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Technical Paper

A Finite Element Model of Region-Specific Response for Mild Diffuse Brain Injury

2009-11-02
2009-22-0007
It is well known that rotational loading is responsible for a spectrum of diffuse brain injuries spanning from concussion to diffuse axonal trauma. Many experimental studies have been performed to understand the pathological and biomechanical factors associated with diffuse brain injuries. Finite element models have also been developed to correlate experimental findings with intrinsic variables such as strain. However, a paucity of studies exists examining the combined role of the strain-time parameter. Consequently, using the principles of finite element analysis, the present study introduced the concept of sustained maximum principal strain (SMPS) criterion and explored its potential applicability to diffuse brain injury. An algorithm was developed to determine if the principal strain in a finite element of the brain exceeded a specified magnitude over a specific time interval.
Technical Paper

Age-Specific Pediatric Cervical Spine Biomechanical Responses: Three-Dimensional Nonlinear Finite Element Models

1997-11-12
973319
In this study, three-dimensional nonlinear finite element models of age-specific one year old, three year old, and six year old pediatric human cervical spine (C4-C5-C6) structures were developed. Their biomechanical responses were compared with the adult human cervical spine behavior under different loadings and at all load levels. The adult human cervical spine model was constructed from close-up computed tomography sections in the axial and sagittal planes, and sequential anatomic cryomicrotome sections. The adult model was validated with experimental moment-rotation data under flexion-extension and compression by correlating bilateral strains in the vertebral body and the lateral masses, and the force-deflection responses with experiments conducted in our laboratory. The adult model was modified to create one, three and six year old pediatric spines by incorporating the local geometrical and material characteristics of the developmental anatomy.
Technical Paper

Anthropometry of U.S. Infants and Children

1975-02-01
750423
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

Biodynamics of the Total Human Cadaveric Cervical Spine

1990-10-01
902309
Spinal trauma produced from motor vehicle accidents, diving accidents, or falls occur at high rates of loading. This study was undertaken to reproduce clinically relevant cervical spine injuries under controlled conditions. Six isolated head - T2 human cadaveric preparations were tested using an electrohydraulic piston actuator at loading rates from 295 to 813 cm/sec. The Hybrid III head-neck was tested similarly at rates from 401 to 683 cm/sec. The input forces for specimen tests were of higher magnitude and shorter duration than the distally measured forces. In contrast, the Hybrid III head-neck revealed similar magnitude and duration force traces from input to output. The specimen preparations were analyzed kinematically at 1200 frames/sec with 20 to 30 retroreflective targets fixed to each level of the cervical spine. With this technique it is possible to temporally follow cervical damage as a function of applied force.
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

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

Biomechanical Analysis of Tractor Induced Head Injury

1994-09-01
941726
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

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

Biomechanical and Injury Response to Posterolateral Loading From Torso Side Airbags

2010-11-03
2010-22-0012
This study characterized thoracoabdominal response to posterolateral loading from a seat-mounted side airbag. Seven unembalmed post-mortem human subjects were exposed to ten airbag deployments. Subjects were positioned such that the deploying airbag first contacted the posterolateral thorax between T6 and L1 while stationary (n = 3 x 2 aspects) or while subjected to left lateral sled impact at ΔV = 6.7 m/s (n = 4). Chestband contours were analyzed to quantify deformation direction in the thoracic x-y plane (zero degrees indicating anterior and 180° indicating posterior), magnitude, rate, and viscous response. Skeletal injuries were consistent with posterolateral contact; visceral injuries consisted of renal (n = 1) or splenic (n = 3) lacerations. Deformation direction was transient during sled impact, progressing from 122 ± 5° at deformation onset to 90° following maximum deflection. Angles from stationary subjects progressed from 141 ± 9° to 120°.
Technical Paper

Biomechanics of Inertial Head-Neck Trauma: Role of Cervical Components

2002-03-19
2002-01-1445
Inertial loading of the head-neck complex occurs in rear impacts wherein the head and neck of the occupant are initially subjected to rearward forces. Epidemiological evidence exists to demonstrate the significance and societal impact of these injuries [4]. From a clinical perspective, trauma secondary to inertial loads belongs to the lower end of the Abbreviated Injury Scale, and no specific diagnostic techniques are available to quantitatively document the injury. Furthermore, identification of the mechanisms of injury and derivation of injury thresholds are limited. In fact, there is a paucity of literature focusing on the reproduction of rear impact-induced neck injuries due to a single-event rear impact. Because the impact acceleration is transmitted to the head from the torso via the cervical column, the components of the human neck play a role in the mechanics of trauma.
Technical Paper

Biomechanics of Lumbar Motion-Segments in Dynamic Compression

2017-11-13
2017-22-0001
Recent epidemiology studies have reported increase in lumbar spine injuries in frontal crashes. Whole human body finite element models (FEHBM) are frequently used to delineate mechanisms of such injuries. However, the accuracy of these models in mimicking the response of human spine relies on the characterization data of the spine model. The current study set out to generate characterization data that can be input to FEHBM lumbar spine, to obtain biofidelic responses from the models. Twenty-five lumbar functional spinal units were tested under compressive loading. A hydraulic testing machine was used to load the superior ends of the specimens. A 75N load was placed on the superior PMMA to remove the laxity in the joint and mimic the physiological load. There were three loading sequences, namely, preconditioning, 0.5 m/s (non-injurious) and 1.0 m/s (failure). Forces and displacements were collected using six-axis load cell and VICON targets.
Technical Paper

Causes of Significant Injuries in Nonfatal Traffic Accidents

1966-02-01
660803
The Vehicular Trauma Research Group of the UCLA School of Medicine is currently conducting intensive studies of selected traffic accidents. Data is presented from an analysis of the first 150 traffic accidents studied. The role of vehicular design, mechanical failure and the performance of the new 1966 windshield in injury causation are discussed and illustrative examples are presented. The importance of detailed studies of traffic accidents is stressed as a method of yielding information not readily available by other methods of study. This approach is mandatory to evaluate new and pending vehicular design modifications and may be the only method of detecting and assessing the role of mechanical failure in traffic accident causation.
Technical Paper

Chestband Analysis of Human Tolerance to Side Impact

1997-11-12
973320
A series of 26 human cadaver tests with chestband instrumentation and accelerometers were completed to assess side impact injury tolerance. A Heidelberg-type sled test system was used with thorax, abdomen, and pelvic load plates. Tests were conducted at the Medical College of Wisconsin and through the Ohio State University College of Medicine at the NHTSA Vehicle Research and Test Center at two different velocities: 24 kph and 32 kph. Test conditions included rigid wall, padded wall, and pelvic offset. Accelerations were recorded at rib 4, rib 8, and T12. Up to three chestbands were placed on each surrogate. Chest deflections were derived by computing chest contours at every millisecond throughout the event. The derived chest deflection-time curves were differentiated to obtain velocity of chest compression. Injury criteria including ASA15N, TTI, normalized chest deflection, and VC were computed. Resulting injuries ranged from AIS = 0 to AIS = 5.
Technical Paper

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

1977-02-01
770154
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

Comparison of PMHS, WorldSID, and THOR-NT Responses in Simulated Far Side Impact

2007-10-29
2007-22-0014
Injury to the far side occupant has been demonstrated as a significant portion of the total trauma in side impacts. The objective of the study was to determine the response of PMHS in far side impact configurations, with and without generic countermeasures, and compare responses to the WorldSID and THOR dummies. A far side impact buck was designed for a sled test system that included a center console and three-point belt system. The buck allowed for additional options of generic countermeasures including shoulder or thorax plates or an inboard shoulder belt. The entire buck could be mounted on the sled in either a 90-degree (3-o'clock PDOF) or a 60-degree (2-o'clock PDOF) orientation. A total of 18 tests on six PMHS were done to characterize the far side impact environment at both low (11 km/h) and high (30 km/h) velocities. WorldSID and THOR-NT tests were completed in the same configurations to conduct matched-pair comparisons.
Technical Paper

Crashworthiness Analysis of Field Investigation of Business Aircraft Accidents

1979-02-01
790587
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

Crashworthiness Investigation of General Aviation Accidents

1975-02-01
750537
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

Development of Side Impact Thoracic Injury Criteria and Their Application to the Modified ES-2 Dummy with Rib Extensions (ES-2re)

2003-10-27
2003-22-0010
Forty-two side impact cadaver sled tests were conducted at 24 and 32 km/h impact speeds into rigid and padded walls. The post-mortem human subjects were instrumented with accelerometers on the ribs and spine and chest bands around the thorax and abdomen to characterize their mechanical response during the impact. Load cells at the wall measured the impact force at the level of the thorax, abdomen, pelvis, and lower extremities. The resulting injuries were determined through detailed autopsy and radiography. Rib fractures with or without associated hemo/pneumo thorax or flail chest were the most common injury with severity ranging from AIS=0 to 5. Full and half thorax deflections were computed from the chest band data. The cadaver test data was analyzed using ANOVA and logistic regression. The age of the subject at the time of death had influence on injury outcome while gender and mass of the subject had little or no influence on injury outcome.
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

Dynamic Axial Tolerance of the Human Foot-Ankle Complex

1996-11-01
962426
Axial loading of the calcaneus-talus-tibia complex is an important injury mechanism for moderate and severe vehicular foot-ankle trauma. To develop a more definitive and quantitative relationship between biomechanical parameters such as specimen age, axial force, and injury, dynamic axial impact tests to isolated lower legs were conducted at the Medical College of Wisconsin (MCW). Twenty-six intact adult lower legs excised from unembalmed human cadavers were tested under dynamic loading using a mini-sled pendulum device. The specimens were prepared, pretest radiographs were taken, and input impact and output forces together with the pathology were obtained using load cell data. Input impact forces always exceeded the forces recorded at the distal end of the preparation. The fracture forces ranged from 4.3 to 11.4 kN.
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