Double Nonlinear Stability Analysis For Combined Boom Of Crawler Crane

With the development of society,crawler crane plays a significant role in all kinds of engineering areas due to its own advantages.The improvement in technology and the request in practical engineering enables the capability of crane to improve increasingly.The length of boom also increases more and more.Especially for the combination boom with large main boom and luffing boom,its geometrical nonlinearity and material nonlinearity are obvious absolutely.The instability of structure usually has convert and abrupt traits,which brings irreparable and enormous damage.Therefore it is necessary and urgent to research on the stability of the combination boom.Based on predecessors' experiences about structure stability,geometrical nonlinearity,material nonlinearity and double nonlinearity,the finite element analysis method of double nonlinearity stability is described in this paper,including the calculating of iteration and the deducing of tangential stiffness matrix.And then the actual operation of double nonlinearity stability calculation on finite element software ANSYS is further described,including rational models are built,double nonlinearity parameters are set and convergent results are discussed.The combination boom of 750 t crawler crane is viewed as object of study in this paper,based on actual parameter,the double nonlinear finite element models with different length of boom and different working radius are set up.The research was done in this paper:Firstly,the structure composition and working principle of the combined boom are deeply understood,the modeling method of the connection of each part is studied,the suitable element is selected to simulate the actual boom and the connection between the main boom and luffing boom,and the key problems in the assembly of the main boom,luffing boom and staypoles by the APDL command flow are studied.Secondly,the theory of double nonlinearity and the implementation method in ANSYS are described,including reference load setting,defect handling method,nonlinear curve determination,easy convergence method and so on.Then the trend of load-displacement curve of the combined boom and the influence of the combination of different arm length on the overall stability are analyzed.The analysis results show that the lateral displacement has a decisive influence on the overall stability,and the arm length has a greater effect on the stability of combined boom than the main arm.This has a good guiding effect on the actual design of the combined boom.