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Bicycle helmet testing is conducted under laboratory conditions, which do not always reflect real-world conditions. This paper reports on a survey of chin strap use among a test group of bicycle riders and the results of three tests: (1) a retention harness system static test to determine elongation properties; (2) a loop and position device test to determine the effects of the combination of the webbing positioner and the elongation properties of the webbing; and (3) a dynamic test to demonstrate the compatibility of the helmet retention system under real-world type dynamic impact loading conditions. The survey showed that bicyclists wear their helmets with an average of 4.76 cm of strap clearance when tested with a 500 gram load. Tests of chin strap shows that substantial motion and elongation can occur under nominal loading conditions. Comparative dynamic testing resulted in a bicycle helmet rotating forward significantly and exposing the back of the dummy head, while an equestrian helmet with...

The development of human injury tolerance is difficult because of the physical differences between humans and animals, the available dummies, and tissue of the cadaver. Furthermore, human volunteer testing can clearly only be done at subinjurious levels. While considerable biomechanical injury evidence exists for the adult human based on cadaveric studies, little information is available for the pediatric population. However, some material is available from skull bone modulus studies and from the fetal tendon strength and early pediatric studies of the newborn. A review of living human, animal, and human cadaveric studies, which forms the basis for head-neck injury criterion are given. Examples of the use of the Hybrid III dummy for injury prediction such as in the Malibu rollover tests and air bag mechanisms show neck injury levels are considerably above the proposed Malibu 2000 N level. Language: en

The mid to lower cervical spine is a common site for compression related injury. In the present study, we determined the patterns of localized strain distribution in the anterior aspect of the vertebral body and in the lateral masses of lower cervical three-segment units. Miniature strain gages were mounted to human cadaveric vertebrae. Each preparation was line-loaded using a knife-edge oriented in the coronal plane that was moved incrementally from anterior to posterior to induce compression-flexion or compression-extension loading. Uniform compressive loading and failure runs were also conducted. Failure tests indicated strain shifting to “restabilize” the preparation after failure of a component. Under these various compressive loading vectors, the location which resulted in the least amount of deformation for a given force application (i.e., stiffest axis) was quantified to be in the region between 0.5–1.0 cm anterior to the posterior longitudinal ligament. The location in which line-loading produced no rotation (i.e., balance point) was in this region; it was also close to where the vertebral body strains change from compressive to tensile. Strain values from line loading in this region produced similar strains as recorded under uniform compressive loading, and this was also the region of minimum strain. The region of minimum strain was also more pronounced under higher magnitudes of loading, suggesting that as the maximum load carrying capacity is reached the stiffest axis becomes more well defined.

This study was conducted to determine the biomechanics of the human head under quasistatic and dynamic loads. Twelve unembalmed intact human cadaver heads were tested to failure using an electrohydraulic testing device. Quasistatic loading was done at a rate of 2.5 mm/s. Impact loading tests were conducted at a rate of 7.1 to 8.0 m/s. Vertex, parietal, temporal, frontal, and occipital regions were selected as the loading sites. Pathological alterations were determined by pretest and posttest radiography, close-up computed tomography (CT) images, macroscopic evaluation, and defleshing techniques. Biomechanical force-deflection response, stiffness, and energy-absorbing characteristics were obtained. Results indicated the skull to have nonlinear structural response. The failure loads, deflections, stiffness, and energies ranged from 4.5 to 14.1 kN, 3.4 to 16.6 mm, 467 to 5867 N/mm, and 14.1 to 68.5 J, respectively. The overall mean values of these parameters for quasistatic and dynamic loads were 6.4 kN (+/- 1.1), 12.0 mm (+/- 1.6), 812 N/mm (+/- 139), 33.5 J (+/- 8.5), and 11.9 kN (+/-0.9), 5.8 mm (+/- 1.0), 4023 N/mm (+/- 541), 28.0 J (+/- 5.1), respectively. It should be emphasized that these values do not account for the individual variations in the anatomical locations on the cranium of the specimens. While the X-rays and CT scans identified the fracture, the precise direction and location of the impact on the skull were not apparent in these images. Fracture widths were consistently wider at sites remote from the loading region. Consequently, based on retrospective images, it may not be appropriate to extrapolate the anatomical region that sustained the impact forces. The quantified biomechanical response parameters will assist in the development and validation of finite element models of head injury.

In an effort to delineate the tolerance of the human facial skeleton with respect to steering wheel impact, research was conducted using human cadavers. We reported the biodynamics of steering-wheel-induced facial trauma due to impacts at the unsupported rim (Yoganandan, Pintar & Sances, 1991). The present study was conducted to determine the probability of facial bone fracture secondary to impact at the spoke-rim junction. Either zygoma was impacted once onto the spoke-rim junction at velocities ranging from 1.4–6.9 m s . A six-axis load cell placed under the hub documented the generalized force histories. Interface force at the impact location was computed using the generalized force and deformation histories recorded at the spoke-rim junction using transformation principles. Bone mineral content was also determined. Facial pathology was evaluated using x-ray, two- and three-dimensional computed tomography, and defleshed skulls. Fractures of the zygoma, orbit, and maxilla were observed. While higher impact velocities resulted in propagation of fracture to the contralateral site, unilateral fractures of less severity occurred at lower speeds. Results indicated that a force level of 1525 N corresponds to 50% probability of facial fracture for the spoke-rim junction. Consequently, significant amelioration of facial injuries can be achieved if the forces are kept below this limit.

A biomechanical test system has been developed and validated to conduct controlled uniaxial impact experiments of head and facial trauma. The design reduces off-axis accelerations which are not in the direction of impact and allows accurate positioning of test specimens. Impact forces, displacement histories, impulses at impact and spectral responses are compared to free-fall test results at contact velocities representative of facial injuries (2.5, 3.1 and 3.8 m s −1 ). Models based on the experimental results are developed to reveal stiffness and inertial properties of impact for use in the design of biomechanically protective steering wheels, air bags and other potential impact structures. The results indicate that the system provides a flexible yet controllable method for positioning and testing impact structures reliably.

The purpose of this study was to examine the force-deformation characteristics of football helmets subjected to compressive loading on the crown surface. Tests were conducted at quasi-static and dynamic rates of loading. Energies were computed from the force-deformation data. The padding systems represented by the helmets differed in their ability to absorb energy under varying loading rates. Helmets using pneumatic or combination pneumatic-foam padding systems were the most successful while suspension helmets were able to absorb the least amount of energy. The evaluation of energy absorption characteristics is an alternative method of describing the effectiveness of football helmets in preventing head injury.

The present study was undertaken to determine the impact biomechanics of the facial skeleton secondary to steering wheel loading. Because of the particular relevance of the zygomatic bony complex in facial trauma during motor-vehicle accidents, tests were conducted by impacting the zygoma using a vertical drop impact test system. Zygoma was impacted once onto either soft or rigid wheel surfaces at velocities of up to 6.7 m/s. Peak impact forces at the cadaver zygoma were computed from the generalized force and deformation histories using matrix transformation principles. Structural abnormalities were assessed using pre- and post-test plain radiography, two-and three-dimensional computed tomography, and defleshing techniques. At impact velocities of 1.7 to 6.7 m/s, the human cadaver zygoma did not exhibit clinically significant fractures if the peak force was below 1335 N for the soft wheel interface and 1153 N for the rigid wheel interface. Consequently, to mitigate facial injuries due to unsupported rim impact, the data from the present study suggests that the peak dynamic force should be kept within these limits.

Electrical burns or ischemia (induced by vascular ligation) were produced in the legs of 15 anesthetized dogs to study evolution of tissue changes compared with impedance alterations. After the application of 1-ampere currents at 60 Hz, animals were monitored from 1 to 4 days. Muscle impendance was measured with frequency sweeping to determine tissue destruction. Nuclear magnetic resonance spectroscopy (phosphorus 31) was used to assess metabolic activity, and results were compared to impedance measurements. In burned limbs, 70% reduction in muscle impedance was seen, which corresponds to decreased metabolic activity (absent organic phosphates) and suggests necrosis. Visually viable tissue had impedance decreases of 25% and levels of organic phosphates slightly lower than normal. Relaxation frequencies in dogs with severe burns exceeded 80 kHz; in viable tissue, 30 to 40 kHz (normal: 30 kHz). In ischemic muscle, organic phosphates decreased rapidly (1 to 2 hours); impedance changes evolved more slowly (1 day), but they ultimately reached the same degree of severity. Measurement of impedance may be a valuable adjunct in the evaluation of electrical burns, since significant changes strongly suggest nonviability.

In this study, the authors have developed a technique to replicate clinically relevant traumatic cervical spine injuries and determined the injury biomechanics. Because of the importance of compressive forces in neck injuries, this research was conducted using compression as the primary load vector. Six fresh human cadaveric head-neck complexes were prepared by fixing the distal end in methylmethacrylate. Tests were done with varying loading rates to include quasistatic and dynamic conditions. For quasistatic experiments, the proximal end was fixed to the piston of the testing device. In dynamic tests, the cranium was unconstrained, and to maintain stability, the effects of the spinal musculature were simulated by means of pulleys, deadweights, and springs in the anterior and posterior parts of the head-neck complex. Quasistatic tests conducted at a rate of 2.0 mm/sec produced cervical spine trauma at forces ranging from 1.7 to 2.3 kN, with deformations ranging from 2.2 to 3.7 cm. The specimens were deep-frozen at the level of injury, preserving the local deformation of the tissues to enable a detailed evaluation immediately after the injury. Dynamic tests conducted at velocities of 3.2 to 5.7 m/sec resulted in impact injuries at one level of the head-neck complex. The applied forces at the vertex were considerably higher than those recorded at the distal end. The failure deformations for both the quasistatic (2.2-3.7 cm) and dynamic (1.7-3.2 cm) tests, however, were found to be similar, suggesting that the human head-neck complex is a deformation-sensitive structure.

The purpose of the study was to investigate the effect of roof deformation and head clearance on the dynamic forces transmitted to the head and neck of a restrained occupant in an automobile rollover. A modified version of the Total Articulated Body three-dimensional model was used. The occupant was modeled using fifteen segments connected by fourteen joints. These segments represented the lower torso, center torso, upper torso, neck, head, right upper leg, right lower leg, right foot, left upper leg, left lower leg, left foot, right upper arm, right lower arm, left upper arm, and left lower arm. The automobile was modeled as primary and secondary vehicle segments. The primary vehicle was modeled by 16 contact planes representing the seat cushion, seat back, floor-board, toe-board, left header, windshield, lower dash, mid-dash, instrument panel, left door, right door, fire-wall, footwell, upper dash, header, and latch. The secondary vehicle simulated the intrusion of the roof into the occupant compartment. A lap belt and a shoulder harness were used to hold the occupant in the driver seat. The components of the vehicle and the ground were represented by planes with specified contacts with body segments. Occupant motions indicated various dynamic contacts with the vehicle interior. Higher forces were generally associated with increased accelerations between the occupant's segments (e.g., head) and the vehicle planes (e.g., roof). Increased roof crush increased the forces transmitted to the head-neck region of the occupant. Increased head clearance for a given roof deformation decreased the forces transmitted to the occupant's head and neck. Without roof crush minimal forces were produced. These simulations indicate that for a restrained non-ejected occupant, there is a critical combination of roof crush and head clearance for a given roll velocity that limits the dynamic forces transmitted to the occupant's head and neck. Beyond this threshold an increase in transmitted forces may lead to injury.

In the event of a large scale, biological or chemical terrorist attack it is unlikely that local emergency response organizations will have sufficient quantities of dedicated ambulances to evacuate all of the affected victims. As a potential solution to this problem, we have developed a device that can be retrofitted to a variety of government or civilian utility vehicles in order to convert them for emergency medical transport (US Pat. 7,028,351). Each installed device allows the host vehicle to safely transport either a single patient on a stretcher or multiple ambulatory patients. Additionally, each device provides a means for temporary or permanent attachment of emergency medical equipment. When not in use, the device can be collapsed to improve ease and efficiency of storage. Preliminary analyses of certain highly loaded structures on the device were carried out using known principles of solid mechanics. The analyses were carried out assuming the highest reasonable loading condition. This condition was determined to occur when the device is configured for the transport three 95th percentile males and 20 kg of medical equipment. This loading condition was assumed to be more severe than any that might occur due to an attendant performing CPR, or any other medical procedures, on a single supine patient. The base sections of the load bearing stretcher supports were then modeled using 3D CAD software and run through a finite element analysis (FEA) as a means to more accurately simulate the stresses that are likely to occur in the actual parts. As the device must be highly mobile, these analyses were used to confirm that the load bearing structures can be manufactured from low cost materials and still be light enough to be easily transported. Future work will include sizing and installation studies to ensure that the production version of the device can be rapidly implemented in a wide variety of private, commercial, and government utility vehicles. Language: en

Side impact crashes are the second most severe motor vehicle accidents resulting in serious and fatal injuries. One of the occupant restraint systems in the vehicle is the three point lap/shoulder harness. However, the lap/shoulder restraint is not effective in a far-side crash (impact is opposite to the occupant location) since the occupant may slip out of the shoulder harness. The present comprehensive study was designed to delineate the biomechanics of far-side planar crashes. The first part of the study involves a car-to-car crash to study the crash dynamics and occupant kinematics; the second part involves an epidemiological analysis of NASS/CDS 1988-2003 database to study the distribution of serious injury; the third part includes the mathematical MADYMO analysis to study the occupant kinematics in detail; and the fourth part includes an in-depth analysis of a real world far-side accident to delineate the injury mechanism and occupant kinematics. Results indicate that the shoulder harness is ineffective in far-side crashes. The upper torso of the belted driver dummy slips out of the shoulder harness and interacted with the opposite vehicle interior such as the door panel. The unbelted occupants had a similar head injury severity pattern compared to belted occupants. The present study is another step to advance towards better understanding of the prevention, treatment and rehabilitation of side impact injuries.

Motor vehicle accidents involving pole impacts often result in serious head and neck injuries to occupants. Pole impacts are typically associated with rollover and side collisions. During such events, the roof structure is often deformed into the occupant survival space. The existence of a strengthened roof structure would reduce roof deformation and accordingly provide better protection to occupants. The present study examines the effect of reinforced (strengthened) roofs using experimental crash study and computer model simulation. The experimental study includes the production cab structure of a pickup truck. The cab structure was loaded using an actual telephone pole under controlled laboratory conditions. The cab structure was subjected to two separate load conditions at the A-pillar and door frame. The contact force and deformation were measured using a force gauge and potentiometer, respectively. A computer finite element model was created to simulate the experimental studies. The results of finite element model matched well with experimental data during two different load conditions. The validated finite element model was then used to simulate a reinforced roof structure. The reinforced roof significantly reduced the structural deformations compared to those observed in the production roof. The peak deformation was reduced by approximately 75% and peak velocity was reduced by approximately 50%. Such a reduction in the deformation of the roof structure helps to maintain a safe occupant survival space.

The present study evaluates the biomechanical aspects of injuries sustained by occupants of passenger cars during collisions with the trailer portion of a tractor/trailer rig. In such collisions, the occupants of the passenger car often sustain serious injuries when the passenger car passes beneath the trailer. This process by which the car "underrides" the trailer occurs due to the mismatch in height between the lowermost edge of the trailer and the crash mitigation structures in the vehicle. The study outlines a car-to-trailer crash testing methodology used to determine the effectiveness of one potential trailer underride guard in preventing serious injuries to occupants of passenger cars. The results from initial crash tests suggest that occupants of cars that collide with the unguarded sides of trailers are at a high risk of serious injury to the head, neck, and chest due the large intrusion of the roof and roof support structures into the occupant compartment. Testing of a trailer fitted with an underride guard showed that occupants of vehicles that collide with the sides of trailers that have been modified to engage the energy absorbing structures of passenger cars are exposed to a smaller risk of injury.

The present study examines the biomechanical implications of 3-point lap/shoulder seat belts and frontal air bags to the injury probabilities for occupants of varying anthropometry, during frontal collisions. Using Mathematical Dynamic Modeling (MADYMO) software, a variety of simulated frontal crash tests were conducted to evaluate the effectiveness of seat belts and air bags in reducing probability of injury to different sized occupants. The simulations included virtual models of the 5th percentile female, 50th percentile male, and 95th percentile male to represent three occupant size classes. The test matrix paired each of these dummy sizes with four restraint system configurations. The configurations examined were seat belt only, air bag only, both seat belt and air bag, and none. Each of the simulated crashes was modeled to replicate a direct (12 O'clock) frontal collision with a total change in velocity of 56.3kph. Likelihood of serious injury was determined through the calculation of Head Injury Criteria (HIC,36ms), angular acceleration of the head center of gravity, and the Nij neck injury criteria. The results generally suggested that air bags produce a more significant reduction in HIC for larger belted occupants than they do for smaller belted occupants, and that whether belted or not, smaller occupants received the largest reduction in head CG angular acceleration due to the existence of an air bag. Though clear trends were not noted in the neck injury values, it was noted that the simulations with out air bags produced two results that failed the injury criterion, while no serious neck injuries would be expected based on the values produced in the simulations with air bags. The study suggested that a properly timed air bag deployment can reduce injury potential for all occupants of all sizes, but that the magnitude of this benefit is dependent on anthropometry.

The National Highway Traffic Safety Administration has concluded that there is a relationship between roof intrusion and the risk of injury to belted occupants in rollovers events. Previous testing on many different production vehicle types indicates that damage consistent with field rollover accidents can be achieved through inverted drop testing from small drop heights. It has been shown in previous drop test pairs with Hybrid III dummies, that the amount of roof intrusion is related to occupant neck injury. This paper analyzes inverted drop testing performed on Ford F250 Crew Cab production and reinforced pickups. Each of these pickup tests used Hybrid III test dummies in order to evaluate the occupant injury potential in relation to roof intrusion. The reinforced truck's residual crush was an order of magnitude less than the production truck crush. These tests indicated that the reduction of roof crush resulted in a direct reduction in neck loading and therefore an increase in occupant protection. In addition, it was found that the restraint loading was inversely related to the neck loading of the dummies.

The distribution of current density induced by magnetic stimulation coils were mapped in five cats using the loaded probe technique [1,2]. Mapping is essential for determination of neural excitation regions, which presently are not well defined. The results show that the current density is dependent on the tissue resistivity, head geometry and coil location. This data will be useful for the verification and development of mathematical models for electromagnetic stimulation.

A better understanding of occupant kinematics in rollover accidents helps to advance biomechanical knowledge and to enhance the safety features of motor vehicles. While many rollover accident simulation studies have adopted the static approach to delineate the occupant kinematics in rollover accidents, very few studies have attempted the dynamic approach. The present work was designed to study the biomechanics of restrained occupants during rollover accidents using the steady-state dynamic spit test and to address the importance of keeping the lap belt fastened. Experimental tests were conducted using an anthropometric 50% Hybrid III dummy in a vehicle. The vehicle was rotated at 180 degrees/second and the dummy was restrained using a standard three-point restraint system. The lap belt of the dummy was fastened either by using the cinching latch plate or by locking the retractor. Three configurations of shoulder belt harness were simulated: shoulder belt loose on chest with cinch plate, shoulder belt under the left arm and shoulder belt behind the chest. In all tests, the dummy stayed within the confinement of the vehicle indicating that the securely fastened lap belt holds the dummy with dynamic movement of 3 1/2" to 4". The results show that occupant movement in rollover accidents is least affected by various shoulder harness positions with a securely fastened lap belt. The present study forms a first step in delineating the biomechanics of occupants in rollover accidents.

Roof crush occurs and potentially contributes to serious or fatal occupant injury in 26% of rollovers. It is likely that glazing retention is related to the degree of roof crush experienced in rollover accidents. Occupant ejection (including partial ejection) is the leading cause of death and injury in rollover accidents. In fatal passenger car accidents involving ejection, 34% were ejected through the side windows. Side window glass retention during a rollover is likely to significantly reduce occupant ejections. The inverted drop test methodology is a test procedure to evaluate the structural integrity of roofs under loadings similar to those seen in real world rollovers. Recent testing on many different vehicle types indicates that damage consistent with field rollover accidents can be achieved through inverted drop testing at very small drop heights. Drop test comparisons were performed on 16 pairs of vehicles representing a large spectrum of vehicle types. Each vehicle pair includes a production vehicle and a vehicle with a reinforced roof structure dropped under the same test conditions. This paper offers several examples of post-production reinforcements to roof structures that significantly increase the crush resistance of the roof as measured by inverted drop tests. These modifications were implemented with minimal impact on vehicle styling, interior space and visual clearances. The results of these modifications indicate that roof crush can be mitigated by nearly an order of magnitude, as roof crush was reduced by 44-91% with only a 1-2.3% increase in vehicle weight. Additionally, this paper analyzes the glazing breakage patterns in the moveable tempered side windows on the side adjacent to the vehicle impact point in the inverted drop tests. A comparison is made between the production vehicles and the reinforced vehicles in order to determine if the amount roof crush is related to glazing integrity in the side windows. Lastly, two drop test pairs, performed with Hybrid III test dummies, indicates that the reduction of roof crush resulted in a direct reduction in neck loading and therefore an increase in occupant protection.

Government recommendations to place children into the rear areas of motor vehicles to avoid airbag induced injuries have been complicated by the fact that most adult occupied front seats will collapse into the rear area during rear-impacts, and thus pose another potentially serious injury hazard to rear-seated children. Many variables affect whether or not a front seat occupant will collapse into the rear child, and whether that interaction could be injurious to the child. For instance, the severity of rear impact, coupled with front and rear occupant sizes (mass and stature), and the level of front seat strength, all interrelate to influence whether or not a rear seated child is likely to be impacted and possibly injured. The most common types of child injuries in these instances are head and chest injuries. In this study, a "high-low" experimental method was employed with a multi-level "factorial analysis" technique to study "multivariate" biomechanics of child head injury potential determined from rear-seated 3 and 6 year-old child surrogates in different types of vehicle bodies mounted to a sled system. The sled-buck systems were towed rearward into crushable barriers that matched the crash pulses of the vehicle types being tested. Various sizes of adult surrogates (i.e. 50 kg up to 110 kg), seated in both the "typical" low strength "single recliner" collapsing type front seat (i.e. 3.2 kN) and a much stronger "belt-integrated" seat design (i.e. up to 14.5 kN), were tested in the two different "sled body-buck" set-ups at various impact levels (i.e. 22.5 to 50 kph). One set-up used a popular minivan vehicle body with "built-in booster" seats for the 3 year-old. The other used a 4-door family sedan vehicle body with the 6 year-old in a standard rear bench seat. The parameters of the tests enabled the experimental data to be combined into polynomial "head injury" functions of the independent variables so the "likelihood" of rear child head-injury potential could be "mapped" over ranges of the key parameters. Accident cases were compared with predictions to verify the methodology.

Seat belt system restrains and protects occupants in motor vehicle crashes and any slack in seat belt system induces additional loading on occupant. Signs of belt loading are more obvious in high-speed frontal collisions with heavy occupants. However subtle changes may occur at low speeds or with low forces from occupants during rollovers. In certain cases, the seat belt webbing is twisted and loaded by the occupant. The loading of webbing induces an observable fold/crimp on the seat belt. The purpose of the study is to biomechanically evaluate the force required to produce such marks using an anthropometric physical test dummy. Two tests were conducted to determine the amount of force required to put an observable fold/crimp in a shoulder belt. A head form designed by Voight Hodgson was used to represent the neck which interacted with the belt. The force was applied with a pneumatic pull ram (central hydraulic 89182 N) and the force was measured with a 44,000 N transducer load cell (DSM-10K). Results indicate that the force of over 1,000 N produced a fold or crimp in the belt.

The seemingly never-ending increase in popularity of the more rollover-prone Sport Utility Vehicle type vehicles (SUVs) has provided an increased focus and urgency on rollover occupant protection. Field research has made clear that traditional, contemporary motor vehicle seatbelt retractors often fail to restrain occupants as expected. Various researchers have documented laboratory tests results and cited numerous real-world case studies describing these circumstances. These studies have typically focused on the response of the retractor’s inertial acceleration sensing lockup device. This device has been shown to allow surprising amounts of seatbelt spool out during long duration accident sequences with resulting multi-directional vehicle acceleration pulses such as those seen in typical rollover crashes. Further, increased injury potential has been discussed and attributed to such webbing spool out. One commonly implemented design countermeasure, or redundancy, to the retractor’s inertial sensor is a webbing velocity sensor intended to lock up the retractor independent of vehicle acceleration. This paper reports laboratory test data evaluating a wide spectrum of webbing velocity sensor designs found in current production vehicles. This study evaluates their relative performance, corresponding injury potential and occupant protection aspects of these designs.Copyright © 2004 by ASME

In this study, computer simulations of rear impacts were performed with an available ATB (Articulated Total Body) computer code to demonstrate an efficient and accurate means for assessing safety performance and hazards associated with occupied front seat collapse into a rear seat area occupied by children. The analysis considered a wide range of different sized front-seated adults (i.e. 50 kg females to 110 kg males), various types of front seats with a range of ultimate collapse strengths (i.e. 3.5kN up to 12.5kN), and various impact severities with speed changes between 20 to 50 kph. A 3 year-old child was used as the model for the rear child surrogate seated in the backbench seat of a 2-door sedan. An actual vehicle crash pulse was used as the basis for the analysis pulses. After performing the computer analysis predictions, sled-buck experimental tests were run with the same parameter range, and a full vehicle interior, to validate the human model predictions. Predicted head accelerations for the rear seated child and the front-seated adult were compared with the test results. Good correlation was achieved for the predicted and test head accelerations, as well as the resultant “head injury criteria” curves with actual accident cases of injured children.Copyright © 2004 by ASME

The purpose of the current study was to evaluate the likelihood of inertial release of various production side release automotive seat belt buckles under acceleration loading conditions that could be expected to occur in real world accident events. Each test sample was secured to a specially designed vertical acceleration test fixture. This produced a rigid mount, which allowed impacts to be transmitted to the test buckle. A commercially available M/RAD 0909 Pneumatic Shock Machine was used to control the magnitude, shape and duration of the pulses transmitted to the fixture and test buckle. To measure and analyze the shock pulse generated by the M/RAD Pneumatic Shock Machine, an M/RAD SRA-1200 Shock Instrumentation System was used with the capacity to capture, display and analyze half-sine, saw tooth and square wave pulses. A display screen and computer printouts record peak accelerations, pulse durations and change in velocity. An ICP 305A04 accelerometer was attached to the base of the test fixture. All information was recorded at a rate of 8 kHz and was filtered using a digital four pole Butterworth zero phase shift filter, and a low pass filtering system set at L-P1 with a cutoff of 1100 Hz. The current test fixture was designed to accommodate various production side release buckles with interchangeable jaw plates, for the different style buckles, to provide a “rigid mount.” A constant load can be placed on the latch plate and can be varied from 4 to 133 N. The forces for a fixed latch side buckle did not open upto accelerations of about 480 G’s. In contrast, unprotected side release buckle released at accelerations of about one fourth that of protected.Copyright © 2004 by ASME

Roof intrusion and roof contact injury are common factors in rollovers. Rollover crashes are the most dangerous collision type for light duty vehicles, measured by the ratios of fatal and serious injuries to the number of occupants involved in tow away crashes according to the National Automotive Sampling System. Over half of those sustaining injury with the occurrence of roof intrusion were belted. NHTSA estimates that roof crush intrusion occurs, and potentially contributes to serious or fatal occupant injury, in about 26% of the rollover crashes. Modern automobile vehicles utilize thin sheet metal construction formed into complex sections, which are spotwelded together. During vehicular rollovers, the roof is subjected to multi-directional loading which generally leads to localized buckling in the sheet metal roof pillars and subsequent intrusion into the occupant’s survival space. The utilization of expanding epoxies and rigid polyurethane foams within the sheet metal sections can delay wall buckling through localized confinement. This composite system, sheet metal sections filled with epoxy, demonstrates significant enhancements in peak force and energy absorption under multiple loading conditions. 4-point bending tests on representative vehicle sheet metal sections show a 6-fold increase in peak strength with the composite systems. Inverted drop tests comparisons document the additional survival space retained using the composite sheet metal and epoxy system.Copyright © 2004 by ASME

The purpose of the study was to determine the force-deflection characteristics of the chest of the human surrogate dummy during the loading typical of traumatic asphyxia conditions. The 5th percentile female Hybrid III and 50th percentile male Hybrid III anthropomorphic dummies were used. The vehicle rear bumper impacted the chest of the dummy at idle speed and was allowed to remain in contact with the chest. A total of 14 tests were conducted. The chest force was measured using the load cell and chest deflection was measured using the potentiometer. High-speed photography was used to collect the kinematics data of the dummy. The measured peak deflection was above the proposed injury assessment reference value for chest compression. The peak force was found to be injurious.

This article outlines the history, development, and safety aspects of glass and its use in motor vehicles. It traces the manufacture and describes the characteristics of laminated and tempered glass. It further compares the differences in injuries caused by impact with laminated and tempered glass. The development, use, and results of high penetration resistance (HPR) laminated glass for windshields are examined. Head and neck injuries from impact with glass and glazing structures are delineated. Results of studies with laminated and tempered glass are presented. The probability and severity of injuries occurring secondary to partial or full ejection of vehicle occupants are discussed, and the differences between the performance of laminated and tempered glass are highlighted. Current research to quantify head and neck injury parameters caused by glass impact during rollover is described. The biomechanics of head and neck injury assessment and the development of injury prediction parameters and reference values, respectively, are reviewed.

Various studies have reported that inertially sensitive buckles are susceptible to impact unlatching. The present work synthesizes the results from various experimental studies conducted over the years to study the mechanical behavior of buckles and subsequent injuries to occupants. First, the side press button seat buckle due to impact a lateral impact from an adjacent child restraint seat component indicated that the side button RCF-67 buckle released at a speed of 2.2 m/sec with a force range of 264 to 440 N and acceleration range of 100 to 175 G. In contrast, the top button Autoliv Lockarm buckles did not release up to 1300 vertical G's. Second, side release RCF-67 buckles when loaded with the webbing required approximately three times more force to open than top press buckles. Inverted occupants in a three-point belt could not release the RCF-67 buckle. Third, a side sled impact on the drivers side of a production vehicle buck with a three-point belt and a RCF-67 buckle was done at 7 m/s to 8 m/s. A convertible child seat with a dummy in the passenger seat moved inboard toward the buckle and unlatched it. Fourth, an intact vehicle drop study at 0.3 m showed that the accelerations on a JDC buckle on a metal stalk are large compared to acceleration of the floor pan. The present study provides comprehensive data to evaluate the mechanical behavior of seat buckles under various motor vehicle crash conditions.

Significantly more fatalities and serious injuries occur due to ejection in roll over accidents. The present study was conducted to determine the occupant retention and head-neck injury potential aspects of laminated glass in side door windows and sunroofs during roll over accidents. The test protocol for this study was based on National Highway Traffic Safety Administration (NHTSA) studies for advanced glazing. The impact study of 18 kg with head-neck form was conducted on laminated glass of side doors and sunroofs from production vehicles. The drop speed was varied from 11 to 16 kph. The Hybrid III 50% male dummy head-neck form was impacted on the approximately center of the glass portion of the windows. The head injury criteria, head resultant acceleration, and neck loads and moments were quantified. A series of drop tests were conducted on roll down side windows with laminated glass. The head-neck biomechanical parameters were well below the critical value injury tolerance limits. Results indicated that the glass contained the dummy assembly and the head-neck biomechanical parameters were below the critical value injury tolerance limits in simulated rollover accidents. The present study demonstrates that head-neck injury is unlikely due to laminated glass side windows and sunroof laminated glass used in production vehicles during rollover accidents and that the dummy is contained by the laminated glazing.

In the mid 1990's the U.S. Department of Transportation made recommendations to place children and infants into the rear seating areas of motor vehicles to avoid front seat airbag induced injuries and fatalities. In most rear-impacts, however, the adult occupied front seats will collapse into the rear occupant area and pose another potentially serious injury hazard to the rear-seated children. Since rear-impacts involve a wide range of speeds, impact severity, and various sizes of adults in collapsing front seats, a multi-variable experimental method was employed in conjunction with a multi-level "factorial analysis" technique to study injury potential of rear-seated children. Various sizes of Hybrid III adult surrogates, seated in a "typical" average strength collapsing type of front seat, and a three-year-old Hybrid III child surrogate, seated on a built-in booster seat located directly behind the front adult occupant, were tested at various impact severity levels in a popular "minivan" sled-buck test set up. A total of five test configurations were utilized in this study. Three levels of velocity changes ranging from 22.5 to 42.5 kph were used. The average of peak accelerations on the sled-buck tests ranged from approximately 8.2 G's up to about 11.1 G's, with absolute peak values of just over 14 G's at the higher velocity change. The parameters of the test configuration enabled the experimental data to be combined into a polynomial "injury" function of the two primary independent variables (i.e. front seat adult occupant weight and velocity change) so that the "likelihood" of rear child "injury potential" could be determined over a wide range of the key parameters. The experimentally derived head injury data was used to obtain a preliminary HIC (Head Injury Criteria) polynomial fit at the 900 level for the rear-seated child. Several actual accident cases were compared with the preliminary polynomial fit. This study provides a test efficient, multi-variable, method to compare the injury biomechanical data with actual accident cases.

Inverted drop testing of vehicles is a methodology that has long been used by the automotive industry and researchers to test roof integrity and is currently being considered by the National Highway Traffic Safety Administration as a roof strength test. In 1990 a study was reported which involved 8 dolly rollover tests and 5 inverted drop tests. These studies were conducted with restrained Hybrid III instrumented Anthropometric Test Devices (ATD) in production and rollcaged vehicles to investigate the relationship between roof strength and occupant injury potential. The 5 inverted drop tests included in the study provided a methodology producing "repeatable roof impacts" exposing the ATDs to the similar impact environment as those seen in the dolly rollover tests. Authors have conducted two inverted drop test sets as part of an investigation of two real world rollover accidents. Hybrid-III ATD's were used in each test with instrumented head and necks. Both test sets confirm that reduction of roof intrusion and increased headroom can significantly enhance occupant protection. In both test pairs, the neck force of the dummy in the vehicle with less crush and more survival space was significantly lower. Reduced roof crush and dynamic preservation of the occupant survival space resulted in only minor occupant contact and minimal occupant loading, establishing a clear causal relationship between roof crush and neck injuries.

The multi-planar and multiple impact long duration accident sequence of a real world rollover results in multidirectional vehicle acceleration pulses and multiplanar occupant motions not typically seen in a planar crash sequence. Various researchers have documented that, while contemporary production emergency locking seatbelt retractors (ELRs) have been found to be extremely effective in the planar crashes in which they are extensively evaluated, when subjected to multi-planar acceleration environments their response may be different than expected. Specifically, accelerations in the vertical plane have been shown to substantially affect the timeliness of the retractors inertial sensor moving out of its neutral position and locking the seat belt. An analysis of the vehicle occupant motions relative to the acceleration pulses sensed at the retractor location indicates a time phase shift that, under certain circumstances, can result in unexpected seat belt spool out and occupant excursions in these multi-planar, multiple impact crash sequences. This paper will review the various previous studies focusing on the retractors response to these multidirectional, including vertical, acceleration environments and review statistical studies based upon U.S. government collected data indicating a significant difference in belt usage rates in rollover accidents as compared to all other planar accident modes. A significant number of real world accident case studies will be reviewed wherein the performance of ELR equipped seatbelt systems spooled out. Finally, the typical occupant injury and the associated mechanism due to belt spool out in real world accidents will be delineated.

Various studies suggest that yielding vehicular seats reduce the potential for injury, in contrast others suggest serious trauma to front and rear seat occupants when front seats collapse rearwards. This study shows that front seat failures cause greater serious injury to front seat occupants with the same change in vehicle speed due to a rear impact.

Potential injury mitigation of padding on vehicular roll bars was evaluated. After market and metal air gap padding markedly reduced the head injury criterion (HIC) angular acceleration and angular velocity compared to the stock foam roll bar padding.

An investigation was made of the validity and repeatability of a vertical drop impact test system (VDITS), through experimental comparison to free-fall test results at an impact velocity of 5.5 mph. The VDITS is designed to simulate the dynamics of traumatic injury to the head and chest. Comparison of the two systems was based on force/moment and kinematic histories, multiaxis frequency responses, and system model parameters. The VDITS test system has proved to be effective in approximating the unconstrained conditions of free-fall while also providing a method for controlling off-axis motion. >

Magnetically induced current density has been measured in different concentrations of saline solution and in the cerebral cortex of cats in vivo. The results show that the current density decreases with distance from the stimulating coil and with increasing resistivity. The presence of the cranium attenuates the current density in the cortical tissue. The studies show that it is possible to measure directly current densities induced by magnetic fields. >

The objective of the study was to delineate the critical regions of the human cervical spine and determine the mechanisms of injury in motor vehicle accidents (MVA). The clinical data were gathered from patient records. Results indicated that while neck injuries in MVA are complex and can occur at any level of the cervical spine, the craniocervical junction (among fatalities) and the lower cervical spine (among survivors) were the most frequently injured. Among survivors with complete or incomplete quadriplegia, compression-flexion was the most common injury mechanism. However, rotation forces appeared to contribute to injury among nonparalyzing neck injuries. >