Design and Analysis of Elastic-Plastic Collision Post for Railway Vehicles

Collision posts have been required at the front end of railway vehicles to provide protection against intrusion under collision in the US market since 1940s, though it is still not a standard required structure in the Europe and Asia markets. In this paper, typical front-end frame with and without collision posts of railway vehicles are compared to illustrate the pros and cons of collision posts in railway vehicles. Then two different front-end frames with collision posts are introduced in detail to discuss how to take the advantages of collision posts and avoid the drawbacks in different applications. In the first design, the collision posts are placed in front of the energy absorbing elements. When collision happens, the collision posts will deform first before the energy absorbing elements act. As a result, the collision posts and many carbody and cab structures, such as the front-end frame, underframe, cab interior and operator console may under repair even the collision speed is low. However, more space can be utilized for the cab and passenger compartment since the collision posts can be located at the very front of the vehicle. In the second design, there are two stages of energy absorbing elements and the collision posts are placed in the middle. The first stage of energy absorbing elements can absorb low-speed collision energy without damaging other structures and can be replaced easily. To make up for the extra space taken by the first stage energy absorbing elements, the shape and dimension of the collision posts have to be optimized. For both designs, finite element analysis has been used to analyze and optimize the design. Then full-scale test specimens are manufactured and tested to further validate the design and analysis. Based on the design, analysis and test results, an overall evaluation of collision post’s role in passenger protection and vehicle design has been generated.