Jib crane lightweighting through composite material and prestressing technique

Abstract

This research reports the results of both the implementation of innovative materials, such as composite material, and the application of the prestressing technique through appropriate tie-rods, for crane construction. The novelty lies in the introduction of both factors in order to reduce and limit the vertical deflection, while also reducing the cross section, which is the main constraint at the machine design phase. In this way, to limit the load-induced deflection of the crane, a constant external action is applied that induces a deflection opposite to that induced by the load. In particular, the object of this research is a jib crane with dimensions 4000x5000 (height and length in mm) with a load capacity of 4905 N. The research involves analytical dimensioning followed by verification of the results obtained using finite elements software (Ansys®). The parameters adopted for sizing, both the boom and the column, are the maximum displacements and safety coefficients concerning both maximum stresses and buckling phenomena. The main result is that the composite crane has the lowest weight: approximately 29 % and 21 % of the weight of the corresponding non-prestressed steel crane, for non-prestressed and prestressed composite configurations, respectively. The last part of the research concerns the construction methods for building cranes, in particular the implementation of the composite solution.