Experimental and numerical investigation of impact force characteristics on track slabs subjected to high-speed ice impacts

Abstract

The impact effect caused by ice blocks detaching from high-speed trains will impair track performance. As the accurate impact force is not only a critical evaluation indicator for the impact damage on track slabs, but also a key input parameter to investigate the damage evolution mechanisms, the impact force characteristics is a primary issue to be addressed. Herein, the ice impact behavior and the influence of ice size, head shape, and impact velocity on force characteristics were investigated through a combination of laboratory experiments and numerical simulations. The impact force was directly measured by the force transducer during impact event, and the impacting fragmentation process of ice block was recorded by the high-speed camera. The numerical models developed by Ls-Dyna were validated through correlation with experimental data, and the relationship between experimental data and calculated results was analyzed. The findings reveal that peak impact forces across all test conditions exhibit an approximately linear growth trend with increasing impact velocity. Larger initial contact areas result in higher peak forces, shorter rise time, and greater impulse magnitudes compared to smaller ones, while the mass of the ice blocks has minimal impact on peak force and rise time. In addition, it is observed that the total impulse of ice blocks, regardless of their head shape or mass, exhibits a linear increase with rising kinetic energy. Additionally, initial fragmentation characteristics were highly dependent on the ice block shape: cylindrical blocks exhibited global fragmentation, while conical blocks demonstrated localized fragmentation. These insights, derived from the numerical and experimental analyses, were used to predict ice impact damage to the track slab, thereby laying the foundation for further research on the characterization and classification of impact damage.