层状介质中受冲击载荷的裂纹问题

本文对由不同正交异性材料组成的层状结构中受冲击载荷的Ⅲ型裂纹动力学问题给出了解的一般表示。文中利用结合面的边界条件,将问题中所有各量用单一未知函数表示,用积分变换方法将受冲击力作用问题化为对偶积分方程,并用Copson方法给出了解。本文方法也可以应用到裂纹表面受任意动载荷的情况。     

正交异性体反平面问题另一形式自相似解的推导

正交异性体的反平面运动方程有几种表达方式，而以自相似解表达方式尤为简单。由于在弹性动力学问题的计算中可以获得解析解，使得考虑的问题相应地简化，并具有一定的普遍性，因此对自相似形式的解的推导具有重要的意义。本文针对这一问题进行研究，利用复变函数论的方法导出另一形式自相似解的一般表达式。应用该法可以很容易地将所讨论的问题转化为Riemann—Hilbert问题，而后一问题可以用同通常的Muskhelishvili方法求解，并且可以相当简单地得到问题的闭合解。这些解在断裂动力学以及弹性动力学问题当中具有重要的应用价值。     

概说并行计算结构力学

基于向量机和并行机两大类并行计算机，对线性静力和动力问题，非线性静力和动力问题，本文概说了相应于这两大类并行机一般的求解方法。     

第二届国际动力学、振动与控制学术会议(ICDVC-2006)介绍

动力学、振动与控制是力学理论和应用的重要分支,也是现代科学技术十分活跃的前沿研究领域.从经典定义的角度来看,动力学与控制学科主要研究牛顿力学的一般原理和一切宏观离散系统的动力学现象.由于连续介质力学问题可以经过离散化而变成有限自由度系统的问题来处理,并且现代动力学理论可以推广到连续系统,因而动力学与控制理论中的原理和方法也同样适用于连续介质力学.     

不同正交异性材料界面上的扩展裂纹问题

本文用复变函数论的方法,对在不同正交异性材料结合面上扩展的具有任意自相似指数的断裂动力学问题,导出了解的一般表示,给出了一般解法.应用本文方法可以迅速将所论问题化为Riemann-Hilbert问题,并可以相当简单的得到问题的闭合解.作为实例,文中对若干问题进行了求解.利用本文解,通过叠加,可以求得任意复杂载荷问题的解析解.     

旋翼激励下直升机振动响应预计及实测对比

旋翼激励是直升机振动的主要源头,影响直升机驾驶员操纵性、机上人员舒适性及结构疲劳寿命。振动问题一般在试飞过程中暴露出来,问题处理和解决往往需要大的周期和代价,影响直升机研制。直升机振动响应预计是解决振动问题的主要手段之一,可以在早期发现振动问题,方便在型号研制早期开展优化设计或解决预案。本研究基于机体动力学仿真模型,以固定坐标系下的桨毂中心振动载荷作为输入,得到机体关键位置的振动响应,形成旋翼激励下直升机振动响应预测的方法。通过某直升机在尾桨激励下关键位置响应预计与实测数据对比分析,表明该方法得到的振动响应随速度的变化规律与实测数据一致,精度满足工程需要。该方法在新机振动响应分析、振动问题排查及振动控制方案制定等工作中具有较高的工程价值。     

脑动静脉畸形供血动脉内压力测量准确性的分析

对脑动静脉畸形供血动脉内压力测量的准确性进行了定量的分析,分析结果认为,以介入导管方法测量脑动脉畸形患者供血动脉内压力时,导管的影响可以导致测量结果偏低,这一结论支持了脑动静脉畸形患者低压灌注的程度一般不易于导致部分脑组织缺血的观点。     

时变动力学的Legendre级数解

时变动力学问题可归纳为一含时变系数微分方程组。该文用状态空间方程,结合Ｌｅｇｅｎｄｒｅ级数展开及Ｌｅｇｅｎｄｒｅ积分算子矩阵,提出一种分析时变动 系统的方法,给出解的一般表达式,从而为有效解决时变力学问题打下理论基础,有助于时变科学的深入研究。     

纳米颗粒多相流体动力学研究及应用

纳米颗粒多相流研究是目前多相流研究中新的研究方向及重点发展领域.为探索纳米尺度多相流相间作用机理及内部存在机制,采用理论分析及数值计算手段,对一般动力学方程的封闭处理、颗粒碰撞率宏观模型的有效构建、颗粒凝并系统动力学演变特性的机理分析、非稀相问题碰撞率的求取、双变量问题求解方法的建立以及一些实际应用进行了系统研究,提出了新的针对纳米尺度颗粒动力学演变的一般动力学方程求解方法,并将其应用于实际工业过程问题的研究.该文对上述研究工作进行了综述.     

关于刚体系统碰撞问题的动力学普遍定理解法

关于刚体系统碰撞问题的动力学普遍定理解法黎邦隆，黎之奇（湖南大学，长沙４１００８２）（中科院力学所，北京１０００８０）对较复杂的刚体系统的碰撞问题，一般都用冲力情况下的拉格朗日方程解答．因为通常都认为，用动力学普遍定理，就要将系统拆开，于是导致各刚体...     

矩形梁受分布荷载的辛解答

在弹性力学平面直角坐标辛体系中,采用分离变量法,放弃齐次边界条件,得到了矩形梁侧边受幂函数形式分布荷载问题的辛解答,给出了这类问题在辛体系中的一般解法,分别对矩形梁受法向和切向分布荷载的问题进行了求解,显示了此方法的有效性.辛解法采用对偶的二类变量进行求解,可同时给出位移和应力;由于辛解法能较好地处理各种边界条件,因此不仅能求解静定问题,也能直接求解静不定问题.     

Unified Way for Dealing with Three-Dimensional Problems of Solid Elasticity

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Propagation crack problems in interfaces between dissimilar orthotropic media

By the theory of complex functions, the general representation of the solution is derived for crack problems of arbitrary index of self-similarity expanding along the interfaces between dissimilar orthotropic media. The problems of Riemann and Hilbert can be formulated immediately and the analytical solution was obtained with this method. Some problems were analyzed as examples. The analytical solution for the cracked body subjected to an arbitrary load can be obtained with the summary method based on the present solution.     

A unified treatment of axisymmetric adhesive contact problems using the harmonic potential function method

A unified treatment of axisymmetric adhesive contact problems is provided using the harmonic potential function method for axisymmetric elasticity problems advanced by Green, Keer, Barber and others. The harmonic function adopted in the current analysis is the one that was introduced by Jin et al. (2008) to solve an external crack problem. It is demonstrated that the harmonic potential function method offers a simpler and more consistent way to treat non-adhesive and adhesive contact problems. By using this method and the principle of superposition, a general solution is derived for the adhesive contact problem involving an axisymmetric rigid punch of arbitrary shape and an adhesive interaction force distribution of any profile. This solution provides analytical expressions for all non-zero displacement and stress components on the contact surface, unlike existing ones. In addition, the newly derived solution is able to link existing solutions/models for axisymmetric non-adhesive and adhesive contact problems and to reveal the connections and differences among these solutions/models individually obtained using different methods at various times. Specifically, it is shown that Sneddon’s solution for the axisymmetric punch problem, Boussinesq’s solution for the flat-ended cylindrical punch problem, the Hertz solution for the spherical punch problem, the JKR model, the DMT model, the M-D model, and the M-D-n model can all be explicitly recovered by the current general solution.     

The auto-adjustable damping method for solving nonlinear equations

I.IntroductionTherearealotofnonlinearproblemsinengineering.Forexamples,theheattrallsfel'with'nonlinearradiation-convectionboundaryalldlimitedheatcapacity,thenonlinearhydrodynamicsandaerodynamics,thenonlillearstrtlcturaldynamicresponsesandtheIihe.Itisalmostimpossibletosolvethe11onlinearequationsbydirectmethodexceptfi)rsomespecialnonlinearequations.Thegeneralapproachislinearizingtheequationsandformingvariousiterationprocedures.Forthestronglynonlillearproblems,thesolutionobtainedintheitcrativep…     

A moving grid method applied to one-dimensional non-stationary flame propagation

The paper presents applications of a moving grid method to the combined problem of ignition and premixed flame propagation in a closed vessel. This method belongs to the general class of adaptive grid techniques for the numerical integration of evolutionary partial differential equations and is based on the method of lines with variable node position. In the present case the motion of the grid and the solution of the partial differential equations are strongly coupled by an implicit formulation. The problem is reduced to an initial value problem for a stiff differential-algebraic system. The continuously moving grid is determined by the equidistribution of a positive function which depends on the solution of the partial differential equations. A differential-algebraic system solver is used for the time integration of the initial value problem. The numerical results of the test problems demonstrate the computational efficiency and the capability of the method to resolve the main features of the solution.     

Weighted Solution of Small-Deflection Buckling Equation of Thin Shell

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Solution of pressure diffusion in radially composite reservoirs

This paper presents a new general method for solving the pressure-diffusion equation in cylindrically radial composite reservoirs, where the rock and fluid properties may change radially as a function ofr. Composite systems, such as formations with wellbore filtrate invasion and reservoirs with peripheral water encroachment, can be encountered as a result of drilling, secondary oil recovery, and water influx.The new solution method utilizes the reflection and transmission concept of electromagnetics to solve fluid flow problems in three-dimensional cylindrically radial reservoirs, where heterogeneity is in only one direction. The Green's function for a point source in a three-dimensional radially composite system is developed by using the reflection and transmission method. The method as well as the point source solution are sufficiently general that they may be applied to similar fluid flow and well testing problems involving single-phase flow.