Mark P. Haffner

Epidemiology and injury biomechanics of motor vehicle related trauma to the human spine

Approximately 40% of spinal cord injuries occur in motor vehicle accidents, resulting in high risks of disability and fatality. This chapter on epidemiology and injury biomechanics of motor vehicle related trauma to the human spine is from a comprehensive textbook on occupant and vehicle responses in rollovers. The authors report on a study in which motor vehicle accident related epidemiologic data were obtained from clinical and computerized accident (National Accident Sampling System, NASS) files. The authors undertook the study to determine the most commonly injured anatomic levels of the cervical spine, to classify these injuries based on an impairment scale, to determine the mechanism of injury at each spinal level, to evaluate the differences (if any) between the patient (survivors) and fatality data with respect to the location and mechanism of injury, and to compare this data obtained from a localized population with literature results and national samples. Results show that while injuries to the cervical column are complex and may occur at any spinal level, they concentrate statistically in two primary zones: at the craniocervical junction for fatal victims, and in the lower cervical spine for survivors. A strong association was also found between craniofacial and cervical spine trauma.

Thoracic trauma assessment formulations for restrained drivers in simulated frontal impacts

Using cadaveric specimens, sixty-three simulated frontal impacts were performed to examine and quantify the performance of various contemporary automotive restraint systems. To characterize the mechanical responses during the impact, test-specimens were instrumented with accelerometers and chest bands. The resulting thoracic injury severity was determined using detailed autopsy and was classified using the Abbreviated Injury Scale.

SEATED POSTURE OF VEHICLE OCCUPANTS

This paper describes the methodology and results from a project involving development of anthropometrically based design specifications for a family of advanced adult anthropomorphic dummies. Selection of family members and anthropometric criteria for subject sample selection were based on expected applications of the devices and on an analysis of U.S. population survey data. This resulted in collection of data for dummy sizes including a small female, a mid-sized male, and a large male. The three phases of data collection included: 1. In-vehicle measurements to determine seat track position and seating posture preferred by the subjects for use in development of laboratory seat bucks; 2. Measurement of subject/seat interface contours for fabrication of an average hard seat surface for use in the buck; and 3. Measurement of standard anthropometry, seated anthropometry (in the buck), and three-dimensional surface landmark coordinates using standard and photogrammetric techniques. For the covering abstract of the conference see HS-036 716. (Author/TRRL)

Cervical Vertebral Motions and Biomechanical Responses to Direct Loading of Human Head

There is little known data characterizing the biomechanical responses of the human head and neck under direct head loading conditions. However, the evaluation of the appropriateness of current crash test dummy head-neck systems is easily accomplished. Such an effort, using experimental means, generates and provides characterizations of human head-neck response to several direct head loading conditions. Low-level impact loads were applied to the head and face of volunteers and dummies. The resultant forces and moments at the occipital condyle were calculated. For the volunteers, activation of the neck musculature was determined using electromyography (EMG). In addition, cervical vertebral motions of the volunteers have been taken by means of X-ray cineradiography. The Ethics Committee of Tsukuba University approved the protocol of the experiments in advance. External force of about 210 N was applied to the head and face of five volunteers with an average age of 25 for the duration of 100 msec or so, via a strap at one of four locations in various directions: (1) an upward load applied to the chin, (2) a rearward load applied to the chin without facial mask, (3) a rearward load applied to the chin with the facial mask, and (4) a rearward load applied to the forehead. The same impact force as those for the human volunteers was also applied to HY-III, THOR, and BioRID. We found that cervical vertebral motions differ markedly according to the difference in impact loading condition. Some particular characteristics are also found, such as the flexion or extension of the upper cervical vertebrae (C0, C1, and C2) or middle cervical vertebrae (C3-C4), showing that the modes of cervical vertebral motions are markedly different among the different loading conditions. We also found that the biofidelity of dummies to neck response characteristics of the volunteers at the low-level impact loads is in the order of BioRID, THOR, and HY-III. It is relevant in this regard that the BioRID dummy was designed for a low-severity impact environment, whereas THOR and HY-III were optimized for higher-severity impacts.

Development of a Finite Element Model of the Thor Crash Test Dummy

The paper describes the development of a detailed finite element model of the new advanced frontal crash test dummy, Thor. The Volpe Center is developing the model for LS-DYNA in collaboration with GESAC, the dummy hardware developer, under the direction of the NHTSA. The modeling approach and test procedures used to create and validate each major subassembly are discussed. Specialized static and dynamic tests were performed to aid in defining and validating appropriate material models, joint characteristic, and dynamic response characteristics. The details of each dummy component are presented along with the validation procedure based on material and subassembly tests. (A) For the covering abstract see ITRD E106349.

Design of Temperature Insensitive Ribs for Crash Test Dummies

Crash test dummies are an important fool in assessing the likelihood of injury in a vehicle crash. The Isodamp damping material (also known as Navy Damp) that is used in the ribs of current crash dummies provides a human-like damping to the thorax under impact. However, the temperature range over which it can be used is very small and a new rib design using laminates of steel, fiberglass, and commercially available viscoelastic material has been constructed. Load-deflection response and hysteresis of the laminated ribs were compared with corresponding conventional ribs fabricated from steel and Isodamp and impact test we conducted on laminated and conventional ribs at varying temperatures. This paper presents details on the design, development, and testing of the new laminate rib.

INTERPRETATION OF NECK LOADS TRANSDUCED BY ADVANCED ANTHROPOMORPHIC TEST DUMMIES. I. BIOMECHANICAL DATA

Publisher Summary This chapter presents a series of experiments for identification of a set of neck injury criteria suitable for representing serious neck injuries sustained by car crash occupants. Cervical spinal injuries have been studied and some injury threshold data for static and dynamic neck loads already exists. The first test of an initial static neck loading test series has been conducted in this program; specifically, a neck tension test of an anesthetized, 12.2 kg, eight-year-old female baboon (Papio hamadryas) is reported. A static tensile loading experiment performed on an anesthetized Papio hamadryas produced neurophysiological evidence that cervical spinal cord function had been seriously impaired at 51% of the load subsequently required for the occurrence of structural failure. It appears likely that dynamic neck loading experiments will confirm that serious functional impairment of the neck can be produced at load levels well below those that cause structural failure of the neck. Existing anthropomorphic automotive test dummies have generally been developed based upon biomechanical data generated from testing performed on human cadavers.