Structural behaviour of dicyclopentadiene-based polymers (DCPD) and GFRP in the automotive sector

A thorough understanding of the components that make up a vehicle is crucial in the automotive industry. This work is part of a research project in which a single-deck coach was evaluated for structural integrity using an ECE R29 regulation adaptation. This research aims to evaluate the replacement of the current exterior panels made of glass-fibre-reinforced polymer (GFRP), with more environmentally friendly panels manufactured of dicyclopentadiene-based polymers (DCPD). To achieve this, the effectiveness and impact resistance of the different materials must be assessed.

The impact performance of the material may be predicted using a typical testing device that simulates small-scale collisions employing a pneumatic gas-gun setup capable of firing hard projectiles commonly applied in ballistics and aeronautics, highlighting the multidisciplinary nature of the study. A custom-designed firing mechanism was developed to evaluate materials by measuring their energy absorption and penetration capacity using 3D DIC. Post-impact analysis uses pulse thermography to characterise the damage from both piercing and non-piercing impacts.

The equipment designed for crashworthiness testing proved successful and shows potential for applications beyond the typical ballistic and aeronautical applications. The use of lock-in thermography enabled detailed fracture analysis. In terms of structural behaviour, DCPD was found to be a better candidate material for incorporating into the design of coaches when subjected to low velocities impact and similar energy under the ECE R29 regulation. However, for high-energy impacts (above 713 kJ), DCPD, when impacted by a spheric projectile, tends to fracture radially, making it inefficient for energy absorption. In such cases, GFRP is considered more capable of maintaining the integrity of the overall components.