The Crashworthiness of Minicars in Frontal Impact Tests

In Japan, the number of minicars is increasing due to market demands resulting from environmental and economic concerns, and constitutes 32% of the registrations among passenger cars (2012). The safety of the minicar for various crashes is a technological challenge due to its small size and mass. In this paper, the crashworthiness of minicars was investigated and the issues that should be addressed are discussed. The crash pulse, deformation, and dummy responses of minicars were examined for various frontal impact tests: full-width rigid barrier (FWRB), offset deformable barrier (ODB), full-width deformable barrier (FWDB), and car-to-car tests. In the FWRB tests, the car accelerations were high and large crash loadings were applied to the occupants. The dummy injury measures were less than injury thresholds because of the high performance of occupant restraint systems: the early and timely restraint system. In the FWDB tests, the deformation mode was relatively comparable to that in the car-to-car tests, and dummy injury measures were higher than those in the FWRB tests. An analysis using a simple spring-mass model indicated that a later restraint trigger time in the FWDB test led to high injury measures of the occupants. In the ODB tests, the passenger compartment was intact for all of the tested minicars. Since the car acceleration in the ODB test was lower than that in the FWRB tests, all of the injury measures of the driver dummy in the ODB tests were smaller than those in the FWRB tests except for the tibia index. In the car-to-car tests, though the minicar has a single-load path, the structural interaction was acceptable since the engine was located forward in the vehicle and interacted with structures of the other car. The passenger compartments of the minicars were intact and injury measures were lower than the injury thresholds until the loading on the vehicles reached the NCAP crash severity level. The crashworthiness of Japanese minicars could be representative of the safety of future mini electric vehicles.