Failure analysis and optimization of an electric vehicle AVAS bracket based on swept-frequency vibration testing and simulation

Abstract

This study investigates the fracture failure of an Acoustic Vehicle Alerting System (AVAS) bracket for an electric vehicle during Z-direction sweep-frequency vibration testing. To identify the root causes and formulate an effective remediation solution, a combined approach of physical experiments and finite element analysis was adopted. First, a sweep-frequency vibration test in the 10–500 Hz range was conducted to replicate the bracket’s fracture mode. A finite element model was then established via HyperWorks to perform Z-direction vibration simulations under the identical test conditions. The simulation results show that the bracket exhibits a stress peak of 393 MPa at 47 Hz, a value close to the yield strength of SPFH590 steel (420 MPa). Failure analysis indicates that the primary causes of the fracture are insufficient structural stiffness and severe stress concentration at sharp geometric corners of the bracket. Accordingly, a structural optimization strategy is proposed, which involves adding transition fillets at the critical stress-concentrated regions, extending the bent section, and introducing stiffening ribs. Simulation verification of the optimized design shows that the maximum stress at the original fracture location is reduced to 244 MPa, which is well below the yield strength of the material. This significantly improves the structural reliability of the bracket under vibrational loads. This research provides a practical analytical method and engineering design reference for improving the fatigue durability of AVAS brackets and similar automotive sheet metal structural components.