2004, 2(2):1-6.
Abstract:This paper first gives a brief review about the three phases of the research of flexible multi-body system dynamics.Then in order to solve the deficiency in the traditional zero-order approach coupling model,a new modeling theory is proposed,and the discretizing method and experiment about "dynamics stiffening" problem and rigid-flexible coupling dynamics problem are investigated based on the new one-order approach coupling model.A set of experiment platform used for the theoretical study and the discovery of dynamic phenomenon is designed and built.Some research results are introduced.Some research targets are given at the end of this paper.
Yao Wenli , Chen Bin , Liu Caishan
2004, 2(2):7-10.
Abstract:This paper studied the solution of impulsive dynamics of multi-rigid-body,systems with friction.By introducing a new dimensional time parameter,the first-order momentum-impulse differential equations were obtained,and the discussion over infinitesimal impulsive interval was transformed into a piece-wise study on the finite region of impulse,so the solution of impulsive dynamics of spatial discrete system with friction was obtained,i,e.,the dynamic response after the impact can be obtained according to the initial conditions before the impact.
2004, 2(2):11-14.
Abstract:First we formulated a set of integral-partial differential governing equations,which describes the non-linear non-planar oscillations of a cantilever beam.Then by applying the Galerkin procedure and the multi-scale method,we obtained the averaged equations;From the partial differential governing equations and from the averaged equation and by using the theory of normal form,we found the explicit formulas of normal form.Based on the normal form obtained above,the dissipative version of the energy-phrase method was utilized to analyze the multi-pulse Shilnikov type orbits.The numerical simulations shows that the multi-pulse Shlnikov type orbits do exist in the nonlinear nonplanar oscillations of the cantilever beam.
Zhang Yunqing , Zhou Fanli , Wang Bo , Chen Liping
2004, 2(2):15-22.
Abstract:Based on the object-oriented technology,the model elements of a complicated mechanical system were analyzed according to their characteristics,and their class architecture in dynamic modelling platform to support dynamics simulation was presented.The two key technologies in the platform,i.e.managememt of relationship and subsystem modelling,were discussed.A simulation and modelling platform-InteDyn was developed using the above two technologies,and a car suspension and a full car models were built by the InteDyn,which validated the effectiveness and feasibility of the technologies.
2004, 2(2):23-28.
Abstract:In the course of spsce docking,the process from the first contact to finishing the capture and buffering after the capture are the research focus of docking dynamics,and establishing the dynamical model and simulation is an effective way for the research.In this paper,in accordance with the docking mechanism of androgynous and peripheral type with inner guide petals,and based on the mechanism physical model,the dynamical models in docking capture process and buffering process were built,and some user-defined modules were developed using the interface of the famous software named DADS,which can accomplish the simulation of docking procedure.
2004, 2(2):29-33.
Abstract:Dynamical modeling and control of a satellite with two antennae tracking big angles were studied by an three-rigid-body model with seven degrees.Through defining several new tensors and based on the assumption that the antennae track objects slowly,the vector dynamical equations were derived by Newton-Eular Method,and the corresponding scalar equations were obtained.The coupling effect between the two antennae was designed,and the control methods were discussed.Several numerical simulations show that the controller is successful.
He Bin , Rui Xiaoting , Lu Yuqi , Yu Hailong
2004, 2(2):34-37.
Abstract:Based on the dynamics equation of shipboard gun component,by using the numerical integral method and expanding the transfer matrix method of vibration mechanics,this paper established b blocking method for launching dynamics of shipboard gun,which was named the discrete time transfer matrix method for launching dynamics of shipboard gun.The method can simulate the dynamic responses of the multibody system of shipboard gun and the simulation results validated the method.
Yu Wei , Yang Lei , Qu Guangji
2004, 2(2):38-42.
Abstract:This paper studied the internal-petal androgynous peripheral attachment system (APAS),its differential electro-mechanical attenuation mechanism,and the dynamics properties of the docking mechanism.The docking mechanism virtual prototyping model was establlished by using Automatic Dynamic Analysis of Mechanical Systems (ADAMS).According to the simulation,the characteristics of the mechanism's equivalent stiffness and damping were obtained.These findings have been essential in ensuring a successful mission.
Zhang Juncui , Hou Shujun , Zhang Xinju , Qin Zhiying , Peng Wei
2004, 2(2):43-47.
Abstract:This paper investigated the coupling dynamics between the rigid-bodies and the bulk solids bed in the vibratory crusher.First the relationship of the bulk solids bed during pressing and releasing was studied by the specially designed experiments.Then the governing equations of the crusher were derived according to the Lagrange's method,and its dynamical performance was investigated by solving these equations by Runge-Kutta Method,so the effect of the bulk solids bed on the trajectory of the four moving jaws was explored.Finally some dynamical experiments were carried out,which agreed well with the numerical nanlysis.Therefore all of the work provides a basis for the dynamics design and development of the new vibratory crushers.
2004, 2(2):48-52.
Abstract:This paper introduces the development of dynamics of space mechanisms for aerospace,and discusses the important senses to study nonlinear clearance models for both designing the structures of new spacecrafts and analyzing the performances of spacecrafts on orbit.Some key problems to be solved are proposed,which include the dynamic modeling and analyzing of space mechanisms with clearances,the movement stability analysis of the mechanisms,the simulation software for realizing the global simulations of performances of the mechanisms.
Ge Xinsheng , Chen Liqun , Liu Yanzhu
2004, 2(2):53-57.
Abstract:This paper investigated the nonholonomic motion planning of the underactrated spacecraft.The attitude motion of a rigid spacecraft can be controlled by using three momentum wheels.If one of the momentum wheels fails, the complete spacecraft equations are not controllable.If the total angular momentum of the system is zero,the control problem of the spacecraft attitude becomes a steering problem for a drift free control system.Based on the optimal control theory,a genetic algorithm for steering a rigid spacecraft with two momentum wheels was proposed,and the numerical simulation proved the genetic algorithm to be effective.
2004, 2(2):58-61.
Abstract:First by using the first kind of Lagrange's equations,this paper presented the dynamical equations of multibody system with friction constraints,and the generalized forces of friction forces were described in the matrix form.Then by using the Baumgarte's method and the augmentation approach,the differential-algebraic equations were converted into the matrix form of differential equation,which can improve the calculating efficiency.Finally the numerical results proved the method to be effective.
2004, 2(2):62-65.
Abstract:Based on the adjoint simplectic subspace iteration method of gyroscopic system,a modal synthetic method of a large gyroscopic system(MSMGS) was proposed.This method divided the large gyroscopic system into several subsystems,and obtaned the first modals of the subsystems via the adjoint simplectic subspace iteration method.The whole transition matrix can be composed of the eigenvector matrices of all the subsystems,and the reduced gyroscopic system can be given through the whole transition matrix.The examples prove that the whole gyroscopic system can be approximated by the reduced gyroscopic system.
Pan Zhenkuan , Ding Jieyu , Wang Yu
2004, 2(2):66-69.
Abstract:The direct defferentiation method and adjoint variable method for dynamics of multibody systems were presented,based on the generic formulation of implicit defferential/algebraic equations with implicit initial conditions and generic end time conditions.The computation of the objective functions and their derivatives ware another contributions of this paper,which transformed the integral type of objective functions to integration ones in order to improve computational efficiency.Finally the method was verified by a numerical example of a planar manipulator with two links.
He Baiyan , Wang Shuxin , Zhang Ying
2004, 2(2):70-73.
Abstract:Joint clearance exists in mechanical multibody systems,which affects the constraint conditions,the degree of freedoms,and the topological structures of the mechanical system.Based on the Hertz's contact law and the Coulomb's friction law,a mechanical model of the planar revolute joint with clearance was built.A two-beam mechanical arm with one rigid beam and one flexible beam was studied,and the elastic distortion of the flexible beam was described by the geometrical deformation constraint method and the modal condensation method.By using the Kane's equation,a complete dynamic model of the mechanical arm,which considered two planer revolute joints with clearance,was built,and the model was more realistic and precise compared to the conventional one.
Feng Zhihua , Rui Yannian , Zhu Xiaodong , Lan Xiangjun , Zhang Wei
2004, 2(2):74-79.
Abstract:A dynamic modeling of an axially narrow-band oscillating cantilever beam was presented.The motion equations for the axially oscillating cantilever beam were derived by using the Kane's equation combining with Rayleigh-Ritz method.The method of multiple scales was used to solve directly the nonlinear differential equations and to derive the nonlinear modulation equation for the principal parametric resonance.The largest Lyapunov exponent was numerically obtained to determine the almost sure stability or instability of the trivial response of the system,and the validity of the stability was verified by direct numerical integration of the equantion.
Jiang Feng , Feng Qi , Wang Yu
2004, 2(2):80-83.
Abstract:In order to overcome some shortcomings of the former analysis methods,this paper proposed a new method to analyse warships' vital force,which regarded the problem of warships' vital force evaluation as the classification problem.The technique of Support Vector Machine was applied in this method,and the calculation model predicting the vital force of the impacted warships was established.As an illustrative instance,the vital force of a warship's subsystem was calculated,which showed that the method was highly efficient and it could be applied extensively.
Yao Yu , Wu Hongtao , Zhang Zaoming
2004, 2(2):84-87.
Abstract:This paper analyzed the natural frequencies for the Stewart transducer based on the Kane's method.In this method,the upper platform,the upper leg,the elastic element and the lower leg of the Stewart transducer were treated as independent substructure,and the equations of kinematics and dynamics were derived systematically according to the theory of the vector and the tensor.Moreover the equations of the natural frequencies for the Stewart transducer were obtained by simplifying the equations of kinematics and dynamics.In order to testify the validation of the Kane's method,a numerical simulation was proposed in mathematica routines.Compared with the traditional Newton-Euler method and the Lagranged method,the Kane's method is explicit and efficient,and especially suitable for calculating with computer.
2004, 2(2):88-91.
Abstract:This paper studied the nonlinear properties of a two stage isolation system with rigid limiters.A discrete model was derived based on the multi-body dynamics with unilateral contacts,and an approximate map was obtained after using the perturbation techniques.By using the above methods,we investigated how the two stage isolation system of a MTU diesel engine responded to external impact.The investigation shows that the system presents complicated nonlinear properties due to impact,and the weak nonlinear part,which could be omitted under no limiters case,may influence the property of the vibroimpact system greatly.Thus the conclusions offers a theoretical reference for designers.
Chang Zongyu , Ding Shoubin , S. Frimpong
2004, 2(2):92-95.
Abstract:The shovel-truck mining system is widely used in surface mining operations for material excavation and haulage.The impact force due to the load under gravity causes huge vibrations,wear and tear of the dump truck,which is ervere for the first load.This paper built an integrated dynamic model including impact model,truck model and human vibration model.Numerical method was applied to solve the differential equation.