含腐蚀缺陷的管道静力性能试验测试研究

为研究腐蚀缺陷对管道承载力的影响,本文分别进行了含腐蚀缺陷管道在轴压载荷、弯曲载荷以及轴压和弯曲复合载荷作用下的静力失效过程测试。通过不同载荷作用下管道的荷载-位移曲线以及荷载-应变曲线来分析管道的失效模式和失效机理;通过有限元分析结果与试验测试结果验证其准确性。结果表明:腐蚀缺陷使管道在三种不同荷载作用下的极限承载力均有所下降;针对文中所研究的管道及其腐蚀缺陷,在轴压载荷作用下管道承载力下降了18.4%,在弯曲载荷作用下管道承载力下降了20.96%,在轴压和弯曲复合载荷作用下管道承载力下降了13.3%;管道中腐蚀缺陷位置的管壁厚度减小,该位置应变发展迅速,首先进入塑性屈服状态,最终导致该腐蚀位置发生弹塑性屈曲失效。     

静风荷载作用下大跨度钢拱桥极限承载力分析

随着铜拱桥垮径的不断增大。铜拱桥的极限承载力问题已引起了人们的广泛重视。本文以上海在建的主垮550m的中承式铜拱桥为例。采用几何和材料非线性分析法详细分析了大跨度铜拱桥在静风荷载作用下的极限承载力，重点讨论了静风荷载中三个分力以及不同桥梁单元上所受风荷载对大跨度铜拱桥极限承载力的影响。     

薄壁曲梁的稳定极限承载力

曲梁极限承载力涉及弯扭强度和稳定两方面的问题．尤其是曲梁进入弹塑性阶段后,截面上弯曲应力和扭转应力将不再保持原有的比例关系,问题变得更为复杂．水平曲梁在弹性和弹塑性阶段工作特性的研究成果为其工程应用提供了理论依据．在总结不同曲梁稳定极限承载力公式的基础上,通过对已有有限元计算结果的非线性回归,得到了工程实用的曲梁极限承载力估算公式．     

冰与海洋结构物作用的极限承载力

为进一步研究冰与海洋结构物作用时的变形和影响,论文将岩土力学中的Smith屈服准则引入到冰材料的弹塑性分析中,从细观力学的角度分析了孔洞存在以及拉、压破坏强度不同的条件下冰材料的力学性能,构造了冰的本构方程;采用分区构造方法分析给出冰与矩形直立结构物作用时应力场的解析解;最后用数值计算的方法分析给出不同压力敏感性参数和拉压强度比下冰的极限承载力.分析结果表明Smith屈服准则能够准确反应孔洞的存在及拉压屈服强度不同对冰材料力学性能的影响.     

用广义阶梯函数简化计算简支圆板在复杂荷载作用下的极限荷载

本文将广义阶梯函数应用于薄板的塑性极限分析问题，用以简化计算简支圆板在复杂荷载作用下的极限荷载。文中针对简支圆板在任意局部均布荷载和线性分布荷载共同作用下的塑性极限分析问题，并考虑荷载的五种不同的分布形式，给出相应的极限荷载的计算公式。     

基于累积荷载效应分析刚架结构极限承载力

传统极限承载力分析的塑性铰法(PHM)及其修正格式(mPHM)没有考虑加载历史累积荷载效应对刚架失效的影响,不能正确处理内力反向问题,由此导致刚架结构极限承载力和失效模式分析结果出现错误。为此,首先研究了前序失效阶段累积荷载效应的影响,据此分析结构迭代计算中相邻迭代步出现内力反向时PHM和mPHM发生错误的原因;然后通过合理修改构件截面强度,以反映结构强度损伤演化规律,据此计算刚架结构极限承载力,并识别结构潜在失效模式,提出了刚架结构的失效判据,建立了刚架结构分析的改进塑性铰法(iPHM);最后,进一步通过iPHM与PHM、mPHM、弹塑性增量加载法对比分析,验证了iPHM的适用性、计算精度和效率。     

复杂条件下地基承载力系数N_γ的上限解

由地基土重量引起的地基承载力系数N_γ的真实解答至今尚未获取．本文根据极限分析法与极限平衡法的等效性,构造出最危险的运动许可滑动机构,得出N_γ尽可能小的上限解．分别定量分析了在荷载倾斜、基底倾斜、地表倾斜对N_γ的影响,提出了近似影响系数公式,并与现有研究结果进行比较．     

圆管截面齐次广义屈服函数与结构极限承载力

为克服圆管截面广义屈服准则不满足比例加载条件,导致采用弹性模量调整法求解该类结构极限承载力时存在计算结果受荷载初值影响、计算精度受损等问题,利用回归分析和最小二乘法研究建立了圆管截面广义屈服函数的齐次多项式,通过误差分析确定了齐次化多项式的阶次;据此定义了圆管截面薄壁构件的单元承载比、承载比均匀度和基准承载比,为高承载比薄壁单元的判别及其弹性模量调整提供了动态判据,进而依据能量守恒准则建立了以单元承载比为基本参数的模量调整公式,结合下限原理提出了圆管截面薄壁结构极限承载力分析的弹性模量缩减法。研究表明,选取齐次化多项式的广义屈服函数能更加准确地考虑各项内力对结构极限承载力的综合影响,具有良好的计算精度和效率,可应用于复杂圆管截面薄壁结构的极限承载力分析中。     

初始缺陷对任意边界板极限承载力的影响分析

板钢结构承载力分析最终可化简为对一任意边界的矩形板在面内荷载作用下的极限承载力分析.从含初始弯曲的大挠度方程出发,以板厚度的折减量为摄动参数,将残余应力考虑成等效荷载,根据实用板与理想板的比较,得出板的厚度折减量和板的极限承载力方程.通过与非线性有限元方法和已有试验数据的验证分析,表明折减厚度法适用范围广、安全、精度高,可作为非线性有限元方法的补充,大大简化了结构极限承载力分析的复杂性.     

复杂条件下地基承载力系数Nr的上限解

由地基土重量引起的地基承载力系数N     

The stability of growth of a through-wall circumferential crack in a pipe subject to combined bending and tensile loadings

The stability of growth of a through-wall circumferential crack in a pipe is analysed for the case where the material has a high crack growth resistance, the analysis being based on the tearing modulus procedure. Rotations and lateral displacements are applied at the ends of the pipe, and this allows the combined effects of bending and tensile loadings on the stability of crack growth to be assessed. The general conclusion is that tensile loadings can have an adverse effect on crack stability, in accord with the conclusion reached in the author's earlier studies of plane strain crack growth in a beam. The stability results are compared with those obtained by Tada, Paris and Gamble, who allowed the tensile loadings to affect the position of the neutral axis, but did not consider instability in terms of the deformations produced by these loadings.     

倒三角形截面板管连接式钢圆弧拱在平面内的稳定承载力研究

采用理论推导与数值模拟相结合的方法,对倒三角形截面板管连接式钢圆弧拱在平面内的弹性屈曲和弹塑性屈曲进行了深入研究.首先,理论推导了拱的截面剪切刚度,并提出了拱在全跨均布径向荷载作用下的弹性屈曲公式.此外,还提出了避免连接板和弦杆在拱发生整体弹性失稳之前发生局部失稳的限制条件.然后,分别研究了在全跨均布径向荷载和全跨均布...     

Solution of the deformation problem for flexible noncircular cylindrical shells subject to bending moments at the edges

An exact analytical solution is found to a nonlinear boundary-value deformation problem for a long noncircular cylindrical shell of variable curvature. The shell is subject to bending moments at the edges. The dependence of the stress-strain state of the shell on the curvature is analyzed __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 11, pp. 93–100, November 2006.     

GENERAL SOLUTION OF THE OVERALL BENDING OF FLEXIBLE CIRCULAR RING SHELLS WITH MODERATELY SLENDER RATIO AND APPLICATIONS TO THE BELLOWS (Ⅳ)-CALCULATION FOR U-SHAPED BELLOWS

This is one of the applications of Part (I), in which the angular stiffness, and the corresponding stress distributions of U-shaped bellows were discussed. The bellows was divided into protruding sections, concave sections and ring plates for the calculation that the general solution (I) with its reduced form to ring plates were used respectively, but the continuity of the surface stresses and the meridian rotations at each joint of the sections were entirely satisfied. The resent results were compared with those of the slender ring shell solution proposed earlier by the authors, the standards of the Expansion Joint Manufacturers Association (EJMA), the experiment and the finite element method. It is shown that the governing equation and the general solution (I) are very effective. Contributed by HUANG Qian Biography: ZHU Wei-ping (1962-)     

GENERAL SOLUTION OF THE OVERALL BENDING OF FLEXIBLE CIRCULAR RING SHELLS WITH MODERATELY SLENDER RATIO AND APPLICATIONS TO THE BELLOWS (Ⅲ)-CALCULATION FOR C-SHAPED BELLOWS

This is one of the applications of Part (I), in which the angular stiffness, the lateral stiffness and the corresponding stress distributions of C-shaped bellows were calculated. The bellows was divided into protruding sections and concave sections for the use of the general solution (I), but the continuity of the stress resultants and the deformations at each joint of the sections were entirely satisfied. The present results were compared with those of the other theories and experiments, and are also tested by the numerically integral method. It is shown that the governing equation and the general solution (I) are very effective. Contributed by HUANG Qian Biography: ZHU Wei-ping (1962-)     

An experimental investigation of heat transfer to pulsating pipe air flow with different amplitudes

Heat transfer characteristics to both laminar and turbulent pulsating pipe flows under different conditions of Reynolds number, pulsation frequency, pulsator location and tube diameter were experimentally investigated. The tube wall of uniform heat flux condition was considered for both cases. Reynolds number varied from 750 to 12,320 while the frequency of pulsation ranged from 1 to 10 Hz. With locating the pulsator upstream of the inlet of the test section tube, results showed an increase in heat transfer rate due to pulsation by as much as 30% with flow Reynolds number of 1,643 and pulsation frequency of 1 Hz, depending on the upstream location of the pulsator valve. Closer the valve to the tested section inlet, the better improvement in the heat transfer coefficient is achieved. Upon comparing the heat transfer results of the upstream and the downstream pulsation, at Reynolds number of 1,366 and 1,643, low values of the relative mean Nusselt number were obtained with the upstream pulsation. Comparing the heat transfer results of the two studied test sections tubes for Reynolds number range from 8,000 to 12,000 and pulsation frequency range from 1.0 to 10 Hz showed that more improvement in heat transfer rate was observed with a larger tube diameter. For Reynolds number ranging from 8,000 to 12,000 and pulsation frequency of 10 Hz, an improvement in the relative mean Nusselt number of about 50% was obtained at Reynolds number of 8,000 for the large test section diameter of 50 mm. While, for the small test section diameter of 15 mm, at same conditions of Reynolds number and frequency, a reduction in the relative mean Nusselt number of up to 10% was obtained.     

混合边界各向异性矩形板的静力分析

采用一般解析解和配点法相结合的方法,求解混合边界各向异性矩形板的弯曲问题.先由弯曲挠度的微分方程求出各种类型的齐次解和特解,然后组成一般解析解,再将板的每个边等分 为很多微小的段,仅对每一微段的中点建立应满足的边界条件,由全部边界条件方程式即可求得全部积分常数.以每边一半边界为平夹、另一半边界为简支或自由的方板为例进行了计算,并与四边均为简支的方板进行了对比,表明理论简单,结果实用.     

GENERAL SOLUTION OF THE OVERALL BENDING OF FLEXIBLE CIRCULAR RING SHELLS WITH MODERATELY SLENDER RATIO AND APPLICATIONS TO THE BELLOWS (Ⅰ)-GOVERNING EQUATION AND GENERAL SOLUTION

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GENERAL SOLUTION OF THE OVERALL BENDING OF FLEXIBLE CIRCULAR RING SHELLS WITH MODERATELY SLENDER RATIO AND APPLICATIONS TO THE BELLOWS (Ⅰ)-GOVERNING EQUATION AND GENERAL SOLUTION

The overall bending of circular ring shells subjected to bending moments and lateral forces is discussed. The derivation of the equations was based upon the theory of flexible shells generalized by E.L. Axelrad and the assumption of the moderately slender ratio less than 1/3 (i.e., ratio between curvature radius of the meridian and distance from the meridional curvature center to the axis of revolution). The present general solution is an analytical one convergent in the whole domain of the shell and with the necessary integral constants for the boundary value problems. It can be used to calculate the stresses and displacements of the related bellows. The whole work is arranged into four parts: (Ⅰ) Governing equation and general solution; (Ⅱ) Calculation for Omega-shaped bellows; (Ⅲ) Calculation for C-shaped bellows; (Ⅳ) Calculation for U-shaped bellows. This paper is the first part.