Durability Over Time of Skin Used for JAMA–JARI Pedestrian Headform Impactor Measured by Biofidelity Certification Testing

Head injuries are the most common cause of pedestrian deaths in car–pedestrian accidents. To reduce the severity of such injuries, the ISO, IHRA and Japan MLIT proposed subsystem tests in which a headform impactor is impacted upon a car bonnet top. JAMA and JARI have developed the headform impactors in compliance with the ISO standard, the IHRA recommendation and the Japan MLIT safety regulation. The impactor consists of the core and skin. Since the skin is made of nonferrous material, the stiffness of the skin would be changed due to time elapse. The stiffness of the skin was confirmed by assessing the peak resultant acceleration of the gravity center measured in the biofidelity certification test, the so-called drop certification test. The ISO, IHRA and Japan MLIT specified the corridor of the peak acceleration impact must range from 245 to 300 G for a child headform impactor. In the present study, the newly developed skin durability over time at 0 month, 13, 16, 19, 22, 25, 28 and 31 months after manufacture was investigated in a room either with or without control of temperature and humidity. The results indicated that the peak acceleration impact using the two skins immediately after manufacture was 270 G. The peak acceleration of 287 G using the skin kept in a room with control of temperature and humidity increased 17G at 31 months after manufacture. The peak acceleration impact of 288 G using the skin kept in a room without control of temperature and humidity increased 18 G at 31 months after manufacture. The respective increases of 17 G and 18 G correspond to 31% and 33% of the range of certification test corridor (55 G), respectively. These results indicate that if the acceleration is close to the middle of the drop certification corridor (272.5 G) immediately after purchase by a testing facility, the skin is available for pedestrian impact test use with a storage period of at least 31 months. The results also suggest that if the acceleration is close to the upper limit of the drop certification corridor (300 G), the skin expiration time may be drawing very near. The findings also indicated temperature and humidity did not significantly affect the skin durability over time.