基于CMDS的新型比磁化系数测定装置的应用

针对测定物质比磁化系数的重要意义和简易比磁化系数测定装置的不足,研制了新型比磁化系数测定装置,开发了比磁化系数测定系统(CMDS)。基于该系统对强磁性、弱磁性物质的比磁化系数进行了系统的测定。     

新型比表面积测定仪在检测中的应用

表面积的测定提供一种操作方便、系统抗干扰性强、运行稳定、测量准确的比表面积测定仪,使我国水泥的物理性能得到正确的测定和评定,从而保证水泥的质量性能.该仪器的研制成功,将解决目前已有比表面积测定仪存在的诸多弊端,为我国建筑行业的质量安全目标的实现和我国建筑行业正确地发展提供保障.     

导热系数测量系统的数值模拟

对中国计量科学研究院的稳态保护热平板导热系数测量系统的温度场分布进行数值计算,并在此基础上对实验材料内测温点的选择进行了分析.结果表明,测温点复盖了实验材料内温度的最低和最高点,且呈线性分布,满足实验材料导热系数测量所需温度梯度测量的要求.此外,对热流密度测量的探讨发现,热流密度测量范围的确定是实现精密测量导热系数的关键.     

瞬态热线法导热系数测量的数值模拟

利用有限元方法对瞬态热线法导热系数测量进行了数值模拟,对各种因素如加热功率、热线半径以及实验温度等对测量过程的影响进行了分析,并将模拟得到的温升曲线与实验测量得到的温升曲线进行了比较,结果表明:通过选择适当的参数值,模拟曲线可以与实测曲线吻合得很好,实验值与模拟值的偏差小于实验结果的不确定度.本结果的获得对进一步理解瞬态热线法导热系数测量过程,提高导热系数测量技术水平具有借鉴意义.     

基于数值模拟的三杯式风速仪线性系数的预测

利用Pro/E建立风速仪几何模型,导入ANSYS CFX进行计算流体动力学分析,计算基于RNG k-ε湍流模型,采用被动滑移网格技术实现风杯的转动。通过对不同风速下风速计的响应进行模拟,预测了风速计的线性系数,减少了风洞实验的成本和反复改进样品的时间。     

磁性液体管道流动的数值模拟

通过将磁性液体的磁化曲线用一个反正切函数来模拟，并且将磁场体积力写成Az的函数形式来模拟磁性液体在圆管申的流动。结果表明，圆管内的磁性液体有最大流量时，磁性液体流在靠近永磁附近呈紊流状态流动，在圆管的最右端，大致呈层流状态流动；圆管内的磁性液体净流量为零时，靠近永磁的磁性液体在原地呈激烈的涡旋流动状态．     

刚粘塑性有限元数值模拟中粘性系数的获取方法

以塑性元件和粘性元件并联的模型为基础,研究材料粘性系数的获取方法,给出了一些材料的粘性系数和影响因素之间的关系曲线,为模拟研究中粘性系数的获取提供一种方便有效的方法.     

覆冰四分裂导线空气动力系数数值模拟

利用Fluent流体动力学分析软件计算典型覆冰四分裂导线在特定风速下的绕流问题,所得各覆冰子导线空气动力系数随风攻角变化曲线与由风洞试验所得规律一致。基于数值模拟和风洞试验所得气动系数确定的Den Hartog系数与Nigol系数随风攻角的变化结果吻合。利用由数值模拟和风洞试验获所得气动参数,采用Abaqus有限元软件模拟典型线路段的舞动,通过舞动特性分析比较发现,利用该两组气动系数模拟得到的导线舞动特性一致,表明采用数值模拟方法确定覆冰导线的空气动力系数可用于模拟覆冰导线舞动。     

稳态法导热系数测定仪校准方法及其不确定度评定

本文以IMDRY300-Ⅱ型双平板法导热系数测定仪为被校准仪器,根据JJF (苏) 98-2010《导热系数测试仪校准规范》,分别使用绝热材料导热系数参比板、薄膜温度计和温度巡检仪对其导热系数示值误差、热板和冷板温度示值误差、平均温度和均匀度进行校准,对校准结果进行不确定度评定。     

临界流喷嘴数值模拟研究初探

介绍了国内外有关CFD软件在喷嘴领域内的应用现状。使用Fluent软件对0.95~0.4背压比下,喉径分别为20mm、8mm和2mm喷嘴的流动进行了数值模拟计算。对临界压力比的模拟结果表明:在相同设计临界背压比下,计算得到的临界背压比较设计值低,且随着临界流喷嘴喉径的增加有缓慢地增加。此外,通过计算得到了各喉径下喷嘴流出系数,模拟与实验结果的差异保持在可接受的范围,且有相同的变化趋势。     

新型复合除尘器的设计及数值模拟

设计一种新型旋风-布袋复合除尘器,采用两级复合除尘技术,弥补旋风除尘对于细颗粒去除效率低的不足.通过FLUENT软件提供的RNG K-ε湍流模型对其内部流场进行了数值模拟,并和未加布袋的普通旋风除尘器内部流场进行对比,探明复合除尘器内压力场和速度场基本特征.数值模拟结果表明,新型除尘器内局部湍流数目减少但切向入口处存在较强局部湍流现象;压力场变化较大,压差主要集中在布袋内外两侧.通过对复合除尘器内流场分析,为以后结构进一步优化设计提供依据.此外,复合除尘器采用嵌入式结构,占用空间小,造价低,具有广泛的应用前景.     

动圈式扬声器数值分析方法

为了全面和准确地预估扬声器的声学特性,提出了一种动圈式扬声器数值分析的完整方法。该方法包括磁路分析、振动分析和声场分析三个方面,基于有限元和边界元法实现对数值模型的求解。以某型号动圈式扬声器为例,详细介绍了三方面的数值分析网格模型、方法、原理、技术难点和结果,同时利用Klippel R&D测量系统和B&K Pulse系统等设备进行了精确测量,将数值分析结果与实际测量结果进行比较分析。实验结果表明,分析得到的力因子Bl值、共振频率、振幅响应以及频率响应曲线等都与实际测量结果基本吻合。     

Experimental study and numerical simulation of pipe-on-pipe impact

Experiments and numerical simulations were conducted to investigate the dynamic response in a pipe-on-pipe impact event, in which a missile (swinging) pipe with one end hinged and the other end free impinges on an orthogonal simply-supported/clamped target pipe at its centre. This study focuses on the effects of the impact location on the missile pipe and the wall thickness of the pipes. The experiments were carried out by using a spring-powered catapult impact setup, the specimens used were made of seamless steel pipes of two different thicknesses, 1 mm and 3 mm respectively, and the target pipes were clamped. Seven tests were carried out using the catapult. Numerical simulations using the explicit finite element code LS-DYNA were performed on an HPC360 workstation for each of the seven test cases. The results of the experiments and numerical simulations were compared, showing good agreement. Having confirmed the validity of the numerical model, numerical simulations were applied to the cases of a simply-supported target pipe, and the partitioning of the energy dissipation was calculated. As the response mode depends significantly on the initial impact position, the evolution of the response mode was examined numerically as the point of impact on the missile pipe was moved from the hinged end to the free end. It was found that there is a particular impact location for which the target pipe was most seriously damaged using the same impact speed.     

覆冰导线舞动的非线性数值仿真研究

导线的覆冰舞动严重威胁特高压输电线路的安全运行。本文利用能考虑扭转自由度的的两节点索单元,并结合分裂导     

格栅式摩擦阻尼器的试验研究与数值模拟

位移型阻尼器具有较小的屈服后刚度,在大震下会出现刚度的突然减小,出现明显的损伤集中现象,造成修复成本较高。提出了一种由多种耗能单元组成的新型格栅式摩擦阻尼器,该装置具有屈服后硬化刚度、双重耗能机制、多节点耗能等特点。对耗能单元设计了含6组试件的系数比测定试验和2组试件的耗能单元拟静力试验,并建立了数值模型。系数比测定试验表明:与黄铜摩擦材料相比,无石棉树脂摩擦材料性能更稳定、摩擦出力大;无石棉树脂材料系数比逐渐减小至恒定值,而黄铜材料系数比先增后降至恒定值。通过耗能单元的拟静力试验发现,平动摩擦和转动摩擦行为协同工作良好,耗能单元具有预期的屈服后刚度硬化行为,表现了多阶段耗能特性;其出力中各组分比例可通过控制试件设计参数(如截面尺寸、杆件数量和施加扭矩)进行调整。最后建立了实体单元数值模型,表明数值模拟结果与试验值吻合较好。     

射孔器腔内压力测试仪设计仿真研究

射孔器枪外环空压力不能直观反映射孔过程,为满足油气井射孔工艺优化以及射孔弹威力评估对腔内压力参数的需求,研制了射孔器腔内压力测试仪.由于射孔器腔内的特殊环境,其对测压仪器的体积以及形态具有严格的要求.鉴于在克拉玛依油田XXX射孔基地射孔作业测试试验的总结,仪器壳体的形变直接影响到仪器内部测试电路,因此在塑性力学基础上采用“弹型”结构对测试仪器的壳体进行了进一步的设计研究.结果表明,“弹型”厚壁壳体结构具有良好的吸能作用,解决了壳体抗震性差的问题.     

一种新型复合材料吸声的理论建模与仿真

建立了压电陶瓷/橡胶复合材料吸声的理论模型,给出了机电类比等效电路,数值仿真分析了材料参数变化时,电损耗效率和吸声系数的变化趋势.     

Development of numerical scheme for phase field crystal deformation simulation

The phase field crystal (PFC) method is anticipated as a new multiscale method, because this method can reproduce physical phenomena depending on atomic structures in metallic materials on the diffusion time scale. Although the PFC method has been applied to some phenomena, there are few studies related to evaluations of mechanical behaviors of materials by appropriate PFC simulation. In a previous work using the PFC method, tensile deformation simulations have been performed under conditions where the volume increases during plastic deformation. In this study, we developed a new numerical technique for PFC deformation simulation that can maintain a constant volume during plastic deformation. To confirm that the PFC model with the proposed technique can reproduce appropriate elastic and plastic deformations, we performed a series of deformation simulations in one and two-dimensions. In one- and two-dimensional single-crystal simulations, linear elastic responses were confirmed in a wide strain rate range. In bicrystal simulations, we could observe typical plastic deformations due to the generation, annihilation and movement of dislocations, and the interaction between the grain boundary and dislocations. Moreover, the deformation behaviors of a nanopolycrystalline structure at high temperature were simulated and the intergranular deformations caused by grain rotation and grain boundary migration were reproduced.     

Experimental study and numerical simulation of split growth for unidirectional composites with a surface notch

An analytical model based on the shear-lag theory has been developed to predict the failure behavior of unidirectional composites with a center surface notch under uniaxial tensile load. A delay effect on two split faces touching each other is taken account in the analytical model. The equations obtained by the analytical model are solved using a variational technique - the principle of minimum potential energy (PMPE). Combining the fracture criterion of energy release rate with the experimental data gathered from tests, we have numerically predicted longitudinal split initiation and split growth. The predicted results are in agreement witht the experimental results. The predicted results and experimental results both apparently show two regions - the first stable split growth and the second rapid split growth.Supported by National Natural Science Foundation of P. R. China.     

基于扩展有限元的钢瓶爆破数值仿真研究

金属钢瓶的爆破压力是其重要的安全技术指标,目前的数值计算方法不能有效对气瓶的爆破压力进行准确预测。提出了基于扩展有限元的数值计算方法对钢瓶的爆破进行了数值仿真,仿真结果表明该方法能准确预测钢瓶的爆破压力,可以为钢瓶工程设计和事故预防提供支撑。