【摘要】 对四类间隙铰模型(连续接触模型、有限元模型、经典碰撞模型和接触变形模型)进行分析比较,给出了经典碰撞和接触变形模式的含间隙多体系统动力学模型。经典碰撞模式的动力学模型着重考察系统动力学的整体行为,不能预测碰撞过程中铰关节局部接触力的变化历程。接触变形模式的多体系统动力学模型考虑了碰撞体间的法向和切向接触力,以及阻力矩,能够求解系统运动过程中间隙铰轴销与孔体的碰撞力。采用间隙铰的非线性弹簧阻尼模型,研究了重力场及其方向性对空间可展机构动力学性能的影响。计算结果表明,无重力与有重力环境时含间隙可展机构动力学行为有较大地差别,重力作用使间隙铰内碰撞减弱。为了保证在地面试验中可靠地预测在太空展开性能,可展机构在地面试验时应采取重力补偿措施。更多还原

【Abstract】 Four different modeling approaches of clearance joints such as the continuous contact method, the finite element method, the classic impact method and the localized contact-deformation method, are discussed. The last two methods are used to model contact-impact events of clearance joints in the multibody systems in this paper. Momentum equations of the systems are employed to solve the jump discontinuity in velocity of generalized coordinates for the classic impact method, but the model can not be used to simulate impact forces of the clearance joints. In the localized contact-deformation method, a virtual spring connecting the two contact points is assumed, considering normal and tangential contact forces, as well as reaction torques between two contact bodies, and the formulations of multibody systems with clearance joints are obtained, which can be used to forecast contact forces of the elements of the clearance joint during contact-impact. Influence of the gravity on dynamic behaviors of a deployable structure with clearance joints are simulated by using the localized contact-deformation method. Simulation results show that the dynamic behaviors of the structure in 0-g environment are more different than the one in the 1-g environment, and the effects of the gravity to the clearance joint make the inner-impacts of the two elements of the joint decrease. To obtain reliable prediction from ground tests for the deployment behavior in space, a gravity compensation method must be applied to space structures during tests on earth.更多还原