高间Melnikov方法

本文把原有Melnikov方法推广到高阶情况.找到了二阶次谐Melnikov函数表达式,并且证明了在一定条件下可以用二阶次谐Melnikov函数来判定系统的次谐或超次谐的存在.     

非线性弹性梁中的混沌带现象

研究了非线性弹性梁的混沌运动，梁受到铀向载荷的作用。非线性弹性梁的本构方程可用三次多项式表示，计及材料非线性和几何非线性，建立了系统的非线性控制方程。利用非线性Galerkin法，得到微分动力系统。采用Melnikov方法对系统进行分析后发现，当载荷P0和f满足一定条件时，系统将发生混沌运动，且混沌运动的区城呈现带状。还详尽分析了从次谐分岔到混沌的路径，确定了混沌发生的临界条件。     

功能梯度材料Timoshenko梁的热过屈曲分析

研究了功能梯度材料Timoshenko梁在横向非均匀升温下的热过屈曲．在精确考虑轴线伸长和一阶横向剪切变形的基础上，建立了功能梯度Timoshenko梁在热-机械载荷作用下的几何非线性控制方程，将问题归结为含有7个基本未知函数的非线性常微分方程边值问题。其中，假设功能梯度梁的材料性质为沿厚度方向按照幂函数连续变化的形式，然后采用打靶法数值求解所得强非线性边值问题，获得了横向非均匀升温场内两端固定Timoshenko梁的静态非线性热屈曲和热过屈曲数值解，绘出了梁的变形随温度载荷及材料梯度参数变化的特性曲线，分析和讨论了温度载荷及材料的梯度性质参数对梁变形的影响。结果表明，由于材料在横向的非均匀性，均匀升温时的梁中存在拉-弯耦合变形．     

行动载荷作用下的连续梁的横向振动问题

本文在考虑行动载荷质量、惯性力及阻尼影响的情况下,研究了机车通过连续梁时横向振动问题的整个过程,并得出了在任意行动载荷PF(t)作用下的连续梁的动力方程的一般解.我们具体计算了单个行动载荷为P_i Q_isin(a_it (?)_i)时的情形并建立了行动载荷作用下的连续梁横向振动问题的动力理论.最后,做为例子,我们求解了两跨梁的横向振动问题,跨中点的挠度如图2和图3所示.     

压电梁的多项式解(Ⅱ)--典型问题解析解

从正交各向异性压电介质平面问题，对于材料3个特征根互不相等情况下，以3个拟调和位移函数表达位移、电势、应力和电位移的通解出发，利用调和多项式的显式表达式，结合试凑法，给出了平面压电梁的若干典型问题的解析解，包括悬臂压电梁自由端作用横向集中力和点电荷，悬臂雎电梁表面作用线性电势和均布载荷，以及两端简支压电梁作用均布载荷等的解析解．     

平面Hamilton系统在小扰动下次谐与超次谐解的讨论

本文提出了处理平面Hamilton系统在小扰动下次谐和超次谐解的方法.利用这个方法对一类系统进行了 处理,发现理论与数值 结果较好地吻合.     

移动载荷作用下轴向运动载流梁的参强联合共振

研究磁场环境中移动载荷作用下轴向运动梁的磁弹性参强联合共振问题.以轴向运动载流梁为研究对象,建立横向磁场中受移动载荷作用下梁的力学模型.应用Hamilton(哈密顿)原理,得到梁的非线性磁弹性振动方程.利用Galerkin(伽辽金)积分法和多尺度法,推得以移动载荷为变量的幅频响应方程.通过数值计算,绘制了振幅随调谐参数、拉力扰动幅值、移动载荷、磁感应强度的变化规律曲线图,分析了电流密度、磁感应强度、移动载荷等变量对参变系统动力学特性的影响.结果表明:系统呈现典型的参强联合共振特性;移动载荷、磁感应强度能够起到抑制共振幅值多值现象的产生.     

周期扰动下卫星运动系统的动力学性质

本文运用Melnikov方法对平面卫星运动系统在周期扰动下所表现出来的动力学性质进行了探讨.首先运用次谐Melnikov方法给出了卫星轨道在周期扰动下存在次谐周期轨道的条件,并进一步运用同宿.Melnikov方法证实了该系统存在Smale马蹄意义下的混沌性质.     

具有分数导数本构关系的粘弹性 Timoshenko 梁的静动力学行为分析

利用粘弹性材料的三维分数导数型本构关系，建立粘弹性Timoshenko梁的静、动力学行为研究的数学模型；分析了Timoshenko梁在阶跃载荷下的准静态力学行为，得出了问题的解析解，考察了一些材料参数对梁的挠度的影响。基于模态函数讨论了粘弹性Timoshenko梁在横向简谐激励作用下的动力响应，并考察了剪切和转动惯性对梁振动响应的影响。     

剪切变形对直线型正交异性层合圆板大幅度受迫振动的影响

本文研究了计及横向剪切变形的直线型正交异性层合圆板在简谐载荷ｑ０ｃｏｓωｔ作用下的非线性受迫振动问题·采用伽辽金方法得到强振频率与振幅关系的解析解·最后，分析了横向剪切对板振动的影响，并给出了板的非线性自由振动的非线性周期对线性周期的比值·     

Transverse nonlinear dynamics of axially accelerating viscoelastic beams based on 4-term Galerkin truncation

This paper investigates bifurcation and chaos in transverse motion of axially accelerating viscoelastic beams. The Kelvin model is used to describe the viscoelastic property of the beam material, and the Lagrangian strain is used to account for geometric nonlinearity due to small but finite stretching of the beam. The transverse motion is governed by a nonlinear partial-differential equation. The Galerkin method is applied to truncate the partial-differential equation into a set of ordinary differential equations. When the Galerkin truncation is based on the eigenfunctions of a linear non-translating beam subjected to the same boundary constraints, a computation technique is proposed by regrouping nonlinear terms. The scheme can be easily implemented in practical computations. When the transport speed is assumed to be a constant mean speed with small harmonic variations, the Poincaré map is numerically calculated based on 4-term Galerkin truncation to identify dynamical behaviors. The bifurcation diagrams are present for varying one of the following parameter: the axial speed fluctuation amplitude, the mean axial speed and the beam viscosity coefficient, while other parameters are unchanged.     

Dynamic modeling for rotating composite Timoshenko beam and analysis on its bending-torsion coupled vibration

A formulation is presented for steady-state dynamic responses of rotating bending-torsion coupled composite Timoshenko beams (CTBs) subjected to distributed and/or concentrated harmonic loadings. The separation of cross section's mass center from its shear center and the introduced coupled rigidity of composite material lead to the bending-torsion coupled vibration of the beams. Considering those two coupling factors and based on Hamilton's principle, three partial differential non-homogeneous governing equations of vibration with arbitrary boundary conditions are formulated in terms of the flexural translation, torsional rotation and angle rotation of cross section of the beams. The parameters for the damping, axial load, shear deformation, rotation speed, hub radius and so forth are incorporated into those equations of motion. Subsequently, the Green's function element method (GFEM) is developed to solve these equations in matrix form, and the analytical Green's functions of the beams are given in terms of piecewise functions. Using the superposition principle, the explicit expressions of dynamic responses of the beams under various harmonic loadings are obtained. The present solving procedure for Timoshenko beams can be degenerated to deal with for Rayleigh and Euler beams by specifying the values of shear rigidity and rotational inertia. Cantilevers with bending-torsion coupled vibration are given as examples to verify the present theory and to illustrate the use of the present formulation. The influences of rotation speed, bending-torsion couplings and damping on the natural frequencies and/or shape functions of the beams are performed. The steady-state responses of the beam subjected to external harmonic excitation are given through numerical simulations. Remarkably, the symmetric property of the Green's functions is maintained for rotating bending-torsion coupled CTBs, but there will be a slight deviation in the numerical calculations.     

杜芬方程的1／3纯亚谐解及其过渡过程

通过谐波平衡法和数值积分法研究了杜芬方程的1／3纯亚谐解,对参数变化的过渡过程的敏感性和扰动初始值的过滤进行了研究,同时,还对谐波平衡法和数值积分法的精度进行了比较,也考虑了亚谐波成分的渐近稳定性。     

Vibrations of a viscoelastic cylinder with an elastic shell

The nonlinear vibrations of a viscoelastic cylinder with an elastic shell subjected to two harmonic forces are investigated using the averaging scheme described in [3, 4]. Nonresonance, resonance, and subharmonic vibrations are examined. It is shown that the presence of viscosity in the system leads to a single stationary equilibrium position for which the stability conditions are given.V. I. Lenin Tashkent State University. Translated from Mekhanika Polimerov, No. 4, pp. 691–697, July–August, 1973.     

压电梁的多项式解(Ⅰ)--若干精确解

从正交各向异性压电介质平面问题，对于材料3个特征根互不相等情况下，以3个拟调和函数表达位移、电势、应力和电位移的通解出发，利用调和多项式的显式表达式，结合试凑法，给出了平面压电梁的一系列精确解，包括刚体平动、刚体转动、均匀电势、均匀拉伸、均匀电位移、纯剪切、纯英曲和两端自由压电梁上下表面作用常电势情况下的精确解。     

Leafwise Brownian Motions and Some Function Theoretic Properties of Laminations

We discuss the value distribution of Borel measurable functions which are subharmonic or meromorphic along leaves on laminations. They are called leafwise subharmonic functions or meromorphic functions respectively. We consider cases that each leaf is a negatively curved Riemannian manifold or Kähler manifold. We first consider the case when leaves are Riemannian with a harmonic measure in L.Garnett sense. We show some Liouville type theorem holds for leafwise subharmonic functions in this case. In the case of laminations whose leaves are Kähler manifolds with some curvature condition we consider the value distribution of leafwise meromorphic functions. If a lamination has an ergodic harmonic measure, a variant of defect relation in Nevanlinna theory is obtained for almost all leaves. It gives a bound of the number of omitted points by those functions. Consequently we have a Picard type theorem for leafwise meromorphic functions.     

Large deflections of tapered functionally graded beams subjected to end forces

The large deflections of tapered functionally graded beams subjected to end forces are studied by using the finite element method. The material properties of the beams are assumed to vary through the thickness direction according to a power law distribution. A first order shear deformable beam element employed the exact polynomials to interpolate the transverse displacement and rotation, is formulated in the context of the co-rotational approach. The large deflection response of the beams is computed by using the arc-length control algorithm in combination with the Newton–Raphson iterative method. The numerical results show that the formulated element is capable to assess accurately the response of the beams by using just several elements. A parametric study is given to examine the influence of the material non-homogeneity, taper ratio as well as the aspect ratio on the large deflection behaviour of the beams.     

Harmonic transforms of complete Riemannian manifolds

Vanishing theorems for harmonic and infinitesimal harmonic transformations of complete Riemannian manifolds are proved. The proof uses well-known Liouville theorems on subharmonic functions on noncompact complete Riemannian manifolds.     

二端面转轴相对转动非线性动力学系统的主共振与次共振解

本文研究在简谐激励力作用下二端面弹性转轴相对转动的主共振、超谐波共振和亚谐波共振.用平均法研究了系统的主共振,得到了系统的渐进稳态周期解,采用多尺度法求得了系统的3次超谐波共振解和1/3次亚谐波共振解.     

Active control of secondary resonances piezoelectric sandwich beams

Secondary resonances of piezoelectric/elastic/piezoelectric sandwich beams submitted to active control are studied in this paper. The proportional and derivative nonlinear potential feedback controls via piezoelectric sensor and actuator layers are used. The dynamics of the beam is modelled by a highly nonlinear ordinary-differential equation. The method of multiple scales is applied and approximate solutions are obtained for hard excitations. Analytical frequency and phase-amplitude relationships as well as the time response are explicitly given for various super- and subharmonic resonances. Static and dynamic stability criteria are elaborated and critical displacement and excitation amplitudes associated to the resulting unstable zones are analytically given. The feedback parameters effects on the subharmonic and superharmonic resonances and on their stability are investigated.