共查询到16条相似文献,搜索用时 282 毫秒
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作大范围运动的矩形板动力分析 总被引:4,自引:0,他引:4
作高速大范围运动的弹性体,由于运动和变形的耦合将产生动力刚化现象,传统的动力学理论难以计及这种影响.本文在有限元方法中首次引入了单元耦合形函数(阵),以此将单元弹性位移表示成为单元结点位移的二阶小量形式.利用几何非线性的应变-位移关系式,在小变形假设条件下确定了单元耦合形函数.在此基础上,根据Kane方程.运用模态坐标压缩,并采用适当的线性化处理,得到了包含动力刚度项的线性动力学方程.针对矩形板编制了动力刚化有限元分析程序.仿真算例证明了理论和算法的正确性. 相似文献
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作大范围运动的空间桁架结构动力分析 总被引:2,自引:0,他引:2
作高速大范围运动的弹性体,由于运动和变形的耦合将产生动力刚化现象,传统的动力学理论难以计及这种影响。本文在有限元方法中首次引入了单元耦合形函数(阵),以此将单元弹性位移表示为单元结点位移的二阶小量形式。利用几何非线性的应变-位移关系式,在小变形假设条件下确定了单元耦合形函数。在此基础上,根据Kane方程,运用模态坐标压缩,并通过适当的线性化处理,得到了一致线性化的动力学方程。编制了计及动力刚化的空间桁架结构有限元分析程序。仿真算例的计算结果验证了理论和算法的正确性 相似文献
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大范围运动刚体-柔性梁刚柔耦合动力学分析 总被引:2,自引:1,他引:1
对自由大范围运动情况下刚体-柔性梁系统的刚柔耦合动力学特性进行了研究.考虑系统作平面大范围运动及柔性梁的纵向和横向变形,在纵向变形位移中计及横向弯曲引起的轴向缩短,即耦合变形项.采用假设模态法对柔性梁进行离散,运用拉格朗日方程推导出系统刚柔耦合动力学方程.分大范围运动为转动、平动,平面运动进行了动力学仿真,重点探讨了大范围平动下的刚体-柔性梁系统的刚柔耦合动力学特性.首先研究了系统在外界激励作用下的耦合动力学,其次分析了已知大范围平动对柔性梁小变形运动的影响.结果表明:零次近似模型不能反映大范围平动和柔性梁小变形运动之间的耦合作用;在不同的大范围平动加速度下,柔性梁中既可存在动力刚化效应,也可存在动力柔化效应. 相似文献
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《振动与冲击》2016,(14)
从连续介质力学非线性位移-应变关系出发,导出计入应力刚化效应的空间柔性梁变形能表达式。利用浮动框架有限元方法和哈密顿变分原理推导了满足小变形假设的空间曲梁的一般运动动力学方程,并利用模态缩减法对动力学方程进行了维数降阶。所推导的动力学方程可用于高速旋转一般运动空间柔性曲梁动力学问题的求解。通过数值仿真讨论了应力刚化效应对大范围运动小变形空间柔性曲梁动力学特性的影响,并与ADAMS软件和ABAQUS软件的仿真结果进行了对比,指出了ADAMS软件在高速旋转柔性多体系统数值计算方面的一些缺陷。所提出的计及应力刚化效应的空间曲梁动力学建模方法为高速旋转一般运动柔性多体系统动力学建模和分析提供了参考。 相似文献
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作大范围运动的柔性梁的动力学分析 总被引:2,自引:1,他引:2
对附着在空间运动体上的柔性悬臂梁的动力学进行了研究,利用微元法建立了中心刚体作任意三维大位移运动时柔性悬臂梁作横向和纵向振动的动力学方程,此动力学方程计及了动力刚化效应。在对柔性梁离散求解时考虑了横向弯曲对纵向变形的影响,最后通过几个例子分析了运动基上柔性梁的动力学行为。 相似文献
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作大范围运动矩形薄板的建模理论和有限元离散方法 总被引:8,自引:1,他引:7
研究了作大范围运动薄板的耦合动力学建模理论和离散化方法。对作大范围运动的薄板建立了耦合动力学模型,计及了在结构动力学中对薄板动力学特性影响很小的二次耦合变形量。用有限元方法对秉性薄板进行离散,基于Jourdain速度变分原理导出了作大范围运动薄板的动力学方程。计算了作旋转运动的薄板的变形,将仿真结果与不计二次耦合变形量的传统方法进行比较表明,随着转速的提高,仿真结果出现明显的差异。此外,将本文有限元与假设模态法的计算结果进行比较,揭示了高速旋转时假设模态法的局限性,表明取无大范围运动的高阶模态可以提高假设模态法的计算精度。 相似文献
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M. KERDJOUDJ F. M. L. AMIROUCHE 《International journal for numerical methods in engineering》1996,39(2):321-354
This paper presents the implementation of the Boundary Element Method in the dynamics of flexible multibody systems. Kane's equations are used to formulate the governing boundary initial value problem for an arbitrary three-dimensional elastic body subjected to large overall base motion. Using continuum mechanics principles, direct boundary element incremental formulations are derived. The Galerkin approach was employed to generate the weighted residual statement which serves as a transitory point between continuum mechanics and boundary integral equations. By adapting the updated Langrangian formulation for large displacements analysis and using the Maxwell–Betti reciprocal theorem, integral representations for geometric stiffening were also derived. The non-linear terms were found to be functions of the time-variant stresses associated with the inertial forces at the reference configuration. The domain integrals arising from body forces (such as gravitational loads, inertia loads and thermal loads, etc.) are presented as DRM integrals (Dual-Reciprocity Method). Using the substructuring technique the elastic body is divided into several regions leading to a system of equations whose matrices are sparse (block-banded). The linearized equations of motion were discretized along the boundary of the body, and an algorithm for the integration involving the Houbolt method was used to establish an algebraic system of pseudo-static equilibrium equations. A Newton–Raphson-type iteration scheme was used to solve these discretized balance equations. To take advantage of the sparsity of the matrices, special routines were used to decompose and solve the resulting linear system of equations. An illustrative example is presented to demonstrate the validity of the method as well as how the effects of geometric stiffening effects are captured. The example consists of spin-up manoeuvre of a tapered beam attached to a moving base. The beam was modelled as two-dimensional plane strain problem divided into a number of substructures. Numerical simulation results show how the phenomenon of dynamic stiffening is captured by the present approach. 相似文献
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Bilin Chang A. A. Shabana 《International journal for numerical methods in engineering》1990,29(1):73-103
In this paper, a method for the non-linear dynamic analysis of rectangular plates that undergo large rigid body motions and small elastic deformations is presented. The large rigid body displacement of the plate is defined by the translation and rotation of a selected plate reference. The small elastic deformation of the midplane is defined in the plate co-ordinate system using the assumptions of the classical theories of plates. Non-linear terms that represent the dynamic coupling between the rigid body displacement and the elastic deformation are presented in a closed form in terms of a set of time-invariant scalars and matrices that depend on the assumed displacement field of the plate. In this paper, the case of simple two-parameter screw displacement, where the rigid body translation and rotation of the plate reference are, respectively, along and about an axis fixed in space, is first considered. The non-linear dynamic equations that govern the most general and arbitrary motion of the plate are also presented and both lumped and consistent mass formulations are discussed. The non-linear dynamic formulation presented in this paper can be used to develop a total Lagrangian finite element formulation for plates in multibody systems consisting of interconnected structural elements. 相似文献
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高速弹性机构动力学模型及其解的研究 总被引:1,自引:0,他引:1
本文采用动态有限元素法建立了高速弹性连杆机构一般形式的动力学方程,导出了考虑剪切变形和转动惯量影响时平面刚架单元的动态形函数,给出了求解动力学方程的闭式迭代算法及其收敛条件,最后对一试验机构进行了数值模拟,结果表明,本文分析方法能够较准确地预测弹性机构的动力学性能。 相似文献
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Shih-Chin Wu Edward J. Haug 《International journal for numerical methods in engineering》1988,26(10):2211-2226
A substructure synthesis formulation is presented that permits use of established flexible multibody dynamic analysis computer codes to account for structural geometric non-linear effects. Large relative displacement is permitted between points within bodies that undergo small strain elastic deformation. Components are divided into substructures, on each of which the theory of linear elasticity relative to a body reference frame is adequate to describe deformation and its coupling with system motion. Normal vibration and static correction deformation modes are used to account for elastic deformation within each substructure. Compatibility conditions are derived and imposed as constraint equations at boundary points between substructures. System equations of motion that include geometric non-linear effects of large rotation, in terms of generalized co-ordinates of a reference frame for each substructure and a set of deformation modes that are defined within the substructure, are assembled. The method is implemented in an industry standard flexible multibody dynamics code, with minimal modification. Use of the formulation is illustrated on the classical problem of a spinning beam with geometric stiffening and on a space structure that experiences large deformation. 相似文献
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The present paper treats dynamic instability problems of non-conservative elastic systems. Starting from general equations of motion, the equations of the perturbed motion are derived. The boundedness of the perturbed motions is studied and sufficient conditions for instability and a necessary condition for stability are deduced. These conditions may determine the instability of non-conservative systems and they are expressed in terms of the properties of generalized tangent damping and stiffness matrices of the systems. Thus, they can easily be incorporated with finite element computations of arbitrary structures. 相似文献