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Technical Paper

Human Factors Aspects of Emergency Egress from a Business Jet

Past research has shown that although occupants often survive crash impacts of business jet aircraft, they are often injured either in the course of egress or because they are unable to evacuate. A physical task analysis was performed to evaluate procedures for emergency egress from a typical business jet to demonstrate how possible human factors problems can be identified. First, the tasks required for the flight crew to evacuate via all possible routes were determined. Second, each task was divided into a series of physical elements, such as reach and grasp, corresponding to each movement or exertion. Third, physical aspects of the aircraft affecting performance of each element such as location and force, were measured. The physical requirements of each element were compared with available human factors data, to rate its difficulty. Selected aspects of the analysis are discussed.
Technical Paper

Biomechanical Evaluation of Steering Wheel Design

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

Impact Protection in Air Transport Passenger Seat Design

Knowledge of human impact tolerance(s) is a basic consideration in the improved design of air transport seat-restraint systems and occupant crash protection. This paper discusses biological factors which influence tolerance, defines tolerance levels, variables including whole body and regional impact, and effect of seat and body orientation. It is concluded that the ultimate inertial forces on the occupant specified in FAR 25.561 are not based upon human tolerance considerations; that human impact survival is estimated to be four to ten times the voluntary levels cited; that improved occupant protection requires dynamically tested structural improvements: and that currently available technology such as the NASA air transport seat, or rear-facing seats, should be utilized.
Technical Paper

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

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

Occupant Impact Injury Tolerances for Aircraft Crashworthiness Design

Human impact injury and survival tolerance levels for various crash conditions are presented on the basis of currently available biomedical and biomechanical knowledge. Consideration of physical factors influencing trauma-including body orientation, restraint system, magnitude, distribution, and time duration of deceleration-are summarized, as well as tabulations and sources of data for both whole body and regional impact tolerances. These biological data concerning human impact tolerances are provided as guidelines for improved engineering design of general aviation crashworthiness.
Technical Paper

Joint Range of Motion and Mobility of the Human Torso

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

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

A Prediction Model of Human Torso Volitional Mobility

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

Experimental Impact Protection with Advanced Automotive Restraint Systems: Preliminary Primate Tests with Air Bag and Inertia Reel/Inverted-Y Yoke Torso Harness

Both the inverted-Y yoke torso harness with inertia reel and the air bag restraint system have had extensive independent development for some time by several engineering and research organizations for both aviation and ground vehicle occupant protection. The research reported in this paper consists of the first biomechanical primate evaluation of these concepts as experimentally adapted for possible automotive use. These tests are a continuation of a study involving the relative impact protection and effectiveness of major restraint systems utilized in general aviation aircraft and in limited automotive use. The objective of this test series was to determine how much protection those advanced restraint concepts provided; to obtain preliminary biomechanical and physiological data; to identify problems of technique and applications in occupant protection; and to provide an initial basis for direction of future test requirements.
Technical Paper

A Systems Engineering Evaluation of Passive Restraint Systems for Crash-Impact Attenuation in Air Transport Aircraft

Advanced crash-impact protective equipment and techniques which have application to crew and passenger crash safety in jet transport aircraft have been evaluated. Thirty-two state-of-the-art concepts have been analyzed from a systems engineering viewpoint with respect to several engineering, psychological, and medical disciplines. In order to provide a framework to determine the function level of each concept, an event-oriented flow chart of the crash and escape event has been prepared. The 17 events occurring during a crash are included, beginning with system installation and concluding with emergency evacuation of a disabled aircraft. Performance with respect to the events on the flow chart are rated in terms of hazards of system use, maintainability, reliability, human factors, and other technological considerations.
Technical Paper

Anthropometry of U.S. Infants and Children

This report presents the results of a three-year study designed to collect analyze, and reduce selected anthropometric data on 4027 infants and children representative of the current U.S. population ranging in age from newborn to 12 years of age. Since the major purpose was to provide basic measurement data most useful and critical to consumer product design, regulatory consideration, or other direct applications, 12 of the 41 measurements taken were applied measurements which have not been previously available. As an example of the direct application to product design, measurement of buttock depth on 3-to 6-month-old infants provided an objective basis for establishment of crib interslat distances. A substantial portion of the study involved the design, fabrication, development, and testing of a new generation of anthropometric measuring devices which transmit measurement signals to a portable mini-computer data acquisition system or to a set of readout meters.
Technical Paper

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

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

Biomechanical Properties of the Human Neck in Lateral Flexion

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

Crashworthiness Investigation of General Aviation Accidents

General aviation accident investigations can provide valuable data to the design engineer concerning the crash performance of current models and can indicate needed improvements for occupant protection in future aircraft. Current statistics and the historical background of major investigations during the past 65 years are provided. A five-year study of general aviation accidents occurring in the State of Michigan is used as a basis to illustrate recent findings relative to occupant injury mechanisms, relative crash protection, and crashworthiness performance of current models of aircraft. Results indicate that the degree of structural damage may not relate to the degree of occupant injury when the cabin area remains relatively intact. A primary requirement is documented for adequate upper-torso restraint for all occupants, and the excellent crash performance of such a system is described.
Technical Paper

Biomechanical Analysis of Swimming Pool Neck Injuries

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

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

Bioengineering of Impact Survival in Business Aircraft

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

Biomechanical Tolerance of the Cranium

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

Biomechanical Analysis of Tractor Induced Head Injury

Head injury is a serious threat to lives of people working around farm machinery. The consequence of head injuries are costly, paralytic, and often fatal. Clinical and biomechanical data on head injuries are reviewed and their application in the analysis of head injury risk associated with farm tractor discussed. A significant proportion of tractor-related injuries and deaths to adults, as well as children, is due directly or indirectly to head injury. An improved injury reporting program and biomechanical studies of human response to tractor rollover, runover, and falls, are needed to understand mechanisms of the associated head injury.