弹性梁

Adopt girder unit and mixed unit to establish finite element model of stack based on the flexible stack. The former stack is simplified into 7 girders and 1 symmetrical space rigid frame of centralized quality.

针对某型机枪的弹性枪架，分别采用梁单元和混合单元建立枪架的有限元模型，前者的枪架被简化成由7个梁、1个集中质量组成的对称的空间刚架结构。

Based on the generalized potential variational principle of nonlinear elasticity theory with large deflection, the incomplete generalized potential energy functional with large deflection is established on the space coupling free vibration of collaborated system structure by considering the effect of axial compressive and shearing strain energy of stiffening girder.

摘要基于大位移非线性弹性理论的广义变分原理，考虑加劲梁轴向压缩应变能和剪切应变能的影响，建立了协作体系斜拉桥空间耦合自由振动的大位移不完全广义势能泛函，通过约束变分导出了协作体系斜拉桥的加劲主梁竖向挠曲振动微分方程。

It consider the effect of the slenderness ratio to the critical loads.

讨论了细长比对梁的临界载荷的影响，给出了不同端部条件下，线性弹性Timoshenko梁的无量纲临界载荷。

However, in designing the beamless slabs with equivalent frame method, the stress is an average values along the depth of section, which varies with the normal service state. Compared with the results by finite element method, the results gained by equivalent frame method cannot satisfy the requirement under the normal service state. Therefore, the tendons of beamless slabs should be designed and arranged based on the results of FEM taking account into vertical load and prestressed load.

本文通过分析，认为采用等代框架法进行无梁板设计时，其内力是基于截面平均的结果，在正常使用状态与实际受力状态有很大的不同，通过对比等代框架法和有限元计算的正常使用极限状态应力可知，按等代框架法设计的预应力布置并不能保证其正常使用极限状态的要求，据此提出了应根据无梁板在竖向荷载和预应力共同作用下弹性有限元分析结果进行预应力筋布置的建议。

This paper is concerned with the vibration responses of an infinite, fluid-loaded, elastic foundation of Bernoulli-Euler beam under the convected forces.

本文即是探讨柏努力－欧拉梁受这移动外力作用下的振动分析；并考虑梁的流体承载与弹性基础的反弹力效应。

Based on rail/wheel reaction and track/bride reaction theory and systems engineering theory, new vehicle-track and vehicle-track-bridge system dynamic models are established and discussed in details, including ballast track model and ballastless track model. The characteristics of the models are:(1) vehicle-track and vehicle-track-bridge system dynamic models are coupled in vertical and lateral;(2) track vibration on bridge is taken in account, track on bridge is considered as one or two layer continuous-point supported rail model, according to actual track structure, interaction between vehicle and bridge transfer from track structure;(3) three type of ballastless track models (tieembanked, elastic-tie-block, slab track) are presented;(4) models reflect the main feature of actual vehicle, track and bridge structure, the response computation frequency of models is relatively broad, which can be applied to analyze both low frequency and high frequency vibration.

基于轮轨相互作用和线桥相互作用特点，本文从系统工程角度出发建立了车辆、有碴轨道和无碴轨道、简支箱梁桥垂向和横向耦合系统动力分析模型，该系统模型具有以下特点：（1）车线、车线桥体系均考虑为垂向、横向耦合振动系统，车线间通过轮轨接触几何关系耦合，轨道与桥梁间通过轨道与梁体间的力与位移协调条件耦合；（2）充分考虑桥上线路在车线桥系统中参振作用，根据桥上线路轨道结构特点将桥上轨道结构模型具体化，即对桥上轨道结构视为多层支承体系，车桥间的动力作用通过轨道结构来传递；（3）建立了三种形式无碴轨道动力分析模型，即长轨枕埋入式、弹性支承块式和轨道板式无碴轨道模型；（4）系统模型详细，分析频带宽，适用范围较广。

But the deformation curve of large deformation satisfy more boundary conditions

变形模型沿用了王汝樑方法的远端弹性地基梁及近端悬臂梁模型，但大变形段的变形曲线满足了更多的边界条件

Calculation results show that general elastics supported continuous beams methods can obtain better precision and can be applied in engineering design.

计算结果表明：采用广义弹性支承连续梁法对矮肋斜T梁桥进行受力性能分析能取得较好的计算精度，并可用于工程设计当中。

Based on Euler-Bernoulli beam in elastic half space and its dynamic solution under moving loads, the solution of reaction force between ground surface and beam is presented.

用弹性半空间Euler-Bernoulli梁及其在移动荷载作用下的动力解，得到地基表面与梁之间的接触反力解答。

The design and construction norm of standingpile wharf (JTJ267-98) calculate longeron and crossbeam by continuous beam with the elastic support. But it cant consider the influence of the wide bearing.

高桩码头设计与施工规范(JTJ267-98)中把纵梁和横梁简化为弹性支承连续梁来进行计算，不能考虑宽支座的影响。

Cynanchum Lingtai apricot production in the average weight 65 grams, the brightly-colored fruit, juicy rich, sweet-sour taste, sweet from the nucleolus, when the late Qing Dynasty famous Shaanxi, Gansu provinces, the Qing imperial court Tongzhi tribute for years.

灵台生产的牛心杏平均单果重65克，果实色泽鲜艳，汁多味浓，甜酸适口，离核仁甜，清末时就驰名陕、甘两省，清同治年间曾为朝廷贡品。

Chenopodium album,Solanum nigrum, and Amaranthus retroflexus were very susceptible to the herbicides. Polygonum persicaria and Abutilon theophrasti were relatively less susceptible to the herbicides, and Lycopersicon esculentum was not susceptible to it. The relationship between reduction rates of weed biomass and PPM values of weed leaves 2,4, and 6 days after treatment was established.

供试的6种杂草对该混剂的敏感性存在显著差异：红心藜Chenopodium album、龙葵Solanum nigrum和反枝苋Amaranthus retroflexus对该混剂最敏感，ED90值分别为47.65、71.67和29.17g/hm2；春蓼Polygonum persicaria和苘麻Abutilon theophrasti敏感，ED90值分别为96.91、114.20g/hm2；而番茄不敏感。