Dual-stage stiffness optimization for elastic plates in high-speed railway turnouts using a refined rigid-flexible coupled approach

Conventional vulcanized rubber elastic plates used in China’s high-speed railway turnouts frequently suffer from failure modes including surface cracking, material peeling, and iron-component corrosion. These defects impair elastic functionality, amplify wheel-rail dynamic forces, and degrade ride quality. To address this issue, a refined rigid-flexible coupling dynamic model was developed to accurately investigate wheel-rail high-frequency impacts induced by uneven stiffness distribution through implementation of optimized variable integration step sizes and advanced contact algorithms incorporating flexible deformation mechanics and nonlinear damping effects. Subsequently, optimized structure of rubber blocks implement three critical innovations: a dual-stage stiffness strategy where stiffness sharply rises at 1.5 mm compression, which overcomes the inherent deficiency in fixed stiffness designs by providing initial compliance for vibration isolation followed by high rigidity for load-bearing stability; vulcanized bonding coatings critically enhancing the rubber-iron interface strength; and a recessed surface design mitigating cyclic damage through optimized stress distribution. This integrated approach achieved precise stiffness control, targeting the identified optimal transition zone stiffness at 22 kN/mm. Simulations demonstrated substantial improvements: 7.62% reduction in wheel-rail force and 27.27% decrease in vehicle vertical acceleration. Finally, 1 year of field tests confirmed zero cracking or corrosion while validating significant performance gains: 28.03% lower the average of rail vibration acceleration, a 3.49% reduction in wheel-rail forces, and controlled structural deformations (Vertical: +9.23%; Lateral: +20.59%). Overall, the proposed structural optimization approach enables more uniform stiffness transitions and reduces mechanical impacts in turnout, thereby contributing to enhanced structural durability and running safety in high-speed railway infrastructure.