Recently, Euro New Car Assessment Programme has implemented a wide set of changes in its protocols so as to increase the severity of its load cases and improve the biofidelity of the anthropomorphic test devices that are used in the tests. With this objective in mind, in the side impact tests, not only has the dummy been changed from EuroSID II to WorldSID; but the test configurations have also been modified.
In the car-to-car impact test, the movable deformable barrier that is used as an impactor has been updated, modifying in this way the force that the vehicle receives from the barrier. In the pole test; however, the changes are found in the impact angle and speed. The crash is now performed with an impact angle of 75º (instead of a purely perpendicular impact) and at an increased speed of 32 km/h (vs. the previous 29 km/h).
In order to study the WorldSID (an advanced side impact dummy which has a high biofidelity) behavior in different impact performances and know their response to new Euro NCAP side tests, pendulum impacts have been carried out at Applus+ IDIADA. They were performed changing the impact speed, impactor mass and impact angle parameters in order to evaluate the effect of these parameters and their criticality. Furthermore, the dummy was not studied as a whole, but only the shoulder was studied, that is the most critical point due to its proximity to the impact point.
Tests were carried out with a similar setup as that of the WorldSID certification. These tests consist in using a Standard Pendulum Rig to impact the dummies in a desired impact point.
Besides, two different WorldSID positioning configurations were chosen:
- Position 1: Impact against the shoulder rib bolt
- Position 2: Impacting against the shoulder rib bolt but disassembling the 1st thoracic rib under the shoulder
For a higher impact angle the rib displacement was reduced but the rib angle was increased because the impact energy is transmitted in a different way. In this case, a higher rotation can be observed in the studied rib.
Impact speed variations
When the impact velocity increases, so does the registered shoulder force. When the test is carried out in position 2, the shoulder registered force is higher than when the test is carried out in position 1. The cause of this fact is that in position 1 the WorldSID arm is in contact with the 1st rib which absorbs part of the impact energy.
The shoulder force reduction, when the rib is not missing, is around 6.80%.
Impactor mass variations
Different shoulder impacts have been carried out changing the impactor mass and keeping the impact speed constant. By increasing the impactor mass, the resulting shoulder force level rises.
Impactor mass and impact speed effect
It has been verified that with a major impact velocity and with a major impact mass, the registered shoulder force is higher. However, increasing the impact velocity has a different effect than increasing the impactor mass. It has been observed that the impact velocity has a major effect than the impactor mass and then it could be concluded that velocity increases the impact severity in a more significant way.
Furthermore, it has been observed that when the impact energy is higher, the first rib absorbs a higher proportion of it and, consequently; the registered force in the shoulder is lower.
These conclusions may be used to develop future vehicles, consequently focusing on the most critical aspects for the occupant.