Communications in Numerical Methods in Engineering最新文献_第4页

Hydraulic conductivity estimation in partially saturated soils using a full-Newton method 用全牛顿法估算部分饱和土的导流系数

Communications in Numerical Methods in Engineering Pub Date : 2007-11-29 DOI: 10.1002/CNM.1064

L. Guarracino, J. Santos

{"title":"Hydraulic conductivity estimation in partially saturated soils using a full-Newton method","authors":"L. Guarracino, J. Santos","doi":"10.1002/CNM.1064","DOIUrl":"https://doi.org/10.1002/CNM.1064","url":null,"abstract":"An iterative algorithm based on a full-Newton method for the estimation of the saturated hydraulic conductivity k from drainage experiments is presented. The water flow in the unsaturated zone is assumed to be described by Richards equation and the well-known van Genuchten constitutive model. The cost functional used for the parameter optimization is defined as the L2-error between the calculated pressure head values and the observed data at discrete points in the soil profile during the drainage process. The derivative of pressure head with respect to the parameter k is obtained as the solution of a differential equation with appropriate boundary and initial conditions. A Galerkin finite element procedure is used to obtain approximated solutions of the two differential problems involved in each iteration: the direct problem and the derivative of the functional. The algorithm was implemented in one-dimensional domains and used to estimate k in layered soils using both synthetically generated data and observed data from an experimental plot in the Azul River basin (Buenos Aires, Argentina). Numerical examples show that the proposed algorithm yields very good estimations of the saturated hydraulic conductivity and becomes a promising method for in situ estimation of this parameter. Copyright © 2007 John Wiley & Sons, Ltd.","PeriodicalId":51245,"journal":{"name":"Communications in Numerical Methods in Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/CNM.1064","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51532956","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Algorithm for analysis of periodic oscillations of structural systems with geometric nonlinearity 几何非线性结构系统周期振动分析算法

Communications in Numerical Methods in Engineering Pub Date : 2007-11-19 DOI: 10.1002/CNM.1073

M. Ragulskis, K. Ragulskis

引用次数: 1

Computation of stress intensity factors for through cracks in plates using p-version finite element method 用p型有限元法计算板内贯通裂纹的应力强度因子

Communications in Numerical Methods in Engineering Pub Date : 2007-11-19 DOI: 10.1002/CNM.1065

K. Munaswamy, Ramalakshmi Pullela

{"title":"Computation of stress intensity factors for through cracks in plates using p-version finite element method","authors":"K. Munaswamy, Ramalakshmi Pullela","doi":"10.1002/CNM.1065","DOIUrl":"https://doi.org/10.1002/CNM.1065","url":null,"abstract":"The present study concerns the analysis of bending of plates and shells subjected to various boundary conditions and load. Bending stress intensity factors for plates containing through-thickness crack under edge bending load are evaluated. To accomplish this task, hierarchical degenerated plate/shell and crack-tip singular plate/shell elements were developed. \u0000 \u0000 \u0000 \u0000The hierarchical degenerated plate shell element has four corner nodes, four mid-side nodes and one central node on the mid-surface of the shell geometry with five degrees of freedom at each node. p-Version shape functions up to order seven were used for defining the displacement field. Enriching the displacement field with the asymptotic displacement field near the crack tip, a crack-tip singular plate/shell element was developed. Some benchmark problems were analyzed and compared. Analyses were performed to obtain the stress intensity factors of plate with through-thickness crack using singular hierarchical degenerated plate/shell element around the crack tip. Numerical results obtained from the present element formulations are compared with analytical/numerical solutions available from literature. It is inferred that numerical results are in good agreement with the benchmark plate and shell problems. Copyright © 2007 John Wiley & Sons, Ltd.","PeriodicalId":51245,"journal":{"name":"Communications in Numerical Methods in Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/CNM.1065","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51532989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7

A diagonal offset algorithm for the polynomial point interpolation method 一种对角偏移算法的多项式点插值方法

Communications in Numerical Methods in Engineering Pub Date : 2007-11-19 DOI: 10.1002/CNM.1076

B. Kanber, Ö. Bozkurt

引用次数: 3

Analysis of rubber‐like materials using meshless local Petrov–Galerkin (MLPG) method 用无网格局部Petrov-Galerkin (MLPG)方法分析类橡胶材料

Communications in Numerical Methods in Engineering Pub Date : 2007-11-19 DOI: 10.1002/CNM.1066

R. Batra, M. Porfiri

{"title":"Analysis of rubber‐like materials using meshless local Petrov–Galerkin (MLPG) method","authors":"R. Batra, M. Porfiri","doi":"10.1002/CNM.1066","DOIUrl":"https://doi.org/10.1002/CNM.1066","url":null,"abstract":"Large deformations of rubber-like materials are analyzed by the meshless local Petrov–Galerkin (MLPG) method. The method does not require shadow elements or a background mesh and therefore avoids mesh distortion difficulties in large deformation problems. Basis functions for approximating the trial solution and test functions are generated by the moving least-squares (MLS) method. A local mixed total Lagrangian weak formulation of non-linear elastic problems is presented. The deformation gradient is split into deviatoric and dilatational parts. The strain energy density is expressed as the sum of two functions: one is a function of deviatoric strains and the other is a function of dilatational strains. The incompressibility or near incompressibility constraint is accounted for by introducing the pressure field and penalizing the part of the strain energy density depending upon the dilatational strains. Unlike in the mixed finite element formulation, in the MLPG method there is no need for different sets of basis functions for displacement and pressure fields. Results computed with the MLPG method for a few sample problems are found to compare very well with the corresponding analytical solutions. Copyright © 2007 John Wiley & Sons, Ltd.","PeriodicalId":51245,"journal":{"name":"Communications in Numerical Methods in Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/CNM.1066","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51533701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

A layer‐integrated approach for shallow water free‐surface flow computation 浅水自由表面流计算的分层集成方法

Communications in Numerical Methods in Engineering Pub Date : 2007-11-16 DOI: 10.1002/CNM.1061

M. Hung, T. Hsieh, T. Tsai, Jinn‐Chuang Yang

{"title":"A layer‐integrated approach for shallow water free‐surface flow computation","authors":"M. Hung, T. Hsieh, T. Tsai, Jinn‐Chuang Yang","doi":"10.1002/CNM.1061","DOIUrl":"https://doi.org/10.1002/CNM.1061","url":null,"abstract":"A novel semi-three-dimensional (semi-3D) layer-integrated approach was proposed in this study for the shallow water free-surface flow computation. A quadratic shape function proposed to approximate the velocity distribution in the layer ensures the continuity of velocities and shear stresses at interfaces. To discretize the governing equations, the finite volume formulation with staggered grid is used. As the two-dimensional (2D) sub-model for locating the free surface is not needed in this approach, the computational time consumption has been dramatically reduced. The model was verified through the wind-induced circulation in a closed basin by comparing the velocity profiles to the analytical solution. The formation of the velocity profiles due to change of viscosity distribution and the evolution process of water surface slope were also investigated. Further, the eddy viscosity is estimated by a function related to discharge, water depth, and Manning's n under the assumption of parabolic distribution of longitudinal velocity along the vertical direction for open channel flows. Two designed hypothetical cases were conducted to examine the proposed eddy viscosity relation and to demonstrate the capabilities of the proposed model. Copyright © 2007 John Wiley & Sons, Ltd.","PeriodicalId":51245,"journal":{"name":"Communications in Numerical Methods in Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/CNM.1061","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51532895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

A Trefftz method for evaluating the T‐stress for cracks emanating from a hole in a rectangular plate 矩形板孔洞裂纹T应力的Trefftz方法

Communications in Numerical Methods in Engineering Pub Date : 2007-11-15 DOI: 10.1002/CNM.1072

Y. Chen, Z. X. Wang, X. Y. Lin

引用次数: 1

Polynomial basis functions on pyramidal elements 金字塔元上的多项式基函数

Communications in Numerical Methods in Engineering Pub Date : 2007-11-09 DOI: 10.1002/CNM.1070

M. Bluck, S. Walker

引用次数: 10

On the applicability of the pseudospectral Legendre method for edge detection 论伪谱勒让德方法在边缘检测中的适用性

Communications in Numerical Methods in Engineering Pub Date : 2007-11-09 DOI: 10.1002/CNM.1068

F. Ahmad, R. M. Castellane, E. L. Miller

引用次数: 0

Computation of the J‐integral for large strains 大应变J积分的计算

Communications in Numerical Methods in Engineering Pub Date : 2007-11-09 DOI: 10.1002/CNM.1069

Á. Horváth

{"title":"Computation of the J‐integral for large strains","authors":"Á. Horváth","doi":"10.1002/CNM.1069","DOIUrl":"https://doi.org/10.1002/CNM.1069","url":null,"abstract":"The phenomenon of failure by catastrophic crack propagation in structural materials poses problems of design and analysis in many fields of engineering. Cracks are present to some degree in all structures. They may exist as basic defects in the constituent materials or they may be induced in construction or during service life. \u0000 \u0000 \u0000 \u0000Using the finite element method, a lot of papers deal with the calculation of stress intensity factors for two- and three-dimensional geometries containing cracks of different shapes under various loadings to elastic bodies. In order to increase the accuracy of the results, special elements have been used. They are described together with methods for calculating the stress intensity factors from the computed results. \u0000 \u0000 \u0000 \u0000At the vicinity of a crack tip, the strains are not always small, but they may also be large. In this case, the J-integral can also be applied to characterize the cracks in elastic or elastic–plastic bodies. \u0000 \u0000 \u0000 \u0000This paper describes the computation of the two-dimensional J-integral for large strains to elastic and elastic–plastic bodies and represents some numerical examples. Copyright © 2007 John Wiley & Sons, Ltd.","PeriodicalId":51245,"journal":{"name":"Communications in Numerical Methods in Engineering","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/CNM.1069","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51533741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1