Abstract:
This study focuses on the design of a non-snagging guardrail post aimed at improving roadside safety by reducing vehicle instability during impacts. The primary issue addressed is wheel snagging, where vehicle wheels become trapped by conventional guardrail posts, leading to instability, rollovers, and increased occupant injury risks. The research employs finite element modeling (FEM) with LS-DYNA to simulate guardrail impacts and analyze alternative post designs.
The methodology begins with the development of a simple one-post sub-model, incorporating a vehicle wheel, suspension, and post. Existing guardrail designs are evaluated, and modifications such as deeper block-outs, longitudinal failure fuses, and lateral failure mechanisms are introduced to prevent snagging. TrueGrid is utilized for mesh generation, ensuring precise element discretization for accurate structural response predictions.
The study further involves material validation for timber posts, comparing finite element simulations with laboratory test results to assess the behavior of wood in impact scenarios. The performance of the modified guardrail post designs is analyzed through dynamic impact simulations, focusing on force time histories, strain energy distribution, and post deformation patterns.
Simulation results indicate that increasing the block-out depth to at least 250 mm significantly reduces snagging potential, while alternative failure mechanisms, such as pre-designed weak points in the post structure, enable controlled energy dissipation. The study highlights the importance of mesh resolution, contact modeling, and soil interaction in achieving accurate impact predictions.
The research concludes that a combination of increased block-out depth and controlled failure mechanisms offers the most effective solution for minimizing wheel snagging in guardrails. Future work will explore further refinements in post geometry and material selection to enhance impact performance and optimize real-world roadside safety implementations.
