Objective To meet the top-level performance targets of CR450 EMU (electric multiple unit), lightweight measures such as structure optimization, material optimization, and functional optimization are adopted for the carbody, bogie and traction systems. However, these measures are still insufficient to meet the lightweight requirement corresponding to an axle load of 14.5 t, making it necessary to further explore additional weight reduction approaches.

Method The structural characteristics of CR450 EMU underframe equipment installation are analyzed, and it is found that the underframe equipment hoisting involves additional mass unrelated to its primary structural functions, indicating further potential for weight reduction. Based on the principles of vibration absorption and vibration isolation, the effects of equipment with different masses, different installation positions, and different hoisting configurations on vehicle dynamics performance are investigated, leading to the determination of a floor slide-rail hoisting method for underframe equipment. A pallet-type hoisting structure is designed to further enhance the structural safety of elastically hoisting equipment. For the equipment compartment, lightweight composite material solutions as well as lightweight cable and lightweight pipeline solutions are studied.

Result & Conclusion  The slide-rail hoisting method is widely applied in high-speed EMUs in China, and further weight reduction is achieved by replacing the traditional underframe side-beam hoisting with floor slide-rail hoisting. The proposed lightweight scheme for underframe structure can reduce the total mass of a CR450 EMU trainset by approximately 8.6 t compared with the CR400BF EMU. Simulation analysis and mainline tests verify that the scheme meets the top-level performance targets and operational requirements of the train. For the equipment compartment, by selecting appropriate materials, structures, and processes, requirements for lightweight design, equipment protection, and airflow guidance during high-speed operation can be satisfied simultaneously.