Research On Coupling Of Considering Foundation Deformation And Crawler Crane Structure

Boom structures of large crawler crane have the characteristics of flexibility,heavy load,and slenderness.When subjected to side disturbance,it will show strong geometric nonlinear behavior and have large lateral displacement in the side direction of the boom.During crane's lifting load and slewing motion,the load will have pendulum motion in the horizontal plane due to its inertia and wind load.It will cause the boom to have side deformation and the two crawler tracks to have uneven contact pressure with the ground This will further cause uneven ground deformation in the slewing direction.The motion of the whole crane and side deformation of the boom will compound with the load's motion.This effect will be worsened by the deformation of the superstructure,undercarriage and the track frames.The whole system will reach steady state until the foundation reaction and contact pressure are in equilibrium.During the process,if the structure strength or the whole crane's stability can't satisfy the safety operation requirement,crane failure will happen.Therefore,it is necessary to obtain the data of foundation inclination and stiffness before construction work,and it is important to consider the influence of foundation inclination and deformation on the strength of the crane boom and the stability of the crane when designing crawler cranes.It is of great theoretical value and engineering practical significance to improve the design quality of large crawler cranes and ensure their safe operation.This is also a current challenge in the design and use of crawler cranes.This paper conducts research in the following issues.A QUY400 crawler crane is used as a demonstration object to verify the theory.(1)In order to obtain the total lateral stiffness of the crawler crane that considering the foundation subsidence and the deformation of the track frame and undercarriage,the Euler-Bernoulli beam on the Winkler foundation model is derived and used to model the interaction between the elastic foundation and the track frame.The method of selecting the rigidity and paving method of the subgrade box is given for the soft elastic foundation with less stiffness,which provides an important reference for the correction of the rated load and the foundation treatment before the construction operation.(2)The calculation process of critical stress and boom head displacement under the nonlinear coupling of the elastic foundation is established.The crawler crane structure has considered the coupled effect of the gravity and axial force of the boom,the elastic deformation of the foundation,and the torsion angle of the top section of the main boom.The calculation method is verified by the scaled down test-rig experiment.And the method which has higher solution efficiency simplifies the modeling steps and makes the programming be able to implement.(3)The rigid-flexible multi-body dynamics model of the elastic foundation and the crawler crane is established by considering the lateral displacement of the load in the slewing condition which will cause the lateral disturbance of the boom system.By analyzing slewing acceleration,slewing speed,hoisting height,and foundation stiffness,it is concluded that the foundation stiffness and the slewing speed have the greatest influence on the strength of the boom and the lateral stability of the crawler crane.And the maximum slewing speed allowed by different foundation conditions is given,which provides an important reference for the safe operation of the crawler crane.(4)An efficient and convenient method for instantaneously obtaining the ground tilting angle and foundation stiffness is designed by analyzing the change of the tilting angle of the superstructure during the slewing process.The longitudinal tilting angle of the superstructure is collected by adjusting the boom to the minimum amplitude and slewing counterclockwise one turn before the construction operation.And the PLC uses the pre-stored data and the algorithm to obtain the ground tilting angle,the foundation stiffness,the rated load and the allowed slewing speed of the crawler crane,so that the crawler crane has a certain intelligence in determining its own lifting capacities.