非惯性参考系中弹性壳的非线性振动分析

给出了弹性壳处于非惯性参系中的运动描述，基于Ｈａｍｉｌｔｏｎ原理建立了中厚壳在非惯性参考系中的非线性运动控制方程，应用多尺度法及谐波平衡法具体地分析了圆柱壳的非线性振动问题     

On 3-dimensional non-axisymmetrical deformation analyses for finite hollow circular cylinders

In this paper, 3-dimensional non-axisymmetrical deformation analyses for finite hollow circular cylinders have been carried out by Pickett's double series expansion method^[1]. Through expanding the displacement potentials as the sum of fourier series and Fourier-Bessel series, we could express the coefficients of one series by those of another under certain boundary conditions. Thus, a set of linear algebraic equations were derived. Solving these equations, we could obtain the solutions of the problems. Numerical examples have been given to show that the method presented here is workable for practical applications.     

钢筋混凝土圆形截面非均匀配筋的图算法

圆形截面是工程中常使用的截面形式之一,但圆形截面的配筋计算较为困难,存在双重非线性(材料和截面宽度变化的非线性),《混凝土结构设计规范》给出了计算均匀配筋的超越方程组,且须迭代求解,无法手算.另外,一些圆形截面构件(如桥墩、桩基的预制桩和灌注桩等)的截面尺寸大,构件长,钢筋用量大,若采用均匀布置的配筋方式,中性轴附近的钢筋应力小,强度利用率低,经济性差.若采用非均匀配筋,在远离中性轴的外围区域布置受力钢筋,可大幅节省钢筋用量,且能充分利用钢筋及混凝土的强度.为此本文通过应变计算应力,再计算出内力的方法推导计算圆形截面配筋的公式,并将计算结果绘制成了能计算配筋的无量纲诺模图,由此可快速手算配筋,该图通用性强,可用于任意直径大小及C50以下的混凝土强度等级,是一能快速计算配筋的实用工具.     

无限长圆管非轴对称问题的Donnell理论的解析解

本文根据圆柱壳体的Ｄｏｎｎｅｌｌ近似理论，用富氏积分变换和留数理论得出了无限胀圆管受非轴对称法向荷载的解析解。     

Further study on vortex shedding flow by a circular cylinder

In the present paper the mechanism involved in vortex shedding flows is investigated in detail. In the early stage of the unsteady separated flow the interaction between secondary vortices and primary vortices is quite strong. In the later stage of the flow, corresponding to the vortex shedding the recirculating flow region on each side of the aft body goes through such a cycle: growth-contraction-growth, the secondary separation occurs periodically rather than continuously. The reduction of circulation is taken into account in three cases with different decay factors to study its influence on the prediction of main flow characteristics. Results show that to simulate vortex shedding flow it is necessary to include the reduction of circulation to bring the calculated results into good agreement with experiments. An improved discrete vortex model is suggested in which both the secondary separation and the reduction are incorporated. The processes of vortex shedding, the forces prediction and other flow characteristics are given and some discussions are made. Porject is supported by National Natural Science Foundation of China.     

非均匀圆柱型正交各向异性圆板的弯曲

研究了非均匀圆柱型正交各向异性圆板在均布横向载荷作用下的弯曲问题，求得了折算刚度随半径按指数规律变化的非均匀圆柱型正交各向异性圆板弯曲问题的渐近解，给出了周边固支和简支条件下的渐近解．通过算例可以看出，这种非均匀性对圆板中心挠度的影响是显著的     

二维直角平面内固定圆形夹杂对稳态入射反平面剪切波的散射

利用复变函数法、多极坐标及傅立叶级数展开技术求解了二维直角平面内固定圆形夹杂对稳态入射反平面剪切（shearing horizontal, SH）波的散射问题。首先构造出介质内不存在夹杂时的入射波场和反射波场,然后建立介质内存在夹杂时由夹杂边界产生的能够自动满足直角边应力自由条件的散射波解，从而利用叠加原理写出介质内的总波场。利用夹杂边界处位移条件和傅立叶级数展开方法列出求解散射波中未知系数的无穷代数方程组，在满足计算精度的前提下通过有限项截断，得到相应有限代数方程组的解，最后通过算例具体讨论了二维直角平面水平边界点的位移幅度比和相位随量纲一波数、入射波入射角及夹杂位置的不同而变化的情况，结果表明了算法的有效实用性。     

圆柱尾流的绝对不稳定性

在水槽和低湍流度水洞中进行亚临界雷诺数圆柱尾流稳定性实验来流速度由零缓慢增长到一定值后保持不变,稳定足够长时间后,在流向某站位处给流场一个有限幅值的脉冲扰动,测量扰动前后相当长时间内下游尾流速度信号的变化情况当雷诺数处于高亚临界值时,未受扰动的尾流速度脉动很小,处于定常状态,但对近尾流进行脉冲扰动后,能够激发出不衰减的旋涡脱落发现扰动位置限制在圆柱后一定范围内才能有效,再往下游则扰动随时间衰减．说明圆柱近尾流中存在一个绝对不稳定区,在该区域内的扰动将在当地放大,经过复杂的演化,最后形成不衰减的旋涡脱落.     

流向强迫振荡圆柱绕流的涡脱落模态分析

通过求解采用ALE方法描述的运动坐标系Navier-Stokes方程组，分析均匀来流下雷诺 数为150的静止和流向振荡的圆柱绕流. 主要研究了强迫振荡频率和较大振幅比 (A/D=0.3-1.2)对圆柱升力、阻力变化特性以及涡脱落模态的影响. 研究表 明，流向振荡圆柱绕流存在多种涡脱落模态，如对称S以及反对称A-I, A-III, A-IV等多种形式；比较研究结果，拓展了各模态下对应的锁定区域，并将其分为5个 子区；A-I模态中圆柱受力较以前所知更复杂；通过分析计算结果，发现最大加速度 比Af_{c}^{2}/Df_{s0}^{2}可能是涡脱落模态(尤其是对称S模态)最有效的控制参数.