Computation and asymptotic analysis in the impact problem

Non-linear numerical method is applied to solve the viscous-elastic-plastic material impact problem. The finite element simulation agrees with the celebrated European crash safety analysis. The complex material stress distribution in the large deformation has been obtained, when the impact happens. Also the posteriorestimate solver and asymptotic analysis have been used for the sensitive pre-stage deformation before the impact happening. This part of simulation is very interesting for the passive safety in automotive protection devices. It is an important part of the mathematical modelling. Supported by the National Natural Science Foundation of China (No. 10871225), Partly supported by EInstitutes of Shanghai Municipal Education Commission, N.E03004; Partly supported by Shanghai Pu Jiang Telent project [2006]118.     

Nonlinear shell-type to beam-type fea simplifications for composite frp poles

This paper presents a semi-analytical finite element analysis of pole-type structures with circular hollow cross-section. Based on the principle of stationary potential energy and Novozhilov’s derivation of nonlinear strains, the formulations for the geometric nonlinear analysis of general shells are derived. The nonlinear shell-type analysis is then manipulated and simplified gradually into a beam-type analysis with special emphasis given on the relationships of shell-type to beam-type and nonlinear to linear analyses. Based on the theory of general shells and the finite element method, the approach presented herein is employed to analyze the ovalization of the cross-section, large displacements, the P-Δ effect as well as the overall buckling of pole-type structures. Illustrative examples are presented to demonstrate the applicability and the efficiency of the present technique to the large deformation of fiber-reinforced polymer composite poles accompanied with comparisons employing commercial finite element codes.     

钢丝绳直线段有限元建模与分析

利用Patran软件设计了1×6钢丝绳直线段股和独立绳芯钢丝绳的有限元模型,利用Nastran进行了有限元分析,计算中考虑了一端固定、一端轴向旋转情况下钢丝绳的载荷与应变的关系和股内各钢丝分载荷情况.对比有限元分析结果、理论计算结果和实验结果发现,三者间误差均在容许范围内,验证了本文有限元模型的有效性.     

On variational formulations with rigid-body constraints for finite elasticity: Applications to 2D and 3D finite element simulations

We investigate a recently proposed variational principle with rigid-body constraints and present an extension of its implementation in three dimensional finite elasticity problems. Through numerical examples, we illustrate that the proposed variational principle with rigid-body constraints is applicable to both single field and mixed finite elements of arbitrary order and geometry, e.g. triangular/tetrahedral and quadrilateral/hexagonal elements, in two and three dimensions. Moreover, we demonstrate that, as compared to the commonly adopted approach of discretizing the rigid domains with standard finite elements, the proposed formulation requires neither discretization nor numerical integration in the interior of each rigid domain. As a comparative result, the variational formulation may reduce the total number of degrees of freedom of the resulting finite element system and provide improved accuracy.     

基于实验的数值反演的滚动轮胎稳态温度场的有限元分析

根据轮胎温度场的单向解耦分析思想,形成了一个基于ABAQUS程序的轮胎稳态温度场的分析方法,单向解耦过程分为变形、损耗、热传导三个分析过程。变形分析中,采用了平衡态的超弹性材料模型;损耗分析中,依据变形分析获得的应力应变场,结合材料粘性损耗特性来获得损耗能量;热传导分析中,依据实测的轮胎胎侧温度场,提出了一种基于实验的数值反演方法来确定胎侧的对流热边界条件。由于轮胎胎侧的形状和结构细节,其对流热边界不同于旋转平圆盘的对流热边界,本文的数值反演方法避免了实测胎侧对流热交换系数的困难。     

数控车床主轴部件及其主轴箱热特性有限元分析

以某数控车床主轴箱为对象,研究了主轴箱的热态特性及其对机床性能的影响.在确定有限元分析所需参数的基础上,建立了主轴箱有限元分析模型,仿真计算了主轴箱的稳态温度场分布情况以及主轴箱热平衡时间,并利用热和结构耦合技术仿真计算了主轴箱在热和结构耦合作用下的温度场及热变形,分析确定了主轴部件和主轴箱的热变形趋势.通过分析可知热...     

受电弓三维温度场仿真分析

利用ANSYS参数化编程语言APDL建立受电弓弓头三维有限元分析模型、编制了循环加载及求解程序,模拟列车行车过程中滑板与接触线滑动接触受流.分析了滑板温升的基本规律,研究了各热源对滑板温升的影响,对比了不同材料时滑板的温升情况.     

碰撞问题中非牛顿边界层计算

建模问题中关于碰撞安全移动边界层的数学模型是重要的课题, 其中理解和运用非牛顿力学大变形 理论乃解决当今科学工程计算中难题的有效途径. 本文研究运用非线性计算方法模拟冲击碰撞时粘滞弹塑性材料的非牛顿力学现象,得到冲击碰撞应力场结果, 并运用后估计算法结合高性能计算软件对其大变形流场及应力场的二维及三维模型进行了研究.     

有限元分析与MATLAB/Simulink在钢桁梁施工控制中的应用

针对传统桥梁施工控制可视化、自动化程度不高的问题,把虚拟现实仿真技术引入了桥梁施工控制中,探讨了基于MATLAB/Simulink的钢桁梁施工仿真建模问题,提出了虚实结合施工控制技术思想。以某钢桁梁悬臂拼装施工模型为例,介绍了该技术思想的实现过程,研究了基于实测结果的有限元模型修正问题。模型试验表明:在室内实验室条件下,该技术思想理念先进、技术实现基本可行,施工控制效果良好。     

煤层气排采螺杆泵定转子接触有限元分析

为了得到煤层气排采中影响螺杆泵寿命的因素,为进一步优化设计参数提供依据,利用有限元及实验方法对定转子接触状况进行了研究。通过建立螺杆泵定转子二维平面应变模型,以转子上圆心附近位置两点运动轨迹为对象,分别得到了不同转速及不同过盈量下的接触应力拟合方程及曲线,得到了在定子内腔不同接触位置处的剪应力及接触应力云图,并与实验分析结果进行比较。结果表明:定转子间过盈量越大,定转子接触磨损痕迹越深。剪应力分布的范围在直线中心处类似椭圆状,且椭圆长轴与直线约成45°夹角,过盈量越大,椭圆越大。剪应力最大的位置为点接触处,而该处粘着磨损较严重,接触应力最大位置为线接触处,与实验的形貌分析结果一致。