Structural redesign and dynamic analysis for lifting machine requalification and life evaluation. Case study: tower crane Liebherr 32 TT

The paper presents a methodology for the structural analysis and the fatigue evaluation of mechanical components though numerical approach. The paper, developed with the collaboration of C.S.S. Engineering, is focused on the problems of redesign concerning tower cranes. Dynamic analysis of a specific tower crane Liebherr 32 TT is performed by using several dynamic software (Multibody and FEM) in order to improve its structural qualities. A multibody model with flexible bodies has been developed, which, after correlation with available experimental data, was reliable and apt to a prevision of the dynamic behavior of the system. In addition to the structural analyses on stresses and deformations, durability analyses were added which provided the evaluation of the fatigue life consumption in the real operation conditions. The methodology adopted made possible also to extend the activity to studies of redesign of the tower crane components and of optimization of its vibrational and fatigue behavior.