多元件粘弹性土模型条件下桩的纵向振动特性与时域响应

研究了桩侧土为4元件粘弹性模型（分别采用两个Voigt体串联或两个Maxwell体并联）及其简化条件下（可简化成多种三元件粘弹性模型）桩土系统的振动特性,并求得了桩顶在瞬态半正弦脉冲荷载作用下,桩的时域纵向响应的半解析解,同时结合基桩完整性检测的机械阻抗法和反射波法研究了各主要模型参数对时域及频域响应曲线的影响。试算分析表明,当采用两个Voigt体串联模型时,桩的振动特性主要受参数较小的一个控制,较大的一个则起辅助作用。而当采用双 Maxwell体并联上模型时,在Maxwell体中,串联的弹簧和阻尼器通过相互耦合发挥作用,即弹簧系数的增加可表现为传统Voigt模型下阻尼作用的增强,而阻尼系数的增加则也可表现为传统Voigt模型下土刚度作用的增强,其中一个元件（弹簧或阻尼器）系数增加的极限状态（趋于无穷大）等效于另一个元件单独存在时的作用结果。研究结果表明,本文得到的理论成果相比于已有理论更加完善并能更好地反映客观实际。     

非线性弹簧阻尼减振装置的探究

将汽车底盘减振装置简化为以非线性弹簧、阻尼器为主的被动阻尼式吸振器．利用Matlab软件对其在简谐力作用下的响应进行定量绘图分析,研究其振幅衰减、缓冲周期以及与由线性弹簧构成的简单模型进行比较,解释了减振装置具体的工作过程以及其中的基本工作原理．     

冲击载荷下土的动态力学性能研究

 利用分离式霍普金森压杆（Split Hopkinson Pressure Bar,SHPB）技术,研究了土体在不同应变率条件下的冲击动态力学性能,发现土体有明显的应变率效应,与静载相比,冲击载荷下土的动强度和动模量均有很大的提高。根据实验曲线的特征,以一根线性弹簧和两个不同松弛时间的Maxwell体并联的粘弹性模型来表达土体的损伤型粘弹性本构模型,两个Maxwell体分别表示土体的低应变率响应和高应变率响应,模型的数值拟合曲线与实测动态本构曲线具有较好的一致性。拟合参数表明,土体对低应变率的响应与混凝土相同,对高应变率的敏感性远远高于混凝土。     

惯性约束聚变软X射线在线标定系统概念设计

长期以来,惯性约束聚变（ICF）研究软X射线诊断科学仪器设备的元器件标定工作主要依赖同步辐射光源X射线辐射计量站进行。该类装置通常与用于开展ICF研究的大型激光装置分处两地,难以满足ICF研究软X射线元器件实时实地的标定应用需求。另外,由于同步辐射和ICF激光等离子体产生的X射线辐射特性存在较大差异,同步辐射计量站的标定结果事实上也不能完全反映元器件在ICF实验应用中的计量响应特性。本文首先介绍一种基于单光学元件的软X射线紧凑型无谐波光源单色化技术,以此为基础提出研制基于ICF激光等离子体X射线源的同源、同几何位形、双束比较校准的多能量通道光源单色化系统,用于ICF应用软X射线元器件的在线标定。新系统一方面可望满足ICF软X射线元器件实时实地的标定应用需求;另一方面,其提供的标定光束的技术特征将最大可能地接近ICF激光等离子体X射线辐射本身。配备相应的X射线二极管（XRD）和标准探测器之后,该系统将形成一套具有在线自校准功能的新型多通道δ能量响应软X射线能谱仪。     

基于子结构技术的光机装置反射镜组件的稳定性分析

反射镜组件是光机装置的重要组成部分,反射镜片的转角稳定性对光路的传输有着直接影响。为了分析获得在地脉动载荷作用下反射镜片的转角响应,分别基于整体结构建模技术和子结构技术建立了某光机装置简化结构的有限元模型,并分析获得了装置中两个反射镜片的转角响应。两种方法得到的反射镜片的转角响应差别分别为3.99%,11.84%,说明基于子结构技术开展光机装置反射镜架组件的稳定性分析是可行的。     

等离子体对共振磁扰动的流体和动理学响应的模拟研究

本文利用MARS-F/K程序和解析方法,模拟研究了‘类-DEMO’平衡下等离子体对共振磁扰动的流体响应和动理学响应.研究发现,当新的有理面经过等离子体边缘台基区时,最外层有理面处总径向扰动场b₍res(tot))¹和等离子体边界X点附近扰动位移ξX两个优化参数在特定的q₉₅(95%归一化极向磁通量处的安全因子)窗口出现峰值,峰值的个数y与环向模数n呈正相关,即y≈n?q₉₅(?q₉₅=3.5).上下两组线圈电流相位差的最优/差值与q₉₅之间满足线性依赖关系,可用线性函数进行拟合.线圈电流幅值的优化不改变电流相位差的最优值,但可以增大优化参数ξX.线圈电流幅值的最优值依赖于环向模数n.包含背景粒子和高能粒子动理学效应的结果表明,对于低β(等离子体比压值)等离子体,动理学响应与流体响应保持一致,与有无强平行声波阻尼无关;而对于高β等离子体,在流体响应模型中需要考虑动理学效应的修正作用.考虑强平行声波阻尼(κ_∥=1.5)的流体响应模型能够很...     

地脉动环境下反射镜架系统的镜片转角响应计算

反射镜组件是光机装置的重要组成部分,反射镜片的转角稳定性对光路的传输有着直接影响。针对大型光机装置中反射镜架在地脉动随机微振动下的稳定性问题,推导了镜片转角响应均方根值的计算公式。在ANSYS中建立了一个镜架结构的有限元模型,并分析了该镜架系统的模态及结构在地脉动载荷下的微振动响应。根据计算结果分析得到了镜片转角响应均方根值; 提出了工程实际中如何通过有限元分析便捷获得镜片转角响应的另一种工程方法。两种方法所得镜片转角具有较好一致性,说明所采用镜片转角计算分析方法是有效的, 为精密反射镜架的稳定性设计分析提供了有效方法。     

基于QMU的高空电磁脉冲下电气电子设备易损性评估方法

高空电磁脉冲（HEMP）可能造成广域基础设施的故障或损毁,考虑到经济原因,需要科学合理地评估其中关键电气电子设备在HEMP辐照下的易损性。将不确定性量化与设备效应评估相结合,总结出基于裕量与不确定性量化（QMU）的电气电子设备易损性评估方法及其工作流程,包括:筛选设备关键参数,通常为耦合通道电流、电压的范数;通过HEMP环境及其与设备耦合的数值仿真及不确定性量化,得到HEMP下设备关键参数的概率分布,作为设备的威胁水平;对工作状态下设备进行HEMP效应试验,通过统计推断得到设备效应阈值概率分布,作为设备在威胁下的强度;计算威胁水平与设备强度间的距离,量化设备关键参数的裕量及其不确定性,评估HEMP下的设备易损性。基于QMU的电气电子设备易损性评估方法还可为后续防护设计提供基础数据和评估方法。     

带有自适应光学系统的ICF装置光束传输程序

 以典型的惯性约束聚变（ICF）装置为基础,根据ICF中光传输、光放大和光倍频等原理,建立了一套含自适应光学校正系统的ICF仿真软件。通过比对国内外相应的文献和专业软件的光的线性传播、非线性传播、光的增益、光的倍频等来验证软件仿真的准确性和可靠性。给出了经自适应光学系统校正前后基频光的近场强度和相位分布,3倍频光的近、远场的光强分布,说明自适应光学在提高ICF装置输出光束质量中的作用。该软件的建立将为优化ICF系统中自适应光学的设计提供参考。     

一类弹性和阻尼双分段非线性约束系统周期响应特性研究

考虑动态条件下的两种典型分段非线性约束, 根据广义耗散Lagrange原理建立一类具有弹性和阻尼双分段非线性约束系统动力学模型. 采用平均法求解得到系统在周期激励下的幅频响应关系. 分别比较系统在不同分段非线性约束条件下的时域响应、分岔响应和幅频响应, 得到受分段非线性约束的系统响应特性以及约束条件变化时系统响应的变化规律. 对比两种约束条件下的幅频响应, 研究得到系统稳定性受不同分段非线性因素影响及两种分段非线性约束之间的相互影响规律.     

ANALYSIS OF THE MULTIPLE-SOLUTION RESPONSE OF A FLEXIBLE ROTOR SUPPORTED ON NON-LINEAR SQUEEZE FILM DAMPERS

The multiple-solution response of rotors supported on squeeze film dampers is a typical non-linear phenomenon. The behaviour of the multiple-solution response in a flexible rotor supported on two identical squeeze film dampers with centralizing springs is studied by three methods: synchronous circular centred-orbit motion solution, numerical integration method and slow acceleration method using the assumption of a short bearing and cavitated oil film; the differences of computational results obtained by the three different methods are compared in this paper. It is shown that there are three basic forms for the multiple-solution response in the flexible rotor system supported on the squeeze film dampers, which are the resonant, isolated bifurcation and swallowtail bifurcation multiple solutions. In the multiple-solution speed regions, the rotor motion may be subsynchronous, super-subsynchronous, almost-periodic and even chaotic, besides synchronous circular centred, even if the gravity effect is not considered. The assumption of synchronous circular centred-orbit motion for the journal and rotor around the static deflection line can be used only in some special cases; the steady state numerical integration method is very useful, but time consuming. Using the slow acceleration method, not only can the multiple-solution speed regions be detected, but also the non-synchronous response regions.     

新型激光装置前端系统激光时间脉冲整形技术

对惯性约束聚变实验而言,激光时间脉冲整形具有非常重要的意义。随着惯性约束聚变技术的不断发展,对终端脉冲的时间填充因子的要求越来越高,直接导致了对前端系统时间脉冲整形技术的要求也越来越高。为了满足惯性约束聚变实验对前端时间脉冲整形技术的要求,自行设计了“刀口器”装置。利用这一装置,并结合改进的时空变换脉冲整形技术,在“神光—Ⅱ”的升级装置上,实现了大功率激光装置上的激光时间脉冲整形,在终端得到了脉宽1．16ns、上升沿337ps、下降沿360ps、时间填充因子为81．2％的方波激光脉冲,满足了物理实验对前端系统激光时间脉冲整形的要求。同时,提出了进一步改进的措施,以满足今后物理实验的更高要求。     

ICF激光装置的任务可用性模型和分析方法

梳理任务可用度的基本模型,构建装置执行任务的过程类型和时间模型图,体现任务时限和修复时限的要求,以此给出装置单次任务可用性评价模型 ;选用曲线拟合和拟合优度检验方法,考虑修复对任务影响程度差异及其发生概率,建立装置多次任务可用性评价模型、评价方法及分析步骤,为系统地开展惯性约束聚变激光装置可用性评价提供一般模型和方法。通过对神光-Ⅲ原型装置使用可靠性数据处理和分析,验证提出的模型和分析方法的正确性和经济性。研究成果将直接应用于神光-Ⅲ主机装置的可靠性工程建设中。     

惯性约束聚变靶三维成像研究

利用计算机层析技术，采用乘代数重建法，编制出三维图像重建程序ＣＴ３Ｄ，通过五个方位对“星光Ⅱ”装置的惯性约束聚变靶进行Ｘ光成像，重建出靶等离子体的三维图像，获得了较好的结果，表明该技术在惯性约束聚变实验中应用的可能性。     

VIBRATIONS OF PARTIALLY FILLED CYLINDRICAL TANKS WITH RING-STIFFENERS AND FLEXIBLE BOTTOM

The dynamics of a tank partially filled with a liquid having a free surface is investigated. In the analysis, the effect of free surface waves is taken into account, so that both bulging and sloshing modes are studied. The structure is completely flexible, and is composed of a vertically standing circular cylindrical shell, with ring-stiffeners, and a flexible bottom that consists of a circular plate generally resting on an elastic Winkler foundation. The plate edge is joined to the shell by coupling rotational springs distributed around the edge. The interaction between the plate and the shell via the fluid is included. Application to the particular cases of (i) a flexible shell with a rigid bottom and (ii) a flexible bottom plate with a rigid cylinder are also presented, as well as a comparison with approximate theories. Ring-stiffeners on the shell are also considered in order to investigate their influence on the modal behaviour of the tank. Solution of this problem is achieved via the method of artificial springs within the framework of the Rayleigh–Ritz theory, while considering strong fluid–structure interaction.     

Active isolation of a flexible structure from base vibration

This paper presents a theoretical and experimental investigation into an active vibration isolation system. Electromagnetic actuators are installed in parallel with each of four passive mounts, which are placed between a flexible equipment structure and a base structure which is either flexible or rigid. Isolation of low-frequency vibration is studied, so that the passive mounts can be modelled as lumped parameter springs and dampers. Decentralized velocity feedback control is employed, where each actuator is operated independently by feeding back the absolute equipment velocity at the same location. Good control and robust stability have been obtained both theoretically and experimentally for the multichannel control systems. This is to be expected if the base structure is rigid, in which case the actuator and sensor are, in principle, collocated and the control system implements a skyhook damper. With a flexible base structure, however, collocation is lost due to the reactive actuator force acting on the base structure, but the control system is still found to be robustly stable and to perform well. Attenuations of 20 dB are obtained in the sum of squared velocities on the equipment structure at the rigid-body mounted resonance frequencies. In addition, attenuations of up to 15 dB are obtained at the resonance frequencies of both the low order flexible modes of the base structure and the equipment structure.     

光机靶室钢混结构基于动刚度等效的简化建模

钢混结构分离式有限元建模方法由于考虑了钢筋的实际分布,其计算精度较高,但建模过程复杂繁琐。开展了基于动刚度等效的钢混结构简化建模研究,该方法将钢筋和混凝土考虑为一种等效材料。研究中首先以典型钢混组合结构为例,以等效模型与分离式模型的模态特性等效为目标,建立了分部件的动刚度等效模型,然后将各部件等效模型组合成整体结构等效模型,数值仿真结果显示在相同载荷作用下,整体参考模型与整体等效模型的响应分布非常接近,而等效模型的规模远小于参考模型,说明了该等效建模方式的有效性。进一步将该等效建模方法应用于神光Ⅲ主机靶室钢混结构的动力学分析中,并计算了该巨型光机结构等效模型在实测基础加速度激励下的随机振动响应,靶球上各方向的响应实测结果与计算结果较为吻合。所采用的动刚度等效建模方法可应用在巨型光机结构动力学稳定性的进一步研究中。     

Modelling and testing of a soft suspension design for a reaction/momentum wheel assembly

The micro-vibrations generated by equipment onboard spacecraft can significantly affect the performance of sensitive payloads; in particular mid to high frequency band micro-vibrations, are difficult to model and control. This study focuses on the micro-vibrations emitted by a wheel assembly (WA) implementing a soft (flexible) suspension system. Both the soft and a “conventional” rigid design were tested using a Seismic Micro-Vibration Measurement System (SMVMS). A Newton–Euler method was employed to develop an analytical model of the WA and the test system, which was then used to model and analyze the micro-vibrations emitted by the reaction/momentum WA, due to the static and dynamic imbalance of the flywheel. When compared with the traditional “rigid” design, the soft suspension system is shown to effectively reduce the high frequency disturbances, and the mathematical model effectively represents the fundamental harmonic disturbances. In addition, the results confirm that the SMVMS shows relatively high measurement accuracy.     

神光Ⅱ终端光学组件的频率变换逆问题研究

在激光惯性约束核聚变(ICF)精确打靶中,对激光束变换、整形和控制要求苛刻,通过数字在线操控技术能够在线实现激光系统的自动校准,而频率变换是数字在线操控技术中的关键一环。在不进行逼近迭代计算的情况下,基于可逆的傅里叶变换和龙格-库塔算法,对神光II终端靶场系统中负单轴晶体KDP的"I+II"类频率变换的逆问题进行了探讨和相应的算法研究,并给出了对应的模拟计算结果。最后,与神光装置运行的实验数据进行比对,验证了频率变换逆问题算法的正确性和稳定性。     

Interpretation of a layer mechanical impedance measured using a hard round die

Theoretical expressions for the impedance characteristics of a layer bound to a rigid base are obtained for various profiles of the normal pressure under a die that vibrates on the layer surface without producing any shear stresses. The frequency dependences of the impedance characteristics of a homogeneous gelatin layer and their variation with changes in the die diameter are measured by means of a specialized software-hardware system. The impedance characteristics are calculated for the models with “uniform,” “parabolic,” and “hyperbolic” pressure profiles under the die, and the results are compared with the experimental data. The model with a uniformly distributed pressure under the die is found to be the most adequate one.