共查询到19条相似文献,搜索用时 890 毫秒
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基于柔性轮对的轨道车辆动力学仿真分析 总被引:1,自引:0,他引:1
为研究柔性轮对对轨道车辆动力学性能的影响,应用ANSYS创建轮对实体有限元分析模型,并选用Guyan缩减法和Lanczos分块法对其进行子结构模态分析.联合SIMPACK创建柔性轮对车辆仿真模型,此模型的构架、车体等部件仍视作刚性体.与刚体车辆仿真模型对比分析出在中国高铁谱和美国六级谱激励作用下两模型的动力学性能的差异.分析结果表明:轮对采用柔性体的车辆非线性临界速度较全刚体车辆的非线性临界速度稍稍降低.在两激励线路下,轮对采用柔性体对车辆的平稳性和曲线通过性能也有一定程度的影响. 相似文献
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柔性板的模态价值降阶及其主动控制研究 总被引:1,自引:1,他引:0
对柔性板的模型降阶和主动控制进行研究,并且进行实验验证.首先采用假设模态方法给出系统的动力学方程,然后采用价值模态分析方法进行降阶研究.考虑到弱阻尼系统,文中给出了一种价值模态分析方法的近似公式.控制律采用最优控制方法进行设计.仿真和实验结果显示,价值模态分析方法能够有效地显示出系统各阶模态的重要程度,因此能够有效地对系统模型进行降阶. 相似文献
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为了研究人体在运动过程中的力学行为,探讨人体运动仿真的建模方法,运用多体系统动力学的建模方法建立了17刚体,55自由度的人体动力学模型,模型对人体颈部和下躯干的柔性效应给予了充分考虑,基于第一类Lagrange方程推导了系统的动力学方程,并以某人体为例,利用该模型对人体的行走过程进行了仿真计算,计算结果表明:采用所建立的人体动力学模型进行人体步态仿真、碰撞仿真等研究是现实可行的,最后结合对人体运动仿真的未来发展趋势的展望,说明人体动力学模型有待进一步完善. 相似文献
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本文针对柔性结构在轨组装任务背景,将自动飞船和待运送部件分别简化为中心刚体和柔性梁附件,研究自由漂浮中心刚体-柔性梁系统的动力学与控制问题.首先基于小变形和低转速假设,将梁用假设模态法离散,采用Lagrange方程导出系统动力学方程.继而设计一种带有应变反馈的PD控制律用于完成中心刚体的状态镇定以及柔性梁振动抑制.此外,本文还使用遗传算法对控制器中的参数进行多目标优化.最后,通过数值算例验证了所设计控制器的有效性. 相似文献
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为保证300t铁水车的安全运输,采用刚-柔混合动力学模型研究了该车的动力学性能.以I-DEAS软件为柔性体仿真平台,ADAMS/Rail软件为多刚体系统仿真平台,给出了创建刚-柔混合动力学模型的技术路线,采用在系统外将所关心的对象柔性化的建模方法建立了某公司研制的特种车辆-300t铁水运输车的刚-柔混合动力学模型.基于刚-柔混合模型的动力学仿真结果表明:弹性轨道对该车运行平稳性和曲线通过性能的影响大于柔性转向架对运行平稳性和曲线通过性能的影响.因此,对这类特种车辆进行动力学仿真应采用弹性轨道.当计算规模很大无法考虑转向架的柔性效应时,仅使用弹性轨道所获得的结果也能达到相当的精度. 相似文献
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This paper presents a mixed modal and tangent coordinate technique for computer aided analysis of flexible mechanical systems whose components undergo large translations and large rotations. In this model the configuration of a flexible component is identified by using two sets of generalized coordinates, namely rigid body and elastic coordinates. The rigid body coordinates define the location and orientation of a body axis, whereas the elastic coordinates define the displacement field of a component with respect to its body axis. The elastic coordinates are introduced by using finite element discretization to model flexible components with complex geometries. A modal analysis technique is used to identify the elastic mode shapes and to eliminate insignificant higher frequency modes. An orthonormalization of constraint Jacobian matrix associated with rigid body coordinates is used to identify the rigid body tangent coordinates. The resulting modal and tangent coordinates are used to develop an automated numerical integration scheme to solve the system differential and algebraic equations. Two numerical examples are considered to show the feasibility of dynamic analysis of flexible mechanical systems using this scheme. 相似文献
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Mohamed A. Omar 《Multibody System Dynamics》2017,41(1):47-74
Passenger cars, transit buses, railroad vehicles, off-highway trucks, earth moving equipment and construction machinery contain structural and light-fabrications (SALF) components that are prone to excessive vibration due to rough terrains and work-cycle loads’ excitations. SALF components are typically modeled as flexible components in the multibody system allowing the analysts to predict elastic deformation and hence the stress levels under different loading conditions. Including SALF component in the multibody system typically generates closed-kinematic loops. This paper presents an approach for integrating SALF modeling capabilities as a flexible body in a general-purpose multibody dynamics solver that is based on joint-coordinates formulation with the ability to handle closed-kinematic loops. The spatial algebra notation is employed in deriving the spatial multibody dynamics equations of motion. The system kinematic topology matrix is used to project the Cartesian quantities into the joint subspace, leading to a condensed set of nonlinear equations with minimum number of generalized coordinates. The proposed flexible body formulation utilizes the component mode synthesis approach to reduce the large number of finite element degrees of freedom to a small set of generalized modal coordinates. The resulting reduced flexible body model has two main characteristics: the stiffness matrix is constant while the mass matrix depends on the elastic modal coordinates. A consistent set of pre-computed inertia shape integrals are identified and used to update the modal mass matrix at each time step. The implementation of the component mode synthesis approach in a closed-loop recursive multibody formulation is presented. The kinematic equations are modified to include the effect of the flexible body modal elastic coordinates. Also, modified constraint equations that include the effect of flexibility at the joint connections and the necessary details of the Jacobian matrix are presented. Baumgarte stabilization approach is used to stabilize the constraint equations without using iterative schemes. A sample results for flexible body impeded in a closed system will be presented to demonstrate the above mentioned approach. 相似文献
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讨论了具有刚体运动与柔性变形的机械系统的动力学建模,将刚体自由度与弹性变形自由度看作广义坐标,利用有限元法对具有刚性运动与弹性变形的机械系统的运动与变形进行了描述,得到了以刚体位移与弹性变形位移表示的单元的广义惯性力;从应力应变入手,得到了表示单元弹性变形与几何非线性变形的结构刚度矩阵与几何非线性刚度矩阵,使用Kane方程推导了弹性连杆机构的单元运动方程,这种建模方法,可以使用在任意结构的机械系统。 相似文献
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When performing modal analyses of active flexible multibody systems, both controller effects and flexible body dynamics should be included in a multidisciplinary system model. This paper deals with the theory of solving the closed-loop eigenvalue problem for active flexible multibody systems with multiple-input multiple-output proportional-integral-derivative (PID) type feedback controllers and multiple degrees of freedom finite element models. Modal analyses are performed on both a simple and complex active flexible multibody system in order to illustrate the difference between current modal analysis method for such systems and the proposed theory derived in this paper. 相似文献
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航天相机结构复杂,相应的有限元模型大,计算机分析效率低,甚至无法求解.为缩减模型自由度,提高计算机求解效率和能力.采用超单元技术划分相机有限元模型,利用部件模态综合法降低系统阶数;着重研究超单元在MSC.Patran中创建时和在MSC.Natran中分析时所遇到的各种关键问题,分析错误产生的原因,提出相应的解决措施;并通过一大型算例验证了超单元模理的准确性.分析结果表明:超单元法与整体有限元分析法比较,求解的前10阶固有频率误差小于4%,而计算时间仅为原来的1/2.超单元法很大程度上缩减模型自由度,提高计算机解算能力,节省计算时间. 相似文献
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Cai X.Zhao M.Zheng Y.Zhang G. 《传感技术学报》2014,(11):1451-1456
In a micro-nano force measurement system based on the principle of static electric field, the mechanism used for force transmission and transformation plays a vital role. The parallelogram flexible hinge mechanism is used as elastic element, in order to realize the measurement of force on the scale of 10-6 N. The mathematical model of the flexible hinge is analyzed to study the static and dynamic stiffness. The theory stiffness is determined according to the system requirement. The finite element method is used for the optimization design and modal analysis. The influence to the hinge stiffness of the machining accuracy is analyzed. The stiffness test and force value measurement results are given by experiments. Results show that the parallelogram flexible hinge can be used in the force measurement system on the scale of 10-6 N. ©, 2014, The Editorial Office of Chinese Journal of Sensors and Actuators. All right reserved. 相似文献
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The use of a multibody methodology to describe the large motion of complex systems that experience structural deformations enables to represent the complete system motion, the relative kinematics between the components involved, the deformation of the structural members and the inertia coupling between the large rigid body motion and the system elastodynamics. In this work, the flexible multibody dynamics formulations of complex models are extended to include elastic components made of composite materials, which may be laminated and anisotropic. The deformation of any structural member must be elastic and linear, when described in a coordinate frame fixed to one or more material points of its domain, regardless of the complexity of its geometry. To achieve the proposed flexible multibody formulation, a finite element model for each flexible body is used. For the beam composite material elements, the sections properties are found using an asymptotic procedure that involves a two-dimensional finite element analysis of their cross-section. The equations of motion of the flexible multibody system are solved using an augmented Lagrangian formulation and the accelerations and velocities are integrated in time using a multi-step multi-order integration algorithm based on the Gear method. 相似文献