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.

Unembalmed human tibias were subjected to static and dynamic three-point bending tests using the Wayne State Translational Impactor. Simple supports potted to the bone near the proximal and distal epiphyses were attached to force transducers and load was applied at midspan by a 32-kg impactor that had a rigid 25-mm diameter cylindrical contact surface. Loads were applied through the normal flesh covering the bone, and were directed from the anterior to posterior or from lateral to medial. Each bone was loaded once and sustained fracture at or near mid-span. Peak bending moments, impact speeds and load-deflection data are presented. Data regarding cross-sectional properties adjacent to the fracture site and mineral content of the specimens are included, along with a study of the correlations of strength with these various parameters.

The purpose of this study is to help understand the thoracic response and injury mechanisms in high-energy, limited-stroke, lateral velocity pulse impacts to the human chest wall. To impart such impacts, a linear impactor was developed which had a limited stroke and minimally decreased velocity during impact. The peak impact velocity was 5.6 ± 0.3 m/s. A series of BioSID and cadaver tests were conducted to measure biomechanical response and injury data. The conflicting effects of padding on increased deflection and decreased acceleration were demonstrated in tests with BioSID and cadavers. The results of tests conducted on six cadavers were used to test several proposed injury criteria for side impact. Linear regression was used to correlate each injury criterion to the number of rib fractures. This test methodology captured and supported a contrasting trend of increased chest deflection and decreased TTI when padding was introduced.

Several types of energy absorbers were tested on a sled simulating a crash deceleration using instrumented, seated erect dummies and cadavers. The energy absorbers were mechanical load limiting devices which attenuated the impact by yielding or tearing of metal. Their principal effects were to reduce the peak deceleration sustained by the occupant with the expected reduction in restraint forces. Constant load level energy absorbers were found to be unattractive because they can easily “bottom out” causing forces and body strains which could be much higher than those without absorbers. Head accelerations were significantly reduced by the energy absorbers as well as some body strain. However, spinal strains in the cadaver were not significantly reduced. They appear to be not only a function of the peak deceleration level but also of the duration of the pulse.

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.

PHASE I - A containment fixture was designed and manufactured to stabilize and preload isolated human pelves within a DYNATUP™ Drop Tower during simulated automotive side impact. The fixture was utilized during thirteen parametric tests aimed at determining boundary conditions which simulate inertial properties of whole cadavers during impacts of the isolated human pelvis. The resulting pelvic injuries (i.e., fractures) ranged from no fracture to complex acetabular fracture. These injuries were sustained with drop masses of 14.2-25.2 kg and impact velocities of 4.1-6.4 m/s. Peak force, measured during impact, ranged from 2.0-8.2 kN. PHASE II - Phrase II studies used nine additional human pelves to explored pelvis stiffness and pubis symphysis mobility under lateral impact to the greater trochanter. The containment device designed and tested in Phase I was utilized to stabilize and compressively preload the specimens during impact.

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.

A comparative study of the safety performance of asymmetric and standard HPR windshields was conducted. The effect of increased interlayer thickness was also quantified. There were four different types of asymmetric windshields which had inner layer thicknesses of 0.8 to 1.5 mm and interlayer thicknesses of 0.76 and 1.14 mm. The experimental program consisted of both full scale sled tests and headform drop tests. A total of 127 vehicular impacts were carried out using a modified Volkswagen Rabbit. The test subject was a 50th percentile Fart 572 anthropomorphic test device. The asymmetric windshields were found to have a lower lacerative potential than that of the standard windshield. The best TLI value of 5.2 was provided by a 0.8 - 0.76 mm windshield at 60 km/h. That for the standard windshield was 7.7 at the same speed. All HIC values were less than 1,000 at 48 km/h.

Heidelberg-type side impact sled tests were conducted using SID side impact dummies. These tests were run under similar conditions to a series of cadaveric sled tests funded by the Centers for Disease Control in the same lab. Tests included 6.7 and 9 m/s (15 and 20 mph) unpadded and 9 m/s padded tests. The following padding was used at the thorax: ARSAN, ARCEL, ARPAK, ARPRO, DYTHERM, 103 and 159 kPa (15 and 23 psi) crush strength paper honeycomb, and an expanded polystyrene. In all padded tests the dummy Thoracic Trauma Index, TTI(d) was below the value of 85 set by federal rulemaking (49 CFR, Part 571 et al., 1990). In contrast, cadavers in 9 m/s sled tests did not tolerate ARSAN 601 (MAIS 5) and 23 psi (159 kPa) paper honeycomb (MAIS 5), and 20 psi (138 kPa) Verticel™ honeycomb (MAIS 4), but tolerated 15 psi (103 kPa) paper honeycomb (average thoracic MAIS 2.3 in six tests).

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.

Human tolerance data have been acquired gradually over the past 25 years and are available for several body regions. There is now sufficient information to design restraint systems which can prevent serious injuries to the user and which have low injury-causing potential. This paper reviews recent research on injury mechanisms and injury tolerance. Most of the research was aimed at solving problems in automotive safety systems. Specific tolerance data for the following body regions are presented: head, chest, spine and lower extremities.

Lateral impact testing has been performed on the shoulder, thorax, abdomen and pelvis of human cadavers by several investigators. The impacts have either been whole body impacts in sled tests or pendulum type impacts to the separate regions. Based on the forces produced in these tests and the accompanying injury, initial recommendations can be made on force-tolerance and padding tolerance to the various regions of the human body in side impact. The pelvis has the highest force tolerance, followed by the shoulder, abdomen and thorax. Padding crush strength tolerance based on these forces and estimated contact areas are presented. This information is of practical importance to engineers who design door interior trim for side impact safety.

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.

Various types of padding have been used in side impact sled tests with cadavers. This paper presents a summary of performance of the padding used in NHTSA and WSU/CDC sled tests, and a summary of material properties of padding used in cadaveric sled tests. The purpose of this paper is to provide information on padding performance in cadavers, rather than optimum padding performance in dummies.

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.