Dynamic Analysis Of The Crane Boom System Based On The Rigid-flexible Coupled Model

The double link jib system of mobile port crane is one of the most complex beam-bar systems,which play an important role in all kinds of engineering machineries.Nowadays,to meet the requirements of modern construction,mechanical equipment are designed to be more enormous and light-weighted while its moving and controlling to be more precisely and immediately.For large flexible beams,the traditional analysis methods of statics,vibration and multibody dynamics are no longer feasible to meet precise motion and timely control.This paper adopts finite segments methods and equivalent element integrate methods to build the dynamical equations of rigid-flexible coupled crane system,and then analyzes the dynamic characteristic of luffing process.On the basis of the existing finite segments model,this paper proposes a new discrete model which concentrate flexibility on the middle of the unit.The finite segments and the flexible hinge coupling models of the flexible cantilever are analyzed by static analysis,and the deformation of the models under different discrete methods are compared.The torsional stiffness of the flexible hinge is determined by the same angle of the free end before discrete or not,and then the relationship between the lateral displacement and the number of segments is deduced.The correctness and superiority of the new finite segments model are verified in ADAMS software.This paper focus on the method of establishing the dynamic equation of finite segments model.The flexible beam is discretized based on the equivalent finite segment integration method,and the dynamic equations of the segment unit and finite segments model of flexible beam are established.Taking the discretized cantilever beam as an example,the modal analysis is carried out on the finite segments model which the mass and inertia are concentrated in the middle of the unit and concentrated at both ends of the unit.Taking the multi-degree-of-freedom crank-slider mechanism with elastic restraint as an example,the dynamic equation of the rigid-flexible coupling system is established,and the dynamic response of the mechanism is obtained by numerical solution.At the same time,this paper research the traditional method to establish the dynamic equations of the finite segments model by using the Houston low-order continuum array and the Kane equation.The method is used to analyze the modes of the discrete cantilever beam with the flexibility concentrated to the center of the units.The rigid-flexible coupling model of crank-slider mechanism is established in ADAMS software,and the difference of various flexible beam modeling methods is compared.Based on the above theory and analysis method,the rigid-flexible coupling dynamics model of the boom system of crane is studied,and the dynamic characteristics of the luffing process are analyzed,which provide the theoretical guidance for the structural design of the crane.