Durability analysis of steel metal structures of hoisting machines at the design preparation stage of production

The reliability and safety of operation of hoisting machines are largely determined by the quality of performance of steel structures, which necessitates the analysis of their reliability. Moreover, this analysis should be carried out at the stage of design and technological planning of the life cycle of the hoisting machine. Reliability analysis as applied to bridge-type hoisting machines is usually performed for critical elements of steel structures, the occurrence of fatigue cracks in which can lead to catastrophic consequences and indicates the exhaustion of the resource of the structure as a whole. These elements of hoisting machines include connections of the main and end beams, fastenings of running wheels, the middle of the main beams, metal structures of cargo bogies. Therefore, this paper proposes an engineering method for analyzing the reliability of steel structures of bridge-type hoisting machines at the stage of design preparation of production, which allows assessing the ability of the hoisting machine to meet the established requirements for durability, determined by the expected number of loading cycles until the crack length in the middle of the main beam of the bridge-type hoisting machine reaches a critical size. Moreover, the critical crack length and its growth rate in the method are calculated based on the stress intensity factor, for the determination of which, based on finite element modeling, the corresponding dependencies on the relative crack size and stresses within the boundaries of the elastic-plastic damage accumulation zone are obtained. Practical application of the proposed method will reduce the operating costs of the designed hoisting machine.