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.     

血管支架输送性的体外测试装置及实验研究

依托自主设计的血管支架力学输送性能测试平台,对316L不锈钢材料的微管雕刻冠脉支架及其输送系统进行了体外输送性实验研究．该测试平台集成了基于PC的数据采集和机器视觉系统,较准确地模拟了体内状况．经重复性实验的验证,实验平台具有很好的精度和数据可重复性（6次重复性实验的标准偏差达0．03N）．实验分别测试了不同输送速度下和不同转弯半径下的输送力的大小,结果表明：支架球囊系统在模拟冠状动脉血管的160mm输送行程中,输送力呈逐渐增大的趋势,最高处达到了1．2N;而在通过弯段血管时,输送力出现显著的上升,随后减小,在圆弧的中点附近存在一个输送力的峰值;输送力随输送速度的增大而增大,随管道的转弯半径的增大而增大,此结果可对临床上心脏介入手术提供一定的参考价值．     

烤燃试验温度压力数值模拟技术研究

针对快速烤燃和慢速烤燃试验过程,本文结合两种烤燃条件和升温速率下密闭容器的试验环境,建立了温度和热应力的有限元模型,利用Ansys软件分别模拟了密闭容器在快速烤燃和慢速烤燃过程中的热传递,研究了烤燃过程中内部各区域温度和热应力的变化情况,得出密闭容器热反应过程中的热传递规律.     

Theoretical and Numerical Aspects in the Thermo-Viscoelastic Material Behaviour of Rubber-Like Polymers

Most current models for finite deformation thermo-viscoelasticity are restricted to linear evolution laws for the viscous behaviour and to thermorheologically simple materials. In this paper, we extend a model for finite deformation viscoelasticity that utilizes a nonlinear evolution law to include thermal effects. In particular, we present a thermodynamically consistent framework for the model and give a detailed form for then on-equilibrium Helmholtz free energy of the material in terms of the isothermal free energy function. The use of the model in a computational setting is addressed and it is shown that an efficient predictor-correct oralgorithm can be used to integrate the evolution equation of the proposed constitutive model. The integration algorithm makes crucial use of the exponential map as has been done previously in elastoplasticity. Numerical examples are presented to show some interesting features of the new model. This revised version was published online in July 2006 with corrections to the Cover Date.     

Numerical Differentiation in the Measurement Model

Measurement Techniques - The problems of increasing the accuracy of numerical differentiation in the measurement model are investigated. We consider the measurements of target characteristics of an...     

室内气流组织数值模拟及仿真软件

不同的气流组织形式对室内空气品质会产生影响,用CFD技术模拟气流组织具体影响,将室内空气品质的研究体现在工程设计上是必要的。本文就数值方法和相关的气流组织模拟软件作了分析和介绍,并说明了在应用过程中的步骤。     

充型过程的数值模拟技术

铸造充型过程的数值模拟技术是铸造领域的前沿技术.采用这些技术进行充型过程的数值模拟可以帮助人们更清楚地了解充型过程中金属液流动的自由表面和速度分布.介绍了充型过程数值模拟的发展过程、数学模型,探讨了充型过程的计算方法以及自由表面的处理,并指出了当前研究中存在的问题.     

带材边界位置的在线测量与计算方法

介绍了带材边界位置测量传感器的原理,并根据传感器的输入-输出特性,提出用最佳一次逼近多项式或近似最佳三次逼近多项式逼近输出函数,从而方便地计算出带材边界的位置。     

Efficient Permeability Measurement and Numerical Simulation of the Resin Flow in Low Permeability Preform Fabricated by Automated Dry Fiber Placement

We propose a new experimental method using a Hassler cell and air injection to measure the permeability of fiber preform while avoiding a race tracking effect. This method was proven to be particularly efficient to measure very low through-thickness permeability of preform fabricated by automated dry fiber placement. To validate the reliability of the permeability measurement, the experiments of viscous liquid infusion into the preform with or without a distribution medium were performed. The experimental data of flow front advancement was compared with the numerical simulation result using the permeability values obtained by the Hassler cell permeability measurement set-up as well as by the liquid infusion experiments. To address the computational cost issue, the model for the equivalent permeability of distribution medium was employed in the numerical simulation of liquid flow. The new concept using air injection and Hassler cell for the fiber preform permeability measurement was shown to be reliable and efficient.     

Numerical Analysis of Thermodynamic Behaviour of Through-Thickness Stitched Sandwich Laminate

Effects of stitching angle on mechanical properties, thermal protection capability and induced thermal stress of stitched sandwich laminate (SSL) are numerically analyzed by ABAQUS codes. Interest centers on the potential for microcracking in the vicinity of the through-thickness stitches and the skins/foam interfaces. Two numerical models, in-depth heat transfer and thermoelastic deformation, are coupled to yield the transient response of the SSL. Six different stitching angles are considered and the simulation results showed that: the heat conductivity ability of the SSL is improved as the stitching angle increasing, which alters the mechanical behaviour and the thermal stress state of the SSL.     

Numerical Simulation of Polymolecular Adsorption

A model of the polymolecular adsorption on homogeneous and inhomogeneous surfaces in the absence of lateral interactions and also with their allowance for the case of the homogeneous surface is presented. A procedure to calculate isotherms on the basis of statistical data on the substance distribution over the surface is suggested. The calculated dependences of the differential adsorption energy on the degree of filling and the isotherms are compared with the experimental data for the system benzene vapor–graphitized soot.     

通风系统运行的数值模拟

通风系统的实际运行往往与设计存在差别,难以达到理想的效果,本文采用数值模拟的方法对通风系统的运行进行分析,以得到系统在实际运行过程中各管段的风量,为系统的调节和控制提供参考数据.     

爆破漏斗形成过程的数值模拟研究

爆破漏斗是爆破破坏的基本形式.利用Ls-dyna软件,模拟了条形药包和集中药包起爆时爆破漏斗的形成过程和形态,对模拟结果进行了分析,计算结果表明:靠近炸药部位的岩石是由于压缩破坏,岩体表面属于拉伸破坏,压缩破坏区和拉伸破坏区存在较明显的分界线.     

摩托车油箱冲压成形数值模拟分析

应用PAM-STAMP软件对摩托车油箱的拉延成形过程进行了详尽的有限元模拟分析,通过对模拟分析和实际冲压结果的比较,验证了摩托车油箱拉延成形模拟分析建模的合理性和模拟结果的准确性.并简要分析了模拟结果和实际冲压结果产生差异的原因.结果表明,采用PAM-STAMP数值模拟软件可准确分析摩托车油箱的冲压成形过程.     

近地面TNT爆炸的试验研究和数值模拟

为了研究近地面化学爆炸的冲击波传播特性,在试验场进行了不同当量的TNT近地面爆炸试验,并应用有限元方法模拟了其中2种工况的冲击波传播过程。数值模拟结果与试验数据吻合较好,表明计算模型和参数选取的合理性和正确性,该模型和算法可以为进一步研究近地面爆炸冲击波传播特性提供有效手段。     

线性聚能装药结构的数值仿真优化

以药型罩开口50 mm为例,利用LS—DYNA对线性聚能装药侵彻钢板的性能进行了数值模拟,通过对装药结构多次正交优化,得到的最终设计方案为三锥形外锥的药型罩,并得到了对应的装药结构,使数值仿真的侵彻过程中射流没有拉断现象,侵彻效果超过了药型罩母线长度的2倍以上(药型罩开口的1.5倍以上)。     

真空辅助成型工艺的数值分析与模拟

真空辅助工艺是一种双移动边界的工艺过程,既有厚度方向的压缩,又有平面内的树脂流动,利用通用有限元软件难以实现模拟分析,本文借助达西定律,建立了压缩模型和渗透率模型,并与专业数值模拟软件相结合,实现了简单2．5维薄壳结构的流动模拟,模拟结果与分析结果相吻合,对于生产工艺具有一定的指导意义。     

变频空调散热器仿真优化设计

为节约开发成本,缩短开发周期,更好满足市场需求,论文以某款变频空调室外机的电子元器件散热为研究对象。在不改变电器盒及散热器安装位置的前提下,利用CFD模拟手段进行散热器仿真分析及优化设计。经实验方案验证,最终在短时期内设计出较优的散热器。     

埋管换热器的实验研究与数值模拟

以自制埋管换热器换热实验台为原型建立模型,用Fluent软件进行数值模拟,模拟进水40℃、45℃、50℃三种工况下连续运行8小时后,埋管换热器周围土壤的温度分布,并用埋管换热器换热实验台做相同工况下的换热实验,取埋深4m、埋深3m、埋深2m处共计12个测温点进行比对,验证数值模拟结果的正确性,并指导数值模拟模型的修正,最后利用数值模拟计算结果分析埋管换热器周围土壤的温度场特性。