Search Results

A kinematic analysis of the head-neck unit has been conducted in 37 simulated traffic accidents in order to investigate correlations between neck response and injuries. Belted fresh human cadavers in the age range 18 to 74 years have been used as front and rear-seat passengers. The analysed data included 23 frontal collisions, impact velocity 30 km/h, 50 km/h and 60 km/h, barrier impact and 14 90°-car to car lateral collisions with near-side passengers (6 cases) as well as far-side rear-seat passengers with an in-board upper anchoring point for the shoulder belt (8 cases). The head bending angle depended on the type of the collision. At the frontal collision, the mean head bending maxima amounted 79°, the evaluated mean angular velocity maxima and angular acceleration maxima corresponded to 41 rad/s and 2208 rad/s2, the mean maximum velocity in trajectory of the head was 10 m/s, the mean maximum acceleration along the path amounted 23 g.

21 low velocity direct occipital and lateral head impacts were performed on 17 cadavers. Both damped and undamped impacts were performed at impact velocities of between 2.8 and 6.1 m/s. Head responses were measured using a 9-accelerometer array, and in 8 cases epidural pressure was measured at the contre-coup site. Base of skull and temporal fractures of AIS severity 3 or 4 were produced with undamped impacts at velocities greater than 4.0 m/s. Brain injuries were also observed; these were subdural and sub-arachnoid haematomas of AIS severity 3 or 4. Only minor cervical spine injuries were observed. Head responses were calculated from the 9-accelerometer array data. Linear centre of gravity head acceleration, HIC and angular accelerations are presented. Angular acceleration time-histories calculated with this method appear to be sensitive to local skull deformations and shock wave transmission.

Frontal, lateral and rear-end collisions with dummy occupied wheel chairs on a deceleration sled were conducted in two test series at a collision velocity of 30 km/h, and a sled deceleration of 8 and 12 g. In the first dummy test series conventional restraint systems were used; in the second test series improved restraint systems were employed. In a further series, four cadaver tests were conducted. For all tests and collision directions the HIC values, as well as the resultant acceleration at the center of gravity lay below the admissible values of Federal Motor Safety Standard 208. Despite the low thorax accelerations numerous rib fractures occurred in the cadaver tests. In two cadaver tests, injury degrees of AIS 5 were observed (multiple liver ruptures, vertebral column injuries).

Our tests with fresh human cadavers were continued (cf. proceedings, 18th Stapp Car Crash Conference). Presented herewith are the results of 103 tests evaluated so far. While the severity of injuries showed an increase with advancing age, it is not obviously dependent upon weight or sex. Under the conditions chosen by us, the 12 to 30-year age group reached the thorax tolerance level at an impact velocity of still below 50 km/h with a stopping distance of 40 cm, the 30 to 50-year age group of below 40 km/h, and the age group beyond 50 years below 30 km/h. A comparison of our results with volunteer tests (Ewing et al., 29) and with evaluated real accidents (Patrick et al., 22) as well as with similar cadaver tests (Tarriere et al., 19) is made. When introducing safety testing regulations for vehicles in the light of dummy tests, the broad spectrum of the respective age groups has to be considered. The thorax injuries may be slightly mitigated due to a lessening of the surface pressure.

By an acceleration track operated through a falling weight (9, 11*) with a crash velocity of 50 km/h and a stopping distance of about 40 cm-corresponding to the crease region of many automobiles-the effect of three-point-retractor belts on 30 fresh cadavers and of two-point belts with kneebar on 19 fresh cadavers had been tested. The age of the cadavers ranged from 12-82 years. Qualitatively, almost all injuries known under the term “seat belt syndrome” could be reproduced. The dependence of the degree of injury in regard to the age was quite evident. It can be expected that persons over 40 years of age will suffer the same dangerous injuries as the tested cadavers, caused by the diagonal belts if the above mentioned crash conditions are existent. This will apply to both belt systems tested by us. The shoulder-belt-forces of all of our tests were between 340 kp and 1000 kp, but more serious injuries of the cadavers of older persons could be observed.

At the 30th Stapp Conference an analysis was presented of human volunteer head-neck response in omni-directional impact tests. It was shown that the relative head motion can be described by a simple two-pivot analog system. The present study extends this analysis to post-mortem human subject (PMHS) tests conducted at the University of Heidelberg. Two test series similar to the human volunteer frontal impacts tests were carried out. One having an impact severity identical to the most severe human volunteer tests. A second series with higher exposure levels are used to verify the proposed analog system for higher impact levels. Test results including neck injury data for five PMHS tests will be given with special attention to trajectories of the head center of gravity, head rotations and head accelerations. It is concluded that the center of gravity trajectories for the PMHS and volunteer tests are similar for both impact levels.

Six European laboratories have evaluated the biomechanical response of the new advanced frontal impact dummy THOR-alpha with respect to the European impact response requirements. The results indicated that for many of the body regions (e.g., shoulder, spine, thorax, femur/knee) the THOR-alpha response was close to the human response. In addition, the durability, repeatability and sensitivity for some dummy regions have been evaluated. Based on the tests performed, it was found that the THOR-alpha is not durable enough. The lack in robustness of the THOR-alpha caused a problem in completing the full test program and in evaluating the repeatability of the dummy. The results have demonstrated that the assessment of frontal impact protection can be greatly improved with a more advanced frontal impact dummy. Regarding biofidelity and injury assessment capabilities, the THOR-alpha is a good candidate however it needs to be brought up to standard in other areas.

The paper presents and describes results of the FAT research-project Phase I “Kinematics and Loadings during Side Impacts: Comparison between Dummies and Cadavers”. It will report on 30 side impacts at 50 km/h under 90° impact angle conducted with three different dummies and cadavers. On the basis of the test results dummy modifications will be proposed. The side impacts caused following main injuries in the cadavers: rib fractures on the impacted side were most frequently observed (AIS thorax 2-4). The most serious injuries were liver ruptures predominantly on right-side impacted cadavers (AIS up to 5). Cervical spine injuries with an AIS value of 1 and 2 were also noted. Fracture of the pelvis occurred only in one, bony head injuries in two cases.