共查询到12条相似文献,搜索用时 19 毫秒
1.
Yajuan Guo Guang Meng Hongguang Li 《Archive of Applied Mechanics (Ingenieur Archiv)》2009,79(2):147-155
The parameter determination of viscoelastic material is a multi-variable, multi-aim nonlinear optimization problem, which
made the optimization process very complicated. In this paper a hybrid optimal algorithm was proposed to determine the viscoelastic
parameters in the constitutive relation according to the experimentally obtained mechanical properties. This algorithm merges
the Broydon–Fletcher–Goldfarb–Shanno search into a genetic algorithm framework as a basic operator in order to enhance the
local search capability. The proposed hybrid algorithm not only can reduce the iterative times greatly but can abolish the
limitation of initial parameter values. Nonlinear material characteristic curve-fitting was carried out using the proposed
algorithm and other existing approaches. And the comparison results show this algorithm is accurate and effective. The numerical
simulation and experimental study of viscoelastic cantilever beam also indicates that the finite element formulation and the
calculative viscoelastic model parameters are reliable. The proposed optimization method can be extended to further complex
parameter estimation researches. 相似文献
2.
基于混合编码遗传算法和有限元分析的压电结构载荷识别 总被引:1,自引:0,他引:1
与传统的优化算法相比,遗传算法不需要计算目标函数的导数信息,便于迭代,可实现全局寻优.因此,本文提出一种采用混合编码的遗传算法与有限元分析相结合,对复合材料层合板、壳进行载荷识别的新方法.在遗传算法求解过程中,设计变量的编码方法选择是其重要环节,二进制编码容易产生连续函数离散化时的映射误差,且其求解精度与染色体的编码长度紧密相关,过长的染色体描述虽可提高精度,但会显著降低算法的求解效率.为此,本文提出采用混合编码的方法进行载荷识别,即用二进制编码表征载荷作用位置,浮点数编码表示载荷的大小.这一方法大大降低了染色体的长度,并显著提高了计算效率和精度. 相似文献
3.
This paper presents a numerical simulation for application of the Kalman filter finite element method. The Kalman filter is employed frequently for the solution of time series analysis including observation and system noises. Applying the Kalman filter to the finite element method, the present method is capable of the estimation in time and space directions. In this method, the matrix generated by the finite element method is applied to the state transition matrix. Using the Kalman filter finite element method, the characteristics of both the Kalman filter and the finite element method can be strengthened. In this paper, the state transition matrix is based on the shallow water equations which are approximated by the finite element method. This method can estimate the tidal current not only in time but also in space directions. 相似文献
4.
This paper is concerned with the implementation of Lagrange-Galerkin finite element methods for the Navier-Stokes equations. A scheme is developed to efficiently handle unstructed meshes with local refinement, using a quad-tree-based algorithm for the geometric search. Several difficulties that arise in the construction of the right-hand side are discussed in detail and some useful tricks are proposed. The resulting method is tested on the lid-driven square cavity and the vortex shedding behind a rectangular cylinder and is found to give satisfactory agreement with previous works. A detailed analysis of the effect of time discretization is included. 相似文献
5.
Kenichiro Shimamura 《International Journal of Computational Fluid Dynamics》2013,27(5-6):209-216
This paper presents an optimal control system that includes a time-delay function for application to flood control setups with a retardation area. This system consists of the present and past controls that express flow behaviour in the retardation area. Optimal control theory is used to obtain a control discharge that satisfies the state equation including the time-delay function and minimizes the performance function. The optimal control and the delayed control discharges are obtained by the solution of an adjoint equation. The weighted gradient method is employed as a minimization algorithm. The Galerkin finite element procedure is employed to discretize the state and adjoint equations in the spatial direction. The bubble function interpolation, originated by the authors' group, using a stabilized term, is employed for the discretization in space. The flood flow in the Tsurumi river is presented as a numerical model. We show in this paper that floods can be controlled by means of a time-delay function. 相似文献
6.
Numerical investigation of hydroplaning characteristics of three-dimensional patterned tire 总被引:6,自引:0,他引:6
J.R. Cho H.W. Lee J.S. Sohn G.J. Kim J.S. Woo 《European Journal of Mechanics - A/Solids》2006,25(6):914-926
Hydroplaning characteristics of patterned tire on wet road are investigated by making use of finite volume and finite element methods. A detailed 3-D patterned tire model is constructed by our in-house modeling program and the rainwater flow is considered as incompressible and inviscid. Meanwhile, the fluid–structure interaction between the highly complicated tire tread and the rainwater flow is effectively treated by the general coupling method. Through the numerical experiments, the rainwater flow drained through tire grooves, hydrodynamic pressure and contact force are investigated and compared with those of the three-grooved tire model. 相似文献
7.
本文的主要目的是开发基于实数编码的杂交遗传算法来识别土体的本构参数。该杂交遗传算法在经典遗传算法框架下开发,融合两个新开发的交叉算子,形成了一个新的杂交策略。为了保持种群的多样性,在算法中采用了一个动态随机变异算子。另外,为了提高算法收敛性,采用了一个基于混沌的局部搜索技术。分别基于室内试验和现场试验,通过识别土的本构参数来测试新算法的搜索能力和搜索效率。为了测试新开发算法的突出表现,特选用5种经典的随机类算法(遗传算法、粒子群算法、模拟退火算法、差分算法和蜂巢算法),分析同样的案例进行比较。结果表明,在收敛速度和最优解的准确度方面,新改进的算法可以很好地处理岩土工程的参数反演。 相似文献
8.
9.
That discussion recognizes that the above paper deals with one of the main problems for reserves and reservoir evaluation, i.e. the determination of capillary pressure curves using the centrifuge technique. However, it is explained that the subject was not properly addressed and that sections of the paper are out of date, confusing or eventually wrong. For a more relevant overview on the subject, it is recommended to refer to the corresponding survey by the Society of Core Analysts. 相似文献
10.
The objective of this study is to propose a parameter identification of a river current and diffusion coefficients by using the reduced Kalman filter finite element method, which has been previously presented and now extended by the authors. For comparison, the estimation computations of velocity, water elevation, and chemical oxygen demand (COD) concentration are carried out on the basis of nonlinear shallow water flow and compared with the observations carried out at the Teganuma river in Japan. A marked discrepancy in COD concentration is found between the computed and observed results. The correlation factor between the computed and observed results is 0.51. To reduce the discrepancy, the authors believe that the diffusion coefficients should be identified. Assuming that the diffusion coefficient is constant in the entire domain and over the entire total duration, satisfactory results were not obtained. Thus, the computational domain is divided into four subdomains according to the water depth. Assuming that the diffusion coefficients are constant in each subdomain, the identification is carried out. Relatively good, albeit unsatisfactory, results are obtained. The discrepancy between the computed and observed COD concentration has special features. In some time zones, the computed results are larger whereas in other time zones, they are smaller than the observed results. To compensate this discrepancy, we assumed that the diffusion coefficient is a function of COD concentration. The correlation factor is improved to be 0.73. The identified diffusion coefficients are time functions that change cyclically with a period of 24 h. This fact suggests that biological phenomenas occurred in the river. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
11.
《Wave Motion》2018
In this work a new finite element based Method of Relaxed Streamline Upwinding is proposed to solve hyperbolic conservation laws. Formulation of the proposed scheme is based on relaxation system which replaces hyperbolic conservation laws by semi-linear system with stiff source term also called as relaxation term. The advantage of the semi-linear system is that the nonlinearity in the convection term is pushed towards the source term on right hand side which can be handled with ease. Six symmetric discrete velocity models are introduced in two dimensions which symmetrically spread foot of the characteristics in all four quadrants thereby taking information symmetrically from all directions. Proposed scheme gives exact diffusion vectors which are very simple. Moreover, the formulation is easily extendable from scalar to vector conservation laws. Various test cases are solved for Burgers equation (with convex and non-convex flux functions), Euler equations and shallow water equations in one and two dimensions which demonstrate the robustness and accuracy of the proposed scheme. New test cases are proposed for Burgers equation, Euler and shallow water equations. Exact solution is given for two-dimensional Burgers test case which involves normal discontinuity and series of oblique discontinuities. Error analysis of the proposed scheme shows optimal convergence rate. Moreover, spectral stability analysis gives implicit expression of critical time step. 相似文献
12.
We consider a fully discrete scheme for a quasistatic frictional contact problem between a viscoelastic body and an obstacle. The contact is bilateral, the friction is modeled with Tresca's law and the behavior of the material is described with a viscoelastic constitutive law with long memory. We state an existence and uniqueness result for the discrete solution, followed by error estimate results. Then, we present numerical simulations in the study of a two-dimensional test example. To cite this article: Á. Rodríguez-Arós et al., C. R. Mecanique 334 (2006). 相似文献