Research On Geometric Nonlinear Stability Of Reinforced Boom Of Crawler Crane

The reinforced boom of super large crawler crane is a kind of integral slender structure strengthened by local section,which plays an important role in lifting operation.Because of the flexible combination of the boom,the variety of the lifting range and the large lifting capacity,it is widely used in the field of Engineering lifting.Among them,the multi variable diameter combined boom is a kind of combination form of boom in Zoomlion.As a kind of reinforced boom,the maximum lifting height of this combination of boom can reach 180 m.In the case of lifting heavy objects,the truss boom structure will produce the characteristics of large displacement and small strain,showing obvious geometric nonlinear effect.When the long and thin truss arm structure loses its stability,due to the existence of lateral load,the truss arm structure will have great displacement deformation,which will cause great strength damage to the main arm.Therefore,the influence of this geometric nonlinearity on the deformation of the truss arm structure cannot be ignored.Based on the co rotating coordinate method and the substructure method,this paper establishes the arm element model.In order to avoid that the self weight of the boom can not participate in the cohesion of degrees of freedom,it is necessary to introduce the gravity influence coefficient matrix when establishing the boom element,to separate the self weight of the truss boom to each node,and to establish a local coordinate system that can move.The traditional path tracking problem can be transformed into solving differential equation by derivation of nonlinear equation,and the tangent stiffness matrix can be derived from the node force balance equation,which can improve the speed of fast path tracking and the accuracy of judging the unstable load.Based on the above theory,the critical buckling load of truss arm structure is solved by MATLAB.The load displacement curve of 96 m conventional boom is analyzed,and the influence on the overall stability performance of the conventional boom is analyzed from two aspects of changing the lifting amplitude and the partial load coefficient.Taking 96 m reinforced boom as an example,the load displacement curve of the reinforced boom with different partial load coefficient and the displacement deformation in the variable amplitude plane and the rotation plane are analyzed.Finally,the influence of the change of lifting amplitude and the analysis of different partial load coefficient on the overall stability of the strengthened truss arm is studied.Thelifting performance of the reinforced main boom is compared with that of the conventional main boom,and the lifting ratio of the reinforced main boom to the conventional main boom is analyzed.