一种用于非线性振动系统的模态分析方法

本文提出了一种用于非线性振动系统的模态分析方法,将求解非线性系统模态的问题化为求解非线性特征值、特征向量的问题,利用模态研究系统的响应,文中分析了非线性保守系统、非线性自治系统和非线性非自治系统的线性模态,导出了三个模态包含原理。     

平带驱动系统的振动分析研究进展

综述汽车发动机中带张紧装置的平带驱动系统振动分析的研究进展,在转动振动的力学模型和相应数学模型基础上,总结了用数值方法,复模态分析方法和增量谐波平衡法进行线性振动和非线性振动分析以及打滑预测的结果,在转动－横向耦合振动的力学模型和数学模型基础上,总结了用数值方法,Holzer法,模态分析法和直接多尺度法进行线性振动和非线性振动分析的结果,最后提出需要深入研究的若干问题。     

智能结构密频系统振动控制及其摄动分析

提出一种智能结构密频控制规律的设计方法。其主要工作为：将密频子空间转化为重频子空间,把密频系统作为重频系统上的摄动;为了解决重频密频子空间相对应的特征向量选取的敏感性问题,通过摄动分析得到与重频密频子空间相对应特征向量的线性组合并利用闭环系统特征值极点配置的方法得到重频密频系统的振动规律;把所设计的振动控制规律作用于原系统和摄动系统上,讨论了结构参数改变后对系统的动态特性的影响;最后通过算例证明该方法的有效性。     

求解任意形状厚板自由振动的微分容积法

用一种新型的数值方法－微分容积法求解具有任意形状的厚板自由振动问题。该方法的基本思想是将任意一个线性微分算子对函数的作用值如一个连续函数或其任意阶偏导数、或其线性组合在某点处的值表示为域内各点函数值的线性加权组合，如此可将问题的控制方程和边界条件离散成为一组线性齐次代数方程。这是一典型的特征值问题，其特征值可用子空间迭代法求解。文中给出了详细的计算公式，用一些数值算例说明了该方法求解中厚板自由振动问题的可行性、有效性和通用性，并通过与有关文献比较验证了该方法的数值精度。     

非线性振动一种稳定的模糊控制方法研究

由于非线性振动系统的非线性本质,在于传统控制理论的线性控制器用于非线性振动控制效果不佳。本文针对非线性振动系统提出了一种模糊自适应滑模控制方案。     

混沌振动压实动力学的仿真研究—（I）混沌识别

本文提出了四自由度混沌振动压路机“机架－振动轮－土”系统的力学模型;建立了其数学模型;对数学模型进行了数值仿真;根据振动轮的运动,利用混沌识别的定性方法（相轨图、功率谱图和Ｐｏｉｎｃａｒｅ图）与定量方法（最大Ｌｙａｐｕｎｏｖ指数）,对系统的混沌特征进行了识别。结果表明：系统的运动是混沌的。     

多自由度固有振动广义特征值问题的复分析证明——工科教育中的理论思维能力培养一例

在振动理论中,"线性系统固有振动的广义特征值问题仅具有非负实特征值"是一个基本的事实,然而现有教材对这一结论的证明一般都是基于矩阵分解理论,这对于绝大多数大学本科生而言属于超前的数学知识,因此会造成学习上的一定困难.本文针对该结论给出了一种基于复分析的较为初等的证明方法,该方法仅利用复数的基本概念和简单的矩阵代数运算而...     

基于奇异值分解的复模态矩阵摄动法

对非自伴随系统的振动重分析问题,提出了一种简单的通用方法。从子空间缩聚出发,基于复矩阵的奇异值分解定理,推导了同时适用于孤立 特征值,相重特征值和相近特征值三种复特征值情况的一阶和二阶摄动公式。算例表明,该方法通用性好,且具有足够的精度。     

黏弹性结构振动阻尼等效化方法的讨论

基于能量等效的原则将黏弹性结构振动阻尼等效简化成黏性阻尼模型来处理是工程上常用的方法.本文首先介绍了能量等效法,并提出了一种基于系统特征值相等原则的等效方法;详细讨论并比较了这两种黏性阻尼等效方法所得到的等效系统,指出基于能量、特征值等效的原则实质上分别等价于系统的频率响应函数、频率响应函数幅值的等效性.     

单自由度振动系数特性的数学仿真实验

根据单自由度振动系统数学模型,设计了单自由度振动系统特性的数学仿真实验,实验结果给出振动方程解析解的表达式,并用几何方式定量描述振动过程及其幅频特性。     

The 7th International Conference on Fluid Mechanics May 24-27,2015,Qingdao,China

正http://www.icfm7.org First Announcement and Call for PapersThe objective of International Conference on Fluid Mechanics(ICFM)is to provide a forum for researchers to exchange new ideas and recent advances in the fields of theoretical,experimental,computational Fluid Mechanics as well as interdisciplinary subjects.It was successfully convened by the Chinese Society of Theoretical and Applied Mechanics(CSTAM)in Beijing(1987,     

INFORMATION FOR CONTRIBUTORS

Contributions： The Journal, Acta Mechanica Solida Sinica, is pleased to receive papers from engineers and scientists working in various aspects of solid mechanics. All contributions are subject to critical review prior to acceptance and publication.     

Preface

This special issue of PARTICUOLOGY is devoted to the first UK-China Particle Technology Forum taking place in Leeds, UK, on 1-3 April 2007. The forum was initiated by a number of UK and Chinese leading academics and organised by the University of Leeds in collaboration with Chinese Society of Particuology, Particle Technology Subject Group （PTSG） of the Institution of Chemical Engineers （IChemE）, Particle Characterisation Interest Group （PCIG） of the Royal Society of Chemistry （RSC） and International Fine Particle Research Institute （IFPRI）. The forum was supported financially by the Engineering and Physics Sciences Research Council （EPSRC） of United Kingdom,     

基于鲁棒滤波的捷联导引头视线角速度估计方法

针对捷联导引头无法直接获取视线角速度等信息的问题,研究了鲁棒滤波在大气层外飞行器捷联导引头视线角速度估计中的应用。为了建立非线性滤波估计模型,考虑目标视线角速度的慢变特性,采用一阶马尔科夫模型建立了状态方程;推导了视线角速度的解耦模型,并建立了量测方程;考虑到实际应用中存在系统噪声统计特性失准的问题,基于Huber-Based鲁棒滤波方法,设计了视线角速度滤波器,并完成了基于Huber-Based滤波方法和扩展卡尔曼滤波方法的数学仿真。仿真结果表明Huber-Based滤波方法的视线角、视线角速度及视线角加速度估计精度分别达到0.1140'、0.1423'/s、0.0203'/s2,而扩展卡尔曼滤波方法的视线角、视线角速度及视线角加速度估计精度仅分别为0.6577'、0.6415'/s、0.0979'/s~2。仿真结果证明了该方法可以有效地估计出相对视线角速度等信息,并且在非高斯噪声的条件下,依然可获得较高的估计精度,具有一定的鲁棒性。     

Guide for authors

正Each of the sections below provides essential information for authors.We recommend that you take the time to read them before submitting a contribution to Acta Mechanica Sinica.We hope our guide to authors may help you navigate to the appropriate section.How to prepare a submission This document provides an outline of the editorial process involved in publishing a scientific paper in Acta Mechanica     

Use specification of multiscale materials for life spanned over macro-, micro-, nano-, and pico-scale

Multiscale material intends to enhance the strength and life of mechanical systems by matching the transmitted spatiotemporal energy distribution to the constituents at the different scale, say—macro, micro, nano, and pico,—, depending on the needs. Lower scale entities are, particularly, critical to small size systems. Large structures are less sensitive to microscopic effects. Scale shifting laws will be developed for relating test data from nano-, micro-, and macro-specimens. The benefit of reinforcement at the lower scale constituents needs to be justified at the macroscopic scale. Filling the void and space in regions of high energy density is considered.Material inhomogeneity interacts with specimen size. Their combined effect is non-equilibrium. Energy exchange between the environment and specimen becomes increasingly more significant as the specimen size is reduced. Perturbation of the operational conditions can further aggravate the situation. Scale transitional functions and/or f_j/j+1 are introduced to quantify these characteristics. They are represented, respectively, by , and (f_mi/ma,f_na/mi,f_pi/na). The abbreviations pi, na, mi, and ma refer to pico, nano, micro and macro.Local damage is assumed to initiate at a small scale, grows to a larger scale, and terminate at an even larger scale. The mechanism of energy absorption and dissipation will be introduced to develop a consistent book keeping system. Compaction of mass density for constituents of size 10⁻¹², 10⁻⁹, 10⁻⁶, 10⁻³ m, will be considered. Energy dissipation at all scales must be accounted for. Dissipations at the smaller scale must not only be included but they must abide by the same physical and mathematical interpretation, in order to avoid inconsistencies when making connections with those at the larger scale where dissipations are eminent.Three fundamental Problems I, II, and III are stated. They correspond to the commonly used service conditions. Reference is made to a Representative Tip (RT), the location where energy absorption and dissipation takes place. The RT can be a crack tip or a particle. At the larger size scales, RT can refer to a region. Scale shifting of results from the very small to the very large is needed to identify the benefit of using multiscale materials.