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Abstract Traumatic brain injury is a leading cause of global death and disability. Clinically relevant large animal models are a vital tool for understanding the biomechanics of injury, providing validation data for computation models, and advancing clinical translation of laboratory findings. It is well-established that large angular accelerations of the head can cause TBI, but the effect of head impact on the extent and severity of brain pathology remains unclear. Clinically, most TBIs occur with direct head impact, as opposed to inertial injuries where the head is accelerated without direct impact. There are currently no active large animal models of impact TBI. Sheep may provide a valuable model for studying TBI biomechanics, with relatively large brains that are similar in structure to that of humans. The aim of this project is to develop an ovine model of impact TBI to study the relationships between impact mechanics and brain pathology.

Abstract Objective: This study aimed to optimize restraint systems and improve safety equity by using parametric human body models (HBMs) and vehicle models accounting for variations in occupant size and shape as well as vehicle type. Methodology: A diverse set of finite element (FE) HBMs were developed by morphing the GHBMC midsize male simplified model into statistically predicted skeleton and body shape geometries with varied age, stature, and body mass index (BMI). A parametric vehicle model was equipped with driver, front passenger, knee, and curtain airbags along with seat belts with pretensioner(s) and load limiter and has been validated against US-NCAP results from four vehicles (Corolla, Accord, RAV4, F150). Ten student groups were formed for this study, and each group picked a vehicle model, occupant side (driver vs. passenger), and an occupant model among the 60 HBMs.

Eighteen research posters were prepared and presented by student authors at the 18th Annual Injury Biomechanics Symposium. The posters covered a wide breadth of works-in-progress and recently completed projects.

Abstract Letter from the Special Issue Editors

Abstract The primary objective of this study was to evaluate the fatality risk of powered two-wheeler (PTW) riders across different impact orientations while controlling for different opponent vehicle (OV) types. For the crash configurations with higher fatality rate, the secondary objective was to create an initial speed–fatality prediction model specific to the United States. Data from the NHTSA Crash Reporting Sampling System and the Fatality Analysis Reporting System from 2017 to 2020 was used to estimate the odds of the different possible vehicle combinations and orientations in PTW–OV crashes. Binary logistic regression was then used to model the speed–fatality risk relationship for the configurations with the highest fatality odds. Results showed that collisions with heavy trucks were more likely to be fatal for PTW riders than those with other OV types.

Abstract In this study, a parametric thoracic spine (T-spine) model was developed to account for morphological variations among the adult population. A total of 84 CT scans were collected, and the subjects were evenly distributed among age groups and both sexes. CT segmentation, landmarking, and mesh morphing were performed to map a template mesh onto the T-spine vertebrae for each sampled subject. Generalized procrustes analysis (GPA), principal component analysis (PCA), and linear regression analysis were then performed to investigate the morphological variations and develop prediction models. A total of 13 statistical models, including 12 T-spine vertebrae and a spinal curvature model, were combined to predict a full T-spine 3D geometry with any combination of age, sex, stature, and body mass index (BMI). A leave-one-out root mean square error (RMSE) analysis was conducted for each node of the mesh predicted by the statistical model for every T-spine vertebra.

Abstract Introduction: The use of less lethal impact munitions (LLIMs) by law enforcement has increased in frequency, especially following nationwide protests regarding police brutality and racial injustice in the summer of 2020. There are several reports of the projectiles causing severe injuries when they penetrate the skin including pulmonary contusions, bone fractures, liver lacerations, and, in some cases, death. The penetration threshold of skin in different body regions is due to differences in the underlying structure (varying degree of muscle, adipose tissue, and presence or absence of bone). Objective: The objective of this study was to further investigate what factors affected the likelihood of skin penetration in various body regions and to develop corresponding penetration risk curves.

Abstract Compressive impacts on the cervical spine can result in bony fractures. Bone fragments displaced into the spinal canal produce spinal canal occlusion, increasing the potential for spinal cord injury (SCI). Human body models (HBMs) provide an opportunity to investigate SCI but currently need to be improved in their ability to model compression fractures and the resulting material flow. Previous work to improve fracture prediction included the development of an anisotropic material model for the bone (hard tissues) of the vertebrae assessed in a functional spinal unit (FSU) model. In the FSU model, bony failure was modeled with strain-based element erosion, with a limitation that material that could occlude the spinal canal during compression was removed when an element was eroded.

Abstract Analysis of Kinetic Metrics in Submarining vs Non-Submarining Conditions for a 6YO Pediatric Human Body Model in Frontal Impacts

Abstract Bilateral knee impacts were conducted on Hybrid III and THOR 5th percentile female anthropomorphic test devices (ATDs), and the results were compared to previously reported female PMHS data. Each ATD was impacted at velocities of 2.5, 3.5, and 4.9 m/s. Knee–thigh–hip (KTH) loading data, obtained either via direct measurement or through exercising a one-dimensional lumped parameter model (LPM), was analyzed for differences in loading characteristics including the maximum force, time to maximum force, loading rate, and loading duration. In general, the Hybrid III had the highest loading rate and maximum force, and the lowest loading duration and time to peak force for each point along KTH. Conversely, the PMHS generally had the lowest loading rate and maximum force, and the highest loading duration and time to peak force for each point along KTH.

Abstract Pre-crash vehicle maneuvers are known to affect occupant posture and kinematics, which consequently may influence injury risks during a collision. In this study, the influence of pre-crash vehicle maneuvers on the injury risks of front-seated occupants during a frontal crash was numerically evaluated. A generic buck vehicle model was developed based on a publicly available FE model, which included the vehicle interior and the front passenger airbag (PAB). The pre-crash phase was simulated using specific rigid-body human models with active joints (GHBMCsi-pre models) developed based on exterior shapes of the simplified deformable human model (GHBMCsi) representing a 50th male subject. Two pre-crash maneuvers representing (1) a generic 1g braking and (2) turning-and-braking scenarios were simulated.

Abstract Pyrotechnic seat belt pretensioners typically remove 8–15 cm of belt slack and help couple an occupant to the seat. Our study investigated pretensioner deployment on forward-leaning, live volunteers. The forward-leaning position was chosen because research indicates that passengers frequently depart from a standard sitting position. Characteristics of the 3D kinematics of forward-leaning volunteers following pretensioner deployment determines if body size is correlated with subject response. Nine adult subjects (three female), ages 18–43 years old, across a wide range of body sizes (50–120 kg) were tested. The age was limited to young, active adults as pyrotechnic pretensioners can deliver a notable force to the trunk. Subjects assumed a forward-leaning position, with 26 cm between C7 and the headrest, in a laboratory setting that replicated the passenger seat of a vehicle.

Abstract The objective of this study was to compare head, neck, and chest injury risks between front and rear-seated Hybrid III 50th-percentile male anthropomorphic test devices (ATDs) during matched frontal impacts. Seven vehicles were converted to rear seat test bucks (two sedans, three mid-size SUVs, one subcompact SUV, and one minivan) and then used to perform sled testing with vehicle-specific frontal NCAP acceleration pulses and a rear seated (i.e., second row) Hybrid III 50th male ATD. Matched front seat Hybrid III 50th male ATD data were obtained from the NHTSA Vehicle Crash Test Database for each vehicle. HIC15, Nij, maximum chest acceleration, and maximum chest deflection were compared between the front and rear seat tests, as well as between vehicles with conventional and advanced three-point belt restraint systems in the rear seat. Additionally, a modified version of the NCAP frontal star rating was calculated for the front and rear seat tests.

Abstract Oblique motor vehicle crashes can cause serious head or brain injuries due to contact with interior vehicle structures even with the deployment of air bags, as they are not yet completely successful in preventing traumatic brain injury. Rotational head velocity is strongly correlated to the risk of brain injury, and this head motion is potentially related to the tangential friction force developed during contact between the head and air bags. Although crash test dummy head skins are designed with appropriate mass properties and anthropometry to simulate the normal direction impact response of the human head, it is not known whether they accurately represent the frictional properties of human skin during air bag interaction. This study experimentally characterized the dynamic friction coefficient between human/dummy skins and air bag fabrics using a pin-on-disc tribometer.

Abstract Letter from the Special Issue Editors

Abstract In autonomous driving vehicles with an automation level greater than three, the autonomous system is responsible for safe driving, instead of the human driver. Hence, the driving safety of autonomous driving vehicles must be ensured before they are used on the road. Because it is not realistic to evaluate all test conditions in real traffic, computer simulation methods can be used. Since driving safety performance can be evaluated by simulating different driving scenarios and calculating the criticality metrics that represent dangerous collision risks, it is necessary to study and define the criticality metrics for the type of driving scenarios. This study focused on the risk of collisions in the confluence area because it was known that the accident rate in the confluence area is much higher than on the main roadway.

Abstract Parking an articulated vehicle is a challenging task that requires skill, experience, and visibility from the driver. An automatic parking system for articulated vehicles can make this task easier and more efficient. This article proposes a novel method that finds an optimal path and controls the vehicle with an innovative method while considering its kinematics and environmental constraints and attempts to mathematically explain the behavior of a driver who can perform a complex scenario, called the articulated vehicle park maneuver, without falling into the jackknifing phenomena. In other words, the proposed method models how drivers park articulated vehicles in difficult situations, using different sub-scenarios and mathematical models.

Abstract The progressive development toward highly automated driving poses major challenges for the release and validation process in the automotive industry, because the immense number of test kilometers that have to be covered with the vehicle cannot be tackled to any extent with established test methods, which are highly focused on the real vehicle. For this reason, new methodologies are required. Simulation-based testing and, in particular, virtual driving tests will play an important role in this context. A basic prerequisite for achieving a significant reduction in the test effort with the real vehicle through these simulations are realistic test scenarios. For this reason, this article presents a novel approach for generating relevant traffic situations based on a traffic flow simulation in SUMO and a vehicle dynamics simulation in CarMaker. The procedure is shown schematically for an emergency braking function.

Abstract In the last decades we have witnessed an increasing number of military operations in urban environments. Complex urban operations require high standards of training, equipment, and personnel. Emergency forces on the ground will need specialized vehicles to support them in all parts and levels of this extremely demanding environment including the subterranean and interior of infrastructure. The development of vehicles for this environment has lagged but offers a high payoff. This article describes the method for developing a concept for an urban operations vehicle by characterization of the urban environment, deduction of key issues, evaluation of related prototyping, science fiction story-typing of the requirements for such a vehicle, and comparison with field-proven and scalable solutions. Embedding these thoughts into a comprehensive research and development program provides lines of development, setting the stage for further research.

Abstract To have a more complete understanding of the fuel effects on each subsequent stage of a stochastic preignition event in a spark-ignition engine and to build on the previous work of understanding the propensity of fuel to initiate and sustain a preignition flame, this work is focused on examining the role of fuel on the onset of knock and the intensity of superknock once the unburned mixture reaches certain conditions ahead of the preignition flame. Using a “skip advance” spark test method to simulate preignition flames initiated at different cylinder conditions, more than 20 single- and multicomponent fuels were ranked based on the condition required to reach the onset of knock (the start of end-gas autoignition) and the condition that leads to severe superknock intensities.