Search Results

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.

Fracture to the lumbo-pelvis region is prevalent in warfighters seated in military vehicles exposed to under-body blast (UBB). Previous high-rate vertical loading experimentation using whole body post-mortem human surrogates (PMHS) indicated that pelvis fracture tends to occur earlier in events and under higher magnitude seat input conditions compared to lumbar spine fracture. The current study hypothesizes that fracture of the pelvis under high-rate vertical loading reduces load transfer to the lumbar spine, thus reducing the potential for spine fracture. PMHS lumbo-pelvis components (L4-pelvis) were tested under high-rate vertical loading and force and acceleration metrics were measured both inferior-to and superior-to the specimen. The ratio of inferior-to-superior responses was significantly reduced by unstable pelvis fracture for all metrics and a trend of reduced ratio was observed with increased pelvis AIS severity.

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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.

Under body blast (UBB) loading to military transport vehicles is known to cause foot-ankle fractures to occupants due to energy transfer from the vehicle floor to the feet of the soldier. The soldier posture, the proximity of the event with respect to the soldier, the personal protective equipment (PPE) and age/sex of the soldier are some variables that can influence injury severity and injury patterns. Recently conducted experiments to simulate the loading environment to the human foot/ankle in UBB events (~5ms rise time) with variables such as posture, age and PPE were used for the current study. The objective of this study was to determine statistically if these variables affected the primary injury predictors, and develop injury risk curves. Fifty below-knee post mortem human surrogate (PMHS) legs were used for statistical analysis. Injuries to specimens involved isolated and multiple fractures of varying severity.

The purpose of the study was to distinguish the role of vehicle structure in frontal impacts in published coded National Automotive Sampling System (NASS-CDS) data. The criteria used: Collision Deformation Classification (CDC) coding rules, crush profile locator data and the projected location of longitudinal structural members in models of vehicle class sizes used by NASS-CDS. Two classifiers were developed to augment the CDC system. The Coincidence classifier indicates the relationship between the quadrant of the clock face the crash vector originates in and the aspect of the end plane the center of damage is located. It has three values: Linear (12 o'clock impacts) Consistent and Variant ("oblique" Principal Directions of Force or PDOFs). The second classifier indicates the number of longitudinal members engaged: 0, 1 or 2. NASS-CDS data for sample years 2005 to 2009 was filtered for occupants involved in impacts with the highest ranked speed change assigned to the front-end plane.

The purpose of this study was to determine neck strength characteristics of children indirectly using scaling relationships through a caprine animal model. Because of the necessity to evaluate airbag designs for injury risk to the out- of-position child, a strong foundation of experimental data is needed to obtain appropriate tolerance values. Cadaver caprine cervical spines of different ages were tested mechanically in non-destructive bending and destructive tensile modes. Injuries induced in destructive testing such as endplate failure and ligament tears were consistent with clinical observations. Specimens demonstrated statistically significant increased strength characteristics with age. Scaling relationships were developed with respect to the adult specimens. For the tensile failure load the scaling percentages were 78%, 38%, 20%, and 12% for the twelve-, six-, three-, and one-year-old, respectively.

The objective of this study was to subject small female and large male cadavers to simulated rear impact, document soft-tissue injuries to the neck, determine the kinematics, forces and moments at the occipital condyles, and evaluate neck injury risks using peak force, peak tension and normalized tension-extension criteria. Five unembalmed intact human cadavers (four small females and one large male) were prepared using accelerometers and targets at the head, T1, iliac crest, and sacrum. The specimens were placed on a custom- designed seat without head restraint and subjected to rear impact using sled equipment. High-speed cameras were used for kinematic coverage. After the test, x-rays were obtained, computed tomography scans were taken, and anatomical sections were obtained using a cryomicrotome. Two female specimens were tested at 4.3 m/s (mean) and the other two were tested at 6.8 m/s (mean), and one large male specimen was subjected to 6.6 m/s velocity.

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.

The purpose of the study was to identify all small overlap impacts using published coded NASS-CDS data. Three sets of criteria were used: CDC measurements; crush profiles for frontal impacts; and crush profiles for oblique side impacts to the fender component. All criteria were applied to passenger and non-passenger cars and their different vehicle class sizes. Data were analyzed based on fatalities and different levels of MAIS trauma. The overall data set based on CDC codes for 2005 to 2008 NASS-CDS data had 9,206 MAIS=0; 13,522 MAIS=1-2; 3,600 MAIS=3-6; 1,092 MAIS=7; and 961 fatal cases. For the weighted ensemble, these data were: 5,800,295; 4,324,773; 269,042; 219,481; and 44,906 cases, respectively. However, these cases reduced to 1071, 1468, 364, 82, and 87 raw cases with the application of the CDC criteria for frontal impacts.

Oblique crashes to the vehicle front corner may not be characteristic of either frontal or side impacts. This research evaluated occupant response in oblique crashes for a driver, rear adult passenger, and a rear child passenger. Occupant responses and injury potential were evaluated for seating positions as either a far-or near-side occupant. Two crash tests were conducted with a subcompact car. The vehicle’s longitudinal axis was oriented 45 degrees to the direction of travel on a moving platform and pulled into a wall at 56 km/h. Dummies utilized for the seating positions were an adult dummy (50th-percentile-HIII and THOR-Alpha) for the front-left (driver) position, 5th-percentile-female-HIII for the right-rear position, and a 3-year-old HIII for the left-rear position.