高耸结构锁定激励响应和极限风压研究

本文从升力振子模型着手,以国外试验数据为依据,详细研究了锁定现象的流固耦联作用机理和对应的高耸结构横向风振的主要形式——涡致锁定激励响应,提出了合理的响应计算方法。在这些研究基础上本文还讨论了横风向受力为主的一类高耸结构的破坏风荷载计算,该研究充分体现了锁定现象的非线性激振特性。     

陀螺监控中的旋转锁定回路技术

本文论述了陀螺监控中的旋转锁定回路技术的必要性、旋转锁定回路的组成及分析与设计方法，并提出了一种利用多极同步器实现锁定控制的方法。工程试验表明设计的旋转锁定回路其锁定精度的重复性优于１＂。     

可调谐三段式DBR激光器波长锁定系统

提出了一种可精确锁定可调谐三段式DBR激光器输出波长的锁定系统。使用PC采集波长漂移信号并自动调节DBR激光器相区注入电流,使其输出波长在24～26℃的温度区间,稳定于四个C波段ITU 100GHz标准信道波长。波长误差在0.01～0.03nm范围内,边模抑制比大于40dB。该方案对可调谐三段式DBR激光器的实用化具有重要意义。     

轴向冲击下直杆动态弹塑性屈曲模态的研究

1.引言杆的动态屈曲研究开始于三十年代1966年,J. N. Goodier等人研究了飞杆对固定靶的撞击问题。由放大函数的概念求出屈曲模态。1987年H. E. Lindberg概括了国外这方面的研究工作。近年来国内也有一些工作,文[4]计及轴向应力波的影响,给出一个屈曲判据。     

泡沫金属夹芯梁在重复冲击下的动态响应

为了研究重复冲击载荷作用下泡沫金属夹芯梁的动态响应,采用Abaqus数值仿真软件,基于可压碎泡沫模型（crushable foam）,建立了泡沫金属夹芯梁遭受楔形质量块冲击的有限元模型。通过将仿真获得的夹芯梁上下面板最终挠度与重复冲击实验结果进行对比,验证仿真方法的准确性。在此基础之上,分析了泡沫金属夹芯梁在楔形质量块重复冲击作用下的变形模式、加卸载过程以及能量耗散特性。结果表明,在重复冲击载荷作用下,夹芯梁的变形不断累积,上面板主要出现局部凹陷和整体弯曲,而芯层则是局部压缩,下面板表现为整体弯曲。在重复加卸载过程中,加卸载刚度随着冲击次数的增加而增大。随着冲击次数的增加,上面板和芯层的能量吸收增量不断减小,而下面板的能量吸收增量不断增加,且最终均趋于稳定。泡沫金属夹芯梁的塑性变形能增量不断减小,而回弹系数随着冲击次数逐渐增加,最后趋于稳定值。     

爆炸荷载作用下多排钢管结构的大变形响应

采用八塑性铰变形模态,对爆炸荷载作用下多排钢管的压扁运动场进行了描述。基于虚速度原理,建立了多排钢管动力压扁模态解方程。由拉格朗日第二类方程确立初始条件,用差分法求解出各层钢管结构的传递荷载和压扁量大变形响应。计及应变率效应和材料硬化效应,计算值与试验结果相符。结果表明,采用模态法求解多排钢管的大变形动响应是可行的。     

实现动基座上动调陀螺仪启停锁定

本文在对动基座上ＤＴＧ启停运动进行分析的基础上，介绍了实现动基座锁定的思想与方法，并具体实现了由单片机完成的动基座上动调陀螺仪的启停锁定。     

模态截断与简谐载荷的响应灵敏度分析

本文解决了如何利用获得的少数低阶模态，通过改进的模态展开法来计算响应及其灵敏度的问题。算例表明本文方法十分有效     

减阻杆气动阻尼研究

基于模态数据和准定常理论,建立了减阻盘-杆-后体这一弹性结构的气动阻尼分析方法;通过刚性模型的动导数风洞试验获得气动阻尼以验证方法可靠性后,计算分析了减阻杆结构在指定工况的气动阻尼特性. 结果表明: 所建方法可用于减阻杆系统的气动阻尼计算;计算工况的气动阻尼值均为正值,对减阻杆系统的振动起抑制作用;存在产生负气动阻尼的影响因素,各项因素对气动阻尼影响的量值有所不同,有待进一步研究.      

Asymptotic theories of elastic beams and rods

Summary Through the asymptotic approach to elastic theory of beam-like structural elements, various categories of problems are distinguished with different first approximation formulations, showing different degrees of non-linearity.

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Sommario Per la teoria elastica di elementi strutturali tipo trave, il metodo asintotico porta a individuare varie categorie di problemi, retti da diverse formulazioni con diversi gradi di non-linearità, qui considerate in forma di prima approssimazione. Il metodo, oltre a fornire giustificazione di formulazioni classiche, offre la possibilità di approfondimenti sistematici.

     

Dynamic response of elastic-plastic ideal sandwich beams

The dynamic response of elastic-plastic ideal sandwich beams is investigated. The plastic deformation is interpreted as a kind of general loads in the elastic beams, while the moving interfaces between elastic and plastic regions are treated as external restraint conditions. Particularly, the dynamic response of a cantilever beam is investigated using the classical method by means of the superposition of the vibration modes of elastic beams. The numerical results show that, compared with the rigid plastic solutions, the dynamic behavior of elastoplastic beam exhibits complex response modes. In some cases, elastic deformation has very important effects on the response mode of the beam, so it should not be ignored.     

紧急锁止式安全带卷收器带感锁止触发过程的运动学研究

对某型号紧急锁止式安全带卷收器的带感锁止触发进行了研究.在阐明安全带带感锁止机构工作原理的基础上,重点研究了带感锁止触发过程的运动学特性.针对非线性触发锁止特性,分别推导了带感锁止触发的接触力-加速度-时间及加速度-分离角度-时间的运动学方程.结合卷收器设计参数方程进行了数值求解,得到了锁止触发的两阶段运动学特性.研究...     

Dynamic deformation of glued beams

The dynamic deformation of two glued rectangular beams is studied. A problem formulation and problem-solving method are given. It is assumed that the structure moves in a vertical plane. The materials of the beams and adhesive interlayer (AI) are homogeneous and isotropic. The geometrical and mechanical characteristics of the beams are different. Assumptions on the stress–strain state of the beams and AI are formulated based on the theory of elasticity. The composite beam is decomposed into three beams. The virtual-displacement principle is formulated for each of them. The problem is solved by finding five functions defined on the beam axis. The formulated principles allow solving different problems of dynamic deformation of glued beams     

薄板几何非线性中的精化元方法及膜闭锁问题

基于放松单元间协调条件的大变形变分原理和全局拉格朗日方法，推导了几何非线性精化三角形薄板单元。对几何刚度矩阵，通过引入特殊的单元位移函数，有效地消除了薄板弯曲问题中伴生的膜闭锁现象。数值结果表明该单元在几何非线性分析中既能消除膜闭锁又具有较高精度。     

Dynamic behavior of braced thin-walled beams

The present paper considers the dynamic behavior of beams with open thin-walled cross-sections along their length with bracings (connecting beams and truss). The effect of the constrained torsion warping, rotary inertia, and flexural-torsion coupling due to nonsymmetric cross-sections is included. In the case of simply supported beams, closed-form solutions for determining coupled natural frequencies and corresponding mode shapes are newly derived. The frequency equation, given in a determinantal form, is expanded in an explicit analytical form and then solved using the Mathcad 2001 Professional symbolic computing package. Some illustrative examples on the application of the present theory are given for coupled bending-torsion vibrations of braced thin-walled beams. As compared with FEM, numerical results demonstrate the accuracy and effectiveness of the proposed method Published in Prikladnaya Mekhanika, Vol. 43, No. 11, pp. 129–143, November 2007.