海洋平台的冰力谱与冰振响应分析

利用原型结构的直接冰力测量数据,建立了锥体结构的冰力谱模型.利用渤海辽东湾的JZ20-2MUQ平台对锥体冰力谱模型进行了验证.为了降低误差,在结构模型分析中,利用实测平台振动数据确定了平台的综合阻尼系数.利用谱分析方法计算了不同冰厚与冰速下的结构甲板振动响应,并与实测的结果进行了比较.结果表明,计算与实测的结构振动响应吻合的比较好,说明了建立的冰力谱模型具有实用性.     

平台结构在冰激励下的平移和扭转耦合共振

用多尺度方法对冰、桩土与海洋平台系统的偏微分非线性动力学模型（见第１部分）进行了摄动分析，发现此系统存在多种组合共振现象，其固有振动频率与模型平台实测结果相符。在主参数内共振条件下，文章讨论了在不同振在型（自激、锁定、强迫）下它的非线性动力学特性，计算结果说明在某冰速范围内模型平台将产生跳跃性的剧烈振动，这与现场观察到的冰激平台共振的现象一致，本文解释了冰激振动的机理，因此为海洋平台结构系统的非线     

码头动力特性现场测试方法研究

码头的动力特性的变化直接影响到码头的安全运行。实测码头的动力特性具有重要意义。通过四种不同的现场检测方法的研究和分析，确定了不同方法的使用范围。说明现场检测的方法可以有效地确定码头的动力特性。     

基于实验研究的轧机垂扭耦合振动分析

以承钢1780热连轧机组的R1为研究对象,依据多自由度系统振动理论,提出了一种垂扭耦合动力学模型的建模方法,建立了R1的垂扭耦合振动微分方程;并结合现场实测数据,确定了系统的耦合系数;分别计算了该轧机垂振、扭振、垂扭耦合振动的固有频率,并进行了比较。分析了考虑耦合振动系统时,轧机固有频率的变化情况,给出了R1垂扭耦合振动的前15阶固有频率。通过对咬钢激励情况下垂扭耦合系统的动态响应分析,分别计算了上下辊系扭振与垂振的最大振幅。通过对振动幅值的比较,论证了扭振与垂振之间的影响程度,并通过现场实测对理论分析结果进行了验证。     

城市道路交通诱发建筑结构振动的实测和数值模拟

为了研究城市道路诱发的环境振动问题，首先对某城市道路交通引起的周围建筑结构振动进行现场实测，并对实测数据进行峰值、功率谱、加速度振级分析，然后建立实测建筑结构的有限元模型，最后分析总结出城市道路环境振动对建筑物的影响及其在结构中的传播规律。实测分析表明：各种交通振源诱发的环境振动的频率范围不同，对于一些对环境振动敏感的特殊建筑，在进行结构振动设计时应综合考虑结构所在地环境振动特点和结构自身动力特性，以满足分频限值评价标准的要求，除考虑竖向环境振动外，还需考虑水平向；有限元分析结果能够给出振动在结构内的传播规律，可用于对结构受环境振动影响的定性分析和敏感性分析；实测和数值分析结果表明：不论是加速峰值还是加速度振级，竖向幅值均随楼层的增加而单调增加，但水平向幅值并不随楼层的增加而单调增加。     

复摆式爆炸振动参数测量仪及其测试方法

本文主要介绍了一种爆炸振动测量仪702型拾振器及其测试方法。大量试验及现场实测表明,该测量仪性能良好,能满足目前工程精度要求。     

弹性薄板结构的等效激励谱反演问题研究

在声纳基阵腔内机械自噪声预报问题的研究中,确定平台区激励一直是个难题,考虑振源设备激励向声纳部位传播过程的复杂性,通过测量平台区振动响应对其外部激励情况进行估算是最具可行性的一种方法。本文根据弹性薄板结构的振动模态理论和简支边矩形薄板的Navier解法,详细探讨了在外部激励的分布状态未知或难以确定的情况下,基于响应相似原则进行等效激励虚拟假设,利用实测板壳结构振动响应和模态参数对等效激励进行反演计算的一般原理方法,分别用解析法和有限元法对等效激励估计实验方案中影响结果可靠性的主要因素进行了分析论证。结果表明,等效激励法是一种适用于激励作用位置缺失情况下,可靠的便于工程应用的环境激励反演评估方法。     

弹性薄板结构的等效激励谱反演问题研究

在声纳基阵腔内机械自噪声预报问题的研究中,确定平台区激励一直是个难题,考虑振源设备激励向声纳部位传播过程的复杂性,通过测量平台区振动响应对其外部激励情况进行估算是最具可行性的一种方法。本文根据弹性薄板结构的振动模态理论和简支边矩形薄板的Navier解法,详细探讨了在外部激励的分布状态未知或难以确定的情况下,基于响应相似原则进行等效激励虚拟假设,利用实测板壳结构振动响应和模态参数对等效激励进行反演计算的一般原理方法,分别用解析法和有限元法对等效激励估计实验方案中影响结果可靠性的主要因素进行了分析论证。结果表明,等效激励法是一种适用于激励作用位置缺失情况下,可靠的便于工程应用的环境激励反演评估方法。     

大型冷锯机切噪声声功率的预估

通过对大型冷锯机锯切过程中主要声源及受力分析,明确了主要锯切噪声是由锯齿脉冲激励引起锯片和工件的局部高频振动所产生的。并用大型有限元结构分析软件ANSYS计算得到的单元速度值,根据结构振动声辐射理论,对冷锯机的锯切噪声进行了定量预估。从理论预估值与现场锯切噪声实测结果的比较可见,本文所建立的大型冷锯机锯切噪声分析及预估理论是正确的。     

地铁隧道毫秒延时爆破环境振动特性研究

基于地铁隧道毫秒延时爆破环境振动特性现场试验，考虑爆破荷载的不规则特性，采用基于非对称加卸载准则的修正Davidenkov本构模型描述场地土体的动力非线性特性；通过改进Friedlander方程来模拟内源爆炸在圆柱形炮孔表面产生的瞬态空气冲击波；实现了包含毫秒延时爆破荷载输入和有限元-无限元耦合边界的地层-爆源体系三维精细化有限元模型，并与现场实测数据对比验证了该模型方法的有效性。对50 ms延时爆破和齐爆引起的环境振动特性进行了数值模拟，对比发现毫秒延时爆破不仅可以有效降低地表峰值振速，而且可以显著改变地表振动的频谱特性。毫秒延时爆破产生的地表振动频带较集中，对分散爆破振动能量的作用显著，且地表速度响应的主频较高，远离建筑结构自振频率，可显著降低爆破施工引起的邻近建筑物的结构振动水平。     

Preface: Current research progress on mechanics of high speed rail

The construction and operation of high-speed rail（HSR）grid within the past two decades in China,in terms of the scale,may be possibly comparable to any national-wide construction in the history of China,even the Great Wall.By counting railways with commercial train service at the speed of200 km/h,China has the world’s longest HSR network with over 19 369.8 km of track in service today and this number     

ACTA MECHANICA SINICA 2014 ANNUAL SUBJECT INDEX

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人造地震动合成中的位移误差分析

三角函数级数法是合成人工地震动常用算法之一,但是通过对加速度积分求取位移时,却存在与零线漂移相类似的位移漂移现象。     

Hermitian space-time finite elements for estuarine mass transport

Space-time finite element solutions of the convection–dispersion equation using higher-order nodal continuity and Hermitian polynomial shape functions are described. Five separate elements ranging from a complete linear element with C^0,0 nodal continuity to a complete first-order Hermitian element with C^1,1 nodal continuity are subjected to detailed analysis. Wave deformation analyses identify the source of leading or trailing edge oscillations, trailing edge oscillations being the major source of difficulty. These observations are confirmed by numerical experiments which further demonstrate the potential of higher-order nodal continuity. The performance of the complete first-order Hermitian element is quite satisfactory and measurably superior to the linear element.     

Rainwater rivulets on a cable subject to windFilets d'eau de pluie sur un câble soumis au vent

Rainwater rivulets appear on inclined cables of cable-stayed bridges when wind and rain occur simultaneously. In a restricted range of parameters this is known to cause vibrations of high amplitudes on the cable. The mechanism underlying this effect is still under debate but the role of rainwater rivulets is certain. We use a standard lubrication model to analyse the dynamics of a water film on a cylinder under the effect of gravity and wind load. A simple criterion is then proposed for the appearance and position of rivulets, where the Froude number is the control parameter. Experiments with several geometries of cylinder covered with water in a wind tunnel show the evolution of the rivulets with the Froude number. Comparison of the prediction by the model with these experimental data shows that the main mechanism of rivulet formation and positioning is captured. To cite this article: C. Lemaitre et al., C. R. Mecanique 334 (2006).     

Cristallisation par onde acoustique : le cas de l'héliumCrystallization by acoustic waves: the case of helium

We establish a theoretical model to explain the nucleation of a crystal of helium by an acoustic over-pressure. We explain the interfacial laws for this ultra-fast cristallization, close to the sound speed. Assuming spherical symmetry and taking into account the experimental data, we recover the dynamics of the growth and melting during an over-pressure impulse. To cite this article: M. Ben Amar et al., C. R. Mecanique 331 (2003).     

Structure initiale et propriétés de liquéfaction statique d'un sableInitial structure and static liquefaction properties of sand.

Based on the use of two different preparation procedures for reconstituting triaxial samples of sand, i.e. wet tamping and dry pluviation, significant differences in associated mechanical behaviour are observed on a reference sand with respect to the phenomenon of ‘static’ liquefaction. Wet tamping favours the initiation of liquefaction instability, whereas dry pluviation favours a more stable behaviour, less susceptible to liquefaction. Microscopic observation of corresponding sand specimens allows us to identify two well differentiated structures, i.e., for wet tamping, an irregular structure with predominance of aggregates (aggregated grains) and macropores, very contractant and unstable and, for dry pluviation, a more regular structure, without macropores, more dilatant and more stable. These observations show the importance of further characterization, based on the introduction of appropriate parameters, of the initial structure of sandy materials, strongly dependant upon their mode of formation (natural or artificial). To cite this article: N. Benahmed et al., C. R. Mecanique 332 (2004).     

INFORMATION FOR CONTRIBUTORS

Contributions： The Journal, Acta Mechanica Solida Sinica, is pleased to receive papers from engineers and scientists working in various aspects of solid mechanics. All contributions are subject to critical review prior to acceptance and publication.     

The 7th International Conference on Fluid Mechanics May 24-27,2015,Qingdao,China

正http://www.icfm7.org First Announcement and Call for PapersThe objective of International Conference on Fluid Mechanics(ICFM)is to provide a forum for researchers to exchange new ideas and recent advances in the fields of theoretical,experimental,computational Fluid Mechanics as well as interdisciplinary subjects.It was successfully convened by the Chinese Society of Theoretical and Applied Mechanics(CSTAM)in Beijing(1987,