Lightweight Design and Static–Dynamic Analysis of a Gantry Crane Main Girder Based on Multi-Objective Topology Optimization

Abstract

Existing lightweight optimization studies on gantry crane girders merely adopt static strength and stiffness constraints, ignoring fatigue damage induced by dynamic loads and welding fabrication, which results in impractical optimal designs. To address this limitation, a novel multi-objective topology optimization method incorporating static, dynamic, fatigue and minimum weld thickness constraints is proposed in this work. With structural weight and compliance minimization and first-order natural frequency maximization as the optimization targets, the model is constrained by structural stress, displacement, vibration frequency and minimum weld thickness, and a modified genetic algorithm is utilized to acquire the Pareto optimal solution set. Finite element analysis is conducted to compare the static performance, modal characteristics and transient dynamic responses of the original and optimized girders under diverse working conditions. The results demonstrate that the optimized girder exhibits comprehensive performance improvements, with a 15.6% reduction in structural mass, 8.3% decrease in maximum equivalent stress, 10.9% reduction in mid-span deflection, 12.1% increase in first-order natural frequency, and 18.3% extension in fatigue life. The proposed method can effectively support the precise lightweight design of crane metal structures and provides a feasible technical solution for their high-efficiency lightweight optimization.