| All terrain cranes have gotten rapid development for the market demands in China since the21st century. Super-lift device is an important component of all terrain cranes, and it refers to the set of two box braces on the basic arm. The box braces which connect the main boom arm from the head by guy-rope and connect the main boom arm from the tail by pull-plate, tow the crane boom to reduce the deflection of it, to improve the state of the main arm of the force, improving the bearing capacity.At present, in most of the domestic super-lift technology researches, the guy-rope is simplified into rod or flexible cable and the pull-plate is simplified into rod. The guy-rope and pull-plate are always in a state of tension. But in the actual application process, they may produce relaxation, which is an important factor affecting the ability of super-lift devices to play. After retrieval, we have not yet found its research, so the design and application of super-lift device also lack a theoretical basis in this regard.In order to better play the role of super-lift device, in this paper, the effect of relaxation on the performance of super-lift is studied. Main work content is as follows:(1) The main arm system of super-lift device which contains finite element model simplification and nonlinear calculation has been researched. According to the mechanical properties, structure of the composition and performance parameters of the boom system on all terrain cranes, the simplified boom model creation method is established, and the simplified model of rationality is verified. At the same time, the nonlinear factors that influence the geometric nonlinearity of the system have been analyzed, and the nonlinear method for solving the model has been established.(2) The influence of guy-rope and pull-plate relaxation on super-lift performance of all terrain cranes has been studied. This paper gets the amount of relaxation by analyzing the reasons for relaxation of guy-rope and pull-plate. Through the analysis of a flexible cable or tension in the suspension process the equation of state, this paper gives the effect mechanism for super-lift performance from guy-rope and pull-plate relaxation and studies the effect of relaxation on the performance of super-lift of super-lift by drawing the sketch of main boom stress and the boom overall stability. (3) This paper gives the preventive measures to improve the guy-rope and pull-plate relaxation. According to the structural characteristics of guy-rope and pull-plate, the connections and the reasons for the relaxation produced, the corresponding improvement measures has been put forward, and the feasibility of this measures has been verified by examples. |
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