Abstract
Mechanical brakes are essential for electric cranes when emergency braking occurs. This paper presents, for the first-time, a dynamic response analysis of emergency braking events of electrical cranes that has modelled crane components as flexible and rigid bodies. Based on the Hamilton principle, a nonlinear and non-smooth dynamic model is derived from a modified Lagrangian function and the virtual work of non-conservative forces. The dynamic responses of a 32-ton overhead travelling crane during the emergency braking process of its lifting mechanism with two service brakes determined by simulating realistic operations. The numerical results show that the loads acting on components of the crane during the braking process depend on the braking capacity and the action time of the mechanical brakes, as well as the magnitude and the initial position of the payload. When a dual-brake scheme of the lifting mechanism is adopted, the maximum load of the high-speed links and the maximum thermal power of the mechanical brake appear in the emergency braking process when one of the two brakes fails to work. In addition, it is found to be a false belief that the lower the initial speed, the lower the maximum loads acting on components of cranes become during the braking process.
Highlights
Braking is applied frequently during the operation of cranes
Carried out a finite element dynamic analysis of the bridge of an overhead travelling crane while its traversing mechanism was in operation and introduced a kind of finite element subjected to a point load
To understand emergency braking operations, this paper focuses on the dynamic behaviour of
Summary
Braking is applied frequently during the operation of cranes. For electric cranes, there are two kinds of braking, referred to as normal braking and emergency braking respectively in this paper. Carried out a finite element dynamic analysis of the bridge of an overhead travelling crane while its traversing mechanism was in operation and introduced a kind of finite element subjected to a point load. Bouc–Wen model, to consider the influence of rope system parameters on dynamic factors due to the inertia effect of the cargo mass during the lifting mechanism operation. To simulate three-dimensional nonlinear seismic responses of container cranes, Kobayashi et al [27] presented a model including the contact problem between the wheels and rails of cranes based on multi-body dynamics formulation. A theoretical approach to investigate the process is presented, and a model and a numerical simulation algorithm of a general overhead travelling crane is established.
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