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本文根据机械阻抗分析法分析了两端任意弹性支承梁在其端点处受到简谐激励时的阻抗特性。在此基础上,计算了几种黄型支承条件下梁的稳态响应、共振频率、反共振频率以及位移导纳函数。 相似文献
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本文以线性支承曲线梁理论为基础,对城市立交桥和高架桥中正在研究的单柱式点支承曲线桥提出解析方法。通过与曲线格子梁理论对比分析,验证了本方法的可靠性。作为实际应用,本文对天津市市政工程勘测设计院正在设计的一座单柱式点支承曲线桥做了计算分析,两种方法所得结果吻合很好。 相似文献
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《东南大学学报》2019,(4)
基于非局部应变梯度理论,研究了轴向功能梯度Bernoulli-Euler微梁在集中载荷和分布载荷作用下的弯曲行为.轴向功能梯度微梁的材料参数沿轴向连续变化.基于最小势能原理,推导了微梁的运动方程以及相应的经典和非经典边界条件,并利用Galerkin加权余量法和归一化技术对控制微分方程进行了求解.在非局部应变梯度理论、非局部弹性理论、应变梯度理论和经典弹性理论的框架下,对受正弦分布荷载作用的轴向功能梯度微梁的横向变形进行了比较.结果表明,微梁的弯曲柔度随材料长度尺度参数与梁高比值的增大而减小,但随材料非局部参数的增大而增大,功能梯度参数对控制微梁挠度具有重要作用.该工作可为相关领域内轴向功能梯度微梁的设计和分析提供理论依据和技术参考. 相似文献
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李爱民 《实验室研究与探索》2018,(5)
研究弹性直梁在受轴向力作用下大变形非线性屈曲分析的方法,并对两端固支的梁进行非线性屈曲分析与仿真实验。根据材料力学,当此弹性直梁所受轴向力大于某一临界值时,梁才会产生大变形,即成为后屈曲梁。直接建立了此后屈曲梁的数学模型,推导出梁受轴向力的理论公式,用椭圆积分法以MATLAB编程求解数学模型,得出其非线性屈曲特征曲线。在Ansys Workbench中建立相对应的模型,添加相应的边界条件,对其进行非线性屈曲分析。通过实验与理论计算和仿真数据进行对比,验证理论计算的正确性。并且发现随着轴向力的改变,弹性直梁的刚度也是可变的。而对梁屈曲等特性的分析研究,在减振、工业建筑领域方面的应用提供理论依据。 相似文献
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根据动力学分析和边界条件推导出轴向运动梁的系统特征方程,利用微分求积法对本征方程离散,计算出梁横向振动的固有频率,并数值模拟了梁运动速度和刚度对固有频率的影响。 相似文献
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在弹性梁与磁弹性力学理论的基础上,应用动力学方法建立电磁场和温度场耦合作用下的载流梁的非线性热磁弹性耦合振动方程。应用Galerkin法导出了系统受电磁力和热力共同作用的非线性振动微分方程组。通过数值计算,给出了不同系统参数下的系统振动的时程图和相图。 相似文献
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单向板楼盖设计中主梁对次梁的支承约束及柱对主梁的约束一般按铰支处理,这种处理方法导致设计结果出现较大偏差。主要分析影响支承性能变化的因素及提出相应的解决方法。 相似文献
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研究了一类离散时滞系统的变结构控制问题．在未知系统状态的条件下,首先设计了系统的状态观测器,然后基于该观测器并结合Lyapunov稳定性理论设计系统的变结构控制器．所得条件均以线性矩阵不等式形式出现,使得该结论应用十分方便． 相似文献
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用频率法测试两端固支的弹性杆轴向拉力时,试验机及其夹具的振动会对杆件振动信号的测量和识别造成干扰,容易导致振动频率及阶次误判;提出了利用弹性杆在无约束自由振动下的频率作为基准值,对实验中杆的振动频率进行修正的方法,得到了弹性杆准确的振动频率及阶次;并发现试验机及其夹具对于两端铰支弹性杆的振动频率的识别不会产生影响;随着弹性杆长径比的增加,试验机及其夹具对两端固支的弹性杆振动频率识别产生的干扰逐渐减小,当轴向拉力不断加大时,这种干扰也呈现下降趋势。 相似文献
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Nonlinear bending of cantilever incompressible poroelastic beams subjected to a uniform load is investigated with the constraint that fluid flow is only in the axial direction. The governing equations for large deflection of the poroelastic beam are derived from theory of incompressible saturated porous media. Then, nonlinear responses of a cantilever beam with impermeable fixed end and permeable free end are examined with the Galerkin truncation method. The deflections and bending moments of the poroelastie beam and the equivalent couples of the pore fluid pressures are shown in figures. The differences of the results between the large deflection and the small deflection theories are analyzed. It is shown that the results of the large deflection theory are smaller than those of the small deflection theory, and the time needed to approach their stationary states for the large deflection theory is shorter than that for the small deflection theory. 相似文献
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The integro-partial-differential equation that governs the dynamical behavior of homogeneous viscoelastic beams with
geometric and material nonlinearities is established. The material of the beams obeys the Leaderman nonlinear constitutive relation. In
the case of simple supported ends, the Galerkin method is applied to simplify the integro-partial-differential equation to a integro
-differential equation. The equation is further simplified to a set of ordinary differential equations by introducing an additional variable.
Finally, the numerical method is applied to investigate the dynamical behavior of the beam, and results show that chaos occurs in the
motion of the beam. 相似文献
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CHEN Li-qun CHENG Chang-jun ZHANG Neng-hui Department of Mechanics Shanghai Institute of Applied Mathematics Mechanics Shanghai University Shanghai China 《上海大学学报(英文版)》2000,(Z1)
l introductionThe Galerkin trUncation is widely used to stody thedynandcal behavior (especially the nonlinear dynamicalbehavior) of,trU.tUre,[i]. The Galerkin method is alsoaPPlied to stUdy dynamical behavior of viscoelashcbeams. Suire and Cederbaum [2] analyzed periodic andchaohc behavior of viscoelastic beams with the Idledeflection, and the constitUtive relation in their work isthe BoltZmann superposition Principle. Argyris[']myes-tigated chaohc motion of viscoelastic beamsbased on a … 相似文献
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研究Mathieu-Gauss(MG)光束通过光阑透镜分离系统的焦开关现象.由Collins公式,推导出了MG光束轴上光强分布公式,在此基础上作了大量的数值分析.研究发现,在光束参数和截断参数的适当取值下,MG光束存在焦开关现象.产生焦开关现象的条件是:光阑和透镜相对间距为1,光束参数必须大于其相应的临界值,而截断参数则须在它的两个临界值之间. 相似文献
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Existence of solutions and positive solutions to a fourth-order two-point BVP with second derivative
姚庆六 《浙江大学学报(A卷英文版)》2004,5(3):353-357
Several existence theorems were established for a nonlinear fourth-order two-point boundary value problem with second derivative by using Leray-Schauder fixed point theorem, equivalent norm and technique on system of integral equations. The main conditions of our results are local. In other words, the existence of the solution can be determined by considering the "height" of the nonlinear term on a bounded set. This class of problems usually describes the equilibrium state of an elastic beam which is simply supported at both ends. 相似文献
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Feras ALZOUB ZHANG Qi LI Zheng-liang 《重庆大学学报(英文版)》2007,6(4):305-310
This paper presents the results of an experimental investigation on the response of pre-damaged reinforced concrete (RC) beam strengthened in shear using applied-epoxy unidirectional carbon fiber reinforced polymer (CFRP) sheet. The reasearch included four test rectangular simply supported RC beams in shear capacity. One is the control beam, two RC beams are damaged to a predetermined degree from ultimate shear capacity of the control beam, and the last beam is left without pre-damaged and then strengthened with using externally bonded carbon fiber reinforced polymer to upgrade their shear capacity. We focused on the damage degree to beams during strengthening, therefore, only the beams with side- bonded CFRPs strips and horizontal anchored strips were used. The results show the feasibility of using CFRPs to restore or increase the load-carrying capacity in the shear of damaged RC beams. The failure mode of all the CFRP-strengthened beams is debonding of CFRP vertical strips. Two prediction available models in ACI-440 and fib European code were compared with the experimental results. 相似文献
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ZHU Bin LEUNG A.Y.T. 《浙江大学学报(A卷英文版)》2006,7(8):1351-1357
INTRODUCTION Thin-walled structures have considerable tech-nological importance in many situations of engi-neering practice. The rotary and warping inertia terms should be considered in the analyses of thin-walled structures (Alwis and Wang, 1996), although it is difficult to obtain the analytical solutions of govern-ing differential equations, especially of thin-walled frame and spatial twisted structure. The finite element method (FEM) is widely used for vibration and sta-bility analy… 相似文献
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地下建筑结构中弹性地基直梁的初参数法 总被引：3，自引：0，他引：3
以文克尔假定推导了弹性地基梁挠度曲线微分方程,并导出地基梁在不同荷载作 用下梁截面的挠度ｙ、转角θ、弯矩Ｍ和剪力Ｑ的计算公式．用初参数法获得基本方程 的解．所得到的计算公式适用于大多数的弹性地基短梁,用此公式可达到令人满意的结果． 相似文献
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Existence of solutions and positive solutions to a fourth-order two-point BVP with second derivative 总被引：2，自引：0，他引：2
~~4[0,1]Csatisfyingand()hr ?*umu'k(mh r)and*uisanonnegativeconcavefunction.Moreover,ifoneofthefollowingconditionsissatisfied:(1)A B>0;(2)C D<0;(3)f(t,0,0) 0,0t1,then*u(t)>0,00suchthatmax{():01,0,80}64,rrr?#ft,u,vtuvthentheproblem(P)hasatleastonesolutionu*C4[0,1]satisfying*urand()*"u8randu*isanonnegativeconcavefunction.Moreover,iff(t,0,0) 0,0t1,thenu*(t)>0,0相似文献