FATIGUE LIFE PREDICTION OF TELESCOPIC BOOMS FOR TRUCK CRANES BASED ON DYNAMIC LOAD SPECTRA AND CRACK PROPAGATION ANALYSIS

To address the challenge of fatigue life assessment for truck crane telescopic booms under complex dynamic operating conditions, this paper proposes a method for evaluating their remaining fatigue life based on the extraction of dynamic load spectra and crack propagation theory.First, to account for the stochastic nature of working loads, a random load spectrum model that accurately reflects real-world engineering conditions was established using field-measured load data combined with the Kernel Density Estimation (KDE) method.The probability density function of this model was optimized through an adaptive bandwidth correction.Subsequently, Finite Element Analysis (FEA) and dynamic simulation were employed to capture the stress-time history of the telescopic boom under complex dynamic conditions, identifying critical regions of high-stress concentration, including the cylinder pin joint of the base boom, the web of the base boom, and the web of the seventh boom section.The maximum stress and deformation at the cylinder pin joint were found to be 806 MPa and 31.28 mm, respectively.Based on these findings, the remaining fatigue life of the identified critical points was assessed by integrating the Paris and Forman models from fracture mechanics with Miner's rule for cumulative fatigue damage.The results indicate that the cylinder pin joint is highest-risk region and the most prone to failure, which is highly consistent with critical locations identified in the literature, with an estimated life of approximately 3.47 to 4.5 years.Furthermore, complex operating conditions were found to reduce fatigue life by 10% to 15% compared to single loading conditions, highlighting the significant impact of multi-source load coupling.This paper provides a theoretical foundation and valuable reference data for the safety assessment of truck crane telescopic booms.