新型局域共振橡胶减振垫振动传递特性测试分析

为了研究一种应用于浮置板轨道结构的新型橡胶减振垫的振动传递特性,对比某基于局域共振新型减振垫与普通橡胶减振垫的减振性能,研究预压质量与激振加速度对振动传递特性的影响,对新型橡胶减振垫进行刚度试验与振动传递特性试验,测试其在30~200 Hz频率下的传递特性,试验过程中采用不同的预压质量与激振加速度,振动传递特性测试采用加速度激振的方法,以加速度传递率作为减振垫振动传递特性的评价指标。结果表明:新型减振垫加速度传递率更小,减振效果更好,最大可以减小10 dB左右;减振垫上方预压质量对振动传递特性有较大影响,预压质量越大,加速度传递率越大,减振效果越差;减振垫的刚度对其振动传递特性有一定的影响,激振的加速度幅值对加速度传递率影响较小。     

汽车动力总成自动化装配线中十字滑台浮动机构应用浅析

文章着重介绍了汽车动力总成自动化装配线上新研发采用的十字滑台浮动环节的机械结构、工作原理以及工作过程,通过此结构在实际现场使用的情况,对比分析了新型结构与传统结构的利弊区别,着重阐述了十字滑台浮动机构在汽车动力总成自动化装配线上所起的作用及其推广优势,以及由此带来的经济效益和社会效益。     

起重船有限元直接计算实例

利用有限元软件MSC．Patran和MSC．Nastran对某驳船改装成500t浮吊的改装方案进行全船结构计算和优化。合理地计算作用在浮吊上的各种载荷并进行平衡调整，使用惯性释放功能对完全自由状态下的船体结构强度进行直接计算，为改造方案提供依据。     

On vehicle/track impact at connection between a floating slab and ballasted track and floating slab track's effectiveness of force isolation

When a vehicle runs over the connection between a floating slab track (FST) and ballasted track, wheel/rail impact may occur because of the stiffness difference in the two kinds of track, and thus a transition sector is usually included at the connection to smoothen the stiffness change. This phenomenon is studied by numerical simulation using a time-domain model for an idealised case without such a transition to determine whether it is actually necessary. Calculation results show that the wheel/rail impact load is moderate for a light FST and increases with the vehicle speed or decreasing the natural frequency of the FST. From simulation the wheel/rail parametric excitation is observed, as a result of variation in the stiffness of the FST with the period of the single slab length. The wheel/rail load due to the parametric excitation also increases with the vehicle speed. In addition, good performance of vibration isolation can be seen for the FST in terms of the force transmitted to the infrastructure.     

异型特大沉箱安装中施工难点的控制

异型特大沉箱是整个29届奥运会青岛国际帆船中心水工工程Ⅰ标段工程中安装难度最大的沉箱。由于该沉箱从重量、高度、面积上都是目前亚洲最大的,安装的码头又是突堤码头,并且该沉箱在船坞内不能环卫,需在海上将沉箱托运到安装现场,这无疑增加了沉箱的安装难度,异型特大沉箱的安装难度主要取决于沉箱浮云出坞门和沉香的安装两个工序。针对施工难点,结合集合施工实际从九个方面进行了论证,包括沉箱的托运、船坞坞壁的设置、卷扬机的使用、划分水区控制摄水量等方面进行了探讨。     

Simplified analysis for estimation of the behavior of a submerged floating tunnel in waves and experimental verification

To achieve rational design in waves for a submerged floating tunnel which has emerged as a new offshore transportation infrastructure, it's necessary to understand its hydrodynamic behavior. For simple but accurate estimation of hydrodynamic forces, a theoretical method is proposed and the tests with physical models in a wave flume were carried out for verification. Morison's equation was used to estimate wave loads composed of inertia force and drag force. Forces calculated by applying the linear wave theory to Morison's equation coincided well with those measured by the tests. The test results showed that mooring systems played a significant role in the movement of the submerged floating tunnel in waves. A pendulum model could be used to describe the motion of the submerged floating tunnel with a single vertical mooring. Based on the verified relations, a simple slack condition which causes the submerged floating tunnel to be unstable was also proposed. The simplified approach proposed by this study proved to be useful in designing the submerged floating tunnel in the initial stage.     

Exploiting floating car data for time-dependent Origin–Destination matrices estimation

The study evaluates the added value generated by estimating dynamic demand matrices by information gathered from Floating Car Data (FCD).

Firstly, adopting a large dataset of FCD collected in Rome, Italy, during May 2010, all the monitored trips on a specific district of the city (Eur district) have been collected and analysed in terms of (i) spatial and temporal distribution; (ii) actual route choices and travel times. The data analysis showed that demand data from FCD are usually not suitable to retrieve directly demand matrices, due to a strong dependence of this information from the penetration rate of the monitoring device. Instead, origin–destination travel times and route choice probabilities from FCD are a much more reliable and powerful information with respect to FCD origin–destination flows, since they represent the traffic conditions and behaviors that vehicles experiment along the path.

Thus, several synthetic experiments have been conducted adopting both travel times and route choice probabilities as additional information, with respect to standard link measurements, in the dynamic demand estimation problem. Results demonstrated the strength and robustness associated to these network based data, while link measurements alone are not able to define the real traffic pattern. Adopting both the information of origin–destination travel times and route choice probabilities during the demand estimation process, the spatial and temporal reliability of the estimated demand matrices consistently increases.     

外海沉管浮运安装作业窗口管理及工艺计划研究

沉管出坞浮运安装是港珠澳大桥岛隧工程中的关键性工程,也是一个连续的、不间断的施工过程。为了降低施工风险,结合船机设备能力,提出作业窗口管理系统,针对每步施工工序提出针对性的作业限制条件,以此寻找最佳的作业时期。潮汐条件是作业窗口因素中的关键因素,根据潮汐预报数编制24~36 h连续的浮运安装工艺计划,选择在最优的水文气象条件下,按照作业窗口管理系统严格按照计划进行作业。经过33节沉管浮运安装的现场验证,浮运安装作业窗口管理系统满足项目要求,有效保障了浮运安装安全,有效降低了施工风险和成本。     

盾构隧道穿越液化地基上浮振动台试验分析

随着城市地铁线路不断增加,可能出现盾构隧道穿越液化地层的现象。一旦发生地震,盾构隧道存在上浮破坏的潜在风险。为深入研究盾构隧道周边液化地层的动力响应,针对相同密实度砂土在3种不同峰值加速度作用下开展室内振动台试验,分析土体中超静孔压的发展特性和隧道上浮规律。结果表明： 1）砂土液化最先发生在地表及浅层土体处,随着深度增加砂土液化程度逐渐降低,即增加隧道埋深有利于降低隧道液化程度。2）模型试验揭示盾构隧道的上浮机制,即使液化地基未完全液化,当超静孔隙水压力引起的上浮力大于隧道残余上覆有效土压力与隧道重力之和时,隧道将出现上浮。设计时可从消除液化地基和增加隧道重力2个方面入手,提高盾构隧道的抗上浮能力,确保隧道结构在地震时的安全。     

12000吨自航全回转起重船强度分析和评估

以某12000吨起重船为研究对象,针对典型工况建立了三舱段与起重基座有限元模型,对其总纵强度和起重基座局部强度进行强度分析,得到了应力评估结果。在此基础上,分析了起重机圆筒式基座的受力特点,提出了关于结构设计的若干合理建议。相关结论对同类型船舶的结构优化设计具有参考意义。