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Technical Paper

Biomechanical Injury Evaluation of Laminated Glass During Rollover Conditions

Significantly, more fatalities and serious injuries occur due to ejection in roll over accidents. The present study was conducted to determine the occupant retention and head-neck injury potential aspects of laminated glass in roll over accidents. The head injury and neck parameters were obtained from Hybrid III 50% male dummy test device impacting on various types of side windows with laminated glass. Results indicated that the glass contained the dummy assembly and the head neck biomechanical parameters were below the critical value injury tolerance limits in simulated rollover accidents.
Technical Paper

Head Injury in Fork Lift Upsets

Phase I, Phase II, Caterpillar, Allis-Chalmers, Clark, Hyster, Toyota, and Entwistle fork lift upset studies have been conducted with Hybrid II dummies, Side Impact Dummies, and stunt men. The investigations concluded that the dummy lacks the ability to brace itself, hold on, and does not have adequate biofidelity to represent the human in a fork lift upset. Crushing injuries and death typically occur when the operator is thrown or jumps from the overturning forklift and is pinned by the overhead guard or canopy. The dummy studies demonstrated a wide range of Head Injury Criteria (HIC) values that were not reproducible. Furthermore, other injury producing variables such as angular acceleration, angular velocity or induced brain stress were not investigated. The injury level of 1000 for the HIC for the mid-sized male, small female, and 6 year-old has been recommended by the National Highway Transportation Safety Administration (NHTSA).
Technical Paper

Injury Analysis of Adult and Child Dummies

Determination of human tolerance to injury is difficult because of the physical differences between humans and animals, dummies and cadaver tissue. Certain human volunteer testing has been done but at subinjurious levels [STAP 86] [EWIN 72] Considerable biomechanical engineering injury studies exist for the adult human cadaver however little is available for the pediatric population [SANC 99] [KLEI 98b]. Studies have been made of pediatric skull bone modulus, fetal tendon and early pediatric studies of the newborn during delivery, however, a paucity of information still exists in these areas. A number of dummies have recently been made available principally for airbag testing to bridge the gap between the 50 percentile Hybrid III male dummy and the 95 percentile male dummy.
Technical Paper

Vehicular Padding and Head Injury

The Federal Motor Vehicle Safety Standard 571.201 discusses occupant protection with interior impacts of vehicles. Recent rule making by the National Highway Traffic Safety Administration (NHTSA) has identified padding for potential injury reduction in vehicles. Head injury mitigation with padding on vehicular roll bars was evaluated. After market 2 to 2.5 cm thick padding and metal air gap padding reduced the head injury criterion (HIC) and angular acceleration compared to the stock foam roll bar padding. Studies were conducted with free falling Hybrid 50% male head form drops on the fore head and side of the head. Compared to the stock roll bar material, a nearly 90% reduction in HIC was observed at speeds up to 5.4 m/s. A concomitant 83% reduction in angular acceleration was also observed with the metal air gap padding. A 2 to 2.5 cm thick Simpson roll bar padding produced a 70 to 75% reduction in HIC and a 59 to 73% reduction in angular acceleration.
Technical Paper

Instrumentation of Human Surrogates for Side Impact

The purpose of this study was to investigate the use of the chestband in side impact conditions by conducting validation experiments, and evaluating its feasibility by conducting a series of human cadaver tests under side impact crash scenarios. The chestband validation tests were conducted by wrapping the device around the thorax section of the Side Impact Dummy at its uppermost portion. The anthropomorphic test device was seated on a Teflon pad on a platform to accept impact from the side via a pendulum system. Tests were conducted at 4.5, 5.7, and 6.7 m/sec velocities using round and flat impactors. Retroreflective targets were placed at each strain gauge channel on the edge of the chestband. The test was documented using a high-speed digital video camera operating at 4500 frames/sec. Deformation contours and histories were obtained using the chestband electronic signals in combination with the RBAND-PC software.
Technical Paper

Thoracic Trauma Assessment Formulations for Restrained Drivers in Simulated Frontal Impacts

Sixty-three simulated frontal impacts using cadaveric specimens were performed to examine and quantify the performance of various contemporary automotive restraint systems. Test specimens were instrumented with accelerometers and chest bands to characterize their mechanical responses during the impact. The resulting thoracic injury severity was determined using detailed autopsy and was classified using the Abbreviated Injury Scale. The ability of various mechanical parameters and combinations of parameters to assess the observed injury severities was examined and resulted in the observation that belt restraint systems generally had higher injury rates than air bag restraint systems for the same level of mechanical responses. To provide better injury evaluations from observed mechanical parameters without prior knowledge of what restraint system was being used, a dichotomous process was developed.
Technical Paper

Tractor Induced Wheel Runover Injuries

In the present investigation a tractor wheel runover accident was simulated to obtain biomechanical information relating to mechanism of injury. Twelve cadaver porcine specimens were runover with the right front wheel of a tractor. Specimens were placed on a six-axis force plate and thorax contours were recorded temporally. Results indicated up to 68% compression of the chest occurred during the runover event. The shear force in the direction of travel was a significant factor in the type of fractures that occurred to the rib cage. Pathology determined from x-ray revealed multiple fractures per rib in the area directly below the path of the tire. Autopsy evaluation revealed soft tissue contusion on the left side in the area of wheel path. There was often extra blood in the pericardial space and examination of the brain showed petechial hemorrhaging subdurally.
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.
Technical Paper

Kinematic and Anatomical Analysis of the Human Cervical Spinal Column Under Axial Loading

The patho-anatomic alterations due to vertical loading of the human cervical column were documented and correlated with biomechanical kinematic data. Seven fresh human cadaveric head-neck complexes were prepared, and six-axis load cells were placed at the proximal and distal ends of the specimens to document the gross biomechanical response. Retroreflective markers were placed on bony landmarks of vertebral bodies, articular facets, and spinous processes along the entire cervical column. Targets were also placed on the occiput and arch of C1. The localized movements of these markers were recorded using a video analyzer during the entire loading cycle. Pre-test two-dimensional, and three-dimensional computerized tomography (CT), and plane radiographs were taken. The specimens were loaded to failure using an electrohydraulic testing device at a rate of 2 mm/s.
Technical Paper

Epidemiology and Injury Biomechanics of Motor Vehicle Related Trauma to the Human Spine

Engineering efforts directed at better occupant safety require a thorough understanding of available epidemiologic data. Epidemiologic studies using clinical as well as accident information facilitates the prioritization of biomechanics research so that controlled laboratory experimentation and/or analytical models can be advanced. This information has also value in dictating levels and types of injury that are critical to the development of anthropomorphic test devices used in crash environments. In this paper, motor vehicle accident related (excluding pedestrians, bicyclists, and motorcyclists) epidemiologic data were obtained from clinical and computerized accident (National Accident Sampling System-NASS) files. Clinical data were gathered from patients admitted to the Medical College of Wisconsin Affiliated Hospitals, and fatalities occurring in Milwaukee County, State of Wisconsin. NASS database with specific focus on spinal injuries of motor vehicle occupants was also used.
Technical Paper

Steering Wheel Induced Facial Trauma

Studies were conducted on twenty-two fresh human cadavers to determine the probability of facial bone fracture following dynamic contact with steering wheel assemblies of both standard (a commercially available) and energy absorbing (EA) types. Using a specially designed and validated vertical-drop impact test system, either zygoma was impacted once onto the junction of the lower left spoke and rim with velocities ranging from 2.0 to 6.9 m/s. Generalized force histories were recorded with a six-axis load cell placed below the hub. The wheel was inclined 30 degrees to the horizontal. Steering wheel deformations were recorded with a system of potentiometers placed below the impact site on the wheel. Dynamic forces at the zygoma (impact site) were computed using transformation principles. A triaxial accelerometer was placed at the posterior parietal region of the specimen opposite to the impact site to record acceleration histories. High speed photography documented the kinematics.
Technical Paper

Biomechanical Investigations of the Human Thoracolumbar Spine

In vitro biomechanical studies were conducted on fresh human cadaveric thoracolumbar spines to establish the limits of tolerance, explain the mechanism of failure, and investigate the effects of improvement in strength and stability of the injured column using Harrington distraction rods, Luque rods and modified Weiss springs. Quasistatic axial tensile loading on ligaments, compressive loads on vertebra) bodies and intervertebral discs, and flexure and compression-flexion force vectors on ligamentous columns, intact torsos and injured spines were applied to delineate the biomechanical and functional patho-anatomic characteristics. Vertical drop tests were conducted with the Hybrid II manikin to predict the forces and accelerations on the vertebral column.
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

Crashworthiness Analysis of Field Investigation of Business Aircraft Accidents

Business and executive aviation represent a combined total of over 40% of the general aviation fleet, but (1977) accounted for only 8.37% of all general aviation accidents recorded. During the period 1964-1977 some 7,351 aircraft engaged in business flying, and 883 in corporate/executive operations, were involved in accidents reported by the NTSB. These accidents were reviewed utilizing the University of Michigan Computerized Accident Files to provide an overall view of the incidence and nature of business/executive aircraft accidents relative to occupant crash injuries. In addition more detailed case studies of selected accidents investigated including a Lear Jet 25B, Cessna 421, Beech Volpar Model 18, and Ted Smith Aerostar 601, are provided to illustrate specific types of crashworthiness, occupant protection, or post-crash emergency egress findings applicable to business/executive operations. Post-crash fire was reported in 29 cases (16.3%) during the 3-year period (1975-1977).
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

General Aviation Crash Survivability

Statistics indicate that during the past decade (1967-1976) the number of general aviation aircraft involved in an accident is equivalent to at least 38% of the total U.S. production during that period. Estimates that an aircraft will be involved in an accident over a 20 year life range are as high as 60-70%. Recognition of this probability has led to crashworthiness and occupant survivability “packaging” design concepts as offering the most realistic approach to reduction of serious and fatal injuries when an accident occurs. This paper reviews and illustrates current general aviation aircraft accident experience relative to occupant impact injury and damage indexes, and provides new data relative to current-generation aircraft.
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

Civil Aircraft Restraint Systems: State-of-the-Art Evaluation of Standards, Experimental Data, and Accident Experience

The importance of crashworthiness and the role of restraint systems in occupant impact protection in U.S. civil aircraft design is being increasingly recognized. Current estimates of the number of fatalities which could be prevented annually in survivable accidents range from 33 to 94%. This study reviews the development of existing Federal Aviation Administration restraint system standards from the first requirement for safety belts in the Air Commerce Regulations of 1926 to present 14 CFR 1.1. The FAA and industry standards are critically evaluated for Parts 23 (small airplanes), 25 (air transports), 27 (rotorcraft), and 29 (transport category rotorcraft). State-of-the-art developments, including an overview of previous accident experience, results of experimental studies, comparison with other standards, and primary data sources are provided.
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.