共查询到20条相似文献,搜索用时 46 毫秒
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研究黏弹性材料中激光激发的Rayleigh波的传播特征. 考虑到黏弹性材料的黏性特征,在频域内建立黏弹性材料中激光激发Rayleigh波的有限元数值模型. 在验证有限元频域数值模型正确性的基础上,模拟脉冲激光作用在黏弹性材料上激发出Rayleigh波,进而讨论激光激发的黏弹Rayleigh波的传播特征,并比较黏弹性材料与弹性材料中激光激发的Rayleigh波差异,同时分析了材料的黏性劲度参量变化对Rayleigh波特征的影响.
关键词:
表面波
激光超声
有限元方法
黏弹性 相似文献
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本文发展了在压电晶体半空间,对于自由表面和金属化表面两种情况下,弹性波场表面激发的普适理论。可以证明广义弹性波场U是广义Green函数G和广义力T的卷积。 U=GT这里符号表示点乘卷积。 广义Green函数与激发条件无关,而只取决于材料参数和取向。 对于压电晶体,不仅表面力源,而且表面电源分布也能激发弹性波场。我们给出了对于力源和电源分布的广义力完整表示。特别对自由表面上电源分布,它可由表面法向电位移不连续,也可由切向电场不连续来构成。 相似文献
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柱面Love波频散分析与SH波场的数值计算 总被引:1,自引:0,他引:1
对贴井壁环型剪切源在柱状双层弹性介质中激发的SH波场进行了理论求解,导出了柱面Love波频散方程,讨论了柱面Love波存在的条件及其区域.通过数值计算考察了柱面Love波的频散特性和激发强度,发现最低阶柱面Love波具有截止频率,这与平面半空间双层弹性介质模型下的Love波无截止频率的特征不同.渐近分析与数值考察都表明,井径r1→∞时,柱面Love波频散方程趋向平面双层半空间的Love波方程,柱面Love波的截止频率趋于零.全波计算还显示用激发SH波来探测侵入带外原状地层的横波信息是一个十分简洁的途径.. 相似文献
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塑料类高分子材料甲基丙烯酸甲酯-亚克力(PMMA)圆柱中亚音速Rayleigh波低频隧穿共振可引起反向散射增强,在低频标准散射体设计等领域具有重要应用价值.提出一种微弱形变的规则波纹表面结构,可实现水中PMMA圆柱反向散射低频共振频率的无源调控.利用微扰法推导了水中微弱形变规则波纹圆柱反向散射低频共振频率偏移的近似解,讨论了波纹微扰系数、周期对规则波纹圆柱共振频率偏移的影响规律.基于Rayleigh波相位匹配方法分析了低频共振频率偏移的机理.研究表明:微弱形变规则波纹圆柱中亚音速Rayleigh波沿微弱形变波纹表面传播,与光滑圆柱体相比,传播路径的改变引起Rayleigh波传播相位变化,导致了Rayleigh波低频共振频率发生偏移.最后开展了微弱形变规则波纹圆柱体声散射特性水池实验,获取了其反向散射共振频率,明显观察到了规则波纹圆柱共振频率偏移现象,与理论预报结果吻合较好. 相似文献
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论述了视场扩大型成像光谱仪的核心部件——组合Wollaston棱镜的结构和分光机理;应用波法线追迹法分析了光在任意方位入射面内,以任意角入射时组合Wollaston棱镜中的波矢传播规律;推导出了光在棱镜中的传播方向及出射点坐标;给出了传播过程中e光和o光之间光程差的理论表达式;采用计算机模拟,给出了光程差随入射角和入射面方位角的变化曲线;在此基础上对组合Wollaston棱镜扩大光谱仪视场的原理进行了深入分析和讨论.上述研究对偏振干涉成像光谱技术的理论研究与技术创新,对自行设计的稳态大视场偏振干涉成像光谱
关键词:
Wollaston棱镜
偏振干涉成像光谱仪
波法线追迹法
视场扩大原理 相似文献
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地层岩石既非各向同性的,也非完全弹性的,正确地描述波在地层中的传播需要搞清楚岩石的各向异性和黏弹性特征.针对裂缝性地层的裂缝发育方位问题,建立具有任意方位角的方位各向异性黏弹性本构关系.使用均匀平面简谐波分析方法研究其频散关系,得到Christoffel方程,进而获得均匀平面波的复速度、相速度、衰减系数和品质因子的表达式.通过黏弹性方位各向异性页岩和砂岩进行模拟,研究了波场在地层中的传播特征,如相速度、衰减系数和品质因子等随频率、方位和入射角的变化关系
关键词:
黏弹性
各向异性
相速度
衰减系数
品质因子 相似文献
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裂缝检测是目前国内外石油勘探界研究的一个热点问题,如何确定裂缝方位等参数是石油公司面临的难题,而解决该难题就要确定裂缝方位等参数与地震波场传播之间的定量关系.但是目前所采用的裂缝性地层介质模型不能完全定量地反映裂缝的方位特征和衰减特征.针对该问题,建立了具有任意裂缝方位的裂缝性地层介质模型;并构造了时间增量的方法,将非线性的卷积积分采用近似的方法实现,建立了以位移场表示的具有任意方位角的黏弹性方位各向异性介质的波动方程.该波动方程定量地给出了黏弹性波场特征与裂缝走向的关系,描述了黏弹性地震波在这种介质中的
关键词:
裂缝
各向异性
黏弹性
波动方程 相似文献
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A. N. Elsukov 《Russian Physics Journal》1965,8(4):39-42
A rigorous solution is given for modes of TMnmo type. The complex resonant frequency n is expressed via a transcendental characteristic equation. Some particular cases are discussed.Read at the Third All-Union Conference on Ferrites, Leningrad, 23 October 1963. 相似文献
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V. I. Bukreev 《Doklady Physics》2002,47(12):880-882
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Molecular-dynamics was used to investigate the structural changes occurring in a three-dimensional solid when the solid is
transferred from an amorphous into a crystalline state. Crystal cells of a new type — pentadecahedrons with five square lateral
faces and ten regular triangular faces at the vertices of a cell — were found for the first time in a computer experiment.
It is shown that a bistructure consisting of crystal cells of different types, including cells with five-fold symmetry axes,
are stable in the solid.
Fiz. Tverd. Tela (St. Petersburg) 40, 1919–1924 (October 1998) 相似文献
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The existence of surface polaritons in a dielectric at a boundary with an ideal metal or superconductor in a static electric
field is predicted. The frequency regions in which polaritons exist are substantially different for opposite orientations
of the electric field, so that a change in the direction of the field signifies “switching on” or “switching off” of surface
polaritons with a fixed frequency.
Pis'ma Zh. éksp. Teor. Fiz. 68, No. 12, 876–880 (25 December 1998) 相似文献
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Yu. D. Chernichenko 《Physics of Atomic Nuclei》2004,67(2):414-423
Within the relativistic quasipotential approach to quantum field theory, a method is developed for solving a finite-difference quasipotential equation for the case where a total quasipotential describing the interaction of two relativistic spinless particles of unequal masses is a superposition of a nonlocal separable and a local quasipotential. The cases are investigated where the local component of the total interaction—it is assumed to be known—either admits or does not admit the existence of bound states. This makes it possible to obtain an exact expression for the increment of the phase shift, to determine the conditions of the existence of bound states, and to give a generalization of the Levinson theorem. 相似文献
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V. P. Glashchenko 《Technical Physics》2014,59(5):754-761
The conditions under which the nonuniform compensating field of the reflector of the mass-reflectron can be generated with an acceptable accuracy at the symmetry axis of the reflector and extrapolated to the radial neighborhood of the axial line are determined. The plots that illustrate the distribution of the calculated nonuniform field of the reflector, the possibilities for implementation, and errors of focusing with respect to time of flight in the radial neighborhood are presented. Analytical expressions for the calculation of the time of flight of ions in the reflector in which the field distribution is described using a power series and analytical expressions for the calculation of the field distribution in the reflector in which the time of flight is determined using a power series are derived. A method for the analytical calculation of the compensating nonuniform field of the reflector based on the given dependence of the time of flight in the absence of such a field is proposed using a solution to the Abel integral equation. The solution to this equation yields analytical expressions for the calculation of the compensating field of the reflector in mass-reflectrons that contain the zero-field drift space and regions of acceleration (deceleration) of ions with a uniform field. 相似文献