整体式桥台-桩基-土相互作用内力计算方法研究

整体桥具有使用寿命长、施工方便、造价及养护费用低等特点,目前在国内外得到了广泛的应用与推广.以某整体桥为工程背景,设计制作了桥台-桩基结构试验模型,开展了整体式桥台-H形钢桩-土相互作用低周往复荷载拟静力试验,主要研究了桥台和桩基的应变、弯矩与剪力等.试验结果表明:桥台正向移动时桩身应变呈现"酒杯"形分布,负向移动时呈...     

Fluid-structure coupled analysis of underwater cylindrical shells

Underwater cylindrical shell structures have been found a wide of application in many engineering fields, such as the element of marine, oil platforms, etc. The coupled vibration analysis is a hot issue for these underwater structures. The vibration characteristics of underwater structures are influenced not only by hydrodynamic pressure but also by hydrostatic pressure corresponding to different water depths. In this study, an acoustic finite element method was used to evaluate the underwater structures. Taken the hydrostatic pressure into account in terms of initial stress stiffness, an acoustical fluid-structure coupled analysis of underwater cylindrical shells has been made to study the effect of hydrodynamic pressures on natural frequency and sound radiation. By comparing with the frequencies obtained by the acoustic finite element method and by the added mass method based on the Bessel function, the validity of present analysis was checked. Finally, test samples of the sound radiation of stiffened cylindrical shells were acquired by a harmonic acoustic analysis. The results showed that hydrostatic pressure plays an important role in determining a large submerged body motion, and the characteristics of sound radiation change with water depth. Furthermore, the analysis methods and the results are of significant reference value for studies of other complicated submarine structures.     

考虑地基与建筑结构相互作用的动态分析

对旋转-摆动多质点系振动模型建立振动微分方程以后,根据时程分析法原理编写电算分析程序,结合算例讨论了是否考虑地基与建筑结构相互作用时对结构地震响应的影响问题,通过对两个模型进行对比、分析,得到了一些有益结果。结果表明,地基和建筑结构的共同作用相当于一种能量消耗器,能够消耗一部分地震能量,起到减少上部结构吸收大量地震动输入能量的作用。利用此模型可以在一定程度上把握其影响,可为抗震设计人员和工程技术人员提供参考。     

基于智能船厂的三维电子地图开发技术

研究基于智能船厂的三维电子地图开发技术，开发三维电子地图相关组件并实现地图瓦片化、动态加载、位置校准、地图缓存等功能，通过直观的地理实景模拟表现方式快速搭建智能船厂三维电子地图服务，为管理者提供设备、人员和中间产品等信息检索服务，有效提升船厂数字化、智能化、信息化程度，可为构建船厂资源管理和工装管理智能化提供技术支撑，进一步挖掘生产和管理环节潜力，推进船舶行业信息化建设。     

Support condition monitoring of monopile-supported offshore wind turbines in layered soil based on model updating

Monopile-supported offshore wind turbines (OWTs) are dynamically sensitive structures whose fundamental frequencies may be close to those of environmental and turbine-related excitations. The changes in fundamental frequencies caused by pile-soil interaction (PSI) may result in unwanted resonance and serious O&M (Operation and Maintenance) issues, which have been identified as major challenges in the research field. Therefore, a novel model updating framework with an implicit objective function is proposed to monitor both the stiffness and damping variation of the OWT system based on the measured vibration characteristics, which is further verified by laboratory tests. In particular, layered soil was considered in the tests to simulate the practical soil conditions of Chinese seas. Different pile lengths were introduced to consider the long-term PSI effects for rigid piles and slender piles. The results showed that the variation in the fundamental frequency is significantly reduced in layered soil compared with the pure sand scenario. For the OWT systems in layered soil, the variation in foundation stiffness is negatively related to the burial depth under cyclic loading. The proposed model updating framework is proven reliable for support condition monitoring of OWT systems in complicated soil conditions.     

Intelligent VIV control of 2DOF sprung cylinder in laminar shear-thinning and shear-thickening cross-flow based on self-tuning fuzzy PID algorithm

A self-tuning fuzzy PID (ST-FPID) control scheme is implemented within a joint interactive (Matlab/Simulink/Fluent) co-simulation framework for effective two degrees of freedom (2DOF) vortex-induced vibration (VIV) control of an elastically-mounted circular cylinder in laminar cross-flow of incompressible non-Newtonian power-law fluids based on the control action of a single transverse force actuator. The model-free controller, which systematically tunes the control parameters online in real time based on given rules, is well-known to be highly advantageous over the previously employed conventional PID controllers. It is particularly capable of handling the intricate non-linear dynamic effects inherent in the complex fluid rheology of non-Newtonian flow past the cylinder in presence of unmodeled system dynamics, high parametric uncertainties, diverse operational conditions, and time-varying external disturbances and control signals. Extensive numerical simulations reveal that the complex shear-thinning and shear-thickening behaviors of fluid viscosity can substantially influence the cylinder dynamic response, applied hydrodynamic forces, and flow structure. In particular, effectiveness and high performance of the adopted ST-FPID control strategy in substantial suppression of the high amplitude coupled 2DOF VIV of the elastically-mounted cylinder at selected critical reduced velocities in the lock-in region are established for a wide range of power-law index parameters (e.g., up to 83% reduction in RMS value of cylinder cross-flow displacement and up to 35% reduction in RMS value of cylinder in-line displacement for n=1and U* = 5 at Re = 100). Also, the vigorous action of the error-driven ST-FPID controller in forcing the high strength vortex shedding patterns of the uncontrolled cylinder out of the lock-in condition into the classical von Kármán vortex street of 2S-type mode of moderately weaker strengths is verified.     

Long marine shafting alignment and optimization considering propeller hydrodynamic force in wake field北大核心CSCD

[目的]针对计入螺旋桨水动力的舰船轴系校中计算,传统方法通常容易忽略船体伴流场的影响,使得螺旋桨水动力计算的结果与真实值之间存在较大偏差,从而导致轴系校中精度下降。[方法]以某舰船长轴系为对象,建立桨-轴-船一体化有限元模型及其伴流场流域模型,利用CFD数值仿真的叠模方法计算螺旋桨水动力;采用流固耦合法将流体计算结果作用于螺旋桨表面,进行轴系校中计算,并得到螺旋桨水动力对轴系整体挠曲线及各轴承状态参数的影响规律。在此基础上,引入多目标优化算法开展轴系多目标优化校中,来解决轴系末端四套轴承间载荷差值过大的问题。[结果]考虑螺旋桨水动力后,轴系尾部挠度变化减小,越靠近螺旋桨处的轴承其载荷所受影响越大,载荷值随进速系数的增大而减小;对比多目标优化前后的轴系校中状态,轴系各轴承之间的载荷差值明显减小,轴系运行状态得到改善。[结论]所提方法提高了计入螺旋桨水动力的轴系校中计算精度,可为轴系校中质量的提升提供参考。     

考虑固液二相互态特性的流固耦合模型

为研究岩土体内的流固耦合作用对道路工程中道路建筑物/构筑物的变形和沉降，聚焦于构建考虑固液二相互态特性的流固耦合模型，首先构建以含水率为参数的固相物性参数方程（弹性模量、体积模量、极限偏应力）和以孔隙比为参数的液相物性参数方程（饱和含水率、残余含水率、Gardner模型参数），其次建立考虑固液二相互态影响的固相本构方程（邓肯-张模型）和液相本构方程（Gardner模型），之后将新构建的本构方程与固液二相控制方程联合使用构建出考虑固液二相互态特性影响的流固耦合模型。以非饱和黄土为研究对象，利用数值模拟软件构建考虑固液二相互态影响的非饱和土流固耦合数值模型，探索固液二相互态特性对非饱和土流固耦合影响机制。研究结果表明：随着含水率的增大，固相物性参数（弹性模量、体积模量、极限偏应力）均呈减小的趋势；含水率增大使得土体强度减小，表现为达到相同的应变，土体的应力减小；含水率增大，相同的变形情况下，土体所承受的荷载变小。随着孔隙比的增加，饱和含水率线性增加，残余含水率线性减小，Gardner模型参数β呈指数减小，土体内有效饱和度也随之增加；孔隙比增大还会导致土体饱和渗透能力的减小，非饱和相对渗透系数增加。在相同的载荷条件下，相较于未考虑互态影响的流固耦合模型，考虑互态影响的模型模拟的土体变形量较大，含水率、压力水头较小。     

Modeling and calculation of acoustic radiation of underwater stiffened cylindrical shells treated with local damping

Damping materials are widely used and playing an essential role in reducing the vibration and noise of various ships and underwater vehicles. In practical engineering, damping materials are often applied over the structural surface of ships and underwater vehicles. They are generally distributed not evenly in the whole area, but locally in some vital regions. The stiffened cylindrical shell is the most representative configuration for the main structure of underwater vehicles. Therefore, research on modeling and calculation of underwater acoustic radiation from stiffened cylindrical shells locally treated with damping has high practical value. This paper introduces a mixed analytical-numerical acoustic-vibration interaction method to achieve efficient calculation of the vibration and acoustic radiation from a locally damped cylindrical shell immersed in water. Two kinds of vibration and noise reduction measures are proposed for the damping treatment of a large-scale stiffened cylindrical shell structure. Calculation and analysis are carried out for both measures. The results can provide reference for developing the technology of reducing vibration and noise from ships and underwater vehicles via damping treatment.