复杂界面(界面层)条件下的弹性波传播问题研究综述

界面（界面层）广泛存在于各种材料和结构中,并具有千差万别的形态．各种界面条件下的波动问题有着重要的理论与实际意义．综述了完好粘接界面、弱连接界面（或界面层）以及接触界面等复杂界面模型下弹性波传播问题的研究现状,主要集中于界面模型的建立、波传播问题的研究方法及主要结论．并提出了值得进一步研究的问题．     

爆炸焊接复合界面波与温度场物质点法分析

爆炸焊接是一门双金属复合工程技术,在炸药爆轰载荷驱动下,飞板高速冲击基板时,两金属板复合界面处在高温高压作用下材料发生塑性流动并形成周期性波状界面,波状界面的形成与复合界面处的材料熔化和变形直接相关。本文应用物质点法对爆炸焊接界面波的形成和界面温度场进行数值模拟,同时开展双金属爆炸焊接实验,并结合物质点法的三维数值模拟对爆炸焊接界面波的形态和界面材料高温软化进行分析。     

波动方程数值模拟的一种显式方法——-界面节点公式的构建

针对成层介质中标量波动的数值模拟, 基于波速有限原理和波动方程柯西问题的解, 导出了界面点在一个短时间窗内的精确解, 由此给出了具有高阶精度的界面节点显式递推公式的一种构建方法, 并以构造弹性杆界面节点的递推公式为例说明其要点. 给出了与已有内节点递推公式的精度阶匹配的二阶和四阶界面节点递推公式. 由此构成的计算格式具有``异质格式'编程简便的特性, 更合理地考虑了界面影响. 最后, 通过数值试验检验这一匹配方案的精度和稳定性.      

爆炸焊接界面波的数值模拟

借助动力学分析软件ANSYS/LS-DYNA 11.0,运用光滑粒子流体动力学方法(SPH方法),建立以Johnson-Cook材料模型和Grüneisen状态方程为基础的热塑性流体力学模型,对同种钢板爆炸焊接界面波进行了数值模拟.结果表明,运用SPH方法可以得到清晰的爆炸焊接界面波形貌.与实验结果的比较表明:模拟误...     

Dynamic effective property of fibrous piezoelectric composites with spring- or membrane-type imperfect interfaces

The present paper studies the dynamic effective property of piezoelectric composites embedded with cylindrical piezoelectric fibers under anti-plane harmonic electro-elastic waves. By using the dynamic generalized self-consistent method (DGSM) of electro-elastic coupling wave, the problem of randomly distributed cylindrical fibers in a piezoelectric medium can be analyzed in terms of a representative volume element with a coated fiber embedded in an equivalent effective medium. The interfaces between the fibers and the matrix are assumed to be imperfect which are here modeled as spring- or membrane-type interfaces. Through wave function expansion method and an iterative method, the effective piezoelectrically stiffened shear modulus and the effective wave number are obtained. Examples are conducted to verify the present solutions and to illustrate the dependence of the effective piezoelectrically stiffened shear modulus on the wave number (frequency) as well as the interface properties. The special size effect related to interfacial imperfection is also discussed.     

激波诱导下的气体界面不稳定性实验研究

界面不稳定性, 特别是Richtmyer–Meshkov (RM) 不稳定性, 是流体
力学中一项重要的研究内容, 无论在学术研究领域还是工程应用领域都有着
重要的研究价值和应用背景. RM 不稳定性问题自提出以来, 得到了学术界
广泛的关注, 其研究无论是在实验方法、数值模拟还是在理论分析方面都取
得了很大的进展. 在激波管中开展激波与界面相互作用的实验研究, 即研究
界面初始扰动在激波诱导下的演化规律, 是目前研究RM 不稳定性的重要手
段. RM 不稳定性实验研究包括3 个部分, 分别是激波的产生、界面的形成
以及流场的观测. 综述了RM 不稳定性的实验研究进展, 并针对目前研究的
局限性提出了RM 不稳定性今后实验研究的重点和方向: 汇聚激波作用下界
面不稳定性的发展规律; 激波冲击下多种形状及大振幅界面的演化机理; 三
维界面的RM 不稳定性发展规律; 可压缩湍流的形成与混合机理.      

柱形汇聚激波冲击球形重气体界面的实验研究

采用高速纹影法实验研究了柱形汇聚激波与球形重气体界面相互作用的 Richtmyer-Meshkov不稳定性问题. 激波管实验段基于激波动力学理论设计, 将马赫数为1.2 的平面激波转化为柱形汇聚激波, 气体界面由肥皂膜分隔六氟化硫(内)和空气(外)得到. 采用高速摄影机在单次实验中拍摄激波运动的全过程, 对柱形激波的形成进行了实验验证, 并进一步观测了汇聚激波与球形气体界面相互作用过程中的波系发展和气体界面变形以及反射激波同已变形界面二次作用的流场演化. 结果表明: 当柱形汇聚激波穿过气泡界面以后, 气泡左侧界面极点沿激波传播方向保持匀速运动, 气泡右侧界面发展成为射流结构, 气泡主体发展成为涡环结构; 在反射激波的二次作用下, 流场中无序运动显著增强并很快进入湍流混合阶段.     

Anti-plane waves near an interface between two piezoelectric half-spaces

We show the existence of certain new waves that can propagate near an interface between two half-spaces of different piezoelectric ceramics, where the interface is modeled by a membrane with the surface/interface elasticity [1]. The current configuration can be reduced into a number of well-known results as special cases, such as Love wave, Bleustein and Gulyaev wave. Together with our previous work for the imperfect interface [2], a full range of consideration of the interface affecting the anti-plane waves is now completed.     

A shock-tube study of the formation of stagnation parameters in N2O gas dynamic lasers

The main regularities of the formation of conditions behind the reflected shock wave in a shock tube in presence of chemical reactions are studied. The dependence of the parameters of supersonic flows on the conditions at the nozzle inlet is discussed.     

两相流中密度波现象的研究及进展

密度波（又称连续波、空隙度波、运动学波）是两相流中的特殊现象，本文评述两相流密度波理论的主要研究进展，这些理论不仅研究了线性密度波和非线性密度波的特性，还研究了气液两相流的流型转变与密度波的关系，流化床中气塞的形成和床层的塌陷现象与密度波的关系等．同时介绍试验和理论研究在密度波的波速、频率、稳定性和色散性等方面取得的主要结论．最后指出密度波的理论和试验研究尚需进一步解决的问题．     

关于水气界面处的气体传输

水气界面处的气体传输问题由于其对于地球大气中温室效应气体收支的重要意义,近年来受到广泛的关注．综述国际上在水气界面处传质研究的新进展,在简评各种基本的传质模型基础上,着重介绍在剪切水气界面附近湍流相干结构及其与气体传输的关系方面的一些新发现、新观点．对于实际海气界面气体传输的若干机制进行了评述．为实际估算海气界面处气体传输速度的目的,建议了一种综合考虑剪切与波破碎两种机制的气体传输复合计算方法,得到与实测较满意的符合．      

One-dimensional linear elastic waves at moving property interface

Smart materials exhibit time-varying properties while time-varying external field is applied. To investigate the one-dimensional (1-D) homogeneous time-varying properties, a moving property interface (MPI) model is proposed, and the propagation of linear elastic waves at 1-D MPI is studied in this paper. Based on the idea of weak solutions and an infinity approximation, a novel method to deal with the difficulties in using the continuities to study the waves at MPI is also proposed. Some interesting phenomena are revealed: (i) besides wave impedance, the property interface motion and wave velocity are also very important factors that influence the wave propagation; (ii) at MPI, there may exist shock waves; (iii) the property interface motion has a significant impact on the wave frequency and energy. This research provides a theoretical viewpoint in the study of smart materials with a time-dependent mechanical properties at different loading conditions.     

浮泥对非线性波的运动响应简

将浮泥作为高黏度牛顿流体,与水体构成互不相混的两相流体,基于垂向二维RANS 方程(Reynolds-averaged Navier-Stokes)、SST 湍流模式(shear-stress transport),利用流体体积法(volume of fluid,VOF),结合数值造波、消波技术模拟波浪,建立了波泥耦合运动的数学模型,研究了线性波、Stokes波和椭余波作用下,浮泥界面的运动响应. 发现在各种波浪条件下,界面位移与表面位移间有相近的波形,两者间存在相位差,其值随周期和波高的变化不大;界面波高基本正比于表面波高,它随周期的增长呈单调增大的趋势.     

流动肥皂膜气体界面及其在柱状汇聚激波作用下演化的实验研究

在Richtmyer-Meshkov(RM)不稳定性实验研究中,形成两种不同密度流体的初始扰动界面是前提和关健.本文提出了一种流动肥皂膜气体界面生成方法,其工作原理是由细丝构成的导流框从激波管实验段穿过,肥皂液从导流框的上端注入并在重力作用下在导流框中形成流动肥皂膜,膜的两测可以分别充入不同密度的气体从而形成稳定的气体...     

界面上应力波传播规律的动态光弹性试验研究

采用动态光弹性方法,对应力波在杆-杆和板-板双材料连接界面上的反射和透射传播规律展开研究．通过对双材料粘接模型施加冲击载荷作用,采集和分析等差线条纹,计算出最大剪应力值．对于两种试验模型应力波在界面上都以透射为主,对应力波的阻隔作用不明显,这与接触式界面对应力波有较强的阻隔作用有较大区别,在应用界面减弱应力波的作用时应注意区分．试验结果与理论计算结果基本保持一致,并由此证明采用动态光弹性法研究应力波在界面上传播规律的可行性．     

弹性波与单侧界裂纹相互作用问题的边界元法

措助边界元法设计了一种迭代修正方法来求解单侧界面裂纹模型与弹性波的相互作用问题,作为对算法的检验,用这种方法我们具体地分析了平面简谐弹性波对一个则界面裂纹的入射,给出了裂纹面的接触形态及应力场。     

Detonation interaction with a diffuse interface and subsequent chemical reaction

We have investigated the interaction of a detonation with an interface separating a combustible from an oxidizing mixture. The ethylene-oxygen combustible mixture had a fuel-rich composition to promote secondary combustion with the oxidizer in the turbulent mixing zone that resulted from the interaction. Diffuse interfaces were created by the formation of a gravity current using a sliding valve that initially separated the test gas and combustible mixture. Opening the valve allowed a gravity current to develop before the detonation was initiated. By varying the delay between opening the valve and initiating the detonation it was possible to achieve a wide range of interface conditions. The interface orientation and thickness with respect to the detonation wave have a profound effect on the outcome of the interaction. Diffuse interfaces result in curved detonation waves with a transmitted shock and following turbulent mixing zone. The impulse was measured to quantify the degree of secondary combustion, which accounted for 1–5% of the total impulse. A model was developed that estimated the volume expansion of a fluid element due to combustion in the turbulent mixing zone and predicted the resulting impulse increment.      

On the Motion of Shock Waves at a Constant Speed in Multimodulus Elastic Media

For piecewise linear models of multimodulus elastic media, exact analytical solutions of one-dimensional dynamic deformation problemswith plane or sphericalwave surfaces are presented. Compression-extension regimes with the appearance of a centered Riemann wave and extensioncompression with formation of a shock wave are considered. As the main solution method for the compression phase, we use the method of inverse determination of the boundary condition from known information on the nature ofmotion of the shock wave. Essential qualitative differences of the solutions obtained from the corresponding classical results for linearly elastic media are especially important in the study of the dynamics of porous and cohesive granular media.     

一般各向异性单侧接触界面上波的反射和折射

研究简谐弹性波在一般各向异性介质单侧接触界面上的反射和折射问题．利用Fouier分析方法将非线性Coulomb摩擦接触边界波动问题化为一组代数方程．给出了确定局部分离、滑移和粘着区的思路和方法及各区域的解；讨论了出现界面局部分离和滑移的条件．对特定材料组合情况进行了详细数值计算，给出了界面力、相对滑移速度、张开位移、高频谐波的反射折射系数等特征参量；考察了平面和反平面波动的耦合及整体滑移等．其中关于高频谐波的结果可对已有实验结果给出很好的定性解释．在大多数情况下，即使对摩擦系数无穷大的粘滞接触界面，分离区端部也总是存在一个很小的滑移区。