GPS／SINS组合导航系统的动基座快速初始对准方法

—本文首先建立了ＳＩＮＳ的误差模型，并对系统模型进行了可观测性分析，然后基于ＳＩＮＳ误差模型的特点，通过对所采用卡尔曼滤波器仿真结果的分析，提出了一种快速估计方位失准角Ｄ的方法，从而大大缩短了初始对准时间，提高了对准速度。最后计算机仿真结果表明了该方法的有效性。     

石墨烯掺杂的陶瓷和金属自润滑材料研究进展

石墨烯(GN)具有独特的纳米层状结构，是一种性能优异的纳米润滑材料，在自润滑材料的研究领域获得了广泛的关注. 文章综述了掺杂石墨烯的陶瓷和金属自润滑材料的最新研究进展，重点探讨了石墨烯对材料力学和摩擦学性能的作用机理，以及石墨烯自身结构不同引起的性能差异，总结了掺杂石墨烯的陶瓷和金属材料的制备方法，简要介绍了各种制备方法的特点. 文章还对现有的研究成果进行总结分析，指出了当前研究中仍待解决的问题，为今后的研究工作提出了建议.      

三轴陀螺稳定平台控制系统设计与实现

针对高精度光电导引系统快速隔离扰动、稳定视轴的要求，设计了以速率陀螺为核心构成的三轴陀螺稳定平台。结合某型号电视导引头设计过程，详细介绍了该三轴陀螺稳定平台的结构组成、主要元器件选型，以及软硬件实现。分析了陀螺稳定平台的隔离扰动原理，设计了多闭环复合控制结构，给出了系统各组成部分的模型，合理简化后建立了系统数学模型，并按照频域分析法设计了控制算法。对于陀螺信号噪声问题，设计了小波阈值滤波方法，有效地消除了反馈信号的噪声，提高了系统控制精度。整机测试表明，该陀螺稳定平台满足了导引头系统设计指标要求，具有较高的跟踪精度；能够在实验室条件下，进行多种电视跟踪模拟实验，为实际设备的研制提供了真实有效的数据。     

力学环境约束下剪切销可靠性分析及优化设计

剪切销是火工装置关键部件，其可靠性不仅表现为点火作用下可靠剪断，还表现为受力学环境激励不发生断裂。本文中以多项式混沌展开方法为基础，建立了力学环境约束下的剪切销分析模型，结合序贯优化与可靠性分析方法，提出了剪切销可靠性优化设计的思路。以某型火工作动装置为应用实例，依据实用的力学环境，进行了剪切销可靠性分析及优化设计，揭示了设计参数与力学环境之间的关系，并获得了影响可靠性的关键参数。最后，开展了优化后的火工作动装置实验测试，结果佐证了优化设计的有效性。     

液体边界层对平板结构振动阻尼效应分析

本文分析了液体边界层对平板振动的阻尼效应，基于液体的Stokes边界层理论，建立了考虑液体边界层阻尼效应的平板振动单自由度系统运动方程，利用Laplace变换方法求解了运动方程，得到了平板结构的位移响应解答，制作了一个单自由度质量-弹簧系统来测量水体粘滞阻尼效应，并将理论与试验结果进行了对比分析，表明Stokes边界层理论能较好模拟水体的粘滞阻尼特性，边界层阻尼明显减小了结构的动力响应，本文最后讨论了所提的分析方法的适用范围．     

陀螺马达电源的研究

本文讨论了三相交流陀螺马达电源的工作原理。根据主要技术指标的要求，设计了陀螺马达电源，给出了该电源的各个组成部分的线路设计，解决了研制中出现的电源振荡问题，论述了该电源的设计特点，给出了使用结论     

地下水流并行有限层方法及同伦反演研究

根据有限层求解格式存在的解耦性，实现了地下水三维流问题的高效并行化计算。在此基础上，结合非线性同伦方法，提出了地下水参数反演分析的并行同伦算法，利用MATLAB编译了相应的正反演计算程序。与已有解析解和有限差分解的对比以及数值算例，验证了并行化正反演方法及程序的正确性，探讨了并行算法的计算效率。研究表明，并行方法可以有效提高计算速度，较串行方法具有明显优势，同时同伦反演方法具有大范围收敛的特点，不依赖于参数值的初始选取。     

用于超弹性分析的高效杂交应变--EAS固体壳单元的研究

提出了一个用于橡胶材料分析的弱变分方程，基于一个可压缩Neo—Hookean模型，将EAS模式和杂交元法有机地结合起来，推导了一个高效、稳定的杂交应变——EAS固体壳单元，通过巧妙地选择应交插值函数和本文中提出的一个精化措施，克服了橡胶材料所表现出的大应变超弹性本构为杂交元正交化法的实施所带来的困难，保证了整个单元列式都仅采用低阶高斯积分，显著提高了计算效率，确保橡胶材料不可压缩性计算的顺利进行，并克服了固体壳元的厚度自锁问题。     

抽样定理法重建流场的三维温度分布

结合气流场温度较低，只能得到较少干涉条纹的实际情况，提出了采用轴样定理法重建流场的三维温度分布的模型，并考查了该方法的计算机模拟运算结果，对具体的对象，进行了实验，并采用图像处理方法对条纹进行了一系列处理，最后重建了二个截面上的温度分布。     

薄壁曲梁的稳定性研究进展

 曲梁是桥梁、建筑、船舶、航空和航天工程中常见的薄壁构件，根据外载荷与主曲率平面的关系，又被称为拱或水平曲梁．随着工程材料的日益发展，如复合材料、功能梯度材料的引入，曲梁的应用范围更加广泛，进一步推进了薄壁曲梁稳定性问题的研究．本文首先对薄壁梁结构的稳定性行为进行了分类．接着简述了薄壁构件的基本假设，对比了近几十年来薄壁曲梁的基本理论，针对复合材料薄壁曲梁，总结了相应的本构关系，并对各理论间存在的分歧进行了归纳．结合最新的薄壁曲梁研究，根据平衡法、能量法和虚位移（虚功）原理推导出控制微分方程，阐述了相应的求解方法，如解析法、半解析法和数值解法．为验证薄壁曲梁理论的准确性，曲梁承载能力试验验证尤为重要，但目前国内外相关研究还很少，亟待发展．最后讨论了现阶段薄壁曲梁研究的局限性和未来发展的方向．     

Viscoplasticity of agglomerated suspensions

This work is a theoretical study on the effects of agglomeration on the fluidity and plasticity of a suspension of neutrally buoyant particles in a Newtonian fluid. The dynamics of a cluster of permanently attached spherical particles in a simple shear field is analyzed. The viscous and plastic components of the drag force acting on each of the agglomerated particles is then calculated and found to depend on the size of the individual particle unit, its location being relative to the center of the cluster and the material properties of the engulfing fluid. This information in conjunction with the knowledge of the interparticle cohesive forces is used to establish criteria for the agglomerate size reduction during dispersive mixing. From the kinematics of the cluster movement and the forces acting on its particulate components the rate of energy dissipation is calculated and utilized to evaluate the viscosity and yield stress of the suspension. These rheological parameters depend on the volume fraction and architecture of the agglomerate, the number of fused particles per cluster, and the viscosity of the suspending fluid. The analysis is also extended to include the case of polydispersity of agglomerate sizes.     

一种基于直接计算高阶奇异积分的断裂力学双边界积分方程分析法

相对于有限元法,边界单元法在求解断裂问题上有着独特的优势,现有的边界单元法中主要有子区域法和双边界积分方程法.采用一种改进的双边界积分方程法求解二维、三维断裂问题的应力强度因子,对非裂纹边界采用传统的位移边界积分方程,只需对裂纹面中的一面采用面力边界积分方程,并以裂纹间断位移为未知量直接用于计算应力强度因子.采用一种高阶奇异积分的直接法计算面力边界积分方程中的超强奇异积分;对于裂纹尖端单元,提供了三种不同形式的间断位移插值函数,采用两点公式计算应力强度因子.给出了多个具体的算例,与现存的精确解或参考解对比,可得到高精度的计算结果.      

大数据条件下结构区间可靠性与概率可靠性比较

对于结构服役期间收集到的结构相关大数据，首先对数据进行整理与分析，根据数据的特征进行分类；然后利用应力-强度干涉理论建立结构大数据条件下区间可靠性计算模型与随机可靠性计算模型，按大数据所分类型，分别计算每一类型大数据中结构区间非概率可靠度指标与随机概率可靠度，在区间非概率可靠度指标与随机概率可靠度计算结果中，最小区间可靠性指标是结构最终的区间可靠性指标，最小随机可靠度是结构最终的随机可靠度．最后，利用两个算例说明了大数据条件下结构区间可靠性计算方法与概率可靠性计算方法的优点与缺点．     

Numerical solution for the flow of viscoelastic fluids around an inclined circular cylinder.

Finite difference solutions have been obtained by the perturbation method to investigate the influence of shear thinning and elasticity on the flow around an inclined circular cylinder of finite length in a uniform flow. In this numerical analysis a generalized upper-convected Maxwell model, in which the viscosity changes according to the Cross model, has been used.The local flow over the cylinder is only slightly deflected. However, in the wake flow behind the cylinder the particle path is remarkably influenced by the axial flow and rapidly flows up parallel to the cylinder's axis. Then it gradually rejoins direction of the incoming flow. It is found that viscoelastic fluids are prone to flow axially in the vicinity of the cylinder. The numerical predictions generally agree with the flow visualization results.The numerical solutions also demonstrate that elasticity has a strong effect on the velocity profile especially around both ends of the cylinder; elasticity increases the asymmetric profiles of both circumferential velocity and axial velocity with respect to equal to 90° and decreases a difference in the circumferential velocity between the windward end and the leeward end.For non-Newtonian fluids, the length of the wake flow is influenced by not only the Reynolds number but also the cylinder diameter and it is larger for the cylinder with the smaller diameter at the same Reynolds number.Partly presented at the 9th Australasian Fluid Mechanics Conference, University of Auckland, New Zealand, 8–12 December, 1986     

Bearing capacity of strip footings with horizontal confinementLa capacité portante des fondations superficielles en présence de parois rigides

For a strip footing under axial loading, the bearing capacity is influenced by the presence of rigid walls confining the foundation soil. This problem is investigated within the framework of the theory of yield design, considering both a perfectly rough and a frictionless contact condition at the interfaces with the walls in the case of a purely cohesive soil. Upper bounds for the correction factor to be applied to the classical value of the bearing capacity are determined, as functions of the non-dimensional geometric parameter of the problem, through the kinematic approach, implementing virtual velocity fields inspired from the solution to the problem of inverted extrusion. In the perfectly rough case, it appears that the new upper bound is a significant improvement of those already available. A very simple relationship is established, which derives the upper bound for the frictionless walls from the upper bound for the rough walls. A general conclusion of the analysis is that, for the values of the geometric parameter that are likely to be encountered in practice, the increase in the bearing capacity due to the presence of the rigid walls remains very small. To cite this article: J. Salençon, C. R. Mecanique 331 (2003).     

Evolution of viscoelastic properties of polyurethane in the course of curing

Simultaneous measurements of the components of dynamic modulus at the set of frequencies were made by Fourier-Transform Mechanical Spectroscopy (FTMS) to investigate the curing process of a segmented polyurethane.The whole process of curing is treated as consisting of three stages. In the first stage, the material can flow and this stage is complete at the gel-point. In the second stage, the curing proceeds in the network and ends with phase separation of aggregating segments (blocks) of polymeric chains. In the third stage, the curing continues in the two-phase system. The object of investigation was the transition from the second to the third stage. It was shown that the position of the maximum of loss tangent depends on frequency and does not coincide with different characteristic points marking the time dependencies of G and G. This is due to the formation of micro-particles of the newly formed phase. The FTMS method is used for separation of the modulus changes into parts related to formation of chemical and physical networks.Special means of treating calorimetric measurements identified a weak maximum heat output at the moment corresponding to the transition point.     

Effet de l'anisotropie élastique cristalline sur la distribution des facteurs de Schmid à la surface des polycristauxInfluence of crystalline elasticity anisotropy on Schmid factor distribution at the free surface of polycrystals

Experimental studies of the plasticity mechanisms of polycrystals are usually based on the Schmid factor distribution supposing crystalline elasticity isotropy. A numerical evaluation of the effect of crystalline elasticity anisotropy on the apparent Schmid factor distribution at the free surface of polycrystals is presented. Cubic elasticity is considered. Order II stresses (averaged on all grains with the same crystallographic orientation) as well as variations between averages computed on grains with the same crystallographic orientation but with different neighbour grains are computed. The Finite Element Method is used. Commonly studied metals presenting an increasing anisotropy degree are considered (aluminium, nickel, austenite, copper). Concerning order II stresses in strongly anisotropic metals, the apparent Schmid factor distribution is drifted towards small Schmid factor values (the maximum Schmid factor is equal to 0.43 instead of 0.5) and the slip activation order between characteristic orientations of the crystallographic standard triangle is modified. The computed square deviations of the stresses averaged on grains with the same crystallographic orientation but with different neighbour grains are a bit higher than the second order ones (inter-orientation scatter). Our numerical evaluations agree quantitatively with several observations and measures of the literature concerning stress and strain distribution in copper and austenite polycrystals submitted to low amplitude loadings. Hopefully, the given apparent Schmid factor distributions could help to better understand the observations of the plasticity mechanisms taking place at the free surface of polycrystals. To cite this article: M. Sauzay, C. R. Mecanique 334 (2006).     

Correlation between interfacial interactions and internal stresses in filled high density polyethylene

The stress relaxation and the creep behaviour of high density polyethylene (HDPE) filled with glass fibres, clay (plate-like particles) or CaCO₃ (particles with irregular shape) were measured in uniaxial extension at room temperature. It was observed that the addition of filler increased the internal stress level, as evaluated from stress relaxation data. This increase was larger than the corresponding increase in the (short-term) elastic modulus. This behaviour may be attributed to a reduced macromolecular mobility in the matrix material close to the filler surface, i.e. to formation of an interphase region in the HDPE-matrix. From the internal stress values, the thickness of this interphase region around each filler particle was estimated, assuming a uniform coverage of the particles. It was suggested that the amount of matrix material with reduced mobility (or the thickness of the interphase region) reflected the degree of adhesion between the filler and HDPE. The change in the internal stress level due to the incorporation of different fillers, which were surface treated in some cases, was also consistent with the observed creep behaviour.     

Reserve ability of parallel system with failed elements

The aim of the analysis is to define for a system with parallel elements conditions at which the failure of one or several elements does not cause immediate failure of the whole system. The critical number of failed elements of such a system is assessed based on the strength probability properties of its structural elements. The condition of the catastrophic failure of the whole system is defined by the shape and scale parameters of the strength probability function and the number of parallel elements. The proposed probabilistic model allows estimating the ability of the parallel systems to continue operation when some of its elements are broken.     

THE DEPTH AND THE BREADTH OF THEORETICAL MECHANICS IN THE TEACHING PRACTICE1)

理论力学是工科专业的基础课,要提升学业挑战度,增加课程难度,拓展课程深度,那么该门课程对于工科专业来说,是首先要进行打造的。专业基础课的深度和广度拓展后,才能支撑后续专业课的拓展。文中从理论力学的教学环节、教学内容、教学方法和手段,以及实践环节几方面,探讨理论力学课堂教学的深度和广度的拓展,力求能够为打造理论力学成为"金课"出一份力。