Stability Analysis Of Crawler Crane Boom

With the development of the construction engineering, crawler crane is widely used. Boom is the important sustain structure. It tends to be larger, taller, of truss-style, and more flexible. It is the extensive use of high-strength steel to improve the structural strength, which makes the rigidity and stability problems more and more obvious. In addition, the complex truss structure is applied to the crawler crane. The stability of the light boom and jib combination are becoming the difficulty in the calculation of boom design. It is difficult to determine the design parameters and calculate the stability under various operating conditions swiftly with the help of existing software.Currently, the design of the boom is mostly complied with the foreign data and makes used of the formula for the stability of the specification checking. The formula, however, can not calculate the stability of light boom. If using the equivalent slenderness ratio in the existing specification, the geometric relationship of the combined boom will cause big changes. It is difficult to conduct the calculation of an overall stability and understand the nonlinear effects of the combined arm-depth.In response to above problems, the structural characteristics of crawler cranes lattice boom was fully analyzed. By exploring of the equivalent inertia moment of truss structure as well as ladder beam cross-section and ladder beam nonlinear effects, the stability of boom can be achieved. The main research work and study of the paper are as follows:(1) Through analyzing the working principle of crawler crane boom, structural features and the load situation, along with understanding the identification of current design parameters and stability calculation of arm problems, the need of feasibility and stability analysis of boom could be determined.(2) Understanding of the existing truss structure and studying the completeness of its approach, formula of simplified structure was proposed to consider shearing. The simplification precision was improved, when the structure was with small slenderness ratio.(3) As light boom is simplified a stepped beam, respectively through differential, energy and finite element method, the stepped beams were analyzed. Equivalent formula for the universal ladder beam was derived of. Then contrasting the theoretical analysis and ANSYS analysis results, a three-step beam equivalent inertia moment was received. It could provide a reference for the calculation of stability for light arms.(4) Considering the bending effect of boom, non-linear stability analysis of simply-supported and cantilever-supported boom are carried out. There were uniformly distributed transverse load and axial force at the same time. Such as non-linear effects of equal cross-section beams and variable beam, every case-response curves were given. Respectively, theoretical curves and the ANSYS curves were compared. Evaluation criteria were proposed. And critical load curve under different conditions could be obtained. The stability of single boom can be achieved.(5) The overall stability of the combined booms (sub-arm condition), in which side load was included during the calculation. Torsion effect of the main arm was considered to carry out the truss structure equivalent of the torsion inertia moment. Final, ANSYS was applied to calculate the stability of the combined arm.