Enhancement of the structural performance of monocoque bus frames to improve rollover safety

The monocoque bus frame plays a critical role in ensuring structural integrity and passenger safety in public transportation. While prior studies have explored aluminum reinforcements to improve rollover crashworthiness, challenges such as high cost and material degradation over time remain. This study introduces an alternative optimization method by integrating lightweight I-shaped aluminum stiffeners into the bus frame structure. Finite Element Analysis (FEA) simulations using LS-DYNA were conducted to assess structural performance under rollover conditions in accordance with ECE R66 standards. The results confirm that the improved frame fully preserves the residual safety space and exhibits a 21.5% increase in flexural stiffness compared to the original configuration, with a negligible 0.06% increase in overall vehicle weight. This lightweight reinforcement solution significantly reduces plastic deformation in critical areas and meets all safety requirements, making it a cost-effective and manufacturable approach for sustainable public transport vehicle design.