共查询到12条相似文献,搜索用时 62 毫秒
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研究了两端简支不可移、轴向运动梁在热冲击作用下的横向振动特性,根据Timoshenko梁理论和Hamilton原理建立了梁的横向振动控制方程,采用微分求积法求解了梁的横向振动问题,分析了热冲击和轴向运动效应对梁固有特性的影响。研究发现:热冲击引起的梁的等效热轴力、热弯矩和弹性模量变化三因素中,热轴力对梁固有频率的影响起主导作用,材料的弹性模量变化和热弯矩起次要作用;当热冲击载荷大于或等于梁的临界压力时,达到梁的第一阶失稳模态;热冲击和轴向运动效应都会降低梁的固有频率,它们的联合作用会导致模态之间的耦合现象,使梁更易达到失稳状态。 相似文献
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K. M. Liew Y. Q. Huang J. N. Reddy 《International journal for numerical methods in engineering》2003,56(15):2331-2351
A moving least squares differential quadrature (MLSDQ) method is developed and employed for the analysis of moderately thick plates based on the first‐order shear deformation theory (FSDT). To carry out the analysis, the governing equations in terms of the generalized displacements (transverse deflection and two rotations) of the plate are formulated by employing the moving least squares approximation. The weighting coefficients used in the MLSDQ approximation are computed through a fast computation of shape functions and their derivatives. Numerical examples illustrating the accuracy, stability and convergence of the MLSDQ method are presented. Effects of support size, order of completeness and node irregularity on the numerical accuracy are investigated. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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T. C. Fung 《International journal for numerical methods in engineering》2003,56(3):405-432
One of the important issues in the implementation of the differential quadrature method is the imposition of the given boundary conditions. There may be multiple boundary conditions involving higher‐order derivatives at the boundary points. The boundary conditions can be imposed by modifying the weighting coefficient matrices directly. However, the existing method is not robust and is known to have many limitations. In this paper, a systematic procedure is proposed to construct the modified weighting coefficient matrices to overcome these limitations. The given boundary conditions are imposed exactly. Furthermore, it is found that the numerical results depend only on those sampling grid points where the differential quadrature analogous equations of the governing differential equations are established. The other sampling grid points with no associated boundary conditions are not essential. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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Ola Ragb M.S. Matbuly 《International Journal for Computational Methods in Engineering Science and Mechanics》2017,18(6):292-301
This work concerns with buckling and vibration analysis of composite plates based on a transverse shear theory. A numerical scheme is introduced to determine the angular frequencies and critical buckling loads of such plates. Moving least square differential quadrature method is employed to reduce the problem to that of eigen value problem. The accuracy and efficiency of the proposed scheme is examined with different computational characteristics, (radius of support domain, basis completeness order, and scaling factors). The obtained results agreed, at less execution time, with the previous ones. Further, a parametric study is introduced to investigate the influence of elastic and geometric characteristics, (Young's modulus gradation ratio, shear modulus gradation ratio, Poisson's ratio, loading parameter, and aspect ratio), of the composite on the values of critical buckling load, natural frequencies, and behavior of mode shape functions. 相似文献
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In this study, dynamic moving load identification of laminated composite beams is performed by introducing a hybrid finite element (FE), time marching differential quadrature (TMDQ) and genetic algorithms (GAs) methods. The first-order shear deformation theory based equations of the beam are discretized in the space and time domains using the FE and TMDQ methods, respectively. Accuracy and efficiency of the TMDQ method for solving the problem are shown via comparing the results with the Newmark’s method. To simulate the measured responses for the load identification problem, random error is applied to the dynamic responses obtained from the finite element and time marching differential quadrature method under a given dynamic load. An objective function as a root mean square error between the calculated and measured responses is defined and the GAs is employed to minimize the function and identify the loading parameters. Applicability and usefulness of the proposed method are shown through solving some examples. 相似文献
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Jia‐Jang Wu 《International journal for numerical methods in engineering》2005,62(14):2028-2052
Four kinds of moving mass elements, 1st‐node, 2nd‐node, full and short‐range mass elements, are presented, where the 1st‐node (or 2nd‐node) mass element refers to that with mass distributed from the first node (or second node) to the arbitrary position of a two‐node beam element, the full mass element is the special case of the 1st‐node (or 2nd‐node) mass element with mass distributed over the full length of the beam element, while the short‐range mass element is the case with its location arbitrary on a beam element. If the total range of a distributed mass is denoted by R and the length of each beam element is denoted by ??, then, for the case of R???, one may model the distributed mass on the beam using the combination of the 1st‐node, 2nd‐node and full mass elements, while for the case of R<??, one may model the distributed mass using the short‐range mass element. It has been found that the effects of the vertical (?) and horizontal (x?) inertia forces, Coriolis force and centrifugal force induced by the moving distributed mass can be easily taken into the formulations by means of the last concept. To illustrate the application of the presented theory, the dynamic analysis of a pinned–pinned beam and that of a portal frame under the action of a moving uniformly distributed mass are performed by means of the finite element method and the Newmark integration method. Numerical results show that some pertinent factors, such as Coriolis force, centrifugal force, acceleration, velocity and total range of the moving distributed mass, have significant influences on the vertical (?) and horizontal (x?) response of a structure. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献