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Technical Paper

Biomechanical Tolerance of the Cranium

1994-09-01
941727
The objective of the study was to investigate the biomechanical response of the intact cranium. Unembalmed human cadavers were used in the study. The specimens were transected at the base of the skull leaving the intracranial contents intact; x-ray and computed tomography (CT) scans were obtained. They were fixed in a specially designed frame at the auditory meatus level and placed on the platform of an electrohydraulic testing device via a six-axis load cell. Following radiography, quasistatic loading to failure was applied to one of the following sites: frontal, vertex, parietal, temporal, or occipital. Retroreflective targets were placed in two mutually orthogonal planes to record the localized temporal kinematics. Applied load and piston displacement, and the output generalized force (and moment) histories were recorded using a modular digital data acquisition system. After the test, x-ray and CT images were obtained, and defleshing was done.
Technical Paper

Accident Investigation and Impairment Study of Lower Extremity Injury

1993-03-01
930096
The automotive safety community has grown increasingly aware of the societal costs of injury impairment and disability resulting from automobile accidents. A significant portion of this impairment can be attributed to lower extremity trauma. An accident data study was conducted to determine lower extremity injury frequencies and mechanisms for restrained front-seat occupants in frontal collisions. A query of the 1988-1990 NASS (National Accident Sampling System) data provided information on pelvis, femur, knee, leg, and ankle and foot injuries. Age, gender, seating position, and delta-V were examined for their effect on the data. Lower extremity injury data were compared with injury data of similar severity (AIS ≥ 2) for the head, chest, thorax, and abdomen. The NASS data was supplemented with injury impairment information which, combined with anthropomorphic and biomechanical data, provides a prioritization scheme for the design of dummy lower extremities and instrumentation.
Technical Paper

Adult Occupant Injuries of the Lower Limb

1986-10-01
861927
Lower limb injuries among motor vehicle occupants are relatively common and are one of the principle causes of permanent disability. The author has reviewed the current literature and his own experience as an orthopaedic surgeon and research accident investigator concerning lower limb injuries among motor vehicle occupants. An unreported series of knee, thigh, hip, pelvis injuries with indepth accident investigation is reported. Incidence rates for specific injury diagnoses are not available. Gross tabulations reveal that lower limb injury is second only to head injury in frequency among injured motor vehicle occupants. Lower limb injuries are possibly the commonest cause of permanent disability and impairment resulting from motor vehicle accidents.
Technical Paper

Biomechanical Evaluation of Steering Wheel Design

1982-02-01
820478
In a crash, impact against the steering assembly can be a major cause of serious and fatal injury to drivers. But the interrelationship between injury protection and factors of surface area, configuration, padding, relative position of the spokes, and number and stiffness of spokes and rim is not clear. This paper reports a series of high-G sled tests conducted with anesthetized animal subjects in 30 mph impacts at 30 G peaks. A total of eight tests were conducted, five utilizing pig subjects, one a female chimpanzee, one an anthropomorphic dummy, and one test with no subject. Instrumentation included closed circuit TV, a tri-axial load cell mounted between the steering wheel and column, seat belt load measurement, six Photo-Sonics 1000 fps motion picture cameras, and poloroid photography. Medical monitoring pre, during and post-impact was followed by gross and microscopic tissue examination.
Technical Paper

Driver Body Size Considerations in Future U. S. Heavy Truck Interior Cab Design

1981-02-01
810218
Accurate data on the body dimensions of truck drivers are needed and such data are not presently available. This paper provides basic source data and an anthropometrical overview of the usefulness and limitations of existing data bases; discusses the influence of population factors, including age, sex, and demographic variables; and reviews population sampling problems. Heavy truck drivers as a whole appear to represent a physically different population from that of either the U.S. general population or other professional groups. Future anthropometric surveys must provide information for improved accommodation for the increasing range of physical size of users, and for obtaining data more useful to engineers involved in heavy truck interior cab design.
Technical Paper

Soft Tissue Injuries of the Neck

1979-02-01
790135
Whiplash is a poorly defined term including ligamentous and muscle strains, hematomas, disc injuries, and less frequently, brain, eye and ear injuries. Diagnosis is difficult because clinical signs and Xrays, electromyography and electroencephalography findings are few. Protection and rest will cure most patients within a year but approximately 2/5th of patients have permanent symptoms and disability. Rear-end impact accidents cause the head and neck to hyperextend over the seat back. Whiplash occurs in 38% of exposed occupants. Head rests give protection but differential rebound may occur producing injurious hyperextension and whiplash. The larynx, trachea and esophagus, in front of the spine, are injured by impact against the dash or steering wheel. Airway obstruction may occur and cause death if not restored quickly. Permanent disability can occur because of scarring and partial airway or esophageal obstruction or vocal cord damage.
Technical Paper

Biomechanical Analysis of Swimming Pool Neck Injuries

1979-02-01
790137
This paper presents an analysis of 67 neck injuries incurred in diving and sliding accidents in swimming pools. The accidents were investigated to establish the appropriate medical and mechanical factors involved. A mathematical model was developed to allow the prediction of the trajectory and velocity of the subjects prior to their injury. Nine of the accidents were selected for real life simulation. The simulation included the selection of test subjects of similar physical build to the accident victims who then performed the maneuvers leading to the injury, but in deeper water. High speed movies (200 frames per second) were taken, above and below the water, to measure the motion. A frame by frame analysis provided data to determine the trajectory and velocity profiles of the test subject. The maneuvers studied included diving from the pool edge, diving from various board types and sliding down various sliding board configurations.
Technical Paper

Study of Human Impact Tolerance Using Investigations and Simulations of Free-Falls

1977-02-01
770915
A study of free-fall accidents and resulting injuries was conducted to determine how useful these types of data could be in establishing human injury tolerance limits. “Tolerance” was examined primarily for children at two levels - reversible injury and threat to survival. The specific objectives were to investigate specific free-falls in sufficient depth to permit biomedical or mathematical reconstruction of the fall, simulate selected free-falls to estimate impact response, and compare predicted responses with observed injuries as a means of estimating human tolerance levels. From more than 2100 reported free-falls, 110 were investigated on-site. Seven head-first and three feet-first falls were then simulated using the MVMA 2-D Crash Victim Simulator. Newspaper reports of free-falls showed that males fell six times as often as females and most often while at work. Children fell from windows and balconies more often than from any other hazard.
Technical Paper

A Critical Assessment of the Use of Non-Human Responding Surrogates for Safety System Evaluation

1976-02-01
760805
The basic physical mechanisms underlying recent experimentally observed anomalous behavior in the impact performance of safety helmets evaluated with soft (human-like) and hard (magnesium alloy) headform surrogates are qualitatively and quantitatively explained in this paper. The principal and physical mechanisms brought to light in the headform surrogate investigation are directly applicable to the utilization of other forms of surrogates (head -neck, thorax, whole body). In particular the results raise a serious question as to the validity of using non-human responding surrogates, with human generated injury tolerance data, for the purpose of assessing safety system performance. The implications of the results are that good crash-impact protective devices (helmets, restraints, etc.) could be penalized and, equally important, less safe crash-impact protective system designs could result from improper assessment of safety system performance.
Technical Paper

Biomechanical Properties of the Human Neck in Lateral Flexion

1975-02-01
751156
Properties of the human neck which may influence a person's susceptibility to “whiplash” injury during lateral impact have been studied in 96 normal subjects. Subjects were chosen on the basis of age, sex, and stature and data were grouped into six primary categories based on sex (F, M) and age (18-24, 35-44, 62-74). The data include: measures of head, neck and body anthropometry in standing and simulated automotive seating positions, three-dimensional range of motion of the head and neck, head/neck response to low-level acceleration, and both stretch reflex time and voluntary isometric muscle force in the lateral direction. Reflex times are found to vary from about 30 to 70 ms with young and middle aged persons having faster times than older persons, and females having faster times than males. Muscle strength decreases with age and males are, on the average, stronger than females.
Technical Paper

Cervical Range of Motion and Dynamic Response and Strength of Cervical Muscles

1973-02-01
730975
Basic physical characteristics of the neck have been defined which have application to the design of biomechanical models, anthropometric dummies, and occupant crash protection devices. The study was performed using a group of 180 volunteers chosen on the basis of sex, age (18-74 years), and stature. Measurements from each subject included anthropometry, cervical range-of-motion (observed with both x-rays and photographs), the dynamic response of the cervical flexor and extensor muscles to a controlled jerk, and the maximum voluntary strength of the cervical muscles. Data are presented in tabular and graphic form for total range-of-motion, cervical muscle reflex time, decelerations of the head, muscle activation time, and cervical muscle strength. The range-of-motion of females was found to average 1-12 deg greater than that of males, depending upon age, and a definite degradation in range-of-motion was observed with increasing age.
Technical Paper

Injury Frequency and Head Restraint Effectiveness in Rear-End Impact Accidents

1972-02-01
720967
All of the rear-end impact accidents occurring in the city of Rochester, New York, in a three-month period were surveyed by tabulation of the police accident reports. Special police information forms, telephone interviews, and mail questionnaires were used for further data acquisition. Vehicle photographs and medical examinations were conducted for approximately every 20th vehicle. During the data collection period, 691 rear-end impacts occurred. Although a computer program revealed 1371 accidents, defects in the program accounted for the large difference. Whiplash injury frequency based on telephone interview and mail questionnaire data obtained one to seven days after the accident revealed a whiplash injury frequency of 38%, which was approximately twice that determined by on-scene police investigators. Head restraints reduced whiplash frequency by 14% and fixed head restraints appeared to be more effective.
Technical Paper

A Prediction Model of Human Torso Volitional Mobility

1972-02-01
720002
Empirical models are presented which predict the threespace position of the torso when responding to reaches with the right arm. Models were derived which specify torso position in terms of the spacial location of 10 surface markers. These markers were positioned over palpable skeletal points of the spine and shoulder girdle. The necessary data were obtained through photogrammetric procedures utilizing four orthogonal cameras. The independent (input) variables to these models are the coordinates of the reach target. A supplementary, slightly more accurate, set of models was also derived in which the set of independent variables was enlarged to include the anthropometric dimensions of the subject. The second, concurrent phase of the analysis resulted in the derivation of a set of models which describes the configuration of the internal, torso skeletal system.
Technical Paper

Joint Range of Motion and Mobility of the Human Torso

1971-02-01
710848
The object of this study has been to develop a quantitative description of the mobility of the human torso, including the shoulder girdle, neck, thoracic and lumbar vertebral column, and pelvis. This has been accomplished by a systematic multidisciplinary investigation involving techniques of cadaver dissection and measurement, utilizing cineradiofluoroscopy for joint center of rotation location, anthropometry, radiography, and photogrammetry for selected positions and motions of living subjects, and computer analysis. Positional and dimensional data were obtained for 72 anthropometric dimensions on 28 living male subjects statistically representative of the 1967 USAF anthropometric survey of 3542 rated officers, including bone lengths of the extremities and vertebral landmarks. Normal excursion of these limbs was measured in the living, utilizing the landmarks established in initial cadaver dissection.
Technical Paper

Door Crashworthiness Criteria

1971-02-01
710864
A study of the biomechanical factors concerned with the design of side structures and doors for crashworthiness has been made. Questions regarding optimum stiffness, location of reinforcing members, effect of armrests, and padding have been answered within the framework of injury criteria models. Results of animal studies, cadaver studies, and anthropometric dummies have been combined to produce injury criteria for lateral impacts to the head, thorax, and abdomen. Impacts were applied utilizing a specially designed “air gun” in a laboratory environment emphasizing reproducibility and control. Full-scale crash simulations were performed on an impact sled to verify the results of the more specialized tests and analyses. Scaled models of current production doors were used in the animal series. Scaling relationships for various species of animals have been developed and extrapolated to man. Significant differences in right and left side tolerances to impact were noted and detailed.
Technical Paper

The Medical Aspects of Driver Protection Systems and Devices Developed Through Automobile Racing

1970-02-01
700660
This three-part paper deals with the medical aspects of driver protection in automobile racing. Part one presents the history of car safety equipment beginning with the development of helmets, belts, roll bars, and other devices to protect competition drivers. This paper describes the evolution from purely optional to mandatory equipment and how their design and accident records have contributed to increased safety in passenger cars. The investigation of injuries sustained in crash, fire, and loss of control caused by road hazards have contributed to the many improvements discussed here, almost all of which are readily adaptable to passenger car models. The second part presents a summary of the influence of racing on the design, testing and performance standards for protective headgear. The significance is indicated of applying basic principles of mechanics and dynamic systems testing to all fields in which head impact is a potential hazard.
Technical Paper

Bioengineering of Impact Survival in Business Aircraft

1969-02-01
690335
Aircraft used for business (executive corporate transportation or personal business) and utility purposes now represent about one-third of the total United States aircraft inventory. Data from accident investigation of business aircraft involved in survivable accidents indicate serious injuries and fatality to the occupants occur most frequently as a result of the unprotected head and neck or chest flailing in contact with aircraft controls, instrument panel, or structure. Improvement of current aircraft to provide increased occupant safety and survival during crash impacts is both necessary and feasible. Design considerations include folding seat back locks to prevent collapse, increased seat tie-down to structure, instrument panels and glare shields designed to absorb energy through structural design and padding, stronger seat structure, lateral protection, design and packaging of knobs and projections to minimize injury in contact, and installation of upper torso restraint.
Technical Paper

Restraint Systems in Racing Accidents

1969-02-01
690246
Some 634 accidents occuring in races sanctioned by the Sports Car Club of America (SCCA) are reviewed. Shoulder harnesses were used in 275 of the accidents. Inverted “Y” or double, separately anchored, shoulder harnesses were used almost exclusively. A significant decrease in the frequency and severity of injuries occurred after harnesses were introduced. Injury from the restraint system was very infrequent; submarining occurred only once. Deep bucket seats, providing lateral support for the chest and forward support for the buttocks, appear to potentiate the effectiveness of restraint systems. The “Y” harness functions well in production seats without lateral support because lateral displacement of the shoulders and upper torso can occur without risk of neck injury.
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