共查询到17条相似文献，搜索用时 46 毫秒
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依托福建省滨海国道涉海浅滩段新型桩板桥梁结构工程,通过波浪水槽开展卷破波冲击桩板桥梁结构水动力特性试验,研究了三个阶段卷破波冲击作用下波浪爬高和桩板桥梁结构所受波浪力水动力特征,并与规则波冲击作用试验结果进行对比,分析了入射波高、波浪周期、水深对波浪爬高和波浪力的影响规律。结果表明：三个阶段卷破波冲击新型桩板桥梁结构的水动力特性显著不同,破碎前阶段和破碎中阶段卷破波会出现明显的波浪爬高现象,破碎前阶段卷破波爬高后的波面高程可达规则波的1.99倍;破碎前阶段的水平波浪力最强,是同阶段竖向波浪力幅值的4.48倍,可达规则波水平波浪力的3.08倍。波浪特征参数和水深对三个阶段卷破波冲击水动力特性影响显著,入射波高和水深的增加会使破碎中阶段卷破波的波面高程和竖向波浪力超过其他阶段;波浪周期的增加会使破碎后阶段卷破波冲击前波面高程和破碎前阶段的竖向波浪力超过破碎中阶段卷破波。 相似文献
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为了评价复杂地震荷载作用下钢筋混凝土(RC)空心桥墩的抗震性能,对3根RC矩形空心桥墩进行了"回型"水平双向反复荷载作用下的拟静力试验,并基于有限元数值分析方法,研究了该类加载制度下RC矩形空心桥墩的水平力-位移滞回曲线,及双向弯曲作用下RC矩形空心截面的弯矩-曲率。分析探讨了轴压比、壁厚、双轴弯曲强度比参数影响下RC矩形空心桥墩的滞回特性、破坏特征和截面受力性能模拟结果,提出了"回型"水平双向加载下RC矩形空心桥墩的滞回曲线模型,该模型考虑了水平双向加载对构件强度、刚度和位移的耦合效应。应用该模型得到的RC矩形空心桥墩的水平力-位移骨架曲线和滞回曲线的计算值与试验结果吻合较好。 相似文献
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为了探究非饱和土地基中波阻板的隔振性能以及提升传统均质波阻板隔振的频宽。基于单相弹性介质理论和非饱和多孔介质理论,对地下动荷载作用下非饱和土地基中双层波阻板的隔振效果进行了研究。利用Fourier积分变换和Helmholtz矢量分解原理,建立了地下动荷载作用下非饱和土地基动力响应的计算列式。分析了双层波阻板各层弹性模量、密度、板厚、埋深、土体饱和度及荷载频率等物理力学参数对双层波阻板隔振性能的影响规律。研究结果表明：通过设计波阻板各层的弹性模量和密度可获得双层波阻板的最佳隔振效果,同等厚度下,双层波阻板的隔振效果要优于均质波阻板。双层波阻板提升了均质波阻板减振的频宽,其对低中高频振动(5 Hz≤f ≤80 Hz)均有良好的隔振效果。双层波阻板的埋深越靠近振源处隔振效果越好,并且存在临界厚度,当波阻板厚度超过其临界厚度时,隔振效果随厚度的增大而减小。土体饱和度对双层波阻板隔振效果影响显著,在低饱和度时双层波阻板可以取得更好的隔振效果。 相似文献
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Breaking waves can run up at the shoreline, inundating coastal regions and causing large property damage and loss of life. In order to proceed to the design of sea defence structures and estimate the possible damage resulting from sea submersion due to a tsunami for instance, it is thus crucial to understand these phenomena. However, due to the mathematical difficulties caused by the complexities of the fluid motion associated with breaking wave, a fully theoretical approach is not possible. Thus most of the investigations regarding breaking waves are experimental and numerical. Some methods were recently developed to perform such simulations, among them Volume Of Fluids (VOF) and Lagrangian methods. In this paper, the gridfree Smoothed Particle Hydrodynamics (SPH) is used. SPH is preferencially used in CFD to simulate complex flows with one or several convoluted free surfaces. Indeed, this type of flows would require distorted meshes with Eulerian finite difference methods or very fine meshes with VOF. The ability of SPH to reproduce a plunging breaking solitary wave and to simulate the different stages of its process is herein investigated. Since breaking waves are characterised by high distorsion, turbulence modelling plays a crucial role in such simulations. Therefore, the turbulence models developed by the authors and presented in earlier publications [relax begingroup catcode ` 12relax catcode `12relax catcode `$12relax catcode `&12relax catcode `#12relax catcode `^12relax catcode `_12relax catcode `%12relax catcode `~12relax endgroup relax cite *{dv_ri:2006}] are here applied. The results, compared to experiments, are on the whole satisfactory, specially the simulation of the splashup phenomenon. Moreover, it is shown that turbulence modelling has a strong influence on the quality of the results. 相似文献
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精确模拟车辆撞击建筑物的受力和变形需建立精细的数值模型并消耗大量的计算时间。但建筑结构防撞设计只针对被撞结构,合理地简化车辆模型能够在保证计算精度的同时提高计算效率。该文首先基于能量守恒原理建立了45°斜向撞击方柱的车辆简化数值模型,并在此基础上分析了撞击方向对柱变形和损伤的影响。分析表明：简化车辆模型能够准确模拟车辆斜向撞击方柱时的撞击力、撞击冲量、柱变形和材料应变响应,同时有效地提高了计算效率;相比正面（90°）撞击,斜向（45°）撞击时车辆变形耗能较小,造成柱损伤和变形更大。 相似文献
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Md. Salah Uddin Afsar Mohammad Rashed Iqbal Faruque Sabirin Abdullah Mohammad Tariqul Islam 《计算机、材料和连续体（英文）》2023,76(1):455-469
This study proposed a new royal crown-shaped polarisation insensitive double negative triple band microwave range electromagnetic metamaterial absorber (MA). The primary purpose of this study is to utilise the exotic characteristics of this perfect metamaterial absorber (PMA) for microwave wireless communications. The fundamental unit cell of the proposed MA consists of two pentagonal-shaped resonators and two inverse C-shaped metallic components surrounded by a split ring resonator (SRR). The bottom thin copper deposit and upper metallic resonator surface are disjoined by an FR-4 dielectric substrate with 1.6 mm thickness. The CST MW studio, a high-frequency electromagnetic simulator has been deployed for numerical simulation of the unit cell in the frequency range of 4 to 14 GHz. In the TE mode, the offered MA structure demonstrated three different absorption peaks at 6.85 GHz (C-band), 8.87 GHz (X-band), and 12.03 GHz (Ku-band), with 96.82%, 99.24%, and 99.43% absorptivity, respectively. The electric field, magnetic field, and surface current distribution were analysed using Maxwell’s-Curl equations, whereas the angle sensitivity was investigated to comprehend the absorption mechanism of the proposed absorber. The numerical results were verified using the Ansys HFSS (high-frequency structure simulator) and ADS (advanced design system) for equivalent circuit models. Moreover, the proposed MA is polarisation and incident angle independent. Hence, the application of this MA can be extended to a great extent, including airborne radar applications, defence, and stealth-coating technology. 相似文献
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海洋环境中的深水桥墩长期受到不规则随机波浪动力作用。传统设计规范中采用的特征波浪计算方法,虽然简单高效,但是无法充分考虑波浪随机性和动力效应对结构的影响。该文以深水桥墩在波浪作用下的动力响应与静力响应之间的概率关系为研究对象,应用贝叶斯更新理论建立简单有效的深水桥墩波浪动力响应概率模型。通过对比深水桥墩动力时程分析结果,验证模型的有效性,并对样本数量和模型形式进行讨论。研究表明：基于贝叶斯更新理论的深水桥墩波浪动力响应概率模型可以快速准确地计算波浪作用下深水桥墩的动力响应,能够有效修正传统静力方法存在的偏差,并可在样本数据非常有限的情况下对深水桥墩的动力响应进行较好估计。 相似文献
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文中建立了沉箱式防波堤弹性振动－摇摆运动分析模型,可对破碎冲击作用下防波堤的弹性振动－摇摆运动过程进行数值模拟。研究了摇摆运动对防波堤位移、转角、滑移力和倾覆力距的影响。结果表明,当倾覆力距大于防波堤的稳定力矩时,防波堤并不一定发生倾倒破坏;只有当防波堤摇摆运动转角大于倾倒的临界角时,防波堤才会发生倾倒破坏。而且摇摆运动可有效减小防波堤的滑移力和倾覆力矩。故在极限设计破碎波浪条件下可考虑允许防波堤出现摇摆运动,以实现更为经济的结构设计。 相似文献
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Zhen Cao Yu Zhu Yang Liu Shurong Dong Xin Chen Fan Bai Shengxin Song Junxue Fu 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(12)
A nanoscale insulator‐based dielectrophoresis (iDEP) technique is developed for rapid enrichment of proteins and highly sensitive immunoassays. Dense arrays of nanorods (NDs) by oblique angle deposition create a super high electric field gradient of 2.6 × 1024 V2 m?3 and the concomitant strong dielectrophoresis force successfully traps small proteins at a bias as low as 5 V. 1800‐fold enrichment of bovine serum albumin protein at a remarkable rate of up to 180‐fold s?1 is achieved using oxide coated Ag nanorod arrays with pre‐patterned sawtooth electrodes. Based on this system, an ultrasensitive immunoassay of mouse immunoglobulin G is demonstrated with a reduction in the limit of detection from 5.8 ng mL?1 (37.6 pM) down to 275.3 fg mL?1 (1.8 f M), compared with identical assays performed on glass plates. This methodology is also applied to detect a cancer biomarker prostate‐specific antigen spiked in human serum with a detection limit of 2.6 ng mL?1. This high sensitivity results from rapid biomarker enrichment and metal enhanced fluorescence through the integration of nanostructures. The concentrated proteins also accelerate binding kinetics and enable signal saturation within 1 min. Given the easy fabrication process, this nanoscale iDEP system provides a highly sensitive detection platform for point‐of‐care diagnostics. 相似文献
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用基于特征线的算子分裂(CBOS)有限元法求解Naiver-Stokes方程：即在每一个时间层上,采用算子分裂法将N-S方程的对流项与扩散项分开求解,对流项离散采用特征线-Galerkin法,显式求解。流体自由表面跟踪采用浓度法,建立了新的水波模型。经过下游河床有水、无水溃坝模型的验证,表明该模型能精确模拟带自由表面流体运动问题。同时,研究了下游河床无水时溃坝模型自由水面运动特征;探讨了下游河床有水时溃坝模型中涌浪波形成原因、波浪翻卷形成过程,并分析了涌浪波与下游河床水体冲击接触瞬间,下游河床压力突然增大这一现象。 相似文献