航空发动机安装节动柔度测量及静子动力特性计算

本文介绍航空发动机安装节动柔度测量方法及数据处理，在此基础上，介绍发动机静子动力特性的一种试验－解析算法，本文经某航空发动机静子系统为例进行了算例分析，给出部分分析结果。     

惯性系统三轴综合测试台结构静动态特性计算及实验研究

本文建立了惯性系统三轴综合测试台的结构分析模型，用有限元法对其进行了结构静动态特性计算。给出了外框架在实际载荷作用下的静动态特性和整机的动态特性，并在此基础上，对该三轴台外框架进行了静态变形的实际测量。实测表明，理论分析和实测结果相吻合。     

一种快速精确的捷联惯导系统初始对准方法研究

传统的多位置对准方法虽然使捷联惯导系统静基座初始对准的精度得到提高，但是用卡尔曼滤波器对其状态变量进行估计时，方位失准角收敛很慢。本提出了一种快速多位置对准估计方位失准角的方法，直接利用两水平失准角快速收敛的估计结果对传统多位置对准中方位失准角的估计，从而大大提高了捷联惯导系统静基座对准的精度和速度，计算机仿真结果验证了该方法的有效性。     

考虑地基-结构-散粒体相互作用时贮仓结构的静、动力研究[Ⅱ]--有限元分析

对贮仓结构的静、动力问题进行了系统的分析计算：考虑到地基—结构—散粒体间的相互作用，引入新的计算模式，对不同地基上的贮仓结构模型进行了系统的有限元静、动力分析计算，并与作者所完成的试验结果进行了比较。结果表明，所提出的计算模式及有限元计算模型是正确的。     

磁场对液态金属流的制动效应

研究在静磁场作用下；连铸坯中液态金属的流动，建立了二维数学模型并考虑了湍流的影响．采用数值分析方法分析了磁场对液态金属流股的制动效应．计算结果说明静磁场可以有效地减小流股速度并使其分散，同时使上升到液态金属液面的反转流减弱．随着哈特曼数增高和雷诺数的减小，磁场的制动效应增强．     

一种新的捷联惯导系统初始对准方法

提出了—种基于多天线GPS载波相位测量的捷联惯导系统静基座初始对准方法。给出了观测方程的详细推导过程，该观测方程中三个失准角均直接可观。最后给出了卡尔曼滤波仿真结果。结果表明，该方法极大地改善了捷联惯导系统静基座初始对准中方位失准角的估计收敛速度和精度。     

磁场对液态金属流的制动效应

研究在静磁场作用下；连铸坯中液态金属的流动，建立了二维数学模型并考虑了湍流的影响．采用数值分析方法分析了磁场对液态金属流股的制动效应．计算结果说明静磁场可以有效地减小流股速度并使其分散，同时使上升到液态金属液面的反转流减弱．随着哈特曼数增高和雷诺数的减小，磁场的制动效应增强．     

液压环境下流体对管柱单元XYZ方向作用力分析

通过对液压环境(即静流体作用)下的管柱进行离散分析,说明了现有模型在分析静流体对管柱单元作用力时的不足。采用微元法结合高斯公式对静流体下管柱单元的受力进行了分析,运用先补全,再减去所补面积的等效方法,得到了静流体对管柱单元侧面产生的作用力的理论计算方法。建立了液压环境下,静流体对任意管柱单元(直线单元或曲线单元)X、Y、Z方向作用力和浮力系数的理论计算模型。基于相关理论计算模型,结合ANSYS有限元进行模拟计算,得出了在水深300m~3000m处,30°和90°等曲率圆弧管柱的X、Y、Z方向作用力的理论计算结果与ANSYS模拟分析结果。相关结果对比表明:ANSYS有限元计算结果与理论计算结果间最大的绝对误差不足0.4%,验证了本文建立的理论计算模型的正确性。     

冲击速度和轴向静载对红砂岩破碎及能耗的影响

地下岩体工程爆破开挖中，距爆源不同距离处岩体承受的地应力和动载荷大小不同，从动载荷的角度表征岩石动态破坏结果与工程实际更吻合。为研究动载荷和地应力大小对岩体破碎和能量耗散特性的影响，利用动静组合加载试验装置，分别设置7个冲击速度和轴向静应力等级，对红砂岩试件进行冲击试验。根据试件的破碎状况，分析不同静应力工况下冲击速度对岩石破坏模式和机理的影响。计算不同工况下的应力波能量值，研究冲击速度和轴向静应力对岩石能耗特性的影响。对破坏试件进行筛分试验，研究岩石破碎分形维数随冲击速度和轴向静应力的变化关系。结果表明，随着冲击速度的增大，试件的破坏程度逐渐加大。无轴压时岩石试件破坏后整体仍是一个圆柱体，属于张拉破坏；有轴压时岩石试件宏观破坏后呈沙漏状，属于拉剪破坏。岩石耗散能随冲击速度的升高呈二次函数关系递增；轴向静应力越高，递增幅度越小。随着冲击速度的升高，岩石分形维数由零逐渐增加；随着轴向静应力的升高，分形维数由零转为大于零的临界冲击速度先升高后降低。     

相对湿度对几种摩擦副静摩擦系数的影响

在自制的试验台上考察了相对湿度对金属－金属摩擦副、金属－石墨摩擦副、金属－TiN涂层摩擦副及金属－WC涂层摩擦副的静摩擦系数的影响。结果发现,相对湿度对金属－石墨摩擦副和金属－WC涂层摩擦副的静摩擦系数没有影响,而对金属－金属摩擦副和金属－TiN涂层摩擦副的静摩擦系数有影响。利用分形接触模型推导并计算了由水膜的弯月面效应引起的附加静摩擦系数,计算结果与实际变化趋势相吻合,静摩擦系数的计算值比实际值稍偏大。     

Surface waves and surface stability for a pre-stretched, unconstrained, non-linearly elastic half-space

An unconstrained, non-linearly elastic, semi-infinite solid is maintained in a state of large static plane strain. A power-law relation between the pre-stretches is assumed and it is shown that this assumption is well motivated physically and is likely to describe the state of pre-stretch for a wide class of materials. A general class of strain-energy functions consistent with this assumption is derived. For this class of materials, the secular equation for incremental surface waves and the bifurcation condition for surface instability are shown to reduce to an equation involving only ordinary derivatives of the strain-energy equation. A compressible neo-Hookean material is considered as an example and it is found that finite compressibility has little quantitative effect on the speed of a surface wave and on the critical ratio of compression for surface instability.     

光纤捷联惯导系统高阶误差模型的建立与分析

针对多位置标定算法中利用的陀螺和加表的误差模型,在捷联惯导系统误差传播方程中,考虑陀螺和加表的标度因数误差和安装误差,建立了一种高阶误差模型。为了评价该模型的准确性,将其与不考虑标度因数误差和安装误差的模型比较,设计了系统静态和动态仿真实验。在系统静态仿真中,分别加入陀螺漂移和加表安装误差,而在动态仿真中同时加入各项误差项,求取以这些误差项为初值的模型微分方程的解,使其与惯导系统输出误差进行比较。仿真结果发现,建立的高阶误差模型比不考虑标度因数误差和安装误差的模型精度高出约三个数量级。     

四种非正交边界板考虑初始荷载效应的后期荷载位移近似解

基于考虑初始荷载效应情况下板的一般形式的静力平衡微分方程,运用坐标变换得到了轴对称情形,考虑初始荷载效应后圆形板的极坐标形式的静力平衡微分方程。运用Galerkin法解得了简支等边三角形板、固支椭圆板、固支圆形板和简支圆形板四种非正交边界板考虑初始荷载效应的后期荷载位移近似解。运用相关文献提出的有限元法验证了近似解的正确性。各位移近似解表达式简单、物理意义明确,清楚地反映了初始荷载及相关因素对后期荷载位移的影响。计算分析表明：初始荷载效应提高了板的弯曲刚度,减小了板的后期荷载位移;板的初始荷载效应主要受初始荷载、跨厚比及边界条件等因素的影响。     

板中正交静应力与任意方向兰姆波波速的关系

运用部分波分析法(或子波分析)理论推导了在正交静应力下,板中任意方向的Lamb波的频散方程,给出了任意方向Lamb波波速、正交静应力和频率之间的关系. 进行了数值计算并讨论了对称方向的Lamb波波速对单向静应力的依赖关系,为将Lamb波用于应力测量提供了理论依据.      

Nonlinear vibration and buckling of circular sandwich plate under complex load

The nonlinear vibration fundamental equation of circular sandwich plate under uniformed load and circumjacent load and the loosely clamped boundary condi- tion were established by von Karman plate theory,and then accordingly exact solution of static load and its numerical results were given.Based on time mode hypothesis and the variational method,the control equation of the space mode was derived,and then the amplitude frequency-load character relation of circular sandwich plate was obtained by the modified iteration method.Consequently the rule of the effect of the two kinds of load on the vibration character of the circular sandwich plate was investigated.When circumjacent load makes the lowest natural frequency zero,critical load is obtained.     

多层压电材料层合板的精确解

抛弃有关位移和应力的所有假设，直接从三维弹性力学理论的静电学理论，先导出正交各向异性压电材料板的状态方程，由此得到四边简支压电材料板的状态主程，再根据矩阵分析理论，建立了单层压电材料板的上下表面状态量之间的关系，进一步建立了多层压电板上，下表面状态量之间关系式，利用上下表面已知状态量，得到上表面未知状态的求解方程解。通过求解方程组，便得上表面未知状态量，最终可以得到任意位置处状态量，最后，同时给出了四边简支，两层不同压电材料组成，不同纵横比的层合板受正弦分布载荷作用下的精确解，其结果与现有解比较，吻合较好。     

单层平面索网幕墙结构的几何非线性问题研究

单层平面索网支承式玻璃幕墙结构是近年来在国内外应用较为广泛的一种新型幕墙结构形式,由于单层平面索网不具有负高斯曲面形式,结构在平面外方向的刚度偏柔,表现出较明显的几何非线性特征.本文采用连续化方法建立了单层平面索网结构考虑几何非线性影响的静力平衡方程和振动方程,得到了结构刚度的解析表达式,并采用谐波平衡法求得非线性频率的简化解析表达式,以此为基础研究了单层平面索网结构的静力非线性和动力非线性问题.研究结果表明:结构的非线性和结构的初始位置密切相关;结构的非线性频率主要取决于索的初始应变、结构振动幅值与跨度的比值,几何非线性对于结构动力性能的影响要小于对结构静力性能的影响;本文得到的结构在地震荷载和平均风荷载作用下的非线性振动方程和非线性频率为结构在地震荷载和脉动风荷载作用下动力响应的求解奠定了基础.     

Plane strain dynamics of elastic solids with intrinsic boundary elasticity, with application to surface wave propagation

In this paper, in a development of the static theory derived by Steigmann and Ogden (Proc. Roy. Soc. London A 453 (1997) 853), we establish the equations of motion for a non-linearly elastic body in plane strain with an elastic surface coating on part or all of its boundary. The equations of (linearized) incremental motions superposed on a finite static deformation are then obtained and applied to the problem of (time-harmonic) surface wave propagation on a pre-stressed incompressible isotropic elastic half-space with a thin coating on its plane boundary. The secular equation for (dispersive) wave speeds is then obtained in respect of a general form of incompressible isotropic elastic strain-energy function for the bulk material and a general energy function for the coating material. Specialization of the form of strain-energy function enables the secular equation to be cast as a quartic equation and we therefore focus on this for illustrative purposes. An explicit form for the secular equation is thereby obtained. This involves a number of material parameters, including residual stress and moment in the properties of the coating. It is shown how this equation relates to previous work on waves in a half-space with an overlying thin layer set in the classical theory of isotropic elasticity and, in particular, the significant effect of omission of the rotatory inertia term, even at small wave numbers, is emphasized. Corresponding results for a membrane-type coating, for which the bending moment, inertia and residual moment terms are absent, are also obtained. Asymptotic formulas for the wave speed at large wave number (high frequency) are derived and it is shown how these results influence the character of the wave speed throughout the range of wave number values. A bifurcation criterion is obtained from the secular equation by setting the wave speed to zero, thereby generalizing the bifurcation results of Steigmann and Ogden (Proc. Roy. Soc. London A 453 (1997) 853) to the situation in which residual stress and moment are present in the coating. Numerical results which show the dependence of the wave speed on the various material parameters and the finite deformation are then described graphically. In particular, features which differ from those arising in the classical theory are highlighted.     

A viscoelastic constitutive model of rubber under small oscillatory load superimposed on large static deformation

Summary  A viscoelastic constitutive equation of rubber that is under small oscillatory load superimposed on large static deformation is proposed. The model is derived through linearization of Simo's nonlinear viscoelastic constitutive model and reference configuration transformation. Most importantly, in this model, static deformation correction factor is introduced to consider the influence of pre-strain on the relaxation function. Natural statically pre-deformed state is served as reference configuration. The proposed constitutive equation is extended to a generalized viscoelastic constitutive equation that includes widely used Morman's model as a special case using objective stress increment. The proposed constitutive model is tested for dynamic behavior of rubber specimens with different carbon black content. It is concluded from the test that the assumption that the effects of static deformation can be separated from time effects, which is the basis of Morman's model, is only applicable to unfilled rubber. The viscoelastic constitutive equation for filled rubber must include, therefore, the influence of the static deformation on the time effects. The suggested constitutive equation with static deformation correction factor shows good agreement with test values. Received 4 January 2001; accepted for publication 13 June 2001     

超薄膜磁头滑块气动力特性

采用有限差分法对广义润滑方程进行数值求解,计算出计算机磁头滑块压强场的分布情况。分析、研究了其稳态和动态气动力特性,并将计算结果分别与求解一阶、二阶修正雷诺方程所得到的结果进行了比较,得到如下三个结论:(1)当飞行高度很小,飞行速度较低时,必须采用广义润滑方程进行磁头滑块的气动力计算,(2)与广义润滑方程结果比较,求解一阶修正雷诺方程所得到的计算结果总是偏高,而求解二阶修正雷诺方程所得到的计算结果总是偏低。此外,还解决了大压缩数下数值失稳问题,使得压缩数可以计算到120万,足以适应任何实际工程的需要。