Search Results

Results indicate the need for a redesigned Hybrid III face capable of accurate force and acceleration measurements. New instrumentation and methods for facial fracture detection were developed, including the application of acoustic emissions. Force/ deflection information for the human cadaver head and the Hybrid III ATD were generated for the frontal, zygomatic, and maxillary regions.

The purpose of this paper is to present a comparison of whole body, target impingement knee impact response for a Part 572 dummy versus that for anthropometrically similar embalmed human cadavers. “Response” is defined here to include the impact force-time history as sensed by 1) femur load cells, and 2) impingement target load cells for the dummy and by the target load cells for the cadavers. The data presented demonstrate significantly higher peak forces and correspondingly shorter pulse durations for the dummy than for the companion cadaver subjects under similar test conditions and at all velocity levels investigated. For the dummy, the ratio of forces measured by the femur load cells to those measured by the impingement target load cells averaged eight tenths.

A series of blunt head impacts has been performed on stationary unembalmed human cadavers. The specimens were prepared to simulate realistic fluid pressures within the cerebrospinal fluid space and cerebral blood vessels. Translational acceleration-time histories of the head were recorded by biaxial accelerometers attached to the skull. Peak resultant head accelerations in excess of 3,000 m/s2 and pulse durations of 5 ms. or less were observed in a series of 10 experiments. The cerebral vascular system was perfused with a carbon particle tracer solution. Following impact, careful gross and microscopic pathologic studies of the cranial soft tissues were performed to assess vascular hemorrahage as represented by extravasation of tracer solution into the brain tissue. Data is presented describing the input forcing function, resultant head acceleration, and detailed necropsy findings.

Previous studies of human thoracic injury tolerance and mechanical response to blunt, midsternal, anteroposterior impact loading were reported by the authors at the 1970 SAE International Automobile Safety Conference and at the Fifteenth Stapp Car Crash Conference. The present paper documents additional studies from this continuing research program and provides an expansion and refinement of the data base established by the earlier work. Twenty-three additional unembalmed cadavers were tested using basically the same equipment and procedures reported previously, but for which new combinations of impactor mass and velocity were used in addition to supplementing other data already presented. Specifically, the 43 lb/11 mph (19.5 kg/4.9m/s) and 51 lb/16 mph (23.1 kg/7.2 m/s) conditions were intercrossed and data obtained at 43 lb/16 mph (19.5 kg/7.2 m/s) and 51 lb/11 mph (23.1 kg/4.9 m/s).

This paper presents conclusions of a study of rollover collisions and the injuries resulting from them. The injury severity, the type of injury, the body region injured, the frequency of injury, and the injury mechanism are all indicated. The study includes statistics on both restrained and unrestrained occupants, and shows that ejected occupants usually sustain more severe injury than contained occupants. Several conclusions are presented as to automobile structures in relation to injury.

At the 1970 SAE International Automobile Safety Conference, the first experimental chest impact results from a new, continuing biomechanics research program were presented and compared with earlier studies performed elsewhere by one of the authors using a different technique. In this paper, additional work from the current program is documented. The general objective remains unchanged: To provide improved quantification of injury tolerance and thoracic mechanical response (force-time, deflection-time, and force-deflection relationships) for blunt sternal impact to the human cadaver. Fourteen additional unembalmed specimens of both sexes (ranging in age from 19-81 years, in weight from 117-180 lb, and in stature from 5 ft 1-1/2 in to 6 ft) have been exposed to midsternal, blunt impacts using a horizontal, elastic-cord propelled striker mass. Impact velocities were higher than those of the previous work, ranging from 14-32 mph.

Forces necessary for fracture under localized loading have been obtained experimentally for a number of regions of the head. Three of these, the frontal, temporoparietal, and zygomatic, have been studied in sufficient detail to establish that the tolerances are relatively independent of impulse duration, in contrast with the tolerance of the brain to closed-skull injury. Significantly lower average strength has been found for the female bone structure. Other regions reported upon more briefly are mandible, maxilla, and the laryngotracheal cartilages of the neck. Pressure distribution has been measured over the impact area, which has been 1 sq in. in these tests, and the relationship between applied force as measured and as predicted from a head accelerometer is examined.

The types and mechanisms of head injury are reviewed, and then the findings of a UCLA study on the electrophysiology of primate concussion is presented. It was found that g loadings, as measured by a triaxial accelerometer attached to the skull of an impacted monkey, correlated well with severity of concussion. Deep and superficial cerebral electrodes were implanted to monitor electroencephalographic and impedance changes after concussion. Resistance dropped and capacitance rose in the impedance electrodes in direct proportion to the severity of concussion. Deep electroencephalographic recordings showed a high amplitude low frequency charfge in the reticular formation areas after impact. Superficial electroencephalographic recordings did not correlate with clinical states. Applications of these data are presented as they relate to the prevention and treatment of head injury.

A study was made of 54 collisions resulting in injuries to rear-seat occupants unrestrained by seatbelts. It was determined that children (who represent a disproportionate percentage of rear-seat occupants) tend to become airborne and to incur severe injuries against the windshield, miror, dashboard and header. Adults tend to injure the face and head against the front seat and to sustain typical leg fractures from trapping their feet under the front seat. The occupants seated at the outside edges of the rear seat sustain dangerous injuries from metal ashtrays and window crank handles out of proportion to the severity of the collision. All unrestrained rear-seat occupants add to the injuries of front-seat occupants by hurtling into them. Terminology to describe the types and severity of collisions is offered to facilitate medical and engineering evaluation of injuries. Recommendations are made for design changes to lessen hazards.