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1.
This paper discusses the validity of (adaptive) Lagrange generalized plain finite element method (FEM) and plate element method
for accurate analysis of acoustic waves in multi-layered piezoelectric structures with tiny interfaces between metal electrodes
and surface mounted piezoelectric substrates. We have come to conclusion that the quantitative relationships between the acoustic
and electric fields in a piezoelectric structure can be accurately determined through the proposed finite element methods.
The higher-order Lagrange FEM proposed for dynamic piezoelectric computation is proved to be very accurate (prescribed relative
error 0.02%–0.04%) and a great improvement in convergence accuracy over the higher order Mindlin plate element method for
piezoelectric structural analysis due to the assumptions and corrections in the plate theories. The converged Lagrange finite
element methods are compared with the plate element methods and the computed results are in good agreement with available
exact and experimental data. The adaptive Lagrange finite element methods and a new FEA computer program developed for macro-
and micro-scale analyses are reviewed, and recently extended with great potential to high-precision nano-scale analysis in
this paper and the similarities between piezoelectric and seismic wave propagations in layered structures and plates are stressed.
Project supported by SRF for ROCS, SEM of China and partially by Zhejiang Provincial Natural Science Foundation (NSF) of China. 相似文献
2.
采用参考面单元技术并引入虚拟杆单元,建立筋条局部脱胶开裂复合材料梁／板结构后屈曲分析的有限元简化模型。着重研究不同开裂尺寸和位SLM置对复合材料层合加筋板后屈曲承载能力的影响。计算表明：开裂位置相同,开裂尺寸增加会导致后屈曲承载能力降低;开裂尺寸相同,随着其位置由筋条中心向端部移动,加筋板的后屈曲承载能力逐渐上升;值得注意的是,筋条端部开裂使加筋板的后屈曲承栽能力显著降低,其影响远大于筋条中心位置开裂。 相似文献
3.
高利军 《邢台职业技术学院学报》2006,23(1):67-69
针对输液管道振动大,噪声污染严重的问题,本文结合振动理论、声场理论、应用有限元以及边界元方法对输液管道受激振动的噪声辐射过程进行研究,并提出了一种新的低噪声管道结构设计方法。 相似文献
4.
基于 CAD 和 CAE 软件的集成设计是现代设计趋势之一。如何将参数化 CAD 建模与有限元分析相结合是一项挑战性工作。通过改变模型参数实现自动建模和有限元分析的研究很少。探讨基于 SolidWorks 尺寸驱动的弹簧参数化建模与基于 Python 的 ABAQUS 二次开发进行有限元分析相结合的方法。在 VB 界面中,通过人机对话窗口对可变参数赋予不同的参数值,自动生成一系列圆柱螺旋压缩弹簧模型。将模型导入 Abaqus有限元软件,采用 Python 语言进行 CAE 模块编辑。将参数化技术与有限元计算有机结合,建立弹簧参数化设计与 CAE 分析系统,实现 CAE 分析的自动建模。实验结果表明,该方法可以得到合理的有限元分析结果。采用基于参数的设计与分析方法,可以缩短设计周期,得到合理准确的结果,且成本较低,弹簧分析方法也适用于其它机械零件。 相似文献
5.
板料成形模拟及其在汽车覆盖件冲压过程中的应用 总被引：3，自引：0，他引：3
基于板料成形模拟的必要性和汽车覆盖件成形的复杂性 ,提出有限元分析是模拟复杂三维板料成形问题的有力工具 .介绍了动态显式有限元法的原理和特点 ,讨论了国际现有的各种商用软件 ,论述了汽车覆盖件模拟的国内外应用现状 .以某新型汽车前门外板为例 ,运用显示有限元分析软件Dynaform对前门外板冲压过程进行了计算机模拟分析 ,预测冲压过程中可能出现的各种工艺缺陷 ,例如坯料的破裂 ,并以模拟结果为依据提出改进方法 . 相似文献
6.
An adaptive finite element-element-free Galerkin （FE-EFG） coupling method is proposed and developed for the numerical simulation of bulk metal forming processes. This approach is able to adaptively convert distorted FE elements to EFG domain in analysis. A new scheme to implement adaptive conversion and coupling is presented. The coupling method takes both advantages of finite element method （FEM） and meshless methods. It is capable of handling large deformations with no need of remeshing procedures, while it is computationally more efficient than those full meshless methods. The effectiveness of the proposed method is demonstrated with the numerical simulations of the bulk metal forming processes including forging and extrusion. 相似文献
7.
设计了一种三维有限元网格自适应局部细分的算法及数据管理系统,利用较简单的有限元误差估计方法对计算结果进行分析,建立了空间8节点等参单元网格自适应局部细分程序,通过对典型算例的计算表明,本方法可有效提高计算精度和计算效率。 相似文献
8.
高琴 《黄山高等专科学校学报》2013,(5):9-12
根据压电陶瓷材料的压电效应,改变压电常数,基于阻抗分析法运用有限元分析,结合阻抗实验对比有限元结果,分析了该方法研究的可行性,讨论了各个压电常数对阻抗的影响规律,调整参数并确定了最利于有限元实验的材料参数,总结了有限元分析的研究意义. 相似文献
9.
The surface acoustic wave (SAW) propagating in a sample of steel is simulated by using finite element method (FEM). The waves are excited by a load function with propagation properties such as phase velocity dispersion and wide bandwidth. A two-dimensional model consisting of surface defects loaded with a wideband 50-200 MHz and short time 0.1 μs displacement function is investigated in the time and frequency domains. By transient dynamic analysis, Fourier transform and dispersion calculation, snapshots of propagating wave and responses from sensing points are presented. It is indicated that this supervision approach is sensitive to the surface cracks and reflections. 相似文献
10.
汤雁 《天津大学学报(英文版)》2004,10(3):225-228
The subject of the work is to propose a series of papers about adaptive finite element methods based on optimal error control estimate. This paper is the third part in a series of papers on adaptive finite element methods based on optimal error estimates for linear elliptic problems on the concave comer domains. In the preceding two papers (part 1 : Adaptive finite element method based on optimal error estimate for linear elliptic problems on concave comer domain; part 2:Adaptive finite element method based on optimal error estimate for linear elliptic problems on nonconvex polygonal domains), we presented adaptive finite element methods based on the energy norm and the maximum norm. In this paper, an important result is presented and analyzed. The algorithm for error control in the energy norm and maximum norm in part 1 and part 2 in this series of papers is based on this result. 相似文献
11.
ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｎｏｎｃｏｎｆｏｒｍｉｎｇｆｉｎｉｔｅｅｌｅｍｅｎｔＱ6(Ｗｉｌｓｏｎｅｔａｌ.,1 973)ｉｍｐｒｏｖｅｓｔｈｅａｃｃｕｒａｃｙｏｆｃｏｎｆｏｒｍ ｉｎｇｆｉｎｉｔｅｅｌｅｍｅｎｔＱ4ｂｙｉｎｃｏｒｐｏｒａｔｉｎｇｈｉｇｈｅｒｏｒ ｄｅｒｎｏｎｃｏｎｆｏｒｍｉｎｇｄｉｓｐｌａｃｅｍｅｎｔｓｗｈｉｃｈｒｅｄｕｃｅｔｈｅｓｈｅａｒｌｏｃｋｉｎｇ,ｓｏｆｔｅｎｔｈｅｓｔｉｆｆｎｅｓｓｏｆｃｏｍｐａｔｉ ｂｌｅｅｌｅｍｅｎｔｓａｎｄｉｎｃｒｅａｓｅｔｈｅｉｎｔｅｒｐｏｌａｔｉｏｎａｃ… 相似文献
12.
一种利用等效模型与遗传算法的动态有限元模型修正方法 总被引：3，自引：0，他引：3
为了解决现有动态有限元模型修正方法计算效率不高或者可能获得局部最优解的问题,提出了一种利用等效模型和遗传算法的动态有限元模型修正新方法.首先,在设计参数的取值范围内,根据预设的多项式模型的阶次以及自变量的个数,利用试验设计方法获得拟合响应面模型所需要的最优样本点;通过有限元分析获得样本数据,并利用回归分析获得响应面模型,从而以响应面模型逼近结构特征与设计参数之间的函数关系.然后,在遗传算法的适应度评估环节,利用响应面模型替代有限元模型计算对应于一组设计参数的结构特征,并计算遗传个体的适应度,最终通过进化获得最优解,即为修正后的设计参数.以汽车车架模型为例,对其进行有限元分析与模态试验,并利用所提出的方法进行模型修正.修正后,模态频率误差的均方值小于2%.用修改后结构的动态特性的测试结果,对修正后有限元模型的预测能力进行检验,模态频率预测误差的均方值小于2%. 相似文献
13.
An efficient adaptive finite element method algorithm with mass conservation for analysis of liquid face seals简 总被引：4，自引：0，他引：4
To improve lubrication effect and seal performance, complicated geometrical hydrodynamic grooves or patterns are often processed on end faces of liquid lubricated mechanical seals. These structures can lead to difficulties in precisely estimating the seal performance. In this study, an efficient adaptive finite element method （FEM） algorithm with mass conservation was presented, in which a streamline upwind/Petrov-Galerkin （SUPG） weighted residual FEM and a fast iteration algorithm were applied to solve the lubrication equations （Reynolds equation）. A mesh adaptation technique was utilized to refine the computation domain based on a residual posterior error estimator. Validation, applicability, and efficiency were verified by comparison among different algorithms and by case studies on seals＇ faces with different groove structures. The study investigated the influence of the order of shape function and the mesh number on the leakage balance. Mesh refinement occurred mainly in cavitation zones when cavitation happened, otherwise it occurred in regions with a high pressure gradient. Numerical experiments verified that the proposed algorithm is a fast, effective, and accurate method to simulate lubrication problems in the engineering field apart from end face seals. 相似文献
14.
本文采用三维杆系力学分析模型对钢结构框架进行分析,避免了传统的有限元方法要对构件大量划分网格进行计算而导致的计算自由度巨大,计算耗时的缺点。对于杆件单元,本文采用了一种变刚度的杆单元模型,建立了考虑塑性铰分布长度影响的构件单元刚度矩阵。在此基础上对经典的算例模型进行了静力全过程分析。 相似文献
15.
大坝与坝基的稳定一直是工程师密切关注的一个安全问题. 论文提出2种分析重力坝和坝基稳定的方法: 一种是基于刚体极限平衡原理的直接分析方法, 它将坝体和岩基作为不变形的刚体, 利用该方法可直接计算出可能滑动面的安全因数; 另一种是基于弹塑性理论的间接分析方法, 它采用非线性有限元方法分析大坝和坝基的应力和变形. 根据收敛和突变准则来确定稳定安全度.结果表明:工程建筑物的破坏不仅仅是由于施加荷载的原因,同时也与组成材料的性质有关. 相似文献
16.
This paper presents a type of vibration energy harvester combining a piezoelectric cantilever and a single degree of freedom (SDOF) elastic system. The main function of the additional SDOF elastic system is to magnify vibration displacement of the piezoelectric cantilever to improve the power output. A mathematical model of the energy harvester is developed based on Hamilton??s principle and Rayleigh-Ritz method. Furthermore, the effects of the structural parameters of the SDOF elastic system on the electromechanical outputs of the energy harvester are analyzed numerically. The accuracy of the output performance in the numerical solution is identified from the finite element method (FEM). A good agreement is found between the numerical results and FEM results. The results show that the power output can be increased and the frequency bandwidth can be improved when the SDOF elastic system has a larger lumped mass and a smaller damping ratio. The numerical results also indicate that a matching load resistance under the short circuit resonance condition can obtain a higher current output, and so is more suitable for application to the piezoelectric energy harvester. 相似文献
17.
Factors such as errors during the fabrication or construction of structural components and errors of calculation assumption or calculation methods, are very likely to cause serious deviation of many strings＇ actual prestressing forces from the designed values during tension structure construction or service period, and further to threaten the safety and reliability of the structure. Aiming at relatively large errors of the prestressing force of strings in a tension structure construction or service period, this paper proposes a new finite element method （FEM）, the ＂tensile force correction calculation method＂. Based on the measured prestressing forces of the strings, this new method applies the structure from the zero prestressing force status approach to the measured prestressing force status for the first phase, and from the measured prestressing force status approach to the designed prestressing force status for the second phase. The construction tensile force correction value for each string can be obtained by multi-iteration with FEM. Using the results of calculation, the strings＇ tensile force correction by group and in batch will be methodic, simple and accurate. This new calculation method can be applied to the prestressed correction construction simulation analysis for tension structures. 相似文献
18.
19.
郝阳 《浙江大学学报(A卷英文版)》2006,7(1):34-40
INTRODUCTION Electromagnetic crystal structures (ECSs) offer the opportunity to control and manipulate electro- magnetic wave propagation as a result of their being formed from small-scale periodic geometric struc- tures. This detailed microscopic configuration can be designed to cause the material (macroscopically) to exhibit either effective permittivity or permeability that is negative over a finite frequency range. This modifies the dispersion relation of electromagnetic waves and a … 相似文献
20.
超长钻孔灌注群桩承载特性的实验研究和数值分析 总被引：1，自引：0，他引：1
采用离心机模型试验和三维有限元模型对天兴洲大桥的超长嵌岩钻孔灌注群桩进行了分析.离心机试验中,根据相似理论,不同的原型材料用不同的指标进行模拟,细砂、桩身、承台分别以天然密度、抗压刚度、抗弯刚度作为指标进行模拟.对土体未开挖阶段、钻孔阶段、混凝土灌注阶段和养护阶段的应力场进行了详细的讨论,并应用ANSYS进行了分析.根据2种方法得到的结果,从荷载沉降曲线、桩身轴力分布和侧向摩阻分布等方面,对比分析了加载和卸载条件下超长钻孔群桩的承载特性.结果表明,有限元计算模型与离心机试验模型沉降观测的结果吻合得很好;桩顶反力的分布规律复杂,与承台的自身刚度、相应的假定和分析方法有关;轴力随着深度先稍微增加,后逐渐减少,并且在岩层中减少的速度远比砂土中快. 相似文献