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1.
IntroductionRecently ,theferroelectricceramicshassuchexcellentcharacteristicsofpiezoelectricityandpyroelectricityetc .thatitbecomesoneofthemostimportantfunctionalmaterials.Forinstance ,thewidelyappliedsensors,transducersandactuatorsetc .aremadeoftheferroe…  相似文献   

2.
IntroductionVibratingobjectsunderwater,suchassubmarineandtorpedo ,transmitnoisetowardsexternalsoundfield ,formachineryvibrationofinsidepowerapparatus.Itwillenhancegreatlytheconcealmentofsubmarineandtorpedoandenforcefightingpowerbycontrollingnoiseofsubma…  相似文献   

3.
Thedifferentialquadraturemethod(DQM)proposedbyR.Bellman[1,2]hasbeensuccessfullyemployedinnumericalcomputationsofproblemsinengineeringandphysicalscience.BecausetheinformationonallgridpointsisusedtofitthederivativesatgridpointsintheDQM,itisenoughtoobta…  相似文献   

4.
IntroductionMuchfamiliarinengineeringareelasticfoundationplates,suchasfoundationbaseplatesincivilengineering,highwaysurface,r...  相似文献   

5.
IntroductionTurbulentflowisanonlinearstochasticprocessandoneofitsbasiccharacteristicsislargereffectivetransportcapabilitythanthatoflaminarflow .Ingeneral,transportinfluidsisgradient,i.e.momentum ,energyaretransportedfromthehighervalueregiontothelowervalu…  相似文献   

6.
IntroductionTheoilformationinsedimentbasins,itsdisplacement,transportandaccumulation,andthefinalformationofoildepositshavebeenthekeyproblemsintheexplorationofoil_gasresources.Howhasoilbeenaccumulatedinthepresentloopaccordingtothemechanicsofimmiscible…  相似文献   

7.
IntroductionThin_walledshellhasmanyappliancesinengineeringsuchasundergroundpipe,outershellofsubmarinewhichareusuallysubjectedtoexternalpressure .Whendesigningthosestructuresweshouldconsidernotonlythestrengthprobleminservice ,butalsothebucklingproblemun…  相似文献   

8.
IntroductionAsearlyas1895,Blackstudiedthephysicalbehaviorofhumanteeth[1].Since1950thestudies Fig.1onmechanicalpropertiesofhumanteethhaveappearedinjournalsandmagazinessuccessively[2~13].Humanteethareverysmallandthespecimensusedfortestingareevensmaller…  相似文献   

9.
IntroductionSwirlingflow (orspiralflow )iswidelyusedinindustry ,e.g .injettechnology ;combustiontechnology ;cyclone/hydrocycloneseparators;pneumatictransportationetc .Swirliscommonlyimpartedtoflowsenteringfurnacesandcombustorsinordertoenhanceflamestabilityan…  相似文献   

10.
IntroductionWiththerapiddevelopmentofthescienceandtechnology ,moreandmorecomplexmechanismandstructuresareputintouse,suchasflexiblerobot,flexiblearm ,aircraftandspacestation .Researcherspaymoreattentiontotheproblemofeffectivedynamicdetectionandcontrolofsu…  相似文献   

11.
Based on the theory of porous media,a general Gurtin variational principle for theinitial boundary value problem of dynamical response of fluid-saturated elastic porous media isdeveloped by assuming infinitesimal deformation and incompressible constituents of the solid andfluid phase.The finite element formulation based on this variational principle is also derived.Asthe functional of the variational principle is a spatial integral of the convolution formulation,thegeneral finite element discretization in space results in symmetrical differential-integral equationsin the time domain.In some situations,the differential-integral equations can be reduced to sym-metrical differential equations and,as a numerical example,it is employed to analyze the reflectionof one-dimensional longitudinal wave in a fluid-saturated porous solid.The numerical results canprovide further understanding of the wave propagation in porous media.  相似文献   

12.
针对增量形式的流体饱和两相多孔介质弹塑性波动方程组,运用基于显式逐步积分格式的时域显式有限元方法对该波动方程组进行求解,并应用基于SMP破坏准则的弹塑性动力本构模型描述两相介质的动力反应性质,对两相介质在输入地震波作用下的弹塑性动力反应进行计算和分析,将计算结果与相应的弹性动力反应的计算结果进行对比;对本文应用的弹塑性...  相似文献   

13.
孔曦骏  邢浩洁  李鸿晶 《力学学报》2022,54(9):2513-2528
流固耦合地震波动问题主要研究由流体和固体构成的复杂系统中地震波传播特性及其规律. 传统模拟方法中一般以声波方程、弹性波方程的数值解分别描述理想流体和弹性固体中的波动, 并实时地处理两种不同性质介质之间的相互耦合作用, 数值格式复杂且限制数值模拟精度与计算效率. 本文采用谱元法结合多次透射公式人工边界条件实现了一种流固耦合地震波动问题的高阶显式数值计算方法. 该方法利用了流固耦合问题统一计算框架,可将饱和多孔介质的Biot波动方程分别退化为理想流体的声波方程和弹性固体的弹性波方程. 通过P波垂直入射的水平成层理想流体-饱和多孔介质-弹性固体场地模型、P波斜入射的不规则层状界面以及任意形状界面的理想流体-饱和多孔介质-弹性固体场地模型等三个算例, 与传递函数法解析解以及集中质量有限元法计算结果进行对比分析, 证明了本文方法的正确性与有效性. 数值模拟结果表明, 本文方法相较传统有限元法可以少得多的节点数量获得更高的数值精度, 并且在较宽的频率范围内都能可靠地模拟出流固耦合系统的动力响应, 充分体现出本文方法兼顾高精度、计算效率和复杂场地建模灵活的特点.   相似文献   

14.
三相介质饱和土自由场中爆炸波的传播规律   总被引:5,自引:0,他引:5  
饱和土是由固体上颗粒、水和少量封闭的空气组成的三相介质。介绍了爆炸波作用下三相介质饱和土有限元基本方程的建立过程,推导了引进人工粘性项的动力有限元方程,得到在饱和土自由场中爆炸波的传播规律;不同空气含量饱和土中爆炸波随深度的衰减规律。文中还给出了有限元与有限差分间断分解结果的比较,以说明本文理论方法的有效性。  相似文献   

15.
刘凯欣  刘颖 《力学学报》2003,35(4):469-473
为了深入研究液饱和多孔介质中应力波的传播,提出了三维两相细观计算模型.基于此模型。应用Galerkin余量法并计及流-固耦合界面的耦合效应,利用直接耦合的技术,开发了三维流-固混合显式动力有限元计算程序.在此基础上对冲击载荷作用下液饱和多孔介质中三维应力波的传播现象进行了数值模拟,并详细讨论了孔隙率,孔隙形状等因素对应力波传播主导波形的影响.  相似文献   

16.
An efficient meshless technique for simulating wave motions in saturated porous media is introduced in this paper. Using radial point interpolation method (RPIM) and considering the precision requirement in wave motion simulation, a lumped-mass RPIM for saturated porous media with clear physical concepts is derived. Combining explicit time integration with the lumped-mass RPIM leads to a decoupled radial point interpolation method (decoupled RPIM) for dynamic analysis without solving algebra equation set. A two-dimensional problem is calculated by the proposed decoupled RPIM, the ordinary RPIM, and the finite element method (FEM). The accuracy and efficiency of these methods are compared, which demonstrate that the proposed decoupled RPIM has comparable accuracy with the ordinary RPIM and the finite element method, but has high efficiency in simulating wave motions in saturated porous media.  相似文献   

17.
流体饱和多孔介质的动力学Gurtin型变分原理和有限元模拟   总被引:2,自引:0,他引:2  
基于多孔介质理论。在两相不可压和小变形的假设下,建立了流体饱和弹性多孔介质的动力学Gurtin型变分原理,并导出了以此变分原理为基础的有限元离散公式,由于Gurtin型变分原理是卷积型的空间积分泛函,空间的有限元离散导致一个关于时间的对称微分—积分方程组,在一般条件下。该积分—微分方程组可转化为对称的微分方程组,这组方程有别于标准Galerkin有限元的非对称离散方程组,作为数值例子,分析了流体饱和弹性多孔介质中一维纵向波的传播和反射,其结果进一步揭示了饱和多孔介质中波的传播特性。  相似文献   

18.
Genetic algorithm optimization of phononic bandgap structures   总被引:1,自引:0,他引:1  
This paper describes the use of genetic algorithms (GAs) for the optimal design of phononic bandgaps in periodic elastic two-phase media. In particular, we link a GA with a computational finite element method for solving the acoustic wave equation, and find optimal designs for both metal–matrix composite systems consisting of Ti/SiC, and H2O-filled porous ceramic media, by maximizing the relative acoustic bandgap for these media. The term acoustic here implies that, for simplicity, only dilatational wave propagation is considered, although this is not an essential limitation of the method. The inclusion material is found to have a lower longitudinal modulus (and lower wave speed) than the surrounding matrix material, a result consistent with observations that stronger scattering is observed if the inclusion material has a lower wave velocity than the matrix material.  相似文献   

19.
固体、流体多相孔隙介质中的波动理论及其数值模拟的进展   总被引:19,自引:1,他引:18  
简要回顾了两相或三相多孔介质中波动理论和数值模拟的研究历史和现状,着重介绍了用有限元方法对饱水土层中波动进行数值模拟的研究进展,并讨论了有待进一步研究的问题.  相似文献   

20.
本文构建了声压波动方程的改进时域间断Galerkin有限元方法.传统时域连续有限元方法在计算高梯度、强间断特征水中声波传播问题时往往会出现虚假数值振荡现象,这些数值振荡会影响正常波动的计算精度.为了解决这一问题,本文通过引入人工阻尼的方式构建了改进的时域间断Galerkin有限元方法,并针对具有高梯度、强间断特征的多障碍物复杂边界和层合液体介质声传播问题进行了计算.计算结果表明,与传统时域连续方法如N ew mark方法计算结果对比,所发展方法能较好地消除高梯度和强间断声压力波传播过程中虚假的数值振荡,具有较高的计算精度.问题的求解为进一步流固声耦合问题的研究奠定了基础.  相似文献   

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