| Combined with advantages of telescopic boom from truck crane and traveling with load feature from crawler crane, telescopic crawler crane is widely applied in cases of limited spaces, uneven pavement and frequent transfers. In the process of traveling with load, random road roughness incentives, inertial force produced by linear acceleration and deceleration, centrifugal force generated by the steering act on the telescopic crawler crane which caused the boom vibration and hoists shimmy will generate impact load. Driving with load is one of the most important working conditions; however, research on the telescopic crawler crane traveling with load is few both at home and abroad. Therefore, the topic select the35t telescopic crawler crane as the research object, using the combined methods of theoretical analysis and dynamic simulation to make research on the impact load generated in the process of the crane moving with load. The main research works of the paper are as follows:(1) The dynamic model of the telescopic crawler crane is established. Make dynamics analysis of the crane traveling with load at maximum speed under different grade of random road excitation with the telescopic boom in three typical postures. Four common grades of road unevenness are built by harmonic superposition methods. Based on the rigid-flexible coupling method, the flexible boom system, flexible steel cable and the rigid model of turntable system are built. The crawler chassis system is simplified, then the road unevenness excitation is acted on the supporting wheels, and the kinetics model is built. Make dynamic simulation for the whole crane, and the driving impact coefficients changing with boom extending state and road grade will be acquired.(2) The nonlinear dynamics model of load shimmy caused by telescopic crawler crane traveling with different acceleration is established. Make dynamics analysis for different acceleration conditions and different length of strings. The load shimmy system model is simplified based on the characteristics of crane traveling with load. The nonlinear dynamic equation of load shimmy system is built based on the second class of Lagrange method. The impact coefficients of both inertial force and tangential inertial force are acquired through numerical solutions.(3) The dynamic model of the telescopic crawler crane steering with load is built. Then make dynamic analysis for crane steering with load at different radius or variable steering accelerations with the telescopic boom in three typical extending conditions. The steering angular velocity and turning radius are acquired through numerical solution based on the force balance and torque balance theory during the process of steering at equal speed. At this foundation the crawler chassis is simplified, and then the dynamic model of the crane steering with load is built. Make dynamic analysis for the telescopic crawler crane steering with load, and the impact coefficients of both inertial force and tangential inertial force which generated at different accelerations and turning radius are acquiredThrough the research on the35t telescopic crawler crane traveling with load, the impact coefficients of the corresponding traveling state are acquired. The analysis method will give reference to the research on impact coefficients of this type of crane. And the analysis results will provide a theoretical basis for choosing the corresponding impact factors when design this type of crane. |
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