预应力矩形渡槽温度应力有限元分析

结合南水北调沸河渡槽工程实例。通过运用三维有限单元法对预应力混凝土矩形渡槽的受力性能进行数值模拟。重点分析预应力和温度荷载对渡槽应力的影响。热应力耦合采用顺序耦合法来实现。计算结果表明：渡槽内力及预应力配筋分布合理,混凝土应力满足规范要求,温度荷载对槽身应力有较大影响。     

刺槐林边坡稳定性有限元分析

该文以刺槐林固坡为例,将根土复合体看作是由土体、根系以及土体与根系之间的接触面单元所联系起来的有机体,运用有限元方法分析了刺槐林木根系边坡的应力和变形特性,探讨了刺槐根系对边坡稳定性的影响。结果表明:无林边坡坡脚向土体内侧存在一个应力和位移的集中带,根系的存在使得有林边坡在坡脚集中带的区域范围减小;根系周围位移等值线变化剧烈,有林边坡最大水平位移发生在边坡根系分布区;斜坡中同一位置处有林边坡的垂直位移明显小于无林边坡的;边坡最大、最小主应力等值线随土层深度的增加而增加,有林边坡最大主应力、最小主应力的最大值小于无林边坡的,说明有林边坡更趋于稳定。     

活塞式磁流变液阻尼器磁场有限元分析

针对磁流变液阻尼器的磁路结构，利用ANSYS软件进行电磁场有限元分析。分析不同结构模型的磁流变液阻尼器的磁场分布，研究了单级磁路与双级磁路在相同激励状况下，所产生的不同的响应。分析活塞结构的变化对磁流变液阻尼器磁场分布的影响，为磁流变液阻尼器的结构设计提供了依据。     

混凝土面板干缩应力计算的接触面模型研究

基于湿度传导理论及一般外荷载作用下的接触摩擦单元理论,经过系统分析,建立了面板与垫层之间接触面的湿度场及干缩应力有限元计算模型。算例结果表明,应用该模型可以获得较为准确合理的接触面湿度场及干缩应力计算结果。     

Prediction and measurement of residual stresses in injection molded parts

Residual stresses were predicted by a flow analysis in the mold cavity and residual stress distribution in the injection molded product was measured. Flow field was analyzed by the hybrid FEM/FDM method, using the Hele Shaw approximation. The Modified Cross model was used to determine the dependence of the viscosity on the temperature and the shear rate. The specific volume of the polymer melt which varies with the pressure and temperature fields was calculated by the Tait’s state equation. Flow analysis results such as pressure, temperature, and the location of the liquid-solid interface were used as the input of the stress analysis. In order to calculate more accurate gap-wise temperature field, a coordinate transformation technique was used. The residual stress distribution in the gap-wise direction was predicted in two cases, the free quenching and the constrained quenching, under the assumption that the shrinkage of the injection molded product occurs within the mold cavity and that the solid polymer is elastic. Effects of the initial flow rate, packing pressure, and mold temperature on the residual stress distribution was discussed. Experimental results were also obtained by the layer removal method for molded polypropylene.     

波纹型推土板减粘降阻的有限元分析

对波纹型几何非光滑推土板与土壤相互作用进行了二维有限元分析，并通过表面应力、位移及土体中的应力场分析了其减粘降阻原因。为非光滑表面的减粘降阻机理的研究提供定量依据。     

Finite element modeling of current stimulating response on the nerve axon

To investigate the characteristics of microphysiological electrical conduction on nerve cell axon, numerical simulation for the dynamic responses of neuronal axon to electrical stimulation is conducted on a three-dimensional (3D) finite element (FE) model. A 3D geometrical model for a segment of a hippocampal neuron axon is developed and assigned biophysical parameters, then the stimulation pulses of various amplitude and duration are imparted on the FE model of neuronal axon. The combination of Hodgkin-Huxley equations and Maxwell equations are performed to get action potential curve and 3D distribution of electric potential. The simulating results show that the resting potential of nerve axon is -65 mV and no action potential occurred under the stimuli of 2 ms duration and 0.01 A/m 2 current intensity, whereas the stimuli of (2 ms, 0.2 A/m 2), (20 ms, 0.01 A/m 2) and (20 ms, 0.2 A/m 2) induced action potentials, and the time arrived at the peak value are 0.012 s, 0.017 s and 0.012 s, respectively. The range of action potential is 100 mV and duration is 2 ms. The simulation results agree well with that of the experiment, which indicates that both the FE model of neuronal axon and the simulation analysis method are reliable and may contribute to further study on neural electrophysiology.     

Numerical analysis on the evolutionary features of deformation and failure modes of slopes

The failure of slope is a gradual accumulation process. Under the effect of many interior and exterior factors, some parts in the slope reach yield with the increase of stress, and sliding surface forms gradually till complete transfixion. With continuous increase of the plastic strain, overall failure happens on the slope. Traditional analysis method cannot display the mechanic conditions and the whole process of deformation, transfixion of sliding surfaces and failure. Meanwhile, FEM strength reduction can quantitatively show the deformation features and the process of occurrence and development of sliding surface. Based on the previous researches, the paper classifies slopes according to the features of rock and soil and the slope structure. Through analyzing the graphs of deformation and the nephograms of plastic strain under different reduction factors or safety factors, the researchers can directly find the deformation tendency of slopes and the whole process of the extension, transfixion and failure of sliding surface with the reduction of safety factor. So, the failure mechanism of slope can be found intuitively, which can provide effective basis for the prevention and governance of slopes.     

基于ANSYS的撑卧式钢闸门模拟研究

撑卧式钢闸门是一种新型的闸门型式,它借助于闸门后被油缸施加到支撑桁架的推力而撑起,起到拦河蓄水的作用,闸门在开启时是通过油缸减小推力,桁架沿着设计好的轨道向下游滑动,在一制动装置的作用下,闸门逐渐倾斜泄水得以实现.本文主要用有限元分析软件ANSYS分析的方法,按实际的三维情况建立钢闸门有限元分析模型,通过对闸门振动模态分析,建立了以基频为约束条件的撑卧式平板钢闸门动力优化设计模型.本文研究结果对于撑卧式钢闸门的探索研究有重要的借鉴意义.     

方钢管混凝土柱-钢梁外隔板节点三维非线性有限元研究

采用通用有限元软件Ansys8.0,对一种新型方钢管混凝土节点进行三维非线性有限元数值模拟和不同强度等级的填充混凝土对节点受力性能影响分析,并与大尺度模型实验结果进行对比.分析结果表明:填充混凝土强度对节点的水平承载力有较大影响,随着混凝土强度的提高,节点的水平承载力增加;节点区域应力分布均匀.考察了不同钢管混凝土柱轴压比对节点力学性能地影响.结果表明:梁端先出现塑性铰,柱的刚度远大于两梁的刚度;节点区域混凝土应力分布均匀,没有出现压溃现象.有限元分析结果与模型试验结果拟合较好,证明了新型节点的可行性和合理性,有一定的工程应用价值.