矩形弹性壳液耦合系统的模态试验分析

通过对矩形弹性壳液耦合系统的模态试验分析,得到分析频率范围内的四阶主振型;改变水的深度,得到系统频率与水的深度关系曲线;在进行系统的激振试验时,发现在一定的激励频率时,液体表面将出现大幅低频重力波现象。     

丁醛转化器应力分析计算

介绍了DN5200／4900mm丁醛转化器有限元应力分析计算方法，该反应换热设备直径大，远超出GB151中的DN2600mm，设计压力较小，结构重力、介质重力和管、壳程流阻压力降等影响不可忽略。Φ88．9mm×3．20mm的换热管，弯曲刚度较大，对按梁和杆模拟换热管分析结果进行比较。为超大型换热设备的设计计算提供参考。     

130t钢包包壳热应力的有限元分析及应用

根据130 t钢包的实际结构,以传热学理论为依据,以ANSYS软件为工具,采用二维轴对称热结构耦合模型,并使用接触单元,提取了耐火衬对包壳的热膨胀压力,发现包壳角部出现压力突变,峰值为65 MPa。因此,对角部耐火衬做了结构改进。然后,采用改进后的二维轴对称热结构耦合模型提取了热膨胀压力及包壳温度载荷。在以上基础上,构建三维包壳模型并施加改进后的温度载荷与热膨胀压力及重力载荷,并建立耳轴与辅助块的接触对来反映包壳的自由热膨胀,进行了高温重载下包壳的强度计算,经计算包壳强度合格。该包壳已应用于工程实际,且使用效果良好。     

立壳管式冷凝器传热过程的分析及计算程序

立壳管式冷凝器管内冷却水系在重力作用下进行膜状流动放热,管外系制冷剂蒸汽在竖管管壁进行凝结放热。传热计算中工程上往往采用试算法或图解法进行,由于它存在双重试算与图解,计算时极其烦琐又十分费时。采用PC-1500计算机进行计算,十分简便而且精度较高,只要对一些变量进行赋值,计算机便可打印出计算结果。文中介绍了计算框图和计算程序。     

转向驱动桥壳的受力与台架试验

桥壳系车辆底盘上的关键零件,又分为转向驱动桥壳及后桥壳。这里所讲的是转向驱动桥壳,无论哪一种桥壳,它的作用都是支承汽车的载重力,将车轮上的各种作用力通过悬架系统传给车架或车身。本文介绍的转向驱动桥壳,     

基于弹性壳体模型的波箔型动压气体径向轴承动特性分析

波箔型气体轴承的动态纲度和阻尼系数是轴颈偏心率、旋转速度及轴心涡动速度的函数,是进行转子临界转速、不平衡响应计算及稳定性分析不可或缺的基本参数。用摄动法建立波箔型气体轴承动特性系数计算分析的数学模型,应用弹性板壳模型计算波箔及平箔的变形,应用有限差分法及有限元法耦合对模型进行求解,获得波箔型气体轴承的动特性系数。将所得结果与已公布的实验数据对比,证明该模型的合理性和精确性。分析偏心率和轴颈转速对动特性系数的影响,结果表明,刚度系数随偏心率和轴颈转速的增加而递增,阻尼系数随偏心率和轴颈转速的增加而递减。     

RV传动机构作用力分析研究

提出一种RV传动机构作用力分析方法。建立了输入轴、行星轮、摆线轮、针齿壳、曲柄轴、行星架的作用力分析模型,考虑切向力、径向力、重力,以矢量形式完整表达了RV传动机构各传动级作用力;基于VB. NET编写作用力计算程序,能快速准确计算出不同曲柄转角下各作用力的实时变化情况。     

气动式摆动柔性关节多状态下的模型与仿真

提出一种结构新颖的摆动柔性关节,给出了关节的基本结构,说明了气压传动的工作原理,确立了弯曲的弹性波壳内腔体积与弹性波壳整体弯曲角度之间的积分方程,结合受力分析,建立了关节角位移与弹性波壳内腔的压力间的数学表达式。在两种工作状况下,构造了关节角位移与时间量之间的动态模型,并进一步根据示例进行动态仿真和分析。     

三圆弧波纹膜片的设计

三圆弧波纹膜片(见图1)是一种常用的膜片。膜片的外边缘波可以有不同的大小,虽然都是圆弧波纹,但随边缘波的大小不同,膜片特性,应力值,有效面积也不同。作者利用环壳理论和初参数法,对不同边缘波的三圆弧波纹膜片进行了大量计算,并与实验做了比较,拟合出不同边缘波的三圆弧波纹膜片的工程简便公式,为工程设计提供了实用而可靠的设计公式和方法。     

基于柔性导向机构的重力分量传感器开发北大核心CSCD

现有机器人打磨重力补偿需要根据姿态来计算重力分量,主要方式是通过机器人的姿态计算或者姿态传感器,存在计算复杂或者成本高的弊端。文中提出一种基于柔性铰链导向机构的重力分量传感器,通过测量柔性铰链导向方向的变形,计算在不同位姿下的柔性铰链弹性力,与水平位置的读数相比,直接计算出重力分量。与重力角度传感器相比,不需要标定,还能计算出由于加速度引起的惯性力部分,重力补偿更加准确。     

Vibration analysis of submerged thin FGM cylindrical shells

This study gives a brief work on vibration characteristics of cylindrical shells submerged in an incompressible fluid. The shell is presumed to be structured from functionally graded material. The effect of the fluid is introduced by using the acoustic wave equation. Love’s first order thin shell theory is utilized in the shell dynamical equations. The problem is framed by combining shell dynamical equations with the acoustic wave equation. Fluid-loaded terms are associated with Hankel function of second kind. Wave propagation approach is employed to solve the shell problem. Some comparisons of numerical results are performed for the natural frequencies of simply supported-simply supported, clamped-clamped and clamped-simply supported boundary conditions of isotropic as well as functionally graded cylindrical shells to check the validity of the present approach. The influence of fluid on the submerged functionally graded cylindrical shells is noticed to be very pronounced.     

浅拱形薄壳在流体作用下的变形与应力分析

应用弹性薄壳的基本理论和流体弹性力学基本方程,结合相容拉格朗日-欧拉法,建立接触面处流体与固体相互作用的运动学方程和动力学方程,深入研究浅拱形薄壳在流体作用下的弯曲变形;给出在倾斜流动和对称流动状态下,法向位移系数的线性方程表达式;结合边界条件求解得到浅拱形壳的变形、压力及应力的算式。并通过具体算例,绘出挠度随壳体材料、壳体厚度、壳体弧长、迎角和流体速度等参数变化的关系曲线,给出发生最大变形、最大应力所在的位置及数值;分析相关参数变化对浅拱形壳体变形和应力状态的影响。其分析结果可供流体作用下浅拱形薄壳的强度与刚度设计参考。     

潜水深度对结构自振特性影响的数值分析

水下结构的自振特性不仅受流体动压力的影响，还受不同水深一的静水压力的影响，本文假设水为无粘、不可压、无旋流体，通过附连水质量解耦，用考虑初应力刚度的有限元方法计算了圆柱壳在不同水深下的自振特性，初步揭示了这种影响，所得结果和方法可供流固耦合方面的研究参考。     

THEORETICAL PREDICTION OF SOUND RADIATION FROM A HEAVY FLUID-LOADED CYLINDRICAL COATED SHELL

０ＩＮＴＲＯＤＵＣＴＩＯＮＡｈｅａｖｙｆｌｕｉｄ－ｌｏａｄｃｙｌｉｎｄｒｉｃａｌｓｈｅｌｉｓｔｈｅｂａｓｉｃｓｔｒｕｃｔｕｒａｌｅｌｅｍｅｎｔｗｉｄｅｌｙｕｓｅｄｉｎｍａｎｙｉｎｄｕｓｔｒｉａｌｆｉｅｌｄｓ．Ｔｈｅｖｉｂｒｏａｃｏｕｓｔｉｃａｎａｌ...     

Non-linear vibrations and instabilities of orthotropic cylindrical shells with internal flowing fluid

In this work, Donnell’s non-linear shallow shell equations are used to study the dynamic instability of perfect simply supported orthotropic cylindrical shells with internal flowing fluid and subjected to either a compressive axial static pre-load plus a harmonic axial load or a harmonic lateral pressure. The fluid is assumed to be non-viscous and incompressible and the flow, isentropic and irrotational. An expansion with eight degrees of freedom, containing the fundamental, companion, gyroscopic, and four axi-symmetric modes is used to describe the lateral displacement of the shell. The Galerkin method is used to obtain the non-linear equations of motion which are solved by the Runge-Kutta method. A detailed parametric analysis clarifies the influence of the orthotropic material properties on the non-linear buckling and vibration characteristics of the shell. Numerical methods are used to identify the effect of the fluid flow and applied loads control parameters on the bifurcations and stability of the shell motions.     

Propagation of Rayleigh waves in a rotating orthotropic material elastic half-space under initial stress and gravity

This paper aims to investigate the influence of rotation, initial stress and gravity field on the propagation of Rayleigh waves in a homogeneous orthotropic elastic medium. The government equations and Lame??s potentials are used to obtain the frequency equation which determines the velocity of Rayleigh waves, including rotation, initial stress and gravity field, in a homogeneous, orthotropic elastic medium has been investigated. The numerical results analyzing the frequency equation are discussed and presented graphically. It is important to note that the Rayleigh wave velocity in an orthotropic elastic medium increases a considerable amount in comparison to the Rayleigh wave velocity in an isotropic material. The results indicate that the effects of rotation, initial stress and gravity field on Rayleigh wave velocity are very pronounced.     

Combined gravity gradient and jitter accelerations acting on liquid-vapor interface oscillations in reduced gravity

The dynamical behavior of fluids affected by the asymmetric combined gravity gradient and jitter accelerations, in particular the effect of surface tension on partially-filled rotating fluids applicable to a full-scale Gravity Probe-B Spacecraft dewar tank, have been investigated. Three different cases of accelerations, one gravity gradient-dominated, one equally weighted between gravity gradient and jitter, and the others gravity jitter-dominated are studied. Results of slosh wave excitation along the liquid—vapor interface induced by gravity gradient-dominated acceleration indicate that the gravity gradient-dominated acceleration is equivalent to the combined effect of a twisting force and torsional moment acting on the spacecraft. Results of the slosh wave excitation along the liquid—vapor interface induced by gravity jitter-dominated acceleration indicate that the gravity jitter-dominated acceleration is equivalent to time-dependent oscillatory forces which push the bubble in the combined directions of down-and-up and sideward -and-middleward as the bubble is rotating with respect to rotating dewar axis. This study discloses the slosh wave excitation along the liquid—vapor interface driven by the combined effects of gravity gradient and jitter accelerations which are two major driving forces affecting the stability of the fluid system in microgravity.     

An inverse method to measure the breathing wave speed in a liquid-filled cylindrical shell

An inverse method is developed for measuring the breathing wave speed in a liquid-filled cylindrical shell. The model used with this method is based on an experimental configuration in which a long cylindrical shell is longitudinally excited by a mechanical shaker at one end. The resulting longitudinal wave propagation produces a spatial field in the shell that consists of extensional and breathing waves. End-mounted accelerometers and force transducers are used to measure the extensional wave speed. Once this is accomplished, transfer functions between five equally spaced hydrophones (in the fluid) and a forward accelerometer are recorded. These data are then combined to yield a closed-form value of the complex, frequency-dependent breathing wave speed. The experiment included to validate this method is extremely easy to implement and can be rapidly executed.     

Frequency characteristics of a thin rotating cylindrical shell using the generalized differential quadrature method

In this paper, the generalized differential quadrature (GDQ) method is used for the first time to study the effects of boundary conditions on the frequency characteristics of a thin rotating cylindrical shell. The present analysis is based on Love-type shell theory and the governing equations of motion include the effects of initial hoop tension and the centrifugal and coriolis accelerations due to rotation. The displacement field is expressed as a product of unknown smooth continuous functions in the meridional direction and trigonometric functions along the circumferential direction so that the three-dimensional dynamic problem may be transformed mathematically into a one-dimensional problem. Based on this approach, the results are obtained for the effects of the boundary conditions on the frequency characteristics at different circumferential wave numbers and rotating speeds and various geometric properties; the effect of rotating speed on the relationship between frequency parameter and circumferential wave number is also discussed. To validate the accuracy and efficiency of the GDQ method, the results obtained are compared with those in the literature and very good agreement is achieved.