Multi-Objective Lightweight Optimization of Levitation-Frame Longitudinal Beam for Medium- and Low-Speed Maglev Trains Using the Kriging Surrogate Model

A finite element model of a novel maglev train levitation frame is developed to achieve optimal load-bearing performance and lightweight construction. Track tests are conducted to validate the model reliability, and the structural strength under critical operating conditions is evaluated in accordance with relevant technical specifications. Surrogate models are constructed for the longitudinal beam of the levitation frame using the Kriging method and the quadratic polynomial response surface method, and their prediction accuracies are compared. A multi-objective optimization approach is applied to the structural parameters of the longitudinal beam to obtain a Pareto-optimal solution set. The results indicate that the Kriging-based surrogate model achieves higher prediction accuracy than the quadratic polynomial response surface model. A parameter set selected from the Pareto-optimal solutions is used for simulation analysis. Compared with the original design, the mass of a single longitudinal beam is reduced by 5.6 kg (23.53%), the mass of a single levitation module is decreased by 11.2 kg, and the safety factor decreases from 3.32 to 2.24. Although the maximum von-Mises stress rises by 47.66%, it remains within the allowable stress range of the material. The optimized structure satisfies structural strength requirements and achieves the lightweight-design objective. The proposed method demonstrates reasonable applicability in structural engineering design.