Validation

Introduction

Current dummies are made for standardized crash tests, which require reproducible measured values for a specific load and impact direction. The impact velocities and the impact directions are predefined, so that the dummies can only be used for nearly similar configurations and loads. Therefore, a consortium of accident research institutions crashtest-service (CTS) and the University of Applied Sciences Dresden have developed a new biofidelic dummy in order to obtain usable and realistic results in forensic crash tests. This dummy could be used for occupants as well as for vulnerable road user like pedestrian and cyclist. Injuries are far better represented by the biofidelic dummy, because it shows the injuries in the form of damage to the skeleton or soft tissues, in contrast to conventional dummies. In addition, the resulting damage to the vehicles is far more realistic, since the strength of the biofidelic dummies is much closer to a real human.

Validation process

Validation has been a continuous process since the beginning of the research and development of the Biofidel-Dummy. This corresponds to a check whether the dummy model can sufficiently accurately reproduce the injury occurrence and biomechanics of an average man (50th percentile) in an accident. These requirements are divided into fixed requirements and minimum requirements. In order to be able to expand the performance spectrum, outstanding requirements are constantly being extended. The verification is carried out on an application-specific basis. For use in accident research and vehicle safety as a pedestrian or occupant surrogate, the dummy has been and continues to be matched using documented volunteer and cadaver tests as well as real injury data from accident research. The used data from real accidents (GIDAS1) have the required informative value and depth of information, which are significant for the verification of human injuries. The focus is mainly on fractures, ruptures of the ligamenta and soft tissue injuries with a high influence on lethality. Furthermore, documented cadaver and volunteer tests are essential for the kinematic response of the dummy.

Experimental sled tests

As a reference for rear impact scenarios, 23 volunteer tests of the study of Ono. et. al. [1] was used up to a collision speed of 8km/h. As a reference for frontal impact tests, 5 volunteer tests of the Smith et. al. [2] study up to a load case of 21km/h were used. For side impact tests, the documentation of 3 cadaver tests of the Shaw et. al. [3] study with a collision speed up to 15km/h was used. A Kistler measuring system is used which is applied in the automotive industry in the standardized children's Q-Dummies. The assembled system includes a crash-proof and inertial measuring unit which is arranged in the head with 3 rotation rate sensors and 3 acceleration sensors. In the thorax area of the spine and in the pelvis area, acceleration measuring systems are arranged, which can measure the acceleration in 3 coordinate directions. In the data recorder, the measured values are stored locally and close to the sensor by the digital sensor module, recorded and stored centrally. Each sensor used is calibrated. The calibration certificate documents and guarantees the traceability to national standards, which produce the physical units of measurements (SI). All measuring devices are traceable to national standards. Trajectory tracking was recorded with a high-speed camera and analyzed using Gom-Correlate software. The deviation of the sled velocity of all tests in relation to the human volunteer tests and cadaver tests is on average 1 %. The maximum deviation is 2.38%. Table 1 shows the data of the references and the results of the Biofidel-Dummy compared to them.

Full scale crash tests

Load cases from a collision speed of 35 km/h were carried out on the crash facility of CTS. The real data from the GIDAS study serve as a model for this. Special attention was paid to the comparability to the dummy regarding age, weight and size. The measurement analysis was of secondary importance. The focus was more on the damage to the dummy. Damage diagnoses of the dummy were made according to a technical autopsy and recorded by means of photo documentation. The analyzed damages of the technical autopsy are divided into four classes: "normal findings", "slightly damaged", "severely damaged", and "see findings". These component- and component group-related technical injuries are assigned to the correlating minimum injury severity and the correlating maximum injury severity. The simplified injury scale AIS3 was used. This provides an approximately realistic and easy-to-understand assessment of possible injuries. With the AIS evaluation, the resulting injuries on the dummy could be compared with the real data. The total evaluation of all crash tests shows that the dummy showed on average 69% of all injuries compared to the real accidents. The MAIS is fully displayed in 89% of the cases. 

Daily compared

The daily crash tests carried out on the crash site enable a comparison of the results.