Structural fatigue failure analysis and lifetime reliability monitoring strategy of the lattice jib in all-terrain cranes.

Abstract

During lifting operations, the boom of large-tonnage all-terrain cranes bears quasi-static loads imposed by the structure weight and wind forces, and alternating cyclic loads caused by the departure, rotation, and landing of cargo. These factors give rise to localized fatigue failure of welded joints, thereby triggering engineering accidents. Current fatigue monitoring strategies mainly rely on historical data and simplified load spectra, which are insufficient to accurately capture the randomness and complexity in crane operations. This study proposes a new fatigue monitoring strategy that integrates real-time operational data with finite element (FE) modeling. The fatigue failure of the lattice jib section (LJS) of an all-terrain crane was investigated through bench testing and FE analysis to establish a fatigue lifetime reliability monitoring strategy for the lattice jib of all-terrain cranes. First, the static loading strain at specific positions, fatigue failure positions, fatigue life and characteristics of the fracture surface were obtained through the implementation of full-scale static load tests, fatigue tests, and fractographic investigation. Then, a refined solid element FE model of the LJS containing weld elements was established, and the hot spot stresses along the wall thickness direction at the weld toes were extracted for fatigue failure analysis. At last, by utilizing the Internet of Things crane operation data and simplified FE model of the entire crane, the fatigue load spectra for components were established, enabling the prediction of cumulative damage rate and potential fatigue failure locations in the crane lattice jib. The simulation method and lifetime monitoring strategy developed in this study can serve as a valuable reference for reliability assessment of crane.