一次性分配的力矩分配法

提出以多跨连续梁为单元参与力矩分配法的设想,导出了任意跨连续梁的杆端转动刚度和结点处弯矩传递系数的递推计算式,使得设想能够实施．改变了传统力矩分配法的渐近解法,只需一次性分配就可求得精确解．     

多结点力矩分配法精确计算研究

针对多结点力矩分配法轮流放松结点只能获得渐近解的不足,提出了一种将分配结点分层并按顺序放松、相邻结点不同时放松、放松后不重新固定的放松策略,即从远端只与基础相连的结点开始将其划分为若干层,按照同层相邻分配结点逐个或间隔放松的原则由外层向内层逐层移除结点约束,引入弹性支座模拟相邻杆件的转动约束作用,通过推导远端转动弹性支承等直杆弯矩形常数,确保结点放松时转动刚度和传递系数已知或可计算,结果表明,按顺序逐层移除约束的放松约束方式一方面各分配弯矩能够直接或通过已放松结点向支座传递,其中,向放松结点传递的弯矩通过结点协调变形依次向远端传递直至支座,而不产生新的不平衡力矩,从而快速消除结点不平衡力矩,结果精确;另一方面各分配结点只经历一轮完整力矩分配与连续传递过程即恢复至最终变形位置,计算量小。

     

多功能力矩分配法

提出了新的力矩分配思想,将角位移和线位移综合考虑,使力矩分配法能直接应用于有侧移结构,且在计算内力的同时还能计算结构的位移,使力矩分配法具有多功能. 实例计算表明,该方法正确、简单,有利用价值.     

力矩分配法的方程解法

在传统力矩分配法的基础上,将渐进的计算过程转化为方程组的求解,可以更好地理解力矩分配法的分析思路及计算过程,同时提高计算效率和精度。该方法所得到的方程与矩阵位移法所得方程形式相同,但未知量完全不同,方程的推导过程更简洁且易于理解,在教学中可以启发学生对矩阵位移法分析思想的思考。     

力矩分配法的快速实用计算研究

对力矩分配法的计算过程进行了改进,采用Excel表格编制出了无侧移框架、连续梁的统一计算表格并给出了计算示例,使这一方法在计算多、高层框架和多跨连续梁的内力时达到快速、准确、实用的目的,对教学、科研和工程设计具有一定的实用意义.     

力矩分配法中的无侧移限制

讨论一般力矩分配法的适用条件. 当研究多种单元和复杂单元,提供必要的分配系数和传递系数后,结点无侧移条件可适当放宽,成为广义的力矩分配法,但已不是工程师所需的手算方法.     

弯矩分配法何去何从

在实际工程中被淘汰的方法,在教学中被淘汰只是迟早的问题,"弯矩分配法" 就面临这样的处境. 该文以"弯矩分配法" 的数学基础为视角,讨论该法在教材中的去、留问题,供教师,特别是《结构力学》教材编者参考.     

力矩分配法在对称结构中的应用

以力矩分配法为基础，探索了对称结构的简化计算方法．为了克服对称结构计算时通常方法所产生的不便，提出了新的力矩分配概念，找出了新的分配系数和传递系数．应用改进的力矩分配法，对对称结构进行了计算，算例表明该方法简化了计算，加快了收敛速度．     

平弯圆弧连续梁的矩阵位移法

本从力法出发建立了平弯圆弧梁单元的刚度矩阵,通过矩阵位移法计算平弯圆弧连续梁,方法简便、易于编程,便于工程设计人员使用。     

连续梁的正交方法解

本文利用正交方法解超静定问题不必解正则方程的优点,针对连续梁的特点,导出了连续梁在荷载作用下支座截面处弯矩计算的矩阵公式.     

A realization of the moment method

The difficulties involved in solving a system of moment equations using two-sided distributions are analyzed. The properties of these distributions do not permit the realization of the moment method (in the case of a collision integral in Boltzmann form) in specific transport boundary-value problems. A method of obtaining analytic solutions of the system of moment equations for linearized transport problems is proposed. The accuracy of the method is analyzed with reference to a classical transport problem.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 185–188, May–June, 1991.     

A NEW HIGH-ORDER MULTI-JOINT FINITE ELEMENTFOR THIN-WALLED BAR

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简支梁绝对最大弯矩计算方法探讨

介绍了结构力学中简支梁绝对最大弯矩的一种简单计算方法. 教学实践证明,用这种方法,学生对计算绝对最大弯矩的规律容易理解、掌握,也容易记忆.     

A modified Gaussian moment closure method for nonlinear stochastic differential equations

Parametric excitation of a nonlinear physical pendulum by modulation of its moment of inertia is analyzed in terms of physics as an example of the suggested approach. The modulation is provided by a redistribution of auxiliary masses. The system is investigated both analytically and with the help of computer simulations. The threshold and other characteristics of parametric resonance are found and discussed in detail. The role of nonlinear properties of the physical system in restricting the resonant swinging is emphasized. Phase locking between the drive and oscillations of the pendulum and the phenomenon of parametric autoresonance are investigated. The boundaries of parametric instability are determined as functions of the modulation depth and the quality factor. The feedback providing active optimal control of amplification and attenuation of oscillations is analyzed. An effective method of suppressing undesirable rotary oscillations of suspended constructions is suggested.     

A moment method for splashing and evaporation processes of polydisperse sprays

A new moment method for the modelling of polydisperse sprays is proposed that simultaneously takes into account the dispersion in droplet size and droplet velocity. For the derivation of this Eulerian method the kinetic spray equation is used which constitutes a partial differential equation for the probability density function of droplets. To reduce the complex kinetic spray equation to a form that can be managed with the available numerical procedures, moment transforms with respect to the droplet velocity and the droplet size are conducted. The resulting moment equations are closed by choosing an approximate probability density function which applies to polydisperse sprays. The method is successfully tested for configurations in which a polydisperse spray is either splashed, evaporated or effected by a Stokes drag force. The tests are organised in such a way that crossing of two spray distributions is always included. The new method is able to capture the polydisperse nature of sprays as well as the bi-(or multi-) modal character of the droplet velocity distribution function, for example, when droplets cross each other.