共查询到20条相似文献,搜索用时 171 毫秒
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以某在建的斜拉桥为例,通过对液体粘滞阻尼器的阻尼参数的优化设计,选取出合理的阻尼参数,计算分析了液体粘滞阻尼器对大跨度斜拉桥纵向地震反应的影响,结果表明,液体粘滞阻尼器可以有效地控制大跨度斜拉桥结构的地震位移反应和内力反应,具有较好的耗能减震效果。 相似文献
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《江苏科技大学学报(社会科学版)》2015,(4)
粘弹性阻尼器是一种常用的被动减震装置,其耗能特性主要受温度、频率和应变幅值的影响.文中介绍粘弹性阻尼器的基本结构和工作机理,根据分数微分模型进行数值计算,编制电算程序,分别改变程序中温度、频率和应变幅值,根据所得的滞回曲线计算储存刚度、损失刚度和损失系数,讨论3种相关因素的影响,据此评定粘弹性阻尼器的软化特性和耗能能力. 相似文献
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《舰船科学技术》2021,43(12)
传统船舶动力机械钢丝绳减震装置,存在变载荷环境下的减震系数控制误差较大的问题,导致状态整体减震效果降低。为了解决上述问题,提出变载荷下船舶动力机械钢丝绳减震装置设计。装置设计主要分为结构硬件设计部分与减震控制算法设计部分:结构硬件指PID控制器功能结构设计,框架采用PID隔震控制器结构,利用多种数据传感单元构建PID控制器;软件部分由隔震变量应用环境算法与PID模糊控制算法两部分。分别对控制器应用环境与控制精度进行针对性优化计算,从而实现准确控制不同变载荷环境下的减震系数,达到最佳的减震效果。通过实例数据比对发现,采用设计装置的减震曲线相较传统减震装置的减震曲线,平滑度更好,且没有畸变现象的出现,证明控制精准度与稳定性良好。 相似文献
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Zhi-Min Chen 《Journal of Marine Science and Technology》2013,18(2):182-191
A dissipative free-surface approach is applied to the potential flow problem with respect to a hydrofoil in a two-dimensional uniform stream. A dissipative source-based panel method is developed for a NACA foil problem with its trailing edge being a stagnation point, and also for a symmetric Joukowski foil problem with its trailing edge being a non-stagnation point. To facilitate the understanding of the further application of the dissipative free-surface approach, an underwater mathematical body model is presented. Numerical simulation with respect to the body in a three-dimensional uniform stream is provided from an analytic formulation obtained by the dissipative free-surface technique. 相似文献
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海洋平台在作业过程中存在遭受船舶碰撞的潜在危险,一旦事故发生将可能导致结构产生严重损伤从而影响平台的作业安全,因此在平台结构设计阶段考虑其抗撞性能具有重要意义.本文以供应船撞击半潜平台为研究对象,基于碰撞外部动力学分析理论,在浮式平台规范法耗散能计算基础上,运用解析法推导出考虑平台艏摇运动响应的船舶非对心撞击平台耗散能求解方程,同时借鉴船-船碰撞耗散能估算方法,得到一般碰撞场景即考虑船-平台在碰撞过程中相对运动的耗散能解析式,并自编计算耗散能程序,实现船-平台碰撞碰撞耗散能的快速估算.最后通过非线性有限元分析(NLFEA)方法,计算出供应船与平台在碰撞过程产生的应变能并与解析法的算例结果进行对比,结果表明:规范法耗散能估算方法较为保守,不适用于一般碰撞场景下的耗散能估算;本文所提出的耗散能解析法可用于准确可靠地估算相类似船-平台碰撞场景下撞击船的耗散能. 相似文献
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通过严格解主方程求出原子-腔场复合系统密度算符矩阵元,研究了初始处于真空耗散腔中二能级原子偶极压缩和腔场压缩特性。结果表明,在共振相互作用下腔耗对原子和场的压缩都有显著影响,但在非共振相互作用条件下腔耗对原子和场的压缩影响下降. 相似文献
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Water wave impacts on jacket structures would result in heavy impulse loads, which induce strong vibrations because of the low damping characteristics of metallic members. In order to resist the wave-impact and suppress the vibration of structures, a novel steel brace that contains a multilayered multistable (MLMS) column is designed for an adjustable product of sufficient stiffness and high damping. According to finite element simulating, the initial stiffness of the MLMS column was almost same as that of the multistable steel column [1], but the energy dissipation was several times larger than that of this column. To understand the hysteresis mechanism of the MLMS column, we performed a hybrid analysis of multilayer lamination and mixed boundary buckling and noted: the soft layer of the MLMS column conducts the neutral axis and bending stiffness, which controls critical buckling load that decides the highness of the hysteresis loop; the eccentric end caps mediates the loading axis of the MLMS column, which induces in the increment of the postbuckling displacement that broadens the width of the hysteresis loop. So, the displacement-force hysteretic relation of the MLMS column can be effectually adjusted by the appropriate physical parameters of the soft layer and the end caps, which is validated by parameter analysis using FEM. Through FEM simulations, we studied a jacket structure assembled with dissipative braces containing MLMS column, which exhibited a several times increment in the decay rate of impact-induced vibration compared to that of the same jacket platform with existing dissipative columns [1]. This study demonstrated the MLMS column is an effective alternative for obtaining high structural stiffness and high damping in marine engineering. 相似文献
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随着货运量的增大,目前我国正大规模改扩建多线船闸,受枢纽已建建筑物和地形条件限制等多因素影响,新建多线船闸多与已建船闸并排布置,共用引航道。双线船闸共用引航道时,一线船闸充泄水将会影响到另一线船闸引航道水流条件,危及另一线过闸船舶安全及船闸结构安全。结合北江飞来峡船闸水力学模型试验成果,探讨同尺度船闸共用引航道的布置及其对通航水流的影响。结果表明:船闸在错开运行时,通过增大中间辅导墙的扩散角可使水流快速扩散,减小非泄水船闸引航道回流范围和回流强度,可通过优化主辅导墙及下游消能工形式,改善双线船闸引航道水流条件。 相似文献
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提出了一种声场重建的新方法,这种方法适合求解类似椭球的声源产生的声场声逆问题.视问题的复杂程度和已知声压的点把整个声场划分为若干个区域,把区域内的声场表示为该区域节点的线性叠加.通过已知声压点的方程联立,使用最小二乘法和奇异值分解来计算区域节点的近似声压,然后就可以确定整个区域的声场.这种新方法只需要较少的测量点,就能高效并且比较精确地重建整个声场,其适用范围不仅可以包括一般的球状声源、椭球声源,而且能够包括近似类椭球声源的声场重构. 相似文献
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This paper considers the problem of ship hydroelasticity, which is an important technical issue in the design of ultra-large vessels. For the analysis of fluid-structure interaction problems, a partitioned method is applied. The fluid domain surrounding a flexible body is solved using a B-spline Rankine panel method, and the structural domain is handled with a three-dimensional finite element method. The two distinct methods are fully coupled in the time domain by using an implicit iterative scheme. The numerical results of natural frequency and the motion responses of simple and segmented barges are computed to validate the present method through comparisons with experimental and numerical results. This study extends to the application to two real ships, 6500 TEU and 10,000 TEU containerships, for more validation and also observation on the practicality of the present method. Based on this study, it is found that the present method provides reliable solutions to linear ship hydroelasticity problems. 相似文献
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参数横摇是船舶因复原特性改变而引起的典型非线性现象。文章采用三维时域方法预报规则迎浪中船舶的参数横摇运动。该方法引入匹配面将流域分为内域和外域,内域中采用Rankine源来满足物面条件和线性自由面条件,而外域中应用时域格林函数来满足线性自由面条件和远场辐射条件。数值方法中,Froude-Krylov力和恢复力是通过对船舶瞬时湿表面积积分获得,同时考虑了横摇、垂荡和纵摇三自由度之间的耦合作用,以及非线性横摇阻尼的影响。数值结果与试验结果吻合很好,说明该方法可以有效地预报参数横摇。 相似文献
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文章采用一种改进的傅里叶级数方法(Improved Fourier Series Method,IFSM)对弹性支撑边界条件下多跨距变轴颈轴系进行了回旋振动动态特性研究。首先推导了考虑集中质量及回旋效应的均匀梁回旋振动微分方程;其次应用一种改进的傅里叶级数方法推导了轴系的质量、刚度及激励力矩阵。在这一方法中,位移函数被表示为傅里叶余弦级数展开与一个辅助的多项式函数的叠加,进而成功地克服了弹性边界的不连续性。采用Newmark方法在时域内直接数值积分求解响应。通过与有限元软件ANSYS仿真结果及国家标准的结果对比,验证了文中分析方法的正确性。并研究了一轴系在额定转速下正逆回旋的动态特性。 相似文献
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In the previous paper, one of the authors proposed a new time-domain nonlinear strip method for a rigid body, in which hydrodynamic
forces are evaluated by a convolution integral with the memory function computed for the instantaneous submerged part of the
transverse sections, and the Froude–Krylov and hydrostatic forces are evaluated on the instantaneous wetted hull surface.
In this paper, first, that nonlinear strip method is extended for an elastic body using a method of superposition of elastic
mode functions, which enabled us to investigate whipping phenomena due to impulsive large waves. Second, the influence of
different approximations of the pressure above the still-water surface is investigated, and then the results calculated by
the proposed nonlinear strip method are compared with the experimental ones. Third, whipping phenomena observed for an elastic
body at higher Froude numbers are studied through a comparison between computed and measured results. Higher-frequency vibrations
in the vertical bending moment due to slamming are discussed. Furthermore, the wave load due to green water on deck is calculated
by introducing a practical model, and the effects of the green water on responses of both rigid and elastic bodies are investigated. 相似文献