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In this work, some new results are presented on the dynamics of a class of multibody mechanical systems, involving contact and friction. The main contribution refers to the development of a systematic, accurate and efficient method for detecting contact among the components of a system of solid bodies. For some simple geometries, this task is achieved by employing analytical means. For systems possessing components with complex geometric shapes a more involved numerical methodology is developed. In both cases, once a potential contact point is detected, the common tangent plane and normal vector are located and the penetration depth is calculated, leading to determination of the force arising between the contacting bodies. This information is then passed to a solver, providing the full dynamic response of the system. The validity and numerical efficiency of the methodology developed is first demonstrated by considering a number of examples with relatively small geometric complexity but large traditional value and interesting dynamic response. Some new results are obtained and presented on the dynamics of these systems. Finally, the same methodology is also tested in a more complicated and demanding mechanical application. 相似文献
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In this paper, the impact between a rigid pendulum and rough surfaces is studied. The rolling friction moment and the coefficient
of rolling friction are introduced, and an improved mathematical model of the planar impact with friction is presented. The
influence of the moment of rolling friction on the energy dissipated by friction during the impact is analyzed. For a simple
pendulum, using the energetic coefficient of restitution, more energy is dissipated for larger values of the coefficient of
kinetic friction and contact radius, and for smaller values of the length of the beam. For a double pendulum using the kinematic
coefficient of restitution, some energetically inconsistent results can be solved for some values of the coefficient of rolling
friction. 相似文献
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In this investigation, a modeling procedure of a telescopic boom of cranes is developed using the absolute nodal coordinate formulation together with the sliding joint constraints. Since telescopic booms are extracted and retracted under various operating conditions, the overall length of the boom changes dynamically, leading to the time-variant vibration characteristics. For modeling the telescopic structure of booms, a special care needs to be exercised since the location of the sliding contact point moves along the deformable axis of the flexible boom and the solution to a moving boundary problem is required. This issue indeed makes the modeling of the telescopic boom difficult, despite the significant needs for the analysis. It is, therefore, the objective of this investigation to develop a modeling procedure for the flexible telescopic boom by considering the sliding contact condition with the dynamic frictional effect. To this end, the sliding joint constraint developed for the absolute nodal coordinate formulation is employed for describing relative sliding motion between flexible booms, while flexible booms are modeled using the beam element of the absolute nodal coordinate formulation, which allows for modeling the large rotation and deformation of the structure. 相似文献
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结合面静摩擦因数分形模型的建立与仿真 总被引:8,自引:2,他引:6
提出一个确定分形维数和分形粗糙度参数(G')的分形函数,并用分形函数逼近结合面的表面粗糙度.根据分形理论和改进后的尺寸分布,推导了静摩擦因数f的解析解.数字仿真结果表明,f随量纲为一的总法向载荷(P')增加而增加.当D较小或较大时,f与(P')之间存在不同的微凸和微凹弧非线性关系,D=1.2时f与(P')的关系基本上是线性的;当D较小时,f随D增加而增加;当D较大时,f随D增加而减小;f随分形粗糙度参数(G')增加而减小,随相关系数K增加而增加,随材料特性(φ)增加而增加. 相似文献
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蒋炜 《应用数学和力学(英文版)》1980,1(3):413-429
Using elements in the form of arbitrary sectors, the author has devised a plan for solving plane problems of elasticity by the force method. The method is characterized by a smaller number of nodes, a more convenient computation and a perfect adaptability to the particular shape of the region in question. 相似文献
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规划-迭代型弹塑性摩擦接触多极边界元法 总被引:3,自引:2,他引:3
提出基于多极展开法的规划-迭代型的高度非线性方程的IGMRES(m)高效求解法,并建立其收敛性理论。本法适用于三维弹塑性摩擦接触多极边界元法,有效处理弹塑性摩擦接触迭代的繁杂和费时问题。数值试验证明,本求解法在确保数值精度的前提下,可减少迭代次数,显著提高计算效率。 相似文献
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采用自制静电传感器进行润滑条件下轴承钢点接触滑动摩擦胶合故障在线监测试验研究.首先分析了磨损过程静电产生机理和静电感应原理,在此基础上设计研制了磨损区域静电传感器并进行轴承钢胶合故障试验,研究了磨损区域静电信号去噪方法,分析了载荷和转速对摩擦系数和静电信号的影响.研究结果表明:奇异值差分谱理论适用于静电信号去噪,取得了较好的效果;静电信号与摩擦系数同时监测到胶合的发生,具有一致性,并且静电在线监测技术能够在胶合故障发生前监测到异常,为视情维修提供支持;静电信号反映了4个阶段(磨合磨损,稳定磨损,早期胶合以及胶合阶段);在稳定磨损阶段,摩擦系数随载荷的增大而降低,随转速的升高而降低,静电信号均方根值随载荷的变化很小,随转速的升高而增大. 相似文献
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基于开放式工程与科学计算集成化软件平台SiPESC,研发了用于多体系统动力学时程分析的一类通用求解算法构架。该构架的核心思想是算法与数据相分离,整个构架由五个基本类及子类组成。本文重点阐述基本类的抽象过程,利用插件技术设计求解器的构架,进一步应用该构架实现了Newmark方法,HHT(Hilber-Hughes-Taylor)方法,Generalized α方法,Bathe方法及祖冲之类Symplectic方法等微分-代数方程组(DAEs)求解器的开发。研究工作表明,本文所提出的DAEs求解算法构架对多体系统动力学的时程分析具有良好的开放性和通用性,可方便进行各种新的DAEs求解算法的动态扩展。 相似文献
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In this paper, we present a strong-form framework for solving the boundary value problems with geometric nonlinearity, in which an incremental theory is developed for the problem based on the Newton-Raphson scheme. Conventionally, the finite element methods (FEMs) or weak-form based meshfree methods have often been adopted to solve geometric nonlinear problems. However, issues, such as the mesh dependency, the numerical integration, and the boundary imposition, make these approaches computationally inefficient. Recently, strong-form collocation methods have been called on to solve the boundary value problems. The feasibility of the collocation method with the nodal discretization such as the radial basis collocation method (RBCM) motivates the present study. Due to the limited application to the nonlinear analysis in a strong form, we formulate the equation of equilibrium, along with the boundary conditions, in an incremental-iterative sense using the RBCM. The efficacy of the proposed framework is numerically demonstrated with the solution of two benchmark problems involving the geometric nonlinearity. Compared with the conventional weak-form formulation, the proposed framework is advantageous as no quadrature rule is needed in constructing the governing equation, and no mesh limitation exists with the deformed geometry in the incremental-iterative process. 相似文献
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研究求解微分-代数方程组(DAEs)的高效率、高精度和高稳定性数值积分方法一直是多体系统动力学领域的热点问题之一。本文将求解结构动力学方程的Bathe数值积分策略应用于DAEs的求解,并基于SiPESC平台开发了开放式多体系统动力学仿真算法软件,综合比较研究了Newmark法、HHT-I3法、Generalizedα方法、Bathe方法和祖冲之类Symplectic方法。通过复摆、刚-柔耦合双摆和对称陀螺三个数值算例研究了算法参数与数值阻尼的关系。数值实验表明,Newmark方法在特定参数下引入的数值阻尼通常不可控,HHT-I3方法、Generalizedα方法和Bathe方法通过选择特定步长和参数可引入可控的数值阻尼,祖冲之类Symplectic方法无数值阻尼。在求解真实高频和低频耦合问题以及高速旋转的陀螺问题时,采用祖冲之类Symplectic方法或者无耗散的Newmar方法能够对系统的高频成分进行准确模拟。 相似文献
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讨论的是一般运动刚体在含有滑动摩擦的情况下的两体碰撞.首先根据欧勒动力
学方程和质心运动定理导出了在碰撞的两个阶段二碰撞点沿公法线和公切线的相对速度的变
化量, 其次利用动量定理导出了系统动能的损失与二碰撞点速度的关系, 最后根据这两个结
论导出了系统动能损失的计算公式, 并给出所得结论成立的条件. 相似文献
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Keh-Ming Shyue 《Shock Waves》2006,15(6):407-423
The aim of this paper is to describe a simple Eulerian interface-capturing approach for the efficient numerical resolution of a hybrid barotropic and non-barotropic two-fluid flow problem in more than one space dimension. We use the compressible Euler equations as a model system with the thermodynamic property of each of the barotropic and non-barotropic fluid components characterized by the Tait and Noble–Abel equations of state, respectively. The algorithm is based on a volume fraction formulation of the equations together with an extended equation of state that is devised to give an approximate treatment for the mixture of more than one fluid component within a grid cell. A standard high-resolution wave propagation method is employed to solve the proposed two-fluid model with the dimensional-splitting technique incorporated in the method for multidimensional problems. Several numerical results are presented in one and two space dimensions that show the feasibility of the algorithm as applied to a reasonable class of practical problems without the occurrence of any spurious oscillation in the pressure near the smeared material interfaces. This includes, in particular, solutions for a study on the variation of the jet velocity with the incident shock pressure arising from the collapse of an air cavity in water under a shock wave. 相似文献
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When solving unsteady computational fluid dynamics problems in aerodynamics with a gridless method, a cloud of points is usually required to be regenerated due to its accommodation to moving boundaries. In order to handle this problem conveniently, a fast dynamic cloud method based on Delaunay graph mapping strategy is proposed in this paper. A dynamic cloud method makes use of algebraic mapping principles and therefore points can be accurately redistributed in the flow field without any iteration. In this way, the structure of the gridless clouds is not necessarily changed so that the clouds regeneration can be avoided successfully. The spatial derivatives of the mathematical modeling of the flow are directly determined by using weighted least‐squares method in each cloud of points, and then numerical fluxes can be obtained. A dual time‐stepping method is further implemented to advance the two‐dimensional Euler equations in arbitrary Lagarangian–Eulerian formulation in time. Finally, unsteady transonic flows over two different oscillating airfoils are simulated with the above method and results obtained are in good agreement with the experimental data. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Abstract The stability and boundedness of mechanical system have been one of important research topics. In this paper ultimate boundedness of a dry friction oscillator, belonging to nonsmooth mechanical system, is investigated by proposing a controller design method. Firstly a sufficient condition of the stability for the nominal system with delayed state feedback is derived by constructing a Lyapunov-Krasovskii function. The delayed feedback gain matrix is calculated by applying linear matrix inequality method. Secondly on the basis of the delayed state feedback, a continuous function is designed by Lyapunov redesign to ensure that the solutions of the friction oscillator system are ultimately bounded under the overall control. Moreover, the ultimate bound can be adjusted in practice by choosing appropriate parameter. Accordingly friction-induced vibration or instability can be controlled effectively. Numerical results show that the pro- posed method is valid. 相似文献