某特种车辆主体结构有限元接触问题的一种分析方法

对某特种车辆主体结构进行刚度和强度特性的有限元分析,车体上部的旋转塔可以绕其座圈转动,和车体的约束关系比较特殊,属于传统的大型非线性接触问题,这将耗费大量的计算机时。为解决这一问题,尝试使用耦合自由度法代替传统大型接触问题的求解方法,以模拟车体和旋塔之间的滚珠特性及其约束关系,从而将车体和旋塔作为一个系统,较真实模拟此特种车辆的整车结构强度特性。此车辆受到的载荷工况包括旋塔分别受到火炮向前和向后不同角度的后坐冲击,以及路面障碍所产生的最大10g加速度的整车振动冲击。根据分析结果得出结论：结构静强度是满足要求的,为车体减轻质量设计提供了理论依据;该求解方法是有效的,同样可应用到其它类似大型结构的接触问题分析。     

The response of viscoelastic-frictionless bodies under normal impact

This paper presents a computational finite element model capable of simulation of the impact response of viscoelastic-frictionless bodies. The variational method is developed to drive the equations of motion. The Lagrange multiplier method is exploited to impose the nonholmonic contact constraints and convert the problem form constraint problem to unconstraint one. The constitutive equations are expressed in integral form. and involving relaxation moduli are adopted to describe the nonaging simple material. Generalized Standard Linear Solid (Wiechert) model is adopted to simulate the internal damping (viscoelastic) behavior of the structure. Wiechert model is exploited in order to drive a recursive relationship and thereby eliminate storage problem. Newmark constant average acceleration is proposed to integrate the governing equation numerically and transfer the problem into a static one for each time increment.     

多孔橡胶材料声传递损失性能分析：模型描述

研究带有无孔薄覆盖层的多孔橡胶板构件的声传递损失特性,考察了从低频、中频到高频范围内,不同结构参数和材料特性对多孔橡胶材料隔声性能的影响.这一部分建立了多孔橡胶板构件的有限元（FE）与统计能量（SEA）混合分析模型.在仿真模型中,多孔橡胶板边界条件为固支连接,在多孔橡胶板模型的一侧有散射声场作为激励,在另外一侧有半无限声场,用以计算和预测其声传递损失.数值结果与文献进行比较,结果显示该模型具有较好的可靠性.     

Prediction of the dynamic response of composite sandwich beams under shock loading

Finite element calculations are reported for the dynamic shock response of fully clamped monolithic and sandwich beams, with elastic face sheets and a compressible elastic–plastic core. Predictions of the peak mid-span deflections and deflected shapes of the beams are compared with the previously reported measured response of end-clamped sandwich beams, made from face sheets of glass fibre reinforced vinyl ester and a core of PVC foam or balsa wood [1]. Good agreement is observed, and the maximum sustainable impulse is also predicted adequately upon assuming a tensile failure criterion for the face sheets. The finite element calculations can also be used to bound the response by considering the extremes of a fully intact core and a fully damaged core. It is concluded that the shock resistance of a composite sandwich beam is maximised by selecting a composite with fibres of high failure strain.     

基于互补变分原理的恒定磁场后验误差估计(Ⅰ)

互补变分原理用于有限元近似解的后验误差估计,从原理本身看是整体误差估计,将其用于局部误差估计是否可行,仍需研究。为此,本文对恒定磁场的拉普拉斯方程非齐次混合边值模型题进行了研究,给出了互补泛函的有限元离散格式,提出了对补泛函中强加二类边界条件的处理方法,解决了互补问题中标量位和向量位的匹配问题;通过逐步加密网格和逐个单元的计算,并与解析解对比,验证了互补变分原理对局部误差估计的可行性。     

我校体育教学积极改革初见成效

近十年,学校的体育教学经历了由中专向大专的转变、积极改革、稳定发展三个阶段。     

三维恒定磁场罚函数有限元法的离散格式

对于三雏线性恒定磁场的罚画数有限元法，本文给出了关于四面体元、直三棱柱元和长方体元这三种常用单元的离散格式。     

板料成形过程有限元模拟中的接触处理

对板料成形过程进行有限元模拟时，为了取得可靠的计算结果，需要准确地描述模具与板料之间的动态接触状态．在全面分析成形中板料与模具接触边界动态变化的基础上，结合ABAQUS有限元分析软件给出了模型的几何描述、接触算法选择及应用VFRIC用户子程序进行接触摩擦模型的建立等具体方法．通过具体实例，证明了这些方法应用于板料成形过程的接触分析的可行性．     

Practical crack control during the construction of precast segmental box girder bridges

Cracks that occurred in the bottom slab of a precast segmental bridge were investigated through a construction sequence analysis, which revealed that the cracks were caused by excessive deformation during temporary post-tensioning while joining the segments. In addition, a parametric study was performed to evaluate the effects of the prestressing sequence, bottom slab thickness, and position of the prestressing anchors. The structural behavior of the girder sections was greatly affected by the thickness of the bottom slab and the position of prestressing anchors, but not by the prestressing sequence. Based on the results, a construction method that prevents the cracks is proposed.     

有限元软件"试验台"的构建

本有限元软件试验台采用面向对象的混合语言编程，将有限元软件分为前处理、有限元分析和后处理3个独立的主模块，它们可以分别编译和调试，再用多进程通信或动态链接库方式结合在一起，3个主模块之间通过数据文件进行通讯，根据具体情况每个主模块又可包括几个可用菜单驱动的独立的功能分模块，以使有限元软件的各部分功能程序可独立编写、分别调试，然后在此试验台上作总体验证。