Robust multigrid preconditioner for fast finite element modeling ofmicrowave devices

A robust preconditioning technique is presented for the fast finite element modeling of microwave devices. The proposed preconditioner is based on a multigrid scheme for the vector-scalar potential finite element formulation of electromagnetic problems. Numerical experiments from the application of the new preconditioner to the finite element analysis of microwave devices are used to demonstrate its superior numerical convergence and efficient memory usage     

基于ANSYS的齿轮运动副的有限元结构分析

文章以渐开线形成的原理、赫兹公式和接触分析的有限元法为理论基础,利用PRO/E软件建立一对啮合的渐开线齿轮的精确模型,利用ANSYS的接触分析功能来实现机构的接触,对齿轮接触面上的接触应力进行分析,比较有限元法和传统赫兹公式分析齿轮接触应力的差异,最终提出齿轮结构改良的建议.     

脉冲CO2激光对K9玻璃损伤机理的仿真计算与研究

ANSYS是计算机辅助工程领域应用最广泛的有限元分析软件,通过脉冲CO2激光损伤K9玻璃有限元模型的建立和网格划分、脉冲激光的加载、设置初始条件和边界条件等几个方面,分析了基于ANSYS仿真脉冲CO2激光损伤K9玻璃过程中的一些关键问题.建立了脉冲CO2激光损伤K9玻璃的有限元模型,对K9玻璃受到脉冲CO2激光辐照时的温度和应力分布进行了数值分析.计算结果表明:在激光能量较小情况下K9玻璃的损伤为热应力损伤,损伤主要由环向拉伸应力所控制,存在体损伤和面损伤两种形式,激光脉宽和光斑半径对损伤效果有较大影响,脉宽越小,产生的热应力越大,损伤效果越好;激光光斑半径越大,产生的热应力越小,损伤效果越差.     

封装器件多应力叠加失效仿真分析与验证

针对某双列直插式(DIP)封装器件在整机温循试验中出现的失效现象,分析在器件与电路板焊接环节、电路板与整机装配环节和整机温循试验环节3个工况下可能的失效原因,对原因分别进行单工况和多工况的失效仿真分析。针对不同仿真模型在不同工况下的叠加仿真难题,提出基于ANSYS Workbench有限元软件的多应力叠加仿真方法,对比单一工况和多种工况下的仿真结果。结果表明,DIP封装器件失效是器件在焊接尺寸不匹配、过定位装配和温循试验三种工况下,机械应力和热应力的叠加使玻璃绝缘子产生裂纹导致的,有限元仿真结果与实验结果基本吻合,为DIP封装器件在多工况下应力叠加失效的故障机理研究提供一种可参考的仿真方法。     

A highly effective preconditioner for solving the finite element-boundary integral matrix equation of 3-D scattering

A highly effective preconditioner is presented for solving the system of equations obtained from the application of the hybrid finite element-boundary integral (FE-BI) method to three-dimensional (3-D) electromagnetic scattering problems. Different from widely used algebraic preconditioners, the proposed one is based on a physical approximation and is constructed from the finite element method (FEM) using an absorbing boundary condition (ABC) on the truncation boundary. It is shown that the large eigenvalues of the finite element (FE)-ABC system are similar to those of the FE-BI system. Hence, the preconditioned system has a spectrum distribution clustered around 1 in the complex plane. Consequently, when a Krylov subspace based method is employed to solve the preconditioned system, the convergence can be greatly accelerated. Numerical results show that the proposed preconditioner can improve the convergence of an iterative solution by approximately two orders of magnitude for large problems.     

Study on the fluid/structure interaction at different inlet pressures in molded packaging

This paper presents the computational study of fluid/structure interaction (FSI) analysis in the molding process using the Mesh-based parallel Code Coupling Interface (MpCCI) method with finite volume coding (FLUENT 6.3) and finite element coding (ABAQUS 6.9). The FSI analysis is implemented on the molded package during the encapsulation process with different inlet pressures. Real-time flow visualization, deformation and stress of the silicon die during the encapsulation process are presented in this paper. A fluctuation phenomenon of the silicon die is found in the encapsulation process when the inlet pressure increases. The maximum deformation during the process is determined at different locations on the silicon die, calculated during the final stage of the filling process. The deformation and stress of the die is exponentially increased with increasing inlet pressure. The maximum stress on the solder bump is concentrated near to the inlet gate. Thus, the present FSI analysis approach is expected to be a guideline or reference and provides better understanding of the encapsulation process for package design in the microelectronic industry.     

A novel simulation methodology for full chip-package thermo-mechanical reliability investigations

A methodology for simulating the accurate 3D structural details of a non-planarized technology chips is presented. FEM is a powerful tool used for electrical, thermal and mechanical analysis in the microelectronics industry. Manual geometry and finite element mesh generation of a 3D non-planar chip topology is extremely tedious and time consuming. Therefore, a new method, which is automatic or semi-automatic, is required to drastically reduce the pre-processing effort required for finite element simulations. Our proposed approach uses a virtual semiconductor fabrication technique to create geometry and finite element mesh on complex chip topology features. A microscopic power metal stack of a power IC was simulated to demonstrate this new simulation methodology and the results are presented. These numerical simulations, which included the non-linear behavior in the matrix, show that the detailed information of the large stress and strain gradients in the micro-fields can be obtained.     

提高天线丝杠传动速度的热应力分析

传动链末级采用丝杠传动的天线转速较低。为了最终提高天线转速,针对传统的结构计算的欠缺,提出了一种基于有限元热-结构耦合分析的设计方法。该方法利用动力学分析功能,结合传热学原理求解热流传递数值;通过引入数值结果的热-结构耦合分析,得到速度与应力的对应关系。通过动力学分析、热分析和静力分析的有机结合,对该类型结构计算进行了有益补充。结合工程案例示范,展示了该方法的应用前景。     

E面分支波导耦合器的二维有限元法分析

基于二维有限元的分析途径 ,本文提出了四端口E面分支波导耦合器的一种分析方法。利用该方法 ,开发了相应的分析软件 ,并已成功应用于“微波模块设计制造一体化系统”中。一个四端口 4 .9dB五分支波导耦合器实例的计算结果与实验结果以及HFSS(一种基于三维有限元的高频结构仿真软件 )仿真结果的比较 ,证明该分析途径及软件实现是精确而有效的 ,并可广泛应用于同类微波器件的分析。     

Stress analysis of 3-dimensional IC package as function of structural design parameters

Solid Liquid Inter-Diffusion (SLID) is a technology that has recently been utilized to fabricate 3D ICs. Since application of this technology is in its infancy stages, manufacturability and reliability of these bonds are still under heavy investigations. This study presents an elastic-plastic finite element and analytical analyses that were implemented to evaluate effect of package design parameters on thermo-mechanical reliability of the SLID bonds and copper interconnects. A numerical experiment is designed in which several design parameters; die thickness, bond size, underfill stiffness and substrate thickness, are varied in 3 levels. Stress in SLID bonds and in copper interconnects were evaluated using the 3-dimensional finite element analysis as well as an analytical approach. The results show that die and substrate thicknesses are the most influential factors among the selected parameters on stress at the interface and on copper interconnects. Main effect results for stress analysis in SLID bonds using finite element shows that die thickness and underfill stiffness are the most influential factors in defining stress at SLID bonds. Results of the analytical approach confirm the finite element analysis. It is shown that effect of interconnect size and pitch is very small compared to die thickness. In average increasing die thickness increases both shear and peeling stresses at the interfaces and copper interconnects.     

剪式压电微喷的设计及分析

利用压电陶瓷的厚度切变振动,设计出一种新型微喷。介绍了它的结构、工作方式及驱动方法。用弹性薄板模型对微喷进行理论分析,推导出振动位移函数,估算了自由振动基频和受迫振动端部位移。用有限元软件模拟振动模态,其模拟结果与理论计算接近。使用微电子及微电子机械系统(MEMS)工艺,在国内首次制备出该类型微喷,加载驱动波形后达到喷射效果。     

基于MEMS技术的仿生纤毛风速传感器的设计和仿真

设计了一种可以实现二维风速测量的电容式纤毛传感器,其特点为通过差分电容检测流速,传感器运动结构所对应的背硅被完全刻蚀。采用有限元分析软件,通过流体-固体-静电场的多物理场仿真,分析得到了传感器的差分电容与风速的变化关系。结合电容传感器AD7746的理论精度,计算得出传感器的风速灵敏度为0.25mm/s。此外,设计了基于SOI硅片的传感器微加工制备的工艺流程。     

Finite Element Techniques for Removing the Mixture of Gaussian and Impulsive Noise

The finite element method has become a very powerful and popular tool to solve boundary value problems coming from science and engineering. Here, we consider a scattered data fitting method based on the finite element method and apply the method to remove the mixture of Gaussian and impulsive noise from an image. Numerical results show the performance of the approach.     

ANSYS在脉冲CO_2激光对K9玻璃损伤过程模拟中的应用研究

从脉冲CO2激光损伤K9玻璃有限元模型的建立和网格划分、脉冲激光的加载、设置初始条件和边界条件等几个方面,分析了基于ANSYS的脉冲CO2激光损伤K9玻璃模拟过程中的一些关键问题,建立了脉冲CO2激光损伤K9玻璃的有限元模型,对K9玻璃受到脉冲CO2激光辐照时的温度和应力分布进行了数值分析.     

Increasing image resolution in electrical impedance tomography

An effective approach to increase the image resolution in static electrical impedance tomography is proposed, in which the image with local high resolution is reconstructed by fine meshing only the impedance abnormal element in the finite element model based on a genetic algorithm. Experimental results from a laboratory phantom are presented     

Stress analysis method for elastically anisotropic material basedoptical waveguides and its application to strain-induced opticalwaveguides

A numerical approach for the stress analysis of elastically anisotropic material-based optical waveguides is newly formulated with the finite element method (FEM). The stress analysis method developed here is linked to the guided mode analysis method to produce a two-step analysis of acoustooptic modulation of optical waveguides. Numerical examples are shown for strain-induced optical waveguides on LiNbO₃ substrates     

利用COMSOL软件对1D-BPM电极影响的仿真及分析(英文)

基于微机电系统(MEMS)微加工技术和Pb(Mg1/3Nb2/3)O3-PbTiO3(PMN-PT)电光材料设计的一维二进制码相位调制器(1D-BPM)可用于激光显示技术中的散斑消除。建立了1D-BPM数学模型,推导出电极在PMN-PT片内产生的电场和PMN-PT折射率变化导致通过的光束相位变化的关系。采用有限元分析方法仿真了电极几何尺寸对相位的影响,发现当电极尺寸在亚微米级时,两电极间相位分布不仅依赖于电极产生的电场大小,而且受到电极几何尺寸的影响。电极角效应是器件设计及优化时需考虑的重要因素。     

球形压力容器有限元分析与应力检测研究

该文通过理论建模、Workbench有限元软件仿真和光纤布喇格光栅测量对存储惰性气体的某型号高压球形压力容器承压结构的应力分布进行了理论和实验分析研究,得出承压结构在工作条件下的应力分布规律,为其安全性能评估提供了理论和实验参考。在仿真实验的基础上将性能优越的光纤布喇格光栅引入该型号压力容器承压结构应力检测中,通过实验测量结果与仿真结果对比分析得出光纤布喇格光栅在应力检测方面的良好性能,为该类型球形压力容器的结构应力测量探寻出新的检测手段。     

Influence of solder bump arrangements on molded IC encapsulation

This paper presents a fluid–structure interaction (FSI) analysis of ball grid array (BGA) package encapsulation. Real-time and simultaneous FSI analysis is conducted by using finite volume code (FLUENT) and finite element code (ABAQUS), which are coupled with MpCCI. A BGA integrated circuit (IC) package with different solder bump arrangements is considered in this study. In the FSI analysis, effects of solder bump arrangements on pressure distribution, void, deformation, and stress imposed on the IC structures are investigated. The maximum deformation and maximum stress on the silicon chip and solder bumps are evaluated. The findings indicate that the full-array solder bump package encounters lower stress and deformation during encapsulation. The void formation of each solder bump arrangement is examined. Scaled-up encapsulation is performed and the predicted flow front advancements are substantiated by experimental results. Results demonstrate the excellent capability of the proposed modeling tools for predictive trends of IC encapsulation. Thus, better understanding of IC encapsulation is provided to engineers and package designers in the microelectronics industry.     

Finite array antenna, scattering, and transmission-line analysisusing the FFT

An efficient unified approach to the solution of a wide class of electromagnetic problems involving finite structures-including analysis of finite-array antennas (both transmission and reflection), scattering problems, and calculation of transmission-line eigenwaves-is presented. This approach is based on the fact that these problems can be described by the same mathematical tool, namely, convolution-type systems of linear algebraic equations (systems with matrices having a Toeplitz type of structure). Efficient methods are proposed for solving them