Optimisation of dynamic loads in elastic elements of load lifting cranes with different methods of lifting

Abstract

DOI: https://doi.org/10.32820/2079-1747-2019-24-6-16

During the work of lifting machinery there are considerable dynamic loads in the elements of the drive and the metal structure, which lead to the rapid failure of the elements of the structure and mechanisms and emergencies. The issue of elimination of dynamic loads has not been solved yet, so in this work, the dynamic loads in the elastic elements (ropes) of load lifting cranes have been optimized within various methods of cargo lifting: “pick-up”, “using weight”, “from the ground”. As a criterion for optimization (minimization of the specified loads) in the transient modes of operation of the crane (start, brake, reversal), the functional, which takes the minimum value and is the root mean square of the dynamic coefficient at the interval of time, corresponding to the dura­tion of the transition, is proposed. Classical variational calculus methods were used to solve the problem of optimizing the mode of motion of the lifting mechanism. With these methods, the ap­propriate (optimal) modes (laws) of cargo movement and the electromechanical system of the drive mechanism of lifting are established.The results obtained in this study can be further used to refine and improve existing engi­neering methods for calculating lifting mechanisms of the crane with flexible suspension both at the design / construction stages and under actual operating conditions.