Bearing loads of dual rotor-bearing system under stationary and transient conditions

Aimed at aeroengine vibration failure, bearing loads of dual rotor-bearing system caused by unbalance are calculated under stationary and transient conditions. The three-dimensional (3-D) finite element method (FEM) model of dual rotor-bearing system was established. Applying the rotor dynamics function of Ansys 12.0, bearing loads were calculated under various unbalance force in stationary condition, and the transient vibration characteristics and the effect of acceleration on bearing loads were discussed. On the basis of simulation results, the influence disciplines of unbalance on bearing loads and theoretic reference for reducing bearing loads during start-up were obtained.     

行车和温度荷载作用下沥青路面的松弛响应分析

目的研究沥青混凝土路面在行车和温度荷载作用下的松弛特性,更好地做到防裂控制工作．方法确定黏弹性材料参数及能够反应温度、沥青混合料黏弹性本构关系,建立典型的路面结构三维有限元模型,模拟面层材料在不同初始变形的应力状态,分析路表弯沉、沥青面层层底和土基顶面的响应．结果沥青路面在荷栽和温度作用下,面层黏弹性材料会使路面应力减小．面层层底和基层层底应力会发生松弛,最后趋于稳定值;在行车载荷作用下弯沉会随着时间的推移发生回弹,最后逐渐趋于稳定．结论松弛是材料本身属性与其他因素无关;应力松弛模量越小,松弛性能越好,低温抗裂性越好．     

超大型船舶变截面梁分段模型的载荷试验研究

为了验证船体弹性效应对波浪载荷的影响,在拖曳水池进行了某超大型高速船舶的分段模型试验.介绍了分段模型的设计原则,并改进了传统的分段模型,采用变截面梁对船体刚度进行模拟,分析了不同航速与模型分段数量对总弯矩响应中高频和低频成分的影响,并对极限海况下规则波和不规则波中的弯矩响应进行分析,发现了颤振现象,计算了颤振响应在总弯矩中所占的比重.最后,分别依据刚体理论、线性与非线性水弹性理论对该船的波浪载荷进行了预报,通过比较发现刚体和线性水弹性计算结果与低频弯矩吻合很好,而非线性计算结果与总弯矩吻合更好.     

Movements with Lateral Constraint

Abstract

The literature on terminal control tasks and continuous tracking tasks suggests a possible model for tasks where the subject must guide a vehicle at his own speed along a course defined by a tolerance band. The model predicts a linear relationship between the average velocity and the width of the tolerance band. Throe experiments are described which simulate vehicle guidance by pencil-and-paper experiments for courses consisting of straight lines and circles. The predictions of the model were confirmed, suggesting that a general measure for the ease of control of a vehicle (or other controlled system) is possible using this technique.     

Dynamic characteristics of the coupled system of footbridge and human

The influence of human body on dynamic characteristics of footbridge was analyzed. A realistic footbridge was measured during a mass event. A simulation experiment system including a simple beam as object and a shaker as back ground excitation was built. The acceleration responses of beam were measured when person in static and active stated stood on the beam. The dynamic parameters of the structure were identified by the time-domain approach and verified by theoretical and laboratory tests. The results showed that for the human-structure coupled system,nature frequency of the structure decreased and damping increased. Moreover,the increase of damping with passive person was bigger than that with active person.     

Base Pressure Measurements under a Scale Model Stockpile

The ability of a granular bulk material to transmit internal shear stress is a fundamental property that is often overlooked or underestimated, yet it is this ability that allows many observed physical phenomena to occur. One such area that continues to be a focus for numerical, theoreticals and experimental researchers is the pressure that a stockpile of granular material places on the supporting surface. While appearing to be a simple problem, the ability of granular materials to transmit shear stress makes this an extremely complex problem. This article presents high-quality data collected under a 2 m high stockpile and full details of the experimental facilities used in the collection of the data.

The work presented is of significant value, having a much greater scale than previous studies (Jotaki & Moriyama, 1979; Lee & Herington, 1971; Smid & Novosad, 1981), and the deliberate inclusion of a central reclaim channel offers insight into stress changes during gravity reclaim and refilling. The results of this work have shown that the so-called 'M' pressure does exist under larger stockpiles both with and without reclaim hoppers; of more significance is the reemergence of the M pressure upon refilling of an emptied stockpile. This clearly illustrates that the M pressure is a robust and natural pressure distribution for a conical stockpile.     

新型外包钢-混凝土组合框架抗震性能试验

按照现行规范的有关规定设计制作了一榀两跨单层新型外包钢-混凝土组合梁-普通钢砼柱的组合框架结构模型,并通过施加恒定竖向荷载和低周反复水平荷载,对模型框架进行了抗震性能试验研究。分析了新型组合框架滞回性能、承载能力、延性、耗能能力、刚度退化等受力性能。试验表明,新型组合框架结构具有良好的抗震能力。     

外挂物吊挂的载荷与强度分析

采用MSC Adams软件计算吊挂载荷,再在MSC Patran/Nastran软件中利用Adams所得到的载荷通过有限元分析计算吊挂的强度.     

液化气体船C型独立液货舱载荷分析

通过对3 500 m3液化气C(LPG)运输船单圆筒形液罐的载荷分析,介绍一种简便的利用MSC Patran/Nastran来确定液罐内部载荷以及载荷施加的方法,同时提出两种计算三维状态下液罐内部载荷和施加载荷的方法.     

国际热核聚变实验堆磁体线圈终端盒的设计

线圈终端盒（CTB）是国际热核聚变实验堆超导磁体系统的重要组成部分，其内部组件的漏热常常是整个磁体系统的主要漏热源之一，在很大程度上决定着低温系统的液氦消耗量。本文从降低热负荷的角度对CTB内部冷屏、超导电流传输线、电流引线、阀及冷却管路、外部盒体的设计进行了详细阐述，为最终结构的确定提供了理论依据。