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The American population is getting heavier and automated vehicles will accommodate unconventional postures. While studies replicating mid-size and upright fore-aft seated occupants are numerous, experiments with post-mortem human subjects (PMHS) with obese and reclined occupants are sparse. The objective of this study was to compare the kinematics of the head-neck, torso and pelvis, and document injuries and injury patterns in frontal impacts. Six PMHS with a mean body mass index of 38.2 ± 5.3 kg/m2 were equally divided between upright and reclined groups (seatback: 23°, 45°), restrained by a three-point integrated belt, positioned on a semi-rigid seat, and exposed to low and moderate velocities (15, 32 km/h). Data included belt loads, spinal accelerations, kinematics, and injuries from x-rays, computed tomography, and necropsy. At 15 km/h speed, no significant difference in the occupant kinematics and evidence of orthopedic failure was observed.

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.

Lower extremity injuries caused by floor plate impacts through the axis of the lower leg are a major source of injury and disability for civilian and military vehicle occupants. A collection of PMHS pendulum impacts was revisited to obtain data for paired booted/unbooted test on the same leg. Five sets of paired pendulum impacts (10 experiments in total) were found using four lower legs from two PMHS. The PMHS size and age was representative of an average young adult male. In these tests, a PMHS leg was impacted by a 3.4 or 5.8 kg pendulum with an initial velocity of 5, 7, or 10 m/s (42-288 J). A matching LS-DYNA finite element model was developed to replicate the experiments and provide additional energy, strain, and stress data. Simulation results matched the PMHS data using peak values and CORA curve correlations. Experimental forces ranged between 1.9 and 12.1 kN experimentally and 2.0 and 11.7 kN in simulation.

Cervical spine injuries can occur in military scenarios from events such as underbody blast events. Such scenarios impart inferior-to-superior loads to the spine. The objective of this study is to develop human injury risk curves (IRCs) under this loading mode using Post Mortem Human Surrogates (PMHS). Twenty-five PMHS head-neck complexes were obtained, screened for pre-existing trauma, bone densities were determined, pre-tests radiological images were taken, fixed in polymethylmethacrylate at the T2-T3 level, a load cell was attached to the distal end of the preparation, positioned end on custom vertical accelerator device based on the military-seating posture, donned with a combat helmet, and impacted at the base. Posttest images were obtained, and gross dissection was done to confirm injuries to all specimens. Axial and resultant forces at the cervico-thoracic joint was used to develop the IRCs using survival analysis.

Recent epidemiology studies have reported increase in lumbar spine injuries in frontal crashes. Whole human body finite element models (FEHBM) are frequently used to delineate mechanisms of such injuries. However, the accuracy of these models in mimicking the response of human spine relies on the characterization data of the spine model. The current study set out to generate characterization data that can be input to FEHBM lumbar spine, to obtain biofidelic responses from the models. Twenty-five lumbar functional spinal units were tested under compressive loading. A hydraulic testing machine was used to load the superior ends of the specimens. A 75N load was placed on the superior PMMA to remove the laxity in the joint and mimic the physiological load. There were three loading sequences, namely, preconditioning, 0.5 m/s (non-injurious) and 1.0 m/s (failure). Forces and displacements were collected using six-axis load cell and VICON targets.

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 objective of the present exploratory study is to understand occupant responses in oblique and side-facing seats in the aviation environment, which are increasingly installed in modern aircrafts. Sled tests were conducted using intact Post Mortem Human Surrogates (PMHS) seated in custom seats approximating standard aircraft geometry. End conditions were selected to represent candidate aviation seat and restraint configurations. Three-dimensional head center-of-gravity linear accelerations, head angular velocities, and linear accelerations of the T1, T6, and T12 spinous processes, and sacrum were obtained. Three-dimensional kinematics relative to the seat were obtained from retroreflective targets attached to the head, T1, T6, T12, and sacrum. All specimens sustained spinal injuries, although variations existed by vertebral level.

A new anthropomorphic test device (ATD) is being developed by the US Army to be responsive to vertical loading during a vehicle underbody blast event. To obtain design parameters for the new ATD, a series of non-injurious tests were conducted to derive biofidelity response corridors for the foot-ankle complex under vertical loading. Isolated post mortem human surrogate (PMHS) lower leg specimens were tested with and without military boot and in different initial foot-ankle positions. Instrumentation included a six-axis load cell at the proximal end, three-axis accelerometers at proximal and distal tibia, and calcaneus, and strain gages. Average proximal tibia axial forces for a neutral-positioned foot were about 2 kN for a 4 m/s test, 4 kN for 6 m/s test and 6 kN for an 8 m/s test. The force time-to-peak values were from 3 to 5 msec and calcaneus acceleration rise times were 2 to 8 msec.

While numerous studies have been conducted to determine side impact responses of Post Mortem Human Surrogates (PMHS) using sled and other equipment, experiments using the biological surrogate in modern full-scale vehicles are not available. The present study investigated the presence of oblique loading in moving deformable barrier and pole tests. Three-point belt restrained PMHS were positioned in the left front and left rear seats in the former and left front seat in the latter condition and tested according to consumer testing protocols. Three chestbands were used in each specimen (upper, middle and lower thorax). Accelerometers were secured to the skull, shoulder, upper, middle and lower thoracic vertebrae, sternum, and sacrum. Chestband signals were processed to determine magnitudes and angulations of peak deflections. The magnitude and timing of various signal peaks are given. Vehicle accelerations, door velocities, and seat belt loads are also given.

During certain events such as underbody blasts due to improvised explosive devices, occupants in military vehicles are exposed to inferior-to-superior loading from the pelvis. Injuries to the pelvis-sacrum-lumbar spine complex have been reported from these events. The mechanism of load transmission and potential variables defining the migration of injuries between pelvis and or spinal structures are not defined. This study applied inferior-to-superior impacts to the tuberosities of the ischium of supine-positioned five post mortem human subjects (PMHS) using different acceleration profiles, defined using shape, magnitude and duration parameters. Seventeen tests were conducted. Overlay temporal plots were presented for normalized (impulse momentum approach) forces and accelerations of the sacrum and spine.

Eight whole fresh-frozen cadavers (6 female, 2 male) that were elderly and/or female were laterally impacted using UMTRI's dual-sled side-impact test facility. Cadavers were not excluded on the basis of old age or bone diseases that affect tolerance. A thinly padded, multi-segment impactor was used that independently measured force histories applied to the shoulder, thorax, abdomen, greater trochanter, iliac wing, and femur of each PMHS. Impactor plates were adjusted vertically and laterally toward the subject so that contact with body regions occurred simultaneously and so that each segment contacted the same region on every subject. This configuration minimized the effects of body shape on load sharing between regions. Prior to all tests, cadavers were CT scanned to check for pre-existing skeletal injuries. Cadavers were excluded if they had pre-existing rib fractures or had undergone CPR.

The objective of the study was to determine the thorax and abdomen deflection-time corridors in oblique side impacts. Data were analyzed from Post Mortem Human Surrogate (PMHS) sled tests, certain aspects of which were previously published. A modular and scalable anthropometry-specific segmented load-wall system was fixed to the platform of the sled. Region-specific forces were recorded from load cells attached to the load-wall plates. The thorax and abdomen regions were instrumented with chestbands, and deflection contours were obtained. Biomechanical responses were processed using the impulse-momentum normalization method and scaled to the mid-size male mass, 76-kg. The individual effective masses of the thorax and abdomen were used to determine the scale factors in each sled test, thus using the response from each experiment. The maximum deflections and their times of attainments were obtained, and mean and plus minus one standard deviation corridors were derived.

NHTSA estimates that more than half of the lives saved (168,524) in car crashes between 1960 and 2002 were due to the use of seat belts. Nevertheless, while seat belts are vital to occupant crash protection, safety researchers continue efforts to further enhance the capability of seat belts in reducing injury and fatality risk in automotive crashes. Examples of seat belt design concepts that have been investigated by researchers include inflatable, 4-point, and reverse geometry seat belts. In 2011, Ford Motor Company introduced the first rear seat inflatable seat belts into production vehicles. A series of tests with child and small female-sized Anthropomorphic Test Devices (ATD) and small, elderly female Post Mortem Human Subjects (PMHS) was performed to evaluate interactions of prototype inflatable seat belts with the chest, upper torso, head and neck of children and small occupants, from infants to young adolescents.

Lateral impact tests were performed using seven male post-mortem human subjects (PMHS) to characterize the force-deflection response of contacted body regions, including the lower abdomen. All tests were performed using a dual-sled, side-impact test facility. A segmented impactor was mounted on a sled that was pneumatically accelerated into a second, initially stationary sled on which a subject was seated facing perpendicular to the direction of impact. Positions of impactor segments were adjusted for each subject so that forces applied to different anatomic regions, including thorax, abdomen, greater trochanter, iliac wing, and thigh, could be independently measured on each PMHS. The impactor contact surfaces were located in the same vertical plane, except that the abdomen plate was offset 5.1 cm towards the subject.

The objective of the present study was to determine the thorax and abdomen deflections sustained by post mortem human surrogate (PMHS) in oblique side impact sled tests and compare the responses and injuries with pure lateral tests. Oblique impact tests were conducted using modular and non-modular load-wall designs, with the former capable of accommodating varying anthropometry. Tests were conducted at 6.7 m/s velocity. Deflection responses from chestbands were analyzed from 15 PMHS tests: five each from modular load-wall oblique, non-modular load-wall oblique and non-modular load-wall pure lateral impacts. The thorax and abdomen peak deflections were greater in non-modular load-wall oblique than pure lateral tests. Peak abdomen deflections were statistically significantly different while the upper thorax deflections demonstrated a trend towards significance.

This study evaluated the biomechanical performance of a rear-seat inflatable seatbelt system and compared it to that of a 3-point seatbelt system, which has a long history of good real-world performance. Frontal-impact sled tests were conducted with Hybrid III anthropomorphic test devices (ATDs) and with post mortem human subjects (PMHS) using both restraint systems and a generic rear-seat configuration. Results from these tests demonstrated: a) reduction in forward head excursion with the inflatable seatbelt system when compared to that of a 3-point seatbelt and; b) a reduction in ATD and PMHS peak chest deflections and the number of PMHS rib fractures with the inflatable seatbelt system and c) a reduction in PMHS cervical-spine injuries, due to the interaction of the chin with the inflated shoulder belt. These results suggest that an inflatable seatbelt system will offer additional benefits to some occupants in the rear seats.

The objective of this study was to determine region-specific deflection responses of the WorldSID and ES2-re devices under pure lateral and oblique side impact loading. A modular, anthropometry-specific load wall was used. It consisted of the Shoulder, Thorax, Abdomen, superior Pelvis, and inferior Pelvis plates, termed the STAPP load wall design. The two devices were positioned upright on the platform of a bench seat, and sled tests were conducted at 3.4, 6.7, and 7.5 m/s. Two chestbands were used on each dummy at the thoracic and abdominal regions. Internal sensors were also used. Effective peak deflections were obtained from the chestband contours. Based on the preselected lateral-most point/location on the pretest contour, “internal sensor-type” peak deflections were also obtained using chestband contours. In addition, peak deflection data were obtained from internal sensor records.

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.

The NASS-CDS (1998-2008) and CIREN datasets were analyzed to identify factors contributing to abdominal injury in crash environments where belt use and airbag deployment are common. In frontal impacts, the percentage of occupants sustaining abdominal injury is three times higher for unbelted compared to belted front-row adult occupants (p≺0.0001) at both AIS2+ and AIS3+ injury levels. Airbag deployment does not substantially affect the percentage of occupants who sustain abdominal injuries in frontal impacts (p=0.6171), while belt use reduces the percentage of occupants sustaining abdominal injury in both nearside and farside crashes (p≺0.0001). Right-front passengers in right-side impacts have the highest risk (1.91%) of AIS 3+ abdominal injury (p=0.03). The percentage of occupants with AIS 3+ abdominal injuries does not vary with age for frontal, nearside, or farside impacts.

This study characterized thoracoabdominal response to posterolateral loading from a seat-mounted side airbag. Seven unembalmed post-mortem human subjects were exposed to ten airbag deployments. Subjects were positioned such that the deploying airbag first contacted the posterolateral thorax between T6 and L1 while stationary (n = 3 x 2 aspects) or while subjected to left lateral sled impact at ΔV = 6.7 m/s (n = 4). Chestband contours were analyzed to quantify deformation direction in the thoracic x-y plane (zero degrees indicating anterior and 180° indicating posterior), magnitude, rate, and viscous response. Skeletal injuries were consistent with posterolateral contact; visceral injuries consisted of renal (n = 1) or splenic (n = 3) lacerations. Deformation direction was transient during sled impact, progressing from 122 ± 5° at deformation onset to 90° following maximum deflection. Angles from stationary subjects progressed from 141 ± 9° to 120°.