共查询到19条相似文献,搜索用时 78 毫秒
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弯压组合中一个不容忽视的问题 总被引:2,自引:0,他引:2
提出了在弯压组合问题的强度计算中,轴向压力对最大挠度和最大弯矩的影响不可忽视,并导出了计算这种影响的解析式,以及忽略和考虑这种影响的判别式. 相似文献
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关于弹性梁的数学模型 总被引:1,自引:0,他引:1
叙述和比较一维弹性体的两种不同建模方法, 即弹性梁的传统建模方法和基于Kirchhoff-Cosserat模型的建模方法. 应用精确Cosserat模型分析梁的三维运动. 考虑中心线的拉伸压缩变形、截面的剪切变形、截面转动的惯性和端部载荷影响等因素, 建立精确的弹性梁动力学方程. 讨论梁的静态和动态平衡稳定性. Kirchhoff杆、铁摩辛柯梁和欧拉--伯努利梁等为Cosserat模型在各种简化条件下的特例. 相似文献
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从理论力学的教学谈过程式启发教育 总被引:8,自引:1,他引:7
以力系平衡为例,提出了在理论力学教学中使用过程式启发教育的方法.%主要过程是:通过精心备课形成知识结构树和认识逻辑树,设置适当的问题情境以引发思考,%启发诱导以引导思维流程,激发头脑风暴以让大多数学生享受思考的乐趣,归纳总结以形成%学生对自己思维特点的再认识. 相似文献
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任意有限个平行移动荷载作用下简支梁绝对最大挠度的解析算法研究 总被引:3,自引:0,他引:3
利用能量原理中的最小势能原理以及多元函数的极值原理,得到了简支梁在任意有限个平行移动荷载作用下的挠度方程与绝对最大挠度的解析算式。建立的可能位移函数既满足了位移几何边界条件,又满足了静力边界条件,故足可以保证简支梁的挠度计算精度。 相似文献
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Numerical analysis of large elasto-plastic deflection of constant curvature beam under follower load
This paper describes a method to analyze the elasto-plastic large deflection of a curved beam subjected to a tip concentrated follower load. The load is made to act at an arbitrary inclination with the tip tangent. A moment-curvature based constitutive law is obtained from linearly hardening model. The deflection governing equation obtained is highly non-linear owing to both kinematics and material non-linearity. It is linearized to obtain the incremental differential equation. This in turn is solved using the classical Runge–Kutta 4th order explicit solver, thereby avoiding iterations. Elastic results are validated with published literature and the new results pertaining to elasto-plastic cases are presented in suitable non-dimensional form. The load to end angle response of the structure is studied by varying normalized material and kinematic parameters. It is found that the response curves overlap at small deflection corresponding to elastic deformation and diverge for difference in plastic property. The divergent response curves intersect with each other at higher deflection. The results presented also show that the approach may be used to obtain desired non-uniformly curved beam by suitably loading a uniform curvature beam. 相似文献
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1 TheSituationofMathematicalAnalysisofStockMarketandTwoAnalyticSystems Mostpublicationsunderthetitleofstockmarket,includinghundredsofauthoritativeguidetocontemporaryinvestmenttheories[1],belongtodatacollection ,summinguptheexperienceofmakingprofits,operatingskills,qualitativeanalysis,andtechnicalanalysisusingsimplemathematics,etc .Thework ,cannotbeconsidered ,ingeneral,asrulequantitativeinvestigationandisstillinadescribingstage.Theliteraturesonbehaviorofstockmarketinvestigatedbyanalytic… 相似文献
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A realistic beam structure often exhibits material and geometrical non-linearity, in particular for those made of metals. The mechanical behaviors of a non-linear functionally graded-material (FGM) cantilever beam subjected to an end force are investigated by using large and small deformation theories. Young's modulus is assumed to be depth-dependent. For an FGM beam of power-law hardening, the location of the neutral axis is determined. The effects of depth-dependent Young's modulus and non-linearity parameter on the deflections and rotations of the FGM beams are analyzed. Our results show that different gradient indexes may change the bending stiffness of the beam so that an FGM beam may bear larger applied load than a homogeneous beam when choosing appropriate gradients. Moreover, the bending stress distribution in an FGM beam is completely different from that in a homogeneous beam. The bending stress arrives at the maximum tensile stress at an internal position rather than at the surface. Obtained results are useful in safety design of linear and non-linear beams. 相似文献
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The aim of this paper is to develop a new method of analyzing the non-linear deflection behavior of an infinite beam on a non-linear elastic foundation. Non-linear beam problems have traditionally been dealt with by semi-analytical approaches that involve small perturbations or by numerical methods, such as the non-linear finite element method. In this paper, in contrast, a transformed non-linear integral equation that governs non-linear beam deflection behavior is formulated to develop a new method for non-linear solutions. The proposed method requires an iteration to solve non-linear problems, but is fairly simple and straightforward to apply. It also converges quickly, whereas traditional non-linear solution procedures are generally quite complex in application. Mathematical analysis of the proposed method is performed. In addition, illustrative examples are presented to demonstrate the validity of the method developed in the present study. 相似文献
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Cemil Tunç 《应用数学和力学(英文版)》1999,20(6):622-628
In this paper, sufficient conditions are established under which all solutions of some non-autonomous differential equations
of the fourth order are bounded and uniformly bounded. 相似文献
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Alexander L. Skubachevskii Hans-Otto Walther 《Journal of Dynamics and Differential Equations》2006,18(2):257-355
For periodic solutions to the autonomous delay differential equation
with rational periods we derive a characteristic equation for the Floquet multipliers. This generalizes a result from an earlier paper where only periods larger than 2 were considered. As an application we obtain a criterion for hyperbolicity of certain periodic solutions, which are rapidly oscillating in the sense that the delay 1 is larger than the distance between consecutive zeros. The criterion is used to find periodic orbits which are unstable and hyperbolic. An example of a non-autonomous periodic linear delay differential equation with a monodromy operator which is not hyperbolic shows how subtle the conditions of the hyperbolicity criteria in the present paper and in its predecessor are. We also derive first results on Floquet multipliers in case of irrational periods. These are based on approximations by periodic solutions with rational periods. 相似文献
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Principal parametric resonances of a slender cantilever beam subject to axial narrow-band random excitation of its base 总被引:1,自引:0,他引:1
The non-linear integro-differential equations of motion for a slender cantilever beam subject to axial narrow-band random excitation are investigated. The method of multiple scales is used to determine a uniform first-order expansion of the solution of equations. According to solvability conditions, the non-linear modulation equations for the principal parametric resonance are obtained. Firstly, The largest Lyapunov exponent which determines the almost sure stability of the trivial solution is quantificationally resolved, in which, the modified Bessel function of the first kind is introduced. Results show that the increase of the bandwidth facilitates the almost sure stability of the trivial response and stabilizes the system for a lower acceleration oscillating amplitude but intensifies the instability of the trivial response for a higher one. Secondly, the first and second order non-trivial steady state response of the system is obtained by perturbation method and the corresponding amplitude–frequency curves are calculated when the bandwidth is very small. Results show that the effective non-linearity of whether the amplitude expectation of the first order steady state response or the amplitude expectation of the second order steady state response is of the hardening type for the first mode, whereas for the second mode the effective non-linearity of whether the amplitude expectation of the first order steady state response or the amplitude expectation of the second order steady state response is of the softening type. Finally, the stochastic jump and bifurcation is investigated for the first and second modal parametric principal resonance. The basic jump phenomena indicate that, under the conditions of system parameters with a smaller bandwidth, the most probable motion is around the non-trivial branch of the amplitude response curve, whereas with a higher bandwidth, the most probable motion is around the trivial one of the amplitude response curve. However, the stochastic jump is sometimes more sensitive to the change of the bandwidth, in other words, a small change of bandwidth may induce a series of stochastic jump and bifurcation. 相似文献