吹塑薄膜成型工艺建模及仿真研究

在为塑料薄膜吹塑过程建立计算模型的基础上 ,利用有限元软件进行了计算和分析 ,将原用于结构计算的有限元软件引用于吹塑薄膜成型工艺 ,研究并计算了从泡颈到薄膜吹胀成型过程中的膜泡半径和厚度变化 (分布 )。     

薄膜成型工艺的物理模拟和数值模拟

本文主要以国外 1993年发表的一项实验结果作为参照 ,将有限元方法用于塑料薄板成型工艺计算领域之中 ,并且得到了较为满意的结果。主要研究了塑料薄板挤吹成形过程中 ,口模到凝固线之间有限元计算模型的建立 ,计算了薄膜成型的半径和薄膜厚度分布 ;对温度分布 ,应力分布等也作了一定程度的分析研究     

圆形薄膜预应力测量

通过测量薄膜在均匀载荷下的中心挠度变化可以推算出薄膜的预应力,达到无损测量的目的,为了验证这个方法的可行性,运用Von Karman’s方程计算薄膜的挠度与预应力以及均匀载荷的对应关系,并运用有限元软件建立模型对薄膜进行建模分析。设计实验测量薄膜在均匀载荷下的中心挠度大小,根据实验数据运用Von Karman’s方程以及有限元软件进行仿真分析。结果表明,Von Karman’s方程可以用于大径厚比的高分子薄膜材料,可以通过这个方程计算均匀压强下的薄膜中心挠度变化,利用方程推算薄膜预应力的方法能够应用于实际的薄膜上,为薄膜后续使用提供测量预应力的基础。     

钛合金TC4板超塑性成形／扩散连接数值模拟

本文讨论超塑性成形与扩散连接（SPF／DB）成形原理和过程。利用有限元软件Marc对钛合金TC4板超塑性成形／扩散连接进行数值模拟。通过模拟预测钛合金Tc4成形件的壁厚分布情况,并获得优化的压力-时间（P-t）曲线,为后续试验的成形气压控制提供参考依据。     

椭圆形封头冲压成形壁厚减薄量精确计算与参数寻优

利用先进的数值计算方法,实现封头冲压成形过程从定性分析向定量控制的转变成为目前研究热点问题之一.然而在有限元数值计算模型中,如何精确读取成品封头壁厚减薄量一直是难点.为此,首先基于一般通用有限元软件建立了一个标准椭圆形封头冲压成形数值计算模型,然后结合大型工程计算与优化软件开发相应用户子程序,实现封头成品各点壁厚值的精确提取,并对封头坯料结构几何参数进行了优化,得到最佳的坯料壁厚值和直径,研究结果可为封头成型制造过程定量控制提供技术支持.     

高分子薄膜双向拉伸成型过程的计算机仿真

采用速率形式的弹塑性大变形静力显式有限元方法和单向拉伸的KMM模型对高聚物薄膜的双向拉伸过程进行了数值模拟,对比分析了薄膜在双向拉伸过程中考虑速率敏感和不考虑速率敏感时的应变分布变化.     

共流型转子的有限元分析

通过建立共流型转子的物理模型、数学模型和有限元模型,并运用POLYFLOW有限元分析软件对共流型转子的混炼过程进行了模拟。通过对混炼过程的速度场和粘度场的求解计算,证明共流型转子具有较好的分散和分布混合功能。     

焊接热传导方程的有限元解法

采用有限元解法解决非线性问题比较方便而实用的方法。另外随着有限元软件的日益成熟这种方法被越来越多的人所接受。文中首先对有限元方程做了整理和归纳,然后应用有限元分析软件,并考虑到材料的物理性能随温度的变化以及外界环境对焊接构件温度场的影响,对不锈钢平板焊接的热传导过程进行有限元分析。获得了平板焊接过程的温度场的分布情况。     

SiCp/Al复合材料挤压过程模拟及缺陷原因分析

采用有限元模拟软件计算碳化硅颗粒增强铝基复合材料挤压成形过程。材料热模拟实验获得复合材料的流动应力曲线,模具逆向工程建模获取模具表面形状,导入模拟软件计算得到温度场、速度场和位移场等难以测试的场变量。通过对计算结果分析得到型材挤压翘曲变形的成因和工艺优化的方向。     

基于ANSYS挤出机机筒加热装置的温度场分析

根据传热学原理以及有限元分析软件ANSYS10.0建立了机筒结构二维有限元模型。通过对机筒设置合理的边界条件,计算和分析了机筒的温度场分布和变化状况,阐述了影响温度场分布的因素,为优化料筒结构设计提供了参考依据。     

Development of a numerically efficient approach based on coupled CFD/FEM analysis for virtual fire resistance tests—Part B: Deformation process of a steel structure

In the present study, the structural analysis of a three-parted steel door during a fire resistance test was examined by FEM simulation. The structural analysis is part of a coupled CFD/FEM simulation approach developed for the prediction of fire resistance tests. The basis of this follow-up work was the calculated temperature in the test specimen from CFD to predict the thermal stresses, deformation and gap formation between the door parts. The spatial information of the temperature in the test specimen was exported. Subsequently, the thermal expansion of the door and the resulting stresses and gaps were calculated. To validate the FEM simulation, the deformation of the steel door was observed. It was found that the simulation predicted the deformation of the steel door in close accordance to the measurement. The maximum displacement was found in the centre of the construction with 141 mm, whereas the simulation predicted a value of 133 mm. In addition to the deformation of the door, also the prediction of the gap formation was validated against the flue gas leakage. The first flue gas exit occurred already after 120 seconds, which was in spatial and temporal conjunction with the maximum gap predicted in the simulation.     

Stress Concentration Due to Fiber-Matrix Fusion in Ceramic-Matrix Composites

Stress concentration in ceramic-matrix composites due to fiber-matrix fusion is investigated using finite-element modeling (FEM) in conjunction with experiment. FEM results indicate substantial stress concentration can be expected when the fiber and matrix are locally fused. The focus of the investigation is sealing through the formation of a reaction product layer (e.g., SiO₂ in a SiC-SiC system). Direct sealing also is considered. Tensile experiments involving a novel SiC-SiC microcomposite system confirm FEM predictions and unambiguously indicate the observed reduction in load-bearing capacity is the result of a SiO₂ reaction product that locally fuses the fiber and matrix.     

有限元法在轮胎结构设计中的分析与应用

简要介绍了轮胎结构分析方法的发展过程，着重介绍了二维和三维有限元法在轮胎结构分析中的应用。通过对轮胎二维和三维有限元实际模型的分析比较．指出了它们各自应用的优缺点，并阐述了有限元法在轮胎结构分析和设计领域中的发展及应用前景。     

啮合型连续混炼机转子流场分析与转子几何造型的理论研究

建立啮合连续混炼机转子的三维非牛顿等温流场模型，并进行流场分析。利用ANSYS软件进行数值模拟，得到流场的压力场、速度场和粘度场，用自编程序对转子流场中的回流量、越过转子棱的流量和平均剪切应力进行了计算，并对转子的几何参数对转子的流场混炼效果的影响进行讨论。     

Overall numerical simulation of extrusion blow molding process

This paper focuses on the overall numerical simulation of the parison formation and inflation process of extrusion blow molding. The competing effects due to swell and drawdown in the parison formation process were analyzed by a Lagrangian Eulerian (LE) finite element method (FEM) using an automatic remeshing technique. The parison extruded through an annular die was modeled as an axisymmetric unsteady nonisothermal flow with free surfaces and its viscoelastic properties were described by a K‐BKZ integral constitutive equation. An unsteady die‐swell simulation was performed to predict the time course of the extrudate parison shape under the influence of gravity and the parison controller. In addition, an unsteady large deformation analysis of the parison inflation process was also carried out using a three‐dimensional membrane FEM for viscoelastic material. The inflation sequence for the parison molded into a complex‐shaped mold cavity was analyzed. The numerical results were verified using experimental data from each of the sub‐processes. The greatest advantage of the overall simulation is that the variation in the parison dimension caused by the swell and drawdown effect can be incorporated into the inflation analysis, and consequently, the accuracy of the numerical prediction can be enhanced. The overall simulation technique provides a rational means to assist the mold design and the determination of the optimal process conditions.     

Stress Analysis of Contact Deformation in Quasi-Plastic Ceramics

A stress analysis is made of Hertzian contact deformation in relatively tough ceramics with heterogeneous microstructures, where the response is essentially quasi-plastic rather than ideally elastic-brittle. Contact data for two such heterogeneous ceramics, a micaceous glass-ceramic with modest hardness and a silicon nitride with high hardness, are presented as illustrative cases. Data from a soft steel serve as a comparative baseline. Two distinctive aspects of the deformation response are explored: indentation stress-strain nonlinearity; and size and shape of the damage zone. For the harder ceramics, the stress-strain nonlinearity is less pronounced, and the quasi-plastic zone is more tightly confined beneath the contact, than in traditional ductile metals. As in metals, the deformation process in the ceramic structures is essentially shear driven, but has its origin in microstructurally localized interfacial sliding faults rather than in dislocation slip. Finite element modeling (FEM) is used to compute the shear stress distributions beneath the spherical indenters for selected experimental loading conditions. The underlying basis of the FEM calculations is an elastic-plastic constitutive relation based on a critical shear condition for yield, but incorporating a strain-hardening characteristic to allow for local elastic constraints on the sliding shear faults. The FEM calculations are able to simulate the main features of the stress-strain curves and the evolving deformation zone geometries. In addition, the calculated tensile stress distributions are able to account, at least in part, for the suppression of conventional brittle fracture tendencies in tougher ceramics.     

降雨渗流作用下残积土边坡的数值分析

介绍了某残积土边坡受降雨影响的变形特点及边坡渗流分析计算理论,得到了残积土边坡降雨作用下的稳定渗流场,编制了考虑降雨渗流引起渗透力作用的边坡非线性有限元计算程序,计算模型采用Duncan非线性弹性模型和修正v值的Duncan模型。根据计算结果,分析了降雨渗流对残积土边坡的应力和变形的影响。边坡应力水平较小,但应重视边坡变形引起裂缝的防治。     

具有堆焊层的复合管板热-结构耦合分析

通过有限元法计算了 15 Cr Mo堆焊 0 0 Cr17Ni14Mo2 Ti的管板结构在热处理及工作状态下的温度场和应力场。结果表明 ,在堆焊交界面附近 ,由材料物理性质差异所引起的热应力非常高 ,成为导致堆焊层剥落的重要因素之一     

高速釜用磁力传动器隔离套的设计与有限元计算

提出了迷宫式的冷却通道结构,并基于有限元法对具有冷却通道结构的两种方案进行计算和分析,通过与隔离套原始结构的对比和评估,进而指导产品具体工程化设计。