Design and finite element analysis of new energy bus body frame

As the core load-bearing component of battery-integrated low-floor buses, the body frame faces critical challenges in structural analysis due to the conflict between computational accuracy and efficiency during preliminary design iterations. Existing finite element approaches for bus frames typically employ full-scale models with 300,000+ nodes, resulting in prohibitive computational costs (25–30 min per solve) that hinder rapid design symmetry-based simplification. Furthermore, separate treatment of static strength verification and modal analysis lacks unified validation against experimental data, raising concerns about model reliability for dynamic performance prediction. This study establishes an integrated finite element analysis framework that couples four critical load cases (bending, cornering, emergency braking, and extreme torsion) with dynamic performance evaluation within a unified computational model. A key methodological innovation is the systematic exploitation of structural symmetry, which reduces the computational scale from 310,000 nodes to 75,000 nodes while maintaining accuracy within 0.5% for stress predictions and 0.3% for natural frequencies—achieving a 58% reduction in GPU solution time (from 28 to 11 min). Experimental validation via hammer impact testing confirms the numerical model’s reliability, demonstrating an average frequency error of 3.2% and Modal Assurance Criterion values exceeding 0.85. Results demonstrate that the Q345 steel frame exhibits maximum equivalent stress of 134.11 MPa (38.9% of yield strength) under extreme torsion, with deformation metrics (bending deflection ratio 1/2,720, torsional angle 0.60°) satisfying urban bus design targets. Modal analysis reveals first-order vertical bending at 5.952 Hz and first-order torsion at 7.216 Hz, providing 3.65 Hz separation from maximum road excitation (2.3 Hz at 60 km/h) and eliminating resonance risks across the operational frequency range of 5.952–18.964 Hz. This validated methodology provides a reproducible workflow for rapid body-in-white development, bridging the gap between computational efficiency and experimental fidelity in new energy bus structural design.