珍珠岩声屏障在高速公路上的应用

介绍了目前国内交通噪声治理的常见措施，重点分析了3种类型声屏障的优缺点。根据江阴至太仓高速公路噪声超标的具体情况，设计了珍珠岩声屏障，收到了良好的效果，对今后国内高速公路声屏障设计具有参考价值。     

基于货运强度变化规律的货运量预测方法

目前我国部分地区货运量统计数据存在收集不全、统计口径不一致及社会经济环境变化大等问题,导致常规的时间序列预测法和回归预测法难以在这些地区应用。鉴于此,分析了国内外货运强度变化的规律,指出人均GDP和第三产业所占比例是影响货运强度的主要因子,提出了通过模糊聚类方法对地区货运发展阶段进行定位,找出其发展阶段所对应的货运强度值,进而提出依据人均GDP和第三产业所占比例进行货运量预测的方法。最后对邢台市的货运量预测进行了实证研究。     

船用气水分离器静强度分析技术研究

从计算船用气水分离器静强度、静刚度的分析需要出发,建立了某型气水分离系统的有限元模型.讨论了静强度分析中,边界条件的处理方法,通过流场分析对作用于惯性级的复杂气流激励提出了等效方法,求得了系统在各工作状态下的应力危险区以及变形幅值.并由抗弯刚度的计算结果指出了设计的不足之处,为船用气水分离器的结构优化设计提供了依据.     

基于裂纹扩展理论的船体结构疲劳评估

疲劳破坏是船舶结构的主要破坏形式之一。为了保证船舶结构有足够的疲劳强度,各国船级社、船厂等均建立了船舶结构疲劳强度校核规范作为船舶疲劳评估的指导性文件,尽管这些规范均是建立在S-N曲线方法基础上的,但由于S-N曲线方法存在自身无法克服的缺陷(如忽略材料的初始缺陷等),对同一节点进行计算得到的疲劳寿命大相径庭。该文作者在基于裂纹扩展理论的基础之上,给出了一套详细的船体结构疲劳评估方法,并应用此方法对大型船舶结构典型节点的疲劳寿命进行评估,以期能为完善船舶结构疲劳寿命的评估提供参考。     

计及空腔能量耗散的尖劈结构声学特性研究

以喇叭型空腔为例分析了声波在尖劈空腔中的传播规律,给出了计及空腔能量耗散作用的尖劈结构吸声系数计算方法,通过声管测试验证了本文算法的有效性。在此基础上,通过数值试验预报了声呐平台区振动及自噪声分布,对比分析了空腔尖劈敷设方案对其声学特性的影响。结果表明：空腔对较低频段声波能量吸收有很大作用,在3 kHz以下频段计算空腔尖劈吸声性能时必须予以考虑;敷设空腔尖劈的声呐平台区的振动及自噪声总声压级显著降低,尖劈部分优化敷设既要兼顾声呐基阵位置处的声压压分布。     

界面声波反射特性在船舶甲板装备噪声测试中的应用分析

针对船舶甲板大型装备噪声测试问题,根据声学原理论述了空气-液体、固体二类界面声波反射特性,当液体或固体横波声阻抗与空气声阻抗之比大于等于2000时,声波通过空气到液体或固体界面时,至少99.8%的声能量被反射。在此基础上,对船舶甲板大型装备噪声在陆地上与在船舶甲板上声场中声压级的差异进行了分析。     

波导中带帽圆柱壳的声辐射快速预报(英文)

In order to predict acoustic radiation from a structure in waveguide, a method based on wave superposition is proposed, in which the free-space Green's function is used to match the strength of equivalent sources. In addition, in order to neglect the effect of sound reflection from boundaries, necessary treatment is conducted, which makes the method more efficient. Moreover, this method is combined with the sound propagation algorithms to predict the sound radiated from a cylindrical shell in waveguide. Numerical simulations show the effect of how reflections can be neglected if the distance between the structure and the boundary exceeds the maximum linear dimension of the structure. It also shows that the reflection from the bottom of the waveguide can be approximated by plane wave conditionally. The proposed method is more robust and efficient in computation, which can be used to predict the acoustic radiation in waveguide.     

以实测振动数据为输入的水下结构振动与辐射噪声预报

  目的  潜艇的主要结构形式是环肋圆柱壳,目前关于肋骨对圆柱壳声辐射特性影响的研究大多集中在中、低频,但是振动声学问题涉及到更宽的频率范围。  方法  采用统计能量法研究宽频范围内肋骨对圆柱壳声辐射特性的影响。首先,分析圆柱壳增加肋骨后统计能量参数的变化;然后,研究耐压壳、外壳分别增加肋骨、改变肋骨间距、改变肋骨形状对圆柱壳声辐射特性的影响;最后,分析激振力作用在不同位置时,环肋圆柱壳声辐射特性的差异。  结果  得到了肋骨影响下双层圆柱壳在500 Hz~100 kHz范围内的统计能量参数和辐射噪声变化规律。  结论  研究结果对合理选用肋骨降低潜艇的振动与辐射噪声有一定参考作用。     

回声测深仪计量检定装置的研究

为研究浅水回声测深仪计量检定标准装置,以完成量值传递,文章介绍了2种不同的检定装置,可根据具体环境条件选择水槽比对方式和模拟器方式对回声测深仪进行检定,并对回声测深仪的基本原理、工作流程、2种检定装置的构造、测试结果和优缺点进行了简要的阐述。     

Characteristics and calculation method of sound radiation of cylindrical shell with porous sound-absorbing material under acoustic excitation北大核心CSCD

［Objective］This paper aims to study the characteristics and calculation method of the vibration and sound radiation of single ring-stiffened cylindrical shells with porous fiber composite materials installed in the inner wall under acoustic excitation. ［Method ］ Based on the equivalent fluid theory model of Johnson–Champoux–Allard (JCA) and the transfer matrix of the multilayer medium, a theoretical formula of the sound absorption coefficient of multilayer sound absorption structures is derived. The three methods for calculating the vibration and sound radiation of a single ring-stiffened cylindrical shell with porous fiber materials under acoustic excitation, namely acoustic solid modeling of porous media, finite element model combined with theoretical formula and imposition of impedance boundary on sound absorption coefficient, are then verified and compared. Finally, the influences of sound-absorbing material's thickness, backed-air gap, static flow resistance, and material arrangement order on the acoustic absorption performance of the cylindrical shell are investigated. ［Results］The results show that laying porous fiber composite materials on the cylindrical shell internally can reduce the vibration and acoustic radiation of cylindrical shell structure. The sound absorption coefficient curve can quickly and effectively predict the resulting trend of the vibration and sound radiation of the cylindrical shell. ［Conclusion］The acoustic absorption performance of sound absorption structures can be effectively improved through the rational design of their properties and arrangement order of the sound-absorbing materials in order to achieve the purpose of vibration and noise reduction. © 2023 Chinese Journal of Ship Research. All rights reserved.