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The air bag system is described in terms of four basic elements: the crash sensors and controls, the inflator, the air bag itself, and the diagnostic circuitry. A general discussion of these elements is provided and a review of air bag related injuries is also presented which includes data from various sources such as the University of Michigan Transportation Research Institute, National Highway Traffic and Safety Administration, Transport Canada, and the Insurance Institute for Highway Safety. The most frequently occurring accident type is the frontal collision and has been the main focus of safety efforts with regard to restraint systems. Air bags are an effective injur/prevention device, however their deployment can introduce new injury mechanisms. Air bags save lives and decrease the severity of major injuries in exchange for increasing the number of minor injuries.

Over 2.4 million eye injuries occur each year in the US, with over 30,000 patients left blind as a result of the trauma. The majority of these injuries occur in automobile crashes, military operations and sporting activities. This paper presents a nonlinear finite element model of the eye and the results of 22 experiments using human eyes to validate for globe rupture injury prediction. The model of the human eye consists of the cornea, sclera, lens, ciliary body, zonules, aqueous humor and vitreous body. Lagrangian membrane elements are used for the cornea and sclera, Lagrangian bricks for the lens, ciliary, and zonules, and Eulerian brick elements comprise the aqueous and vitreous. Nonlinear, isotropic material properties of the sclera and cornea were gathered from uniaxial tensile strip tests performed up to rupture. Dynamic modeling was performed using LS-Dyna.

This paper examines an originally designed airbag deployment system for use in static experimental testing. It consists of a pressure vessel and valve arrangement with pneumatic and electric controls. A piston functions like a valve when operated and is activated pneumatically to release the air in the tank. Once released, the air fills the attached airbag. The leading edge velocity can be controlled by the initial pressure in the tank, which can range up to 960 kPa. Three different test configurations were studied, which resulted in leading edge deployment speeds of approximately 20 m/s, 40 m/s, and 60 m/s. In experiments using this system, seven types of airbags were tested that differed in their material, coating, and presence of a tether. Data for each series of tests is provided. High speed video and film were used to record the deployments, and a pressure transducer measured the airbag's internal pressure.

Carotid artery injury due to motor vehicle crash has been attributed to direct impact to the neck and stretching of the artery. This study examines the response of a finite element model of the neck and carotid arteries given a farside vehicle impact. This regional carotid artery model was developed using existing material properties and based on a spine model developed by NHTSA. The finite element model was subjected to loading conditions derived from farside PMHS tests conducted at Medical College of Wisconsin. The PMHS tests represented four inboard belt loading conditions of the neck. The belts were located high on the neck, for maximal compression of the vessel, or low on the neck, for maximal excursion of the head. There was a low speed and a high speed test for each of the belt configurations. These boundary conditions were implemented in the model and the response of the carotid was quantified using strain measurements.

The objective of this study was to investigate the use of a fiber optic based sensor, ShapeTape, as an instrument for measuring abdominal and chest deflection, and to compare it to the current instrument used in impact biomechanics applications, the chestband. Drift, pressure, and temperature tests were conducted for ShapeTape alone, whereas quasi-static and dynamic loading tests were conducted as comparison tests between the chestband and ShapeTape. The effects of drift and temperature on ShapeTape were very small, averaging 0.26% and 1.2% full scale changes respectively. During the pressure test at a load of 1000 N the ShapeTape sensor tested experience a 7.47% full scale voltage change. The average errors in reporting maximum deflection of the chest form during the quasi-static loading tests were 3.35% and 1.64% for ShapeTape and the chestband respectively.

Computer simulations, dummy experiments with a new enhanced upper extremity, and small female cadaver experiments were used to analyze the small female upper extremity response under side air bag loading. After establishing the initial position, three tests were performed with the 5th percentile female hybrid III dummy, and six experiments with small female cadaver subjects. A new 5th percentile female enhanced upper extremity was developed for the dummy experiments that included a two-axis wrist load cell in addition to the existing six-axis load cells in both the forearm and humerus. Forearm pronation was also included in the new dummy upper extremity to increase the biofidelity of the interaction with the handgrip. Instrumentation for both the cadaver and dummy tests included accelerometers and magnetohydrodynamic angular rate sensors on the forearm, humerus, upper and lower spine.

Multiple series of frontal sled tests were performed to evaluate the new Thor-Lx/HIIIr lower extremity developed by the National Highway Traffic Safety Administration for retrofit use on the 50th percentile male Hybrid III. This study's objective was to compare the Thor-Lx/HIIIr to the existing Hybrid III dummy leg (HIII) from the standpoint of repeatability and effects on femur and upper body response values.\ The test-to-test repeatability of the dummy responses, as measured by the coefficient of variation (CV), was generally acceptable (CV < 10%) for all of the test conditions for both legs. Overall, tests with the Thor-Lx/HIIIr legs produced upper body movement and injury criteria values for the head and chest that were acceptably consistent and were generally indistinguishable from those produced with the HIII leg. Low right femur loads, which ranged from 4 to 25 percent of the injury assessment reference value, varied substantially test-to-test for tests with both types of legs.

The Facial and Ocular CountermeasUre Safety (FOCUS) headform is intended to aid safety equipment design in order to reduce the risk of eye and facial injuries. The purpose of this paper is to present a three part study that details the development and validation of the FOCUS synthetic eye and orbit and the corresponding eye injury criteria. The synthetic eye and orbit were designed to simulate the force-deflection response to in-situ dynamic impacts. In part I, the force-deflection response of the eye was determined based on dynamic blunt impact tests with human eyes. These data were used to validate the appropriate material for a biofidelic synthetic eye. In part II, force-deflection corridors developed from ten dynamic in-situ eye impacts were used to validate the design and material selections for the synthetic orbit assembly.

Pulmonary contusion is the most commonly identified thoracic soft tissue injury in an automobile crash and after blunt chest trauma and affects 10-17% of all trauma admissions. The mortality associated with pulmonary contusions is significant and is estimated to be 10-25%. Thus, there is a need to develop a finite element model based injury metric for pulmonary contusion for the purpose of predicting outcome. This will enable current and future finite element models of the lung to incorporate an understanding of how stress and strain may be related to contusion injuries. This study utilizes 14 impacts onto male Sprague-Dawley rats. In 5 of these tests, a calibrated weight (46 g) is dropped from a height of 44 cm directly onto the lungs of intubated, anesthetized rats in situ. Contused volume is estimated from MicroPET scans of the lung and normalized on the basis of liver uptake of 18F-FDG.

Automobile crashes are the largest single cause of death for pregnant females and the leading cause of traumatic fetal injury mortality in the United States. Current research for pregnant occupant safety utilizing computational models is limited by available pregnant tissue data. The purpose of this study is to collect experimental data from biaxial tissue tests on pregnant uterine tissue at a dynamic rate. Experimental tests were completed on pregnant porcine uterus which was chosen as a surrogate for the human pregnant uterus given its similarity and availability. Biaxial dynamic tensile tests were performed using a custom-designed system of linear motors to pull a cruciform-shaped specimen in tension simultaneously with four tissue clamps. The test series included 23 tests with corresponding peak stress and strain measurements of the central region of the specimen where optical markers tracked local displacements.

Real-world crash investigations have suggested that lower limb injury risk is increased with the occurrence of toepan intrusion in a frontal collision. In order to more closely evaluate the effects of different modes of toepan intrusion, a rotational and translational intrusion device was built for the test sled at the University of Virginia. Sled tests were performed at a velocity of 56 km/h with a belted Hybrid III occupant and a simulated knee bolster and steering wheel air bag. Lower limb injury risk measures were obtained with Hybrid III and Thor Lx dummy lower extremities. Dummy response variables of interest included tibia axial and shear loads, tibia bending moments, ankle rotations and foot and tibia accelerations. The tests were conducted with no intrusion and with a translational intrusion with a peak deceleration of approximately 175 g's with 14 cm of translation.

The purpose of this study was to develop a fracture tolerance for the elbow joint, or proximal ends of the ulna and radius, relative to the fracture risk under side-impact airbag loading. Forty experiments were performed on the elbow joints of small female cadavers. The energy source, a pneumatic impactor, was configured to apply compressive loads that match the onset rate, peak force, and momentum transfer of previously conducted side-impact airbag tests with small female subjects. Three initial orientations of the impact load angle relative to the longitudinal axis of the forearm were selected based on analysis of side-impact airbag tests with the instrumented dummy upper extremity. These included loading directions that are 0°, 20°, and 30° superior of the longitudinal axis of the forearm. Post-test necropsy revealed that 11 of the 40 tests resulted in chondral, osteochondral, or comminuted fractures of the proximal radial head or the distal trochlear notch.

This paper presents a parametric study that utilized the CVS/ATB multi-body simulation program to investigate the interaction of the hand and wrist with a door handgrip during side air bag loading. The goal was to quantify the relative severity of various hand and handgrip positions as a guide in the selection of a test matrix for laboratory testing. The air bag was represented as a multi-body system of ellipsoidal surfaces that were created to simulate a prototype seat-mounted thorax side air bag. All simulations were set in a similar static test environment as used in corresponding dummy and cadaver side air bag testing. The occupant mass and geometric properties were based on a 5th percentile female occupant in order to represent a high-risk segment of the adult population. The upper extremity model consisted of wrist and forearm rotations that were based on human volunteer data.

The purpose of this study was to investigate ocular injuries from high velocity objects projected during an automobile collision. A computational model of the human eye was developed that included ocular structures such as the orbital fatty tissue, extraocular muscles and bony orbit. In order to validate the model, the results predicted by the model were compared to those previously found experimentally. In these experiments, porcine eyes were impacted with foam particles representative of those released during the deployment of an airbag through a seamless module cover. After simulating the identical experimental conditions, the results predicted by the model were in agreement with those found experimentally. A parametric study was conducted to determine the effect of these anatomical boundary conditions. Using MADYMO, a glass particle was projected into the eye. With the fatty tissue and muscles in place, a maximum Von Mises stress of 12.8 MPa occurred in the cornea.

The purpose of this study was to develop injury risk functions for dynamic bending of the human femur in the lateral-to-medial and posterior-to-anterior loading directions. A total of 45 experiments were performed on human cadaver femurs using a dynamic three-point drop test setup. An impactor of 9.8 kg was dropped from 2.2 m for an impact velocity of 5 m/s. Five-axis load cells measured the impactor and support loads, while an in situ strain gage measured the failure strain and subsequent strain rate. All 45 tests resulted in mid-shaft femur fractures with comminuted wedge and oblique fractures as the most common fracture patterns. In the lateral-to-medial bending tests the reaction loads were 4180 ± 764 N, and the impactor loads were 4780 ± 792 N. In the posterior-to-anterior bending tests the reaction loads were 3780 ± 930 N, and the impactor loads were 4310 ± 1040 N. The difference between the sum of the reaction forces and the applied load is due to inertial effects.

This paper presents a load distribution-specific viscoelastic structural characterization of the Hybrid III 50th percentile male anthropomorphic test dummy thorax. The dummy is positioned supine on a high-speed material testing machine and ramp-and-hold tests are performed using a distributed load, a hub load, and a diagonal belt load applied to the anterior thorax of the dummy. The force-deflection response is shown to be linear viscoelastic for all loading conditions when the internal dummy instrumentation is used to measure chest deflection. When an externally measured displacement (i.e., a measurement that includes the superficial skin material) is used for the characterization, a quasilinear viscoelastic characterization is necessary. Linear and quasilinear viscoelastic model coefficients are presented for all three loading conditions.

Crash test dummies rely on biomechanical data from cadaver studies to biofidelically reproduce loading and predict injury. Unfortunately, it is difficult to obtain equivalent measurements of leg loading in a dummy and a cadaver, particularly for bending moments. A methodology is presented here to implant load cells in the tibia and fibula while minimally altering the functional anatomy of the two bones. The location and orientation of the load cells can be measured in all six degrees of freedom from post-test radiographs. Equations are given to transform tibial and fibular load cell measurements from a cadaver or dummy to a common leg coordinate frame so that test data can be meaningfully compared.

The objectives of this study were to evaluate and compare the responses, repeatability, and durability of the Thor-Lx/HIIIr and Hybrid III/Denton lower extremities in frontal sled tests. Effectiveness of the two limb types was studied by evaluating responses in different test configurations using existing and proposed Injury Assessment Reference Values (IARVs) for both leg designs. Hybrid III or Thor-Lx legs were attached to the distal femurs of a 50th percentile male Hybrid III dummy, which was subjected to three series of 56 km/h frontal sled tests with and without toepan intrusion. Due to the design differences, many of the absolute response values were different between the Hybrid III and Thor-Lx legs. The expanded measurement capabilities, modified geometry and refined responses of the Thor-Lx limbs provide a more thorough and conservative judgment of injury risk.

This paper presents a study characterizing the interaction between a small female upper extremity and a deploying side air bag. The results are based on 12 tests with small female cadavers, and 15 tests with the instrumented SAE 5th percentile female upper extremity attached to the 5th percentile Hybrid III female dummy. The upper extremity was loaded by a deploying seat mounted thoracic side air bag in a static test environment. Three types of inflators were used that varied in peak pressure and pressure onset rate. Three upper extremity positions where chosen that maximized loading to the humerus and elbow joint. Upper extremity instrumentation for both the cadaver and dummy tests included accelerometers and angular rate sensors on the forearm, humerus, and upper spine. Additional instrumentation on the cadavers included strain gage rosettes on the anterior and posterior humerus.

The goal of this project was to evaluate the effect of occupant seating and seatbelt placement on the risk of adverse fetal outcome from a motor vehicle crash. Unrestrained, 3-pt belt, and 3-pt belt plus airbag tests were simulated with the Virginia Tech pregnant occupant computational model in both a driver-side and passenger-side vehicle interior in frontal impacts at 35 kph. The pregnant occupant model is a small female human body model modified to include a finite element uterine model. The model was previously created and validated with abdominal force-deflection responses. Peak uterine strain was reduced by 30% to 50% in passenger-side simulations vs. driver-side simulations. However, in the unrestrained, passenger-side simulation, the pregnant occupant sustained a HIC score of 2820, suggesting immediate maternal death and a high likelihood of fetal death. Additional simulations were run in which the vertical position of the lap-belt was varied through three heights.