转炉除尘系统循环供水的水质稳定

分析了影响转炉除尘水水质稳定的因素,并就保证水质稳定的措施和方法进行了探讨.     

三维Boussinesq方程有限元格式的POD降维模型

针对帝国理工大学三维海洋模型(Boussinesq方程)的无结构有限元格式,用特征正交分解方法(POD)得到了降维模型.并且给出了POD降维模型的误差估计.最后,通过数值算例验证了POD方法的可行性和有效性.     

锻压机架的有限元计算与模型实验研究

本文利用有限元方法计算分析了锻压机架的结构应力，并用模型实验检验了有限元计算的正确性。结果表明：机架理论计算的危险断面与实际断裂位置完全相符合。本文可以作为锻压机架设计和结构改进的理论参考     

基于可变模糊集的海洋水质环境综合评价模型——以青岛疏浚物海洋倾倒区为例

传统的水质评价方法,往往将评价标准或参考标准处理成点的形式,难以反映水质分级的区间特征,本文探索将可变模糊数学模型应用到海洋水质环境综合评价中,同时将熵权理论与主观权重相结合,以综合权重作为基础构建基于可变模糊集的海洋水质环境评价模型,并将其应用于青岛倾倒区海水水质综合评价中,实例研究证明,该模型能够很好地对海洋水质环境综合情况进行准确评价,该模型通过变化模型参数（α与p,4个模型,1个线性,3个非线性）,4种模型相互检验,将稳定结果作为最后评价结果,评价结果更为可信,同时,该模型能够通过级别特征值精确区分各海洋水质采样点的水质优劣,对各采样点的水质级别有更准确的定位,为改进和完善海洋环境评价研究领域提供了新的思路和方法。     

Dynamic Viscoelastic Beam Model for Finite Element Method

A finite element formulation is presented for the viscoelastic dynamic responses of Euler‐Bernoulli beams. A time‐stepping procedure based on New‐mark's method is employed. The changes in creep strain during a time step are treated as additional fictitious body forces for the next time step. A uniaxial Norton‐type strain‐hardening material law is employed. The aims of the proposed formulation are model simplicity, efficiency of the solution procedure, and ease of application. Quasi‐static and dynamic viscoelastic responses for beams under quasi‐static and earthquake motion are obtained. The results are compared with existing alternate solutions to demonstrate the validity of the present work.     

Stable Boundary Element Method/Finite Element Method Procedure for Dynamic Fluid–Structure Interactions

The stability problem has prevented the application of the boundary element method/finite element method (BEM/FEM) coupling procedure in dynamic fluid–structure interaction problems for the last 2 decades. It has been proved that the linear θ method can make a significant stability improvement for the time domain BEM scheme. With the use of the linear θ method, the BEM/FEM coupling procedure is applied to two-dimensional time domain fluid–structure interaction problems. The fluid domain is acoustic and modeled by taking advantage of the BEM scheme that is suitable to either finite or infinite domains. An internal source has been considered in BEM formulations, and no artificial boundary needs to be introduced for the infinite domain. The structure is modeled by finite elements that can be either linear or nonlinear. Two classical examples are given to show the validity of the coupling procedure in fluid–structure interaction problems and the significant stability improvement given by the linear θ method to the BEM/FEM coupling procedure.     

One-Dimensional Numerical Model for Nonuniform Sediment Transport under Unsteady Flows in Channel Networks

In this study, the proposed one-dimensional model simulates the nonequilibrium transport of nonuniform total load under unsteady flow conditions in dendritic channel networks with hydraulic structures. The equations of sediment transport, bed changes, and bed-material sorting are solved in a coupling procedure with a direct solution technique, while still decoupled from the flow model. This coupled model for sediment calculation is more stable and less likely to produce negative values for bed-material gradation than the traditional fully decoupled model. The sediment transport capacity is calculated by one of four formulas, which have taken into consideration the hiding and exposure mechanism of nonuniform sediment transport. The fluvial erosion at bank toes and the mass failure of banks are simulated to complement the modeling of bed morphological changes in channels. The tests in several cases show that the present model is capable of predicting sediment transport, bed changes, and bed-material sorting in various situations, with reasonable accuracy and reliability.     

Finite Analytic Model for Flow and Transport in Unsaturated Zone

The finite analytic method is employed to solve the vertical, two-dimensional subsurface flow and transport equations in an unsaturated zone. The finite analytic method treats the nonlinear coefficient terms of the governing equations as constants in the element so that linearized partial differential equations can be obtained and solved in each element. The accuracy and limitations of the numerical method are systematically explored. The flow and transport simulations are examined using a one-dimensional laboratory infiltration test and an analytical solution of a two-dimensional subsurface transport problem, respectively. In the advection-dominant, vertical, one-dimensional infiltration problem, nine spatial weighting schemes are proposed to evaluate the averaged unsaturated hydraulic conductivity in a discretized element. Among them, the geometric mean weighting scheme provides the most accurate results as compared with the infiltration data. In verification of the two-dimensional solute transport problem, the nine-node elements are placed in the interior domain, and different layers of five-node elements are placed at the boundaries to investigate if the numerical experiment setup was proper and the algorithm was accurate. The developed numerical model is then applied to an irregular-domain landfill leaching problem to reveal the features of subsurface transport in unsaturated zone. Numerical aspects to be further explored are suggested.     

3D Finite Element Model for Asphalt Concrete Response Simulation

An extensive experimental, analytical, and numerical investigation on the response of asphalt concrete is currently in progress at Delft University of Technology. The objectives of this Asphalt Concrete Response (ACRe) project are: (a) the formulation and finite element implementation of a three‐dimensional, strain‐rate sensitive, temperature‐ and loading history‐dependent constitutive model, and (b) the development of the necessary experimental set‐ups, testing procedures, and data analysis methods for determination of the model parameters. These objectives are strongly interrelated: on the one hand, the model dictates what should be measured in a test, while on the other hand, the response observed in the tests sets the requirements for the model. As a result, model development/verification and experimental testing have been progressing in parallel throughout the project. In this contribution both the finite element and the experimental aspects of the project will be presented. The constitutive model has been implemented in the finite element system INSAP. The system has been used to simulate the initiation and propagation of damage in two flexible pavement structures due to repeated loading. The simulations illustrate the influence of geometry and material characteristics on the development of damage.     

New Stabilized Finite Element Method Embedded with a Cap Model for the Analysis of Granular Materials

Standard displacement-based finite element formulations show a tendency to lock in the modeling of nearly incompressible materials. This overly stiff response often leads to an overestimation of the collapse load for the system. In this paper we present a stabilized mixed displacement-pressure finite element method that can effectively model the nearly incompressible materials in their elastic and inelastic range. The stabilized formulation is free of volumetric locking effects and allows equal low-order interpolation for both the displacement and the pressure fields. The formulation is integrated with a three-surface elastoplastic cap model for the simulation and analysis of granular materials. The good performance of the method is demonstrated via numerical examples of the hydrostatic compression test for concrete and the bearing capacity and limit load analyses of flexible footings.     

Nonlinear Spline Finite Element Method for Ribbing of Cold-Rolled Coils

 The ribbing problem has serious influence on the steel product quality, which produces additional shape waves on the surface of uncoiled steel strip on the process of curl. Nonlinear spline finite element method (n-spline FEM) is adopted to establish the relationship between the ribbing height and deflection of additional shape wave, for example, post-buckling deformation. The proposed spline FEM is more effective and convenient than traditional finite element method in the buckling analysis. Using the spline FEM, the shape wave caused by the ribbing is calculated, and then the ribbing values can be obtained which are difficult to measure in practice. At the same time, the judgment rule is also given for estimating the strip quality according to the ribbing value.     

变截面Timoshenko梁的有限元解法

把J.Thomas等提出的常截面Timoshenko梁的单元矩阵扩展应用于变截面的Timoshenko梁。从计算结果和按简单梁处理的比较中可以看出:梁的粗端的剪切变形和转动惯性对系统的固有频率有较大影响。