简支梁在移动载荷作用下的最大剪力和最大弯矩

应用剪力图、弯矩图和代数二次函数极值的知识，对简支梁受移动载荷作用时的最大剪力和最大弯矩的计算方法进行了论证。     

双小车主梁最大弯矩位置的探讨分析

双小车双梁在设计主梁时,需确定主梁的最大弯矩位置,这对主梁承载的几种工况受力分析可以简化许多繁琐的计算。文中从经典的受力分析出发,对双小车的主梁最大弯矩位置进行了分析探讨。     

基于二阶理论的2端弹性约束压弯梁的稳定性分析和最大弯矩计算

运用二阶理论对2端弹性约束压弯梁的稳定性进行了分析,通过求解其挠曲微分方程得到其变形及临界载荷的精确表达式,随后给出了方便工程应用的高精度实用近似计算式。推导了弹性约束简支压弯梁在各种横向载荷作用下的跨中最大弯矩的精确计算式,进而讨论了GB／T13752-1992《塔式起重机设计规范》中的非弹性约束压弯梁的最大弯矩近似计算公式对计算弹性约束简支压弯梁的跨中弯矩的适用性问题。通过分析推导证明：在加入了必要的修正项之后,规范中的最大弯矩近似计算式仍可用于弹性约束简支压弯梁的跨中弯矩的计算,从而为规范的补充修订提供了理论依据。     

弹性约束悬臂压弯梁的稳定性及最大二阶弯矩

利用变形微分方程，对弹性约束悬臂压弯梁的稳定性进行分析，给出了其临界载荷的精确计算式和实用近似计算式，推导了弹性约束悬臂压弯梁约束端二阶弯矩的精确计算式，并讨论了《塔式起重机设计规范》中的非弹性约束压弯梁的最大二阶弯矩近似计算式在考虑了约束端弹性时的适用性。     

悬臂梁支座的最佳间距

正确地设置支座,就能使悬臂梁上的最大弯矩减到最小,从而使梁的尺寸和重量减到最小。现在我们就来看一个典型的双支座均布载荷等截面梁的情况。梁的最大弯矩可以通过设置右支座而被平衡。其结果是右支座上的最大弯矩等于两支座间的最大弯矩。由材料力学得知,右支座的最大弯矩为:     

地震时卧式容器的弯矩

建立地震时有附加设备卧式容器的轴向弯矩方程,解析弯矩方程,用Excel进行数据处理后画出弯矩图,确定卧式容器轴向弯矩极大值的位置和产生最大弯矩的截面,并给出工程适用的计算方法、计算式。     

悬臂梁支座的最佳间距

<正> 正确地设置支座,就能使悬臂梁上的最大弯矩减到最小,从而使梁的尺寸和重量减到最小。现在我们就来看一个典型的双支座均布载荷等截面梁的情况。梁的最大弯矩可以通过设置右支座而被平衡。其结果是右支座上的最大弯矩等于两支座间的最大弯矩。由材料力学得知,右支座的最大弯矩为:M_(Rmax)=(W/1)(a~2/2) (1)而两支座间的弯矩M_L 表示为:M_L=R_Lx-[(W/1)(x~2/2)] (2)这里x 为沿梁方向距离,R_L 是左支点的反作用力。由∑M_R=0得反作用力R_L 为:     

移动载荷与三载荷的简支梁上引起的弯矩及剪力通用方程的研究

通过对作用在简支梁上的任意的移动载荷与三载荷（移动、集中和均布载荷）引起的弯矩及剪力的研究。推导出不受任何条件约束即可直接准确地计算出梁上任意位置的弯矩及剪力和最大弯矩及其位置的新方法。特别用三载荷弯矩及剪力通用方程的建立，把力学中各自独立的移动载荷、集中载荷、均布载荷及其之间相互成为组合时的弯矩及剪力计算方法有机地联系到一起，它们的弯矩及剪力方程是三载荷弯矩及剪力用通方程的特殊形式。该计算方法比常规的计算方法更严密、科学和准确。并消除叠加法求最大合成弯矩存在的误差。     

球窝接合的应力计算

我们可以施加一个压力将轴或杆件安装在平面内的承窝里——形成承受轴端载荷的“球窝接合”。但是,首先要估算轴的挠度和平面上支承点的应力。经验表明,用普通悬臂梁方程式分析球窝接合,计算轴的弯曲应力,不能永远具有足够的精确度。例如,其弯矩方程式表明最大弯矩——因而最大弯曲应力产生于轴和支承面相接处(见图1)。实际上最大弯矩出     

桥式起重机双小车轮压对主梁产生最大弯矩的截面

桥式起重机双小车轮压对主梁产生最大弯矩的截面武汉冶金设备制造公司研究所黄初龙通常的双梁桥式起重机只有一台小车，每根主梁上作用有两个不等的轮压，如图１的Ｐ１和Ｐ２。当起重量为７５ｔ或更大时，为使小车轮压分散，小车运行机构多采用平衡台车，一根主梁上作用有...     

Interaction yield hypersurfaces for the plastic behaviour of beams—I. Combining bending, tension and shear

A variational method has been used to construct envelopes of the interaction yield surfaces for elastic, perfectly plastic beams subjected to combined bending moment, axial tension and transverse shear force. A lower bound of the envelope for the interaction yield curves relating bending moment and transverse shear force is obtained using a numerical scheme for beams having rectangular-shaped cross-sections. The result is recast into a simple equation with the aid of the least-squares method. A good upper bound of the envelope for the interaction yield curves which combine transverse shear force and axial tension is also derived. A formula for the interaction yield surfaces for combined bending moment, axial tension and transverse shear force is suggested.     

多跨连续梁结构静力计算软件开发

利用有限元法开发出多跨连续梁结构的内力和变形计算软件，结合图形建模，对计算模型进行单元全自动划分和载荷自动等效，能处理多种约束(支承)类型，可快速绘制弯矩图、剪力图和变形曲线。     

基于虚拟仪器的活塞杆弯曲试验测试系统

利用NI公司的LabVIEW软件和PCI-6220数据采集卡,开发了基于虚拟仪器的测试系统,并在减振器活塞杆弯曲试验中加以应用.该测试系统通过对活塞杆弯曲过程中力和挠度的实时测试,实现了弯曲力-挠度曲线和加载速度的实时显示,完成了活塞杆屈服弯曲力、最大弯曲力、最大挠度、指定挠度处的弯曲力和指定弯曲力处的永久变形等参数的测试.实验结果表明,该测试系统具有使用方便、界面友好、性能完善、测试精度稳定等特点.     

浅谈弯矩图的简明画法

以截面法为依据求梁横截面上的弯矩,向上的外力产生正弯矩,反之产生负弯矩;绘出梁的弯矩图是梁强度计算的基础,对于梁的设计具有重要意义.     

双帽箱型点焊薄壁构件的局部翘曲分析

针对汽车上广泛使用的箱型点焊薄壁构件，研究在考虑焊点处的弹性特性基础上，对箱型点焊薄壁构件受扭矩时焊点处的局部翘曲变形进行分析研究，提出一种计算局部变形的近似方法。把扭矩转换成通过焊点的剪力，此剪力又由置换剪力和置换力偶矩代替，然后计算相应的局部翘曲。计算结果与运用平面薄板理论的平面应力问题和平面弯曲问题的弹性力学解之间具有较好的对应关系和精度。     

Stochastic analysis of non-top-top contacting rough surfaces

Within the framework of the Hertz-Mindlin theory of contact the dependence of the mean values of the resulting bending moments, the torsion moment and the shear and vertical forces of stochastically rough surfaces in elastic contact on the shape of the asperities, and the effect of lateral contact of the asperities on the vertical force in the slip-free and slip-afflicted cases are investigated.     

The forming limit curve for bending processes

The maximum strain that metal can suffer in some bulk forming processes is limited by the phenomenon of shear band formation, which precedes ductile fracture. The process of strain localization in the shear band has been analysed theoretically on the basis of the theory of plastic flow. It is assumed that the material does not only undergo strain-hardening, but also strain-softening, due to the growth and coalescence of voids and microcracks. Taking into account the post-stability stage of the strain localization process the limit strain, i.e. the maximum strain outside the shear band has been determined as a function of stress ratio. The theoretically predicted forming limit curve for bending processes shows satisfactory correlation with the curve obtained experimentally for 0.39% C carbon steel. In both cases the limit strain reaches its minimum for plane states of strain. The analysis does not include plastic anisotropy, strain rate sensitivity and other metallurgical features of the material.     

Design optimization of a wind turbine blade to reduce the fluctuating unsteady aerodynamic load in turbulent wind

Design optimization of the wind turbine of a NREL 1.5-MW HAWT blade was studied to minimize the fluctuation of the bending moment of the blade in turbulent wind. In order to analyze the unsteady aerodynamic load of a wind turbine, FAST code was used as the analysis code. To consider turbulent wind as the wind input model in FAST, TurbSim was used as a turbulent wind simulator. For effective geometrical representation of the aerodynamic shape of a wind turbine blade, the shape modeling function was used to represent the chord length and twist angle. The fluctuation of the out-of-plane bending moment at the blade root was minimized by maintaining the required power of the wind turbine. Through the redistribution of the section force in the radial direction between both the primary and tip regions, the magnitude of the fluctuation of the out-of-plane bending moment was reduced by about 20%, and the rated power of 1.5-MW was maintained. The local angles of attack for the optimized blade were near the point of the maximum lift-to-drag ratio in the primary and tip regions compared to the baseline blade. The fluctuating unsteady aerodynamic load in the optimized blade was reduced within the operating range of the wind speed. With the optimized blade shape, the wind turbine can be operated with decreased fluctuating aerodynamic loads and have a longer life in turbulent wind.     

Maximum load for toruslike shells

Maximum loads for toruslike shells with constant thickness loaded with an axial force, internal pressure, and a bending torque are calculated. The rigid plastic body model, the Tresca yield condition, and the plastic yield law associated with it are used. Application of the finite element method for calculation of the maximum load on a shell is considered. A significant increase in the characteristic deformation of a shell is used as a criterion. The corresponding formulas for maximum loads are obtained based on the kinematic method of the limit equilibrium theory. The difference between the obtained results and the static solution does not exceed 3%.