This paper deals with the prediction of fatigue damage in transport machinery frames subjected to random multiaxial loading using finite element analysis (FEA). The main objective is the application of optimization techniques to multiaxial rainflow analysis, allowing accurate assessment of cumulative fatigue damage under non-proportional stress states. The damage is calculated using the Corten-Dolan hypothesis, and the methodology is implemented in a custom finite element solver, FEM_MRFA, developed in MATLAB. The approach is demonstrated through the analysis of the frame structure of the track maintenance machine DELTA, focusing on the behavior at critical nodes and analyzing time-dependent principal stress responses. The paper discusses general multiaxial rainflow decomposition methods, including the critical plane approach and optimization procedures for identifying the most damaging stress orientations. The resulting fatigue life estimation under given boundary and material conditions provides valuable insights for the design and durability evaluation of vehicle frame structures operating under dynamic excitation.

Acknowledgement: This research work was supported by the gran project KEGA 002ŽU-4/2023, 005ŽU-4/2024 and VEGA 1/0753/24.