Search Results

A common injury type among foot and ankle injury is the Lisfranc trauma, or injury to the forefoot. The Lisfranc injury indicates abnormal alignment of the tarsal-metatarsal joints with the loss of their normal spatial relationships. In 2003, Smith completed a laboratory study of this injury mechanism at Wayne State University [1, 2]. He found Lisfranc trauma was correlated with impact force to the forefoot. He proposed a probability of injury function that is based on the applied force to the forefoot. This study examined the instrumentation in the foot of the dummies in the USA New Car Assessment Program (NCAP) and Insurance Institute of Highway Safety (IIHS) frontal crashes. Nineteen different passenger vehicles representing four different vehicle classes were selected based mostly on a large presence in the USA vehicle fleet. Both NCAP and IIHS crashed these nineteen makes and models.

The research reported in this paper is a follow-on to a five year research program conducted by General Motors in accordance with an administrative Settlement Agreement reached with the US Department of Transportation. This paper is the fourth in a series of technical papers intended to disseminate the results of the ongoing research [Digges 2003, 2004, 2005]. This paper summarizes progress in several of the projects dealing with underhood fires and testing of a hydrogen fuel tank. Calorimeter tests of underhood materials found a wide range of flammability for the structural plastics as well as the underhood sound insulation. Calorimeter tests of underhood fluids (lubricants and hydraulic fluid) showed that their flash points were less than 188°C and the minimum temperature of a hot surface to cause ignition was less than 325°C. Tests of four different vehicles to determine the exhaust manifold operating temperatures found a range between 241°C and 550°C.

In this paper the characteristics of rear impact crashes are examined. General information about rear impact collisions is derived from recent data from the National Automotive Sampling System, General Estimates System (NASS/GES) and Fatality Analysis Reporting System (FARS) as reported in the annual National Highway Traffic Safety Administration (NHTSA) Traffic Safety Facts. Additional details about the frequency, severity, type, and cause of injuries to front seat outboard occupants is analyzed using the National Automotive Sampling System, Crashworthiness Data System (NASS/CDS) data from 1997 to 2005. Serious head and neck injuries are focused on for further analysis. Specific cases from the CDS database that meet this classification are examined. Federal Motor Vehicle Safety Standard (FMVSS) 301-R test data is used to analyze occupant, seat, and vehicle kinematics in single impact rear collisions and to look at the occupant rebound velocity.

In recent years the AFFDL has actively attempted to develop improved techniques and criteria for providing aircraft with a capability for landing on substandard fields. A number of R&D programs have been conducted to this end. These programs have involved the participation of not only the AFFDL Landing Gear Test Facility, but also the Vicksburg Waterways Experiment Station, and various aircraft and landing gear contractors. The scope of approaches investigated includes expandable tires, extra wide tires, low pressure tires, track gear, air cushion gear, and basic flotation criteria. This paper summarizes the significant results of these programs. The paper briefly summarizes the presently available criteria for ground flotation on bare soil and indicates approaches for improving aircraft ground flotation characteristics. Also included are the results of AFFDL tests of conventional tires tested at high deflection, and of unconventional (expandable) tires which collapse for stowage.

This paper examines the distribution of injuries to belted occupants involved in frontal crashes, using data from the National Accident Sampling System. Similar studies of data from Canada, Britain, and Federal Republic of Germany are summarized. The studies are consistent in showing that head and chest injuries continue to be the most harmful to belted occupants. For restrained drivers, liver injuries contribute a significant level of harm among chest/abdominal injuries. Other significant lesions of nearly equal weight are arterial, heart, lung/pulmonary, skeletal, and crushing injuries. Brain injuries are by far the most harmful head injury, followed by skull fracture and facial fracture. The diverse distribution of injuries, and the wide variation in occupant sizes and injury tolerances are significant considerations in optimizing restraint systems for maximum injury reduction in real crashes.

The research reported in this paper is a follow-on to a five year research program conducted by General Motors in accordance with an administrative Settlement Agreement reached with the US Department of Transportation. This paper is the third in a series of technical papers intended to disseminate the results of the ongoing research [Digges 2003 and 2004]. This paper summarizes progress in several of the projects. A statistical analysis of FARS and NASS/CDS indicates that frontal collisions are the most common in both fatal and non-fatal crashes with fires. NASS/CDS indicates that most major and minor fires originate under the hood. Fire rates in FARS are higher in rollovers than in planar crashes, and most rollover fires in NASS/CDS originate under the hood.

The Crash Victim Simulator Three Dimensional Model (CVS-3D) allows the simulation of the kinematics and responses of a motor vehicle occupant or pedestrian during a crash. This paper summarizes the data requirements for the CVS-3D Model, the sources of data, and the research underway to provide additional data for modeling the occupant and the vehicle. An example of the use of the model in reconstructing an offset frontal accident is included. The results computed by the model are quite reasonable when compared with the injuries received by the occupant. The insights into the events which occurred during the crash are excellent.

The research reported in this paper is a follow-on to a five year research program conducted by General Motors in accordance with an administrative Settlement Agreement reached with the US Department of Transportation. This paper is the fourth in a series of technical papers intended to disseminate the results of the ongoing research [Digges 2004, 2005, 2006]. This paper summarizes progress in several of the projects to better understand the crash factors that are associated with crash induced fires. Part I of the paper presents the distribution of fire cases in NASS/CDS by damage severity and injury severity. It also examines the distributions by crash mode, fire origin, and fuel leakage location. The distributions of cases with fires and entrapment are also examined. Part II of the paper provides summaries of recent projects performed by MVFRI contractors. Technologies to reduce fuel leakage from siphoning and rollover are documented.

The CVS/ATB (Crash Victim Simulator/ Articulated Total Body) computer program solves the equations of motion in three dimensional space for a set of rigid bodies connected by joints. The program permits the specification of contact interaction properties between the rigid bodies and the surrounding environment. It is, therefore, possible to specify initial conditions of motion for the rigid bodies, and calculate the subsequent motion resulting from the forces imposed by the environment. The program is sufficiently general that it can be applied to a wide range of physical dynamic situations. However, the principal motivation for its development was to evaluate the interactions of the human body with the environment inside a motor vehicle during a crash. Subsequently, it has been applied to a number of other dynamic simulations including pedestrian to vehicle impacts and the emergency escape of air crew from aircraft. The CVS/ATB program is in the public domain.

This study continued the biomechanical investigations of forearm fractures caused by direct loading of steering-wheel airbags during the early stages of deployment. Twenty-four static deployments of driver airbags were conducted into the forearms of unembalmed whole cadavers using a range of airbags, including airbags that are depowered as allowed by the new federal requirements for frontal impact testing. In general, the depowered airbags showed a reduction in incidence and severity of forearm fractures compared to the pre-depowered airbags tested. Data from these twenty-four tests were combined with results from previous studies to develop a refined empirical model for fracture occurrence based on Average Distal Forearm Speed (ADFS), and a revised value for fifty-percent probability of forearm-bone fracture of 10.5 m/s. Bone mineral content, which is directly related to forearm tolerance, was found to be linearly related to arm mass.

This paper uses the National Automotive Sampling System/Crashworthiness Data System (NASS/CDS) to estimate the population of front seat occupants exposed to far-side crashes and those with MAIS 3+ and fatal injuries. Countermeasures applicable to far-side planar crashes may also have benefits in some far-side rollovers. The near-side and far-side rollover populations with MAIS 3+ injuries and fatalities are also calculated and reported. Both restrained and unrestrained occupants are considered. Populations are subdivided according to ejection status – not ejected, full ejection, partial ejection and unknown ejection. Estimates are provided for the annual number of MAIS 3+ injuries and fatalities that occur each year in each category for the following belt use scenarios: (1) belt use as reported in NASS and (2) 100% belt use. In scenario 1, the exposure and casualties for the unbelted population are also shown. About 34% of the MAIS 3+F injuries in side crashes are in far-side crashes.

The National Highway Traffic Safety Administration has sponsored extensive research to improve the frontal protection of motor vehicles. Most of the research was conducted during the 1970's when belt usage rates were less than 10%. At that time, the research objectives did not anticipate the combination of air bags and three point manual belts as the restraint of choice for the 1990's. Consequently, little research was undertaken to extend the performance of this combination. However, the research conducted at that time offers opportunities for significant additional improvements in frontal protection. The purpose of this paper is to summarize some of the relevant research which was sponsored by NHTSA under the direction of the authors. Results will be highlighted which are particularly applicable to current vehicle configurations. Opportunities for further improvement, and required research are discussed.

This paper presents an analysis of the National Automotive Sampling System (NASS) and the Fatal Accident Reporting Systems (FARS) data for the combined years 1988–97 with respect to side impacts. Accident variables, vehicle variables, occupant variables and their interactions have been considered, with special emphasis on occupant injury patterns. The crash modes considered are car-to-car, car-to-LTV (light trucks and vans) and car to narrow object, with special emphasis on the latter two. This study was undertaken to obtain a better understanding of injury patterns in lateral impacts, their associated causation factors, and to obtain information that will assist in prioritizing crash injury research problems in near side impacts. Of particular interest is the increase in the population of light trucks and vans and their influence on side impact priorities. Conclusions will be drawn regarding the frequency and injury severity of car-to-LTV’s and car to narrow objects.

Two new techniques for investigating the thermal skin-burn potential of airbags are presented. A reduced-volume airbag test procedure has been developed to obtain airbag pressures that are representative of a dynamic ridedown event during a static deployment. Temperature and heat flux measurements made with this procedure can be used to predict airbag thermal burn potential. Measurements from the reduced-volume procedure are complemented by data obtained using two gas-jet simulators, called heatguns. Gas is vented in controlled bursts from a large, heated, pressurized tank of gas onto a target surface. Heat flux measurements on the target surface have been used to develop quantitative models of the relationships between gas jet characteristics and burn potential.

This study investigated the mechanisms of traumatic rupture of the aorta (TRA). Eight unembalmed human cadavers were tested using various dynamic blunt loading modes. Impacts were conducted using a 32-kg impactor with a 152-mm face, and high-speed seatbelt pretensioners. High-speed biplane x-ray was used to visualize aortic motion within the mediastinum, and to measure deformation of the aorta. An axillary thoracotomy approach was used to access the peri-isthmic region to place radiopaque markers on the aorta. The cadavers were inverted for testing. Clinically relevant TRA was observed in seven of the tests. Peak average longitudinal Lagrange strain was 0.644, with the average peak for all tests being 0.208 ± 0.216. Peak intraluminal pressure of 165 kPa was recorded. Longitudinal stretch of the aorta was found to be a principal component of injury causation. Stretch of the aorta was generated by thoracic deformation, which is required for injury to occur.

This paper describes and references published NHTSA safety research relative to problem definition and countermeasures evaluation for light trucks and vans. The research cited includes accident data analysis, vehicle component developments, air bag and passive belt research, and testing procedure developments in both crashworthiness and crash avoidance areas. Research programs underway which have application to light trucks and vans are indicated.

A total of eight low-speed, rear-end impact tests using two Post Mortem Human Subjects (PMHS) in a seated posture are reported. These tests were conducted using a HYGE-style mini-sled. Two test conditions were employed: 8 kph without a headrestraint or 16 kph with a headrestraint. Upper-body kinematics were captured for each test using a combination of transducers and high-speed video. A 3-2-2-2-accelerometer package was used to measure the generalized 3D kinematics of both the head and pelvis. An angular rate sensor and two single-axis linear accelerometers were used to measure angular speed, angular acceleration, and linear acceleration of T1 in the sagittal plane. Two high-speed video cameras were used to track targets rigidly attached to the head, T1, and pelvis. The cervical spine kinematics were captured with a high-speed, biplane x-ray system by tracking radiopaque markers implanted into each cervical vertebra.

The principal focus of this study was the measurement of relative brain motion with respect to the skull using a high-speed, biplanar x-ray system and neutral density targets (NDTs). A suspension fixture was used for testing of inverted, perfused, human cadaver heads. Each specimen was subjected to multiple tests, either struck at rest using a 152-mm-diameter padded impactor face, or stopped against an angled surface from steady-state motion. The impacts were to the frontal and occipital regions. An array of multiple NDTs was implanted in a double-column scheme of 5 and 6 targets, with 10 mm between targets in each column and 80 mm between columns. These columns were implanted in the temporoparietal and occipitoparietal regions. The impacts produced peak resultant accelerations of 10 to 150 g, and peak angular accelerations between 1000 and 8000 rad/s2. For all but one test, the peak angular speeds ranged from 17 to 22 rad/s.

A significant number of documented ankle injuries incurred in automobile accidents indicate some form of lateral loading is present to either cause or influence injury. A high percentage of these cases occur in the absence of occupant compartment intrusion. To date, no specific ankle injury mechanism has been identified to explain these types of injuries. To investigate this problem, several resources were used including full-scale crash test data, finite element models, and case study field data. Results from car-to-car, offset frontal crash tests indicate a significant lateral acceleration (10-18 g) occurs at the same time as the peak in longitudinal acceleration. The combined loading condition results in a significant lateral force being applied to the foot-ankle region while the leg region is under maximum compression.

The objectives of this study were to examine the response, repeatability, and injury predictive ability of the Hybrid III small-female dummy to static out-of-position (OOP) deployments using a depowered driver-side airbag. Five dummy tests were conducted in two OOP configurations by two different laboratories. The OOP configurations were nose-on-rim (NOR) and chest-on-bag (COB). Four cadaver tests were conducted using unembalmed small-female cadavers and the same airbags used in the dummy tests under similar OOP conditions. One cadaver test was designed to increase airbag loading of the face and neck (a forehead-on-rim, or FOR test). Comparison between the dummy tests of Lab 1 and of Lab 2 indicated the test conditions and results were repeatable. In the cadaver tests no skull fractures or neck injuries occurred. However, all four cadavers had multiple rib fractures.