规则隔震结构等效简化模型的研究

在Kelly等人研究的基础上,以结构周期、总基底剪力和总基底弯矩相等为等效准则,将多自由度结构简化为与之等效的两自由度模型结构。通过对一些规则结构的数值模拟分析,给出了这个模型结构系统参数的简化计算公式。这样对简化后的等效模型结构应用振型分解反应谱法,可求出原结构考虑高阶振型影响的结构最大地震反应。其计算简单、可不依靠计算机进行。而将这种等效方法应用于高层隔震结构,可较准确的对其最大地震反应进行预测。计算实例也证明了,这种等效方法是简便可行的。这为高层隔震结构实用设计方法的研究提供了基础。     

水封爆破装药结构优化数值分析及其应用

以温泉隧道为研究背景,从应力、振速变化、动态损伤以及爆后粉尘的角度对药柱上部水间隔、两端水间隔和下部水间隔三种装药结构进行模拟分析,选取最优结构用于工程施工。研究结果表明:(1)药柱底部水间隔装药结构易造成孔口围岩破碎导致爆炸气体流出,降低爆破效果;药柱上部和两端水间隔装药结构爆炸应力持续时间较长,有利于围岩破碎,其中药柱两端水间隔装药结构底部存在水介质,对孔底围岩起到保护作用;(2)采用两端水间隔装药结构能够同时降低炮孔两端围岩振速和所受应力,减少炸药能量流失,使其充分作用于围岩进行破碎,降低炸药单耗;(3)药柱上部水间隔装药结构对孔口围岩损伤最小,导致爆破后岩石块度较大;药柱底部水间隔装药结构形成的整个损伤区域最小,采用这种装药结构炸药单耗偏高;药柱两端水间隔装药结构形成的损伤区域规整,爆破后岩石块度最小;(4)三种装药结构中,下部水间隔结构爆后粉尘浓度最高,两端水间隔装药结构爆破后粉尘浓度稍高于上部水间隔装药结构,但是相差不大,而两端水间隔装药结构的爆破效果要优于上部水间隔装药。综上所述,药柱两端水间隔装药结构最优,可用于工程施工。综上所述,药柱两端水间隔装药结构最优,可用于工程施工。     

Effect of support structure design toward residual stress of part build using selective laser melting

Selective laser melting process required post-processing of support structure and it is compulsory to use it at overhanging part. There is certain condition where support structure cannot be remove using wire cut machine because of limited access to part and need to be remove manually. This is where the removability of support structure plays important role because support structure needed to be design so that it can be easily remove using manual way. In addition, when comparing contour type of support structure with the most commonly use block type of support structure it shows that contour type is easier to be remove. Furthermore, no research has been done on optimizing the contour type of support structure. A research experiment is conducted in this work to optimize the parameter of contour support structure which is contour offset, teeth height, teeth top length and teeth base length. The result indicates amount of residual stress and the time required for support removal are significantly influenced by contour offset, while all parameters are significant for support volume. The optimum parameter to get low residual stress is contour offset is 0.6 mm, teeth height is 1.4 mm, teeth top length is 0.75 mm and teeth base length is 1.55 mm.     

双重抗震结构及其设计参数的分析研究

本文根据多道抗震设防概念,对双重抗震结构的设防目标进行了探讨,明确了主、 次结构的功能．文中利用单自由度双重结构分析模型,对主、次结构的合理参数关系进行了 计算分析,提出了有关抗震设计建议。有关结果同样也适用于滞迟型减震控制结构。     

密肋复合墙板支撑框架结构自振周期计算方法

密肋复合墙板支撑框架结构是由框架与其内部嵌入的密肋复合墙板组成的一种双重抗震结构,框架内部嵌入复合墙板所组成的受力构件,其变形特征不同于普通框架和剪力墙,由此导致结构的自振周期计算方法不能直接按照一般框架-剪力墙结构进行计算。本文以Timoshenko双变量梁理论及协同工作模型为基础,建立了复合墙板支撑框架结构的频率方程,结合边界条件导出了结构的自振周期计算公式,并给出了基本自振周期的近似计算方法。算例分析表明：复合墙板支撑框架结构自振周期受复合板抗剪刚度影响较大,且影响随着振型的增加而增大,高振型时复合墙板剪切变形的影响不可忽略;采用似计算方法计算基本自振周期的误差不大,可以满足工程计算精度要求。     

简单悬挂结构的非光滑模型建立

悬索结构在外激励作用下,下部悬挂结构可能会发生飘浮,以致连接主索与下部结构的吊索部分产生松弛.由于索结构只能在张拉情况下承受拉力,不能承受压力,基于这一特点,吊索应考虑为具有非光滑性的单向约束.以简单悬挂结构为研究对象,建立其在外激励作用下的非光滑的动力学模型,运用神经网络确定每一步真实发生的约束情况,并进行了数值分析.     

Li-based anode: Is dendrite-free sufficient?

Achieving non-dendritic Li deposition is generally believed to be a prerequisite for the successful commercialization of lithium metal batteries (LMBs). However, it is discussed here that eliminating the growth of the dendritic Li structure seems not to be sufficient to propel the LMB technology from laboratory research to practical applications. Other types of the electrochemically generated Li structure, besides the dendritic structure, must be further studied. It is suggested that considerable research effort be focused on studying the electrochemical nature of generated Li structures, in addition to finding novel strategies to eradicate them.     

Intra-particle coupling and plasmon tuning of multilayer Au/dielectric/Au nanocrescents adhered to a dielectric cylinder

A 3D numerical study on surface plasmon resonance is presented for a multilayer Au/dielectric/Au nanocrescent structure adhered to a dielectric cylinder. Investigations are carried out on the structure’s coupling modes, local field enhancement (LFE) and plasmon tuning capability. The cavity coupling via the cylinder is found to be dominant in tuning the plasmon wavelength. This provides the possibility of tailoring the device's plasmon band by adjusting the cylinder’s size and material. By using a cylinder with higher permittivity, the plasmon peak significantly shifts to the near- or mid-infrared regime without increasing the size of the crescents, thus increase of radiation loss can be fully avoided. Extra crescent layers can also be added to the structure to induce intra-particle couplings among Au crescents and enlarge the areas of the hot-spots, without shifting the plasmon band. The LFE of the multiple-layer structure is shown to be dramatically increased through the intra-particle coupling among the Au crescents, compared with a single layer Au nanocrescent structure. Further increase of LFE can be achieved by substituting semiconductors for the dielectrics in the structure due to the charge transport at metal-semiconductor interfaces.     

Ⅰ型双块式无砟轨道传力杆受力研究

随着我国高速铁路的不断发展,Ⅰ型双块式无砟轨道结构得到了广泛应用。由于Ⅰ型双块式无砟轨道是连续结构,当铺设在温度变化较大的线路上时,会出现严重的开裂和上拱问题。为了适应兰新二线大温度跨度、大温差的线路条件,考虑将道床板断开为单元板,并在伸缩缝处设置传力杆,以保证轨道结构竖向和横向的稳定性。该文主要用有限元法计算不同传力杆数目时轨道结构的应力和变形,来研究传力杆的力学性能并确定传力杆最佳数目,最终建议传力杆数目不少于4根。     

分析小型水下圆柱壳结构冲击响应的一种近似方法

根据小型水下圆柱壳状结构受爆炸冲击后散射现象严重的特点，提出了一种新的冲击加速度的近似计算方法。首先把带加强筋的柱壳结构简化为光滑柱壳，并将冲击波分解为不同频率谐和平面波的迭加，然后，采用耦合模态法分析了受爆炸冲击水下圆柱壳状结构周围的散射场，求出了圆柱壳水下结构的表面接收压力，进而分析其受到爆炸冲击后的冲击加速度，并研究了结构的弹性变形、材料特性对冲击加速度响应的影响。工程应用实例的分析结果表明，该方法具有物理概念清晰，运用方便，准确高度的特点，可适用于分析小型水下圆柱壳状结构受到冲击加速度响应。     

Determinantal method for locally modified structures. Application to the vibration damping of a space launcher

In order to improve the dynamic behaviour of an existing or already designed structure, local modifications can be performed by taking advantage of the relative displacement between two points of the structure. A stiffner, damper or viscoelastic rod may be added and its effect on the initial structure must be assessed. A new formulation is developed, based on the response of the initial structure at the attachment points of the local modification. A determinantal equation results, whose roots are the eigenvalues of the modified structure. The equation is solved numerically with a dedicated algorithm and it is shown that this is faster than performing an eigenvalue problem reanalysis. The method is able to deal with both undamped and damped systems, and can handle several modifications simultaneously. It is applied on the last stage of a space launcher, along with a double modal synthesis method.     

基于动力学环境试验数据的模态参数识别

在被测系统做动力学环境试验的同时，将振动台台面和被测系统组成的新系统作为分析对象，以振动台给定的力谱（或加速度谱）作为激励，对被测系统进行模态参数的识别。基于结构的振动台环境试验数据，通过被测系统频域中的测点加速度测量值与台面加速度测量值之间的传递率函数，导出了一个被测系统的“广义频率响应函数”，并且通过对边界条件的进一步简化和假设，最终得到了系统的模态参数。仿真算例验证了本方法的有效性。     

On the application of the locality principle in structural dynamics

Summary A complicated mechanical structure as an assemblage of substructures is considered. A method which enables us to find the exact vibrational state of any substructure within the whole structure will be offered. In order to achieve this aim a particular element will be under precise consideration, while the rest of the structure will be described integrally. It is shown that the vibration of a certain particular element of the structure depends mainly upon the composition of the element itself and upon certain generalized properties of the remote elements of the structure, and does not depend upon details of its composition. As a result of a consideration of two examples, the effect of backward influence of the vibration of a particular element on the general vibrational state of a whole structure will become evident. This means that the usual methods of neglecting the existence of a whole structure, and investigating a simplified problem such as a particular element under excitation are not correct in the general case.     

Structural vibrations induced by HVI – Application to the Gaïa spacecraft

Given the growing stability needed for spacecraft in operation to ensure functioning of future instruments whose sensitivity requires an important technological step, perturbations encounter in orbital conditions that used to be negligible, become today an issue. This is the case of micrometeorite impacts whose energy could induce modal response of the flexible structure and imply a dynamic response of the spacecraft which could probably be disturbing for the instrument functioning. The impact environment that could be encountered by the spacecraft is preliminary studied before the definition of test to recreate the excitation with light-gas gun. Experiments are made on samples of structure representative of the ongoing Gaïa astrometric mission project. Response of the structure is recorded to be correlated to finite elements model of the sample. The excitation is then extrapolated to orbital conditions and to Gaïa finite elements model. The final perturbation is compared to the specification. The main conclusion is that for daily impact event, dynamic response of the structure will not disturb Gaïa functioning. Nevertheless, for a yearly impact event, the astrometric mission will largely be disturbed by the dynamic response of the structure to the impact.     

自适应天线结构位移最优控制

为保证大型天线结构的形状精度,传统的方法是使结构具有足够的刚度。当采用自适应结构控制天线形变规律的时候,可以大大降低结构的重量并使结构具有更高的形状精度。针对嵌入压电作动器的自适应抛物面天线结构,建立了以天线反射面最佳吻合抛物面的精度和作动器能耗为综合目标的多目标优化控制模型,模型以结构强度和作动器性态作为约束条件,并用线性加权和法转化为单目标二次规划问题。算例表明,可以用较少的作动器,实现大型天线结构的高精度控制。     

Optical gain of 1.3 /spl mu/m GaAsSbN/GaAs quantum well lasers

Optical gain of 1.3 mum GaAsSbN/GaAs quantum well (QW) structure is investigated using the multiband effective mass theory. The results are compared with those of 1.3 mum InGaNAs/GaAs and GaAsSb/GaAs QW structures. The optical gain of the GaAsSbN/GaAs QW structure is found to be similar to that of the InGaAsN/GaAs QW structure. In contrast, GaAsSbN/GaAs and InGaNAs/GaAs QW structures show significantly larger optical gain than the GaAsSb/GaAs QW structure. This is mainly attributed to the fact that the former has a larger optical matrix element than the latter. In addition, GaAsSbN/GaAs and InGaNAs/GaAs QW structures have much smaller threshold current density than the GaAsSb/GaAs QW structure. This is because the Auger recombination current density gives dominant contribution to the threshold current density and the former has smaller threshold carrier density than the latter. On the contrary, the threshold current density of the GaAsSbN/GaAs QW structure is shown to be similar to that of the InGaAsN/GaAs QW structure     

Automatic mesh generation with tetrahedron elements

To reduce the manual work involved in the application of the FEM in practice, preprocessors can be applied for the construction of network structures, which are complicated in generation strategy and do not form any optimum discrete structure. The time necessary for generation can be minimized even more by the application of only one element type within the whole network structure. A technique for the automatic generation of 3D-network structures with tetrahedron elements is presented in this paper. In this proposed technique, the nodal points of the network structure must be defined manually before the generation procedure, since a random positioning of points is usually undesirable for FEM calculation. The nodal points are connected by a program to a network structure consisting of tetrahedron elements which have optimum form for the numerical computation of the element matrices. After the generation, the element sides forming any part of the boundary surface of the network structure can be automatically identified. If necessary, the network structure can be automatically refined.     

爆破切口高度对框架结构后坐影响的数值分析

以框架结构爆破后坐理论分析为指导,根据力学原理,提出爆破切口高度太大不利于楼房倒塌,并导出了框架结构爆破拆除的合理爆高。结合工程实例,利用ANSYS/LS-DYNA建立框架结构爆破倒塌的数值模型,其模拟结果与实际情况基本吻合,表明采用数值模拟方法预估楼房爆破后坐是可行的;通过对12层框架结构定向爆破的模拟分析,提出框架结构楼房爆破,要倾覆力矩大,产生后坐小,爆破切口高度应选择在框架结构重心H_0的1/2处;要使楼房爆破后坐小,后排立柱也要炸,爆高只需在后排立柱根部形成转动铰支即可;若后排立柱不炸,应削弱柱根强度,以确保楼体在柱根处形成转动铰支;为阻止楼房爆破时后坐,可在楼房后排立柱根部堆一定高度和强度土渣。     

带TMD结构随机地震响应分析的复模态法

本文对多自由度带TMD结构的随机地震响应问题进行了系统研究。首先将结构简化成多层剪切型模型。然后建立运动方程，根据结构的振动反应以第一振型为主，将结构按第一振型展开，针对所得方程为非经典阻尼，非对称质量和非对称刚度情况，运用复模态理论进行解耦，获得了以第一振型表示的结构地震响应的解析解，对单自由度体系，此解即为结构响应的精确解，从而建立了两自由度体系在任意非经典阻尼，非对称质量和刚度情况下随机地震响应解析解分析的一般方法。本文方法也可用于基础隔震结构和无损伤“加层减震”加固结构的随机地震响应分析与优化设计。     

基于介电常数调制的曲面雷达罩蜂窝积水传感器设计

研制了一种基于介电常数调制的曲面雷达罩的蜂窝积水传感器。介电常数表示电介质在电场中贮存静电能的相对能力,而水的介电常数又远远大于空气和雷达罩材料的介电常数,因此可以利用介电常数调制法来检测雷达罩的蜂窝积水。为保证测试灵敏度,设计的传感器极板必须贴紧被测结构,而雷达罩外形决定了极板应该采用柔性的、可以贴合曲面的探头结构形状。采用多极片之间用铜条焊接的方法构成传感器探头,并利用ANSYS仿真分析对结构进行了设计优化。通过对蜂窝结构的曲面雷达罩积水实验验证,结果证明该传感器可以实现雷达罩蜂窝积水的检测,具有较高的测试灵敏度和重复性。