Dynamic elastic-plastic buckling phenomena in a rod due to axial impact

Dynamic elastic-plastic buckling phenomena which might develop in a rod from an axial impact loading are studied in order to identify the conditions for quasi-static behaviour. A discrete model for dynamic elastic-plastic buckling, which retains the axial and the lateral inertia forces, is proposed, and the relationship between the model parameters and the characteristics of an actual structure is given. Examples of different external loadings and boundary conditions are considered in order to clarify the influence of elastic-plastic axial wave propagation on the buckling process. The critical time for the initiation of buckling is obtained and the post-buckling behaviour of the model is analysed. Particular attention is paid to the role of the striking mass on the characteristics of the buckling process and on the development of the buckling shape. The numerical study reveals that the inertia of the striking mass affects considerably the development of the buckling shape causing different patterns of axial strain distributions at the initiation of buckling. The comparisons which are made between the model predictions and some previously published experimental data show that the buckling process is governed by the impact velocity as well as by the external loading history provided by the experimental technique.     

The effect of temperature on the dynamic characteristics of heat-resistant thermoplastic composites

Two thermoplastic and two thermosetting fibrereinforced plastic composites were subjected to dynamic tests over a wide range of temperature, covering both cryogenic and hot environments. The thermal behaviour of each composite, as indicated by its dynamic mechanical properties, was assessed individually, and was compared collectively with that of the other composites.     

底敞口充气浮箱研究和试验

提出底敞口充气浮箱的结构和概念。经模型模拟试验研究分析，经典浮力定律可用于这种浮箱的浮力计算；其动充气状况还具有一定的允许伤损面积。它的研究将为水陆两用车辆增大浮力，缩小外形，提高水上自下而上能力和潜驶潜伏提供具有诱惑力的工程应用前景。     

催化裂化装置动态机理模型 Ⅱ.再生器部分

建立了前置烧焦罐式高效再生器动态机理模型。烧焦罐再生段采用轴向扩散模型，包括催化剂上碳含量、氢含量和再生温度动态分布参数方程、气体中氧含量拟稳态分布参数方程和催化剂藏量动态方程。二密相床气速低，采用气固全返混模型，并考虑了气体外扩散对烧碳速率的影响。二密相床数学模型包括再生剂碳含量和催化剂藏量的动态集中参数方程和烟气中氧含量的拟稳态代数方程。     

How to Control Robots Interacting with Dynamic Environment

The goal of this paper is to shed light on the control problem of constrained robot motion from the aspect of the dynamical nature of the environment with which the robot is in contact. Therefore, the criticism of traditional hybrid control which allows position/force feedback loops to split into independent control with respect to position and force, is not the main point we want to make. Reference to the papers written by the founders of hybrid control and their numerous followers served only to better understand the reason and motivation for suggesting a different approach to control of robots interacting with environment.The paper has a predominantly review character, based on recently published work. It also contains some new, unpublished results in the framework of the unified approach to the position/force control of robots, proposed by the present author and his co-workers. By pointing to the possibility of introducing an environment dynamics in the contact tasks of the machining type, the author emphasizes that the proposed dynamically interactive control can be applied to a completely different class of tasks, in which a contact is made between the system (constructions or structure) and very specific kinds of dynamic environments.     

钨铜合金药型罩及其性能

钨铜合金药型罩的应用可以提高射流对均质钢靶的侵彻能力.这一提高得益于射流密度的提高以及断裂时间的延长. 本文对钨铜合金射流及其断裂形态通过X光照像进行了研究.它的旋转效应及其炸高特性也进行了实验研究. 钨铜合金药型罩的威力实验在φ30 mm的破甲弹上进行.在相同装药条件下与紫铜罩相比,威力提高20～30%.     

鱼雷罐喷粉预处理优化研究

在已经得到的描述鱼雷罐喷粉处理基本参数具体表达式的基础上，运用多目标非线性优化方法，对工艺操作参数进行优化。     

转子叶片在非均匀来流条件下的流体激振特性

该文通过研究得出非均匀来流对转子叶片流体激振的三个重要特征 :非均匀来流相对于转子叶片的非定常流中主频分量是产生叶片动应力的决定因素 ;非均匀来流的非均匀度 (相当于非定常流的波幅 )大小和叶片流体激振的动应力大小成正比 ;转子叶片流体的定常压力水平与叶片动应力的水平密切相关。图 4表 2     

泡沫铝的动态压缩性能和吸能性研究

通过测量泡沫铝在动态和准静态压缩条件下的应力 -应变曲线 ,研究了泡沫铝的准静态和动态压缩行为以及不同应变条件下的吸能性 ,并对其应变率效应进行了分析。结果表明 ,在高应变速率和准静态压缩下 ,泡沫铝的σ -ε曲线均表现出弹性变形段、平缓段和密实段三阶段特征 ;泡沫铝的压缩性能具有明显的应变速率敏感性 ,随应变速率的提高 ,流动应力上升 ,吸能性升高     

基桩反射波法动测曲线的数值模拟与特征分析

采用美国PDI公司开发的PDI-S软件,对不同缺陷基桩的反射波法低应变动测曲线进行数值模拟,对动测曲线的特征进行归纳与总结,以便在解释反射波法曲线时作为参考与借鉴,提高基桩质量检测的可靠度。