Specific Energy Absorption Improvement of Rear Crash Attenuator by Numerical Modelling for Various Angles of Impact

Abstract

This research* aims on developing a reliable finite element framework to investigate the Specific Energy Absorption (SEA) of the rear crash attenuator of an open-wheel type Indycar vehicle. A meshed model representing the crash structure was designed and its failure behaviour was learnt on the basis of various non-linear finite element modelling techniques to simulate a crash as per regulations from the governing body of Indycar. All the numerical analysis was performed utilizing the LS-DYNA software with the Progressive Failure Model (PFM) and Continuum Damage Model (CDM) of MAT058_LAMINATED_COMPOSITE_FABRIC card. The sandwich structure material characterization for the tuning of the material model was done by the means of a correlation with experimental data and adjusting the non-physical input parameters in the software. Post calibration, the development of the rear impact attenuator was performed with the model. A combined failure mode was observed with a gradual crushing phenomenon during the analysis on head-on impacts (0°) while in case of oblique impacts performed at 30° off axis shows the structure failing at its rear attachment points to the bulkhead. The specific energy absorption was determined at different configurations of impact of this reinforced sandwich structure by evaluating the force over a crushed displacement. The layup was adjusted, the sensitive points at the attachments were stiffened, and the core thickness was varied throughout the structure to improve the overall specific energy absorption by 27.8% with a gradual deceleration value to that of the prescribed. Finally, the results were compared to the previous Indycar structure and the rear crash attenuator was redesigned with highlights of the refreshed results.