Simplified modeling of a wooden vehicle restraint system to reduce computation time

Vehicle restraint systems (VRS) are components installed on roadsides or freeways to ensure the safety of road users. The validation of a VRS is conditioned by crash tests in accordance with standards EN 1317-1 and EN 1317-2. Due to the high cost of crash testing, manufacturers rely on their experience, analytical calculations, and upstream numerical simulations to design VRS that meet the standards before experimental validation. However, these simulations can have a high computational cost. Therefore, the aim of this study is to propose a simplified model of a wooden VRS, close to a reference numerical model, enabling a significant reduction in computational time. The proposed design comprises rails and posts connected by joints, with a solid wood rail made up of 2-m-long elements. Numerical simulations show that this design satisfies the TB32 test, corresponding to a 1500 kg vehicle launched at 110 km/h with an impact angle of 20°. However, as the computational time is strongly influenced by the assemblies, a reference model with a continuous rail has been proposed, constituting a first simplification. The results indicate that only the parts of the VRS close to the impact zone are subject to high levels of deformation. Consequently, it is possible to simplify the parts remote from this zone in order to further optimize the computational time. Three approaches are proposed to represent these parts: the LS model replaces the remote zones with longitudinal springs; the LTS model uses longitudinal and transverse springs; and the beam (B) model uses the remote parts using beam-type finite elements. All three simplified models are validated and are able to reproduce the reference model with a continuous rail. The EN 1317-1 and EN 1317-2 criteria and the computational time show that the B model is closer to the reference model than the other two. In particular, the computational time is reduced by a factor of approximately 1.8 for the simplified models, while maintaining good agreement with the reference results. The B model, therefore, provides a good representation of the reference model at a lower computational cost.