Kinematic and structural analysis of the hydraulic drilling rig mast assembly for load optimization and structural validation

The current market landscape in the heavy foundation engineering sector has encouraged Soilmec S.p.A. to strengthen its commitment toward performance optimisation and sustainable development of its machinery portfolio. In this context the mast mechanism of the SM-6 drilling rig was selected for detailed investigation, as it plays a central role in transmitting thrust forces during operational cycles. The SM-6 mast is characterised by a multi-link articulated mechanism actuated by hydraulic cylinders, responsible for sustaining substantial external loads under demanding working conditions. Due to the magnitude of these loads, structural components are traditionally designed with conservative safety margins to ensure reliability. Thus, systematic load evaluation and structural assessment of mast assembly was therefore undertaken. The work presented in this thesis focuses on the kinematic and static analysis of the SM-6 mast mechanism, with particular emphasis on the determination of internal forces acting on the hydraulic cylinders and structural links. The study began with development of an analytical model of the planar mechanism, applying static equilibrium equations to calculate reaction forces under defined loading configurations. To ensure robustness of the results, a geometrical force-triangle method was employed as an independent validation tool. Subsequently, a rigid dynamic simulation of the assembly was carried out in ANSYS to replicate the load transfer in the mechanism. The numerical results were compared with analytical calculations, providing cross-validation. Finally, static structural FEM analysis was performed on Link 4, identified as a critical structural component, to evaluate stress levels and verify compliance with material strength criteria. The results confirm the consistency between analytical and numerical approaches and demonstrate that the examined component operates within acceptable stress limits under the considered loading scenarios.