineering and Applied Mechanics at McGill University. His research focuses on travel behaviour, transportation safety and evaluation of sustainable transport strategies. Martin Lee-Gosselin recently retired as Full Professor at the Graduate School of Planning and CRAD, Université Laval, Québec, and is Visiting Professor at Imperial College London. His research interests are transport and telecommunications behaviour, survey methods, energy efficiency and the impacts of transport on the environment and public health. 相似文献