Vehicular Causation Factors and Conceptual Design Modifications to Reduce Aortic Strain in Numerically Reconstructed Real World Nearside Lateral Automotive Crashes

Aortic injury (AI) leading to disruption of the aorta is an uncommon but highly lethal consequence of trauma in modern society. Most recent estimates range from 7,500 to 8,000 cases per year from a variety of causes. It is observed that more than 80% of occupants who suffer an aortic injury die at the scene due to exsanguination into the chest cavity. It is evident that effective means of substantially improving the outcome of motor vehicle crash-induced AIs is by preventing the injury in the first place. In the current study, 16 design of computer experiments (DOCE) were carried out with varying levels of principal direction of force (PDOF), impact velocity, impact height, and impact position of the bullet vehicle combined with occupant seating positions in the case vehicle to determine the effects of these factors on aortic injury. Further, a combination of real world crash data reported in the Crash Injury Research and Engineering Network (CIREN) database, Finite Element (FE) vehicle models, and the Wayne State Human Body Model-II (WSHBM-II) indicates that occupant seating position, impact height, and PDOF, in that order play, a primary role in aortic injury

Finite element reconstruction of real world aortic injury in near-side lateral automotive crashes with conceptual countermeasures

Traumatic rupture of the aorta (TRA) remains the second most common cause of death associated with motor vehicle crashes after brain injury. On an average, nearly 8,000 people die annually in the United States due to blunt injury to the aorta. It is observed that more than 80% of occupants who suffer an aortic injury die at the scene due to exsanguination into the chest. With the advent of more accurate and established human body finite element (FE) models, FE crash reconstruction methods may become a valuable tool when assessing crash scenarios and occupant injury mechanisms. The current study is divided into five main aims, near side left lateral real world finite element reconstructions, sensitivity study, thresholds for TRA, aorta mechanics in racing crashes and conceptual countermeasures. In the first study eight nearside left lateral impacts, in which a TRA occurred, were reconstructed using a combination of real world crash data reported in the Crash Injury Research and Engineering Network (CIREN) database and FE models of vehicles and occupants. The average maximum principal strain (AMPS) in the root, ascending, and the isthmus regions of the aorta were calculated and model predicted high strain areas were compared with real world injury reports. In seven of the eight cases aortic failure occurred in the isthmus region and, the average peak tensile isthmic strain, 20±7 mm distal to the left subclavian artery, was 18±6%. To identify key parameters for injury causation, 16 Design of Computer Experiments (DOCE) runs, generated using a Latin square sampling technique on modeFRONTIER with FE models of vehicles and the WSHBM as described earlier were performed to evaluate the role of PDOF, impact velocity, impact position, impact height and occupant seating position on aortic strain, aortic pressure and compartmental intrusion. The AMPS decreased significantly with an increase in the PDOF (from 270 degrees). Of the four PDOFs simulated, a PDOF of 270 degrees generated the highest average maximum principal strain in the aorta. Further, strain increased with increase in impact velocity while pressure in the aorta decreased with an increase in PDOF (from 270 degrees). The data obtained in the CIREN reconstructions were further compared with three CIREN cases without aortic injury to understand and delineate the mechanism for TRA. A paired comparison based sensitivity study was carried out and data compared with literature. It was seen that in nearside left lateral impacts the PDOF of impact played a crucial role in TRA. Further, three Indycar based racing crashes were simulated as part of a comparison study involving nine other simulated cases. It was seen that for TRA to occur, acceleration along was not enough. Thoracic deformation was essential and the shoulder-clavicle complex played a crucial role in TRA by causing relative motion of the sternum and the thoracic spine. Utilizing six design factors; B-pillar beam, crossbeam, side conceptual blanket airbag, thickness factor, yield strength and by varying the dimensions of the B-pillar beam, 18 DOCE simulations were carried out. The current study suggest that the protective effects of an improved side-construction standard can be enhanced further by the more rational placement of an airbag-like structure, to buffer head and chest contact with the B-Pillar along its entire length from car seat to roof. It is suggested that the combination of these two safety measures, B-pillar beam and thickness is likely to result in a significant reduction in both head and aortic Isthmus injury and thus to substantially reduce mortality subsequent to lateral motor vehicle crashes

Development of a Small rear Facing Child Restraint System Virtual Surrogate to Evaluate CRS-to-Vehicle Fitment

ABSTRACT Child restraint systems (CRS) No. 213 as "child restraint systems" (CRS), give parents and caregivers a plethora of makes and models providing optimum safety through the developmental periods of a child's life. The success of CRS at reducing injury in motor vehicle crashes hinges largely upon their proper installation as well as their interface with the vehicle seat. Unfortunately, despite the best efforts by parents and caregivers a staggering amount of CRS are found to be installed improperly. In a study supported by the National Highway Traffic Safety Administration (NHTSA), critical errors were identified in as many as 72.6% of all CRS installations on a case-by-case basi

Techniques for Reducing Speeding Beyond Licensure: Young Drivers\u27 Preferences

Young drivers need continued training and educational efforts beyond licensure. The latest in-vehicle monitoring technologies provide a promising way to monitor and advise driving behaviors in real-time. Literature to-date suggests limited success for changing driving behaviors via the use of in-vehicle monitoring technologies, and teens and parents have mixed perceptions about such devices. We argue that certain reinforcement techniques and parameters may lead to more sustainable behavioral changes. This paper describes the findings of an interview with young drivers on their perspectives of in-vehicle monitoring technologies and a feasibility driving simulator experiment that incorporated key reinforcement techniques. Eighteen young drivers participated in individual semi-structured interviews and 17 participated in the simulator experiment. Participants saw values in having a smartphone application-based system that can monitor their driving and provide positive recognition for safe behaviors and negative alerts for unsafe behaviors. Preliminary behavioral data from the simulator experiment showed mixed results. The findings show promise for incorporating reinforcement techniques in continued education beyond licensure but further research is needed to understand the timing for using such techniques

How do novel seat positions impact usability of child restraints?

Autonomous driving technology and changes in regulations may create an environment that allows novel vehicle interiors. It is important to consider impact on all types of passengers when contemplating interior design, particularly for vehicles that may be used by families with children. We developed a fixture that enables us to change the orientation of each of 4 car seats and used it to simulate three different vehicle interiors. Ten families with children aged 3 months to 7 years interacted with each of the simulated interiors as part of a usability study. Times to install and remove child restraint systems were not significantly different across the three simulated vehicle interiors, but parents were able to release children fastest when using the “X” configuration, which had all seats on a diagonal facing the middle of the vehicle. While overall experience ratings didn’t differ significantly, seven out of ten parents indicated that they liked the “X” configuration better than the other two configurations tested. Reasons included: ability to interact with other passengers, ability to see the road, and legroom/comfort. However, many participants disliked having some passengers not facing forward. Overall, parents liked facing their children, but several said that they would only be comfortable if they could see out of the front windshield; meanwhile, children liked seeing their parents’ faces but also preferred to face forward. Child restraint system and vehicle manufacturers could benefit from considering this study when designing new products

Rearward-Facing Infant Child Restraint Systems with Support Legs in Frontal and Frontal-Oblique Impacts

Previous studies of support legs in rearward-facing infant CRS models have focused on frontal impacts and have found that the presence of a support leg is associated with a reduction in head injury metrics. However, real-world crashes often involve an oblique principal direction of force. The current study used sled tests to evaluate the effectiveness of support legs in rearward-facing infant CRS models for frontal and frontal-oblique impacts with and without a simulated front row seatback. Frontal and frontal-oblique impact sled tests were conducted using the simulated Consumer Reports test method with and without the blocker plate, which was developed to represent a front row seatback. The Q1.5 anthropomorphic test device (ATD) was seated in rearward-facing infant CRS models, which were tested with and without support legs. The presence of a support leg was associated with significant reductions of head injury metrics below injury tolerance limits for all tests, which supports the findings of previous studies. The presence of a support leg was also associated with significant reductions of peak neck tensile force. The presence of the blocker plate resulted in greater head injury metrics compared to tests without the blocker plate, but the result was non-significant. However, the fidelity of the interaction between the CRS and blocker plate as an adequate representation of the interaction that would occur in a real vehicle is not well understood. The findings from the current study continue to support the benefit of support legs in managing the energy of impact for a child in a rearward-facing CRS

How do novel seat positions impact usability of child restraints?

Autonomous driving technology and changes in regulations may create an environment that allows novel vehicle interiors. It is important to consider impact on all types of passengers when contemplating interior design, particularly for vehicles that may be used by families with children. We developed a fixture that enables us to change the orientation of each of 4 car seats and used it to simulate three different vehicle interiors. Ten families with children aged 3 months to 7 years interacted with each of the simulated interiors as part of a usability study. Times to install and remove child restraint systems were not significantly different across the three simulated vehicle interiors, but parents were able to release children fastest when using the “X” configuration, which had all seats on a diagonal facing the middle of the vehicle. While overall experience ratings didn’t differ significantly, seven out of ten parents indicated that they liked the “X” configuration better than the other two configurations tested. Reasons included: ability to interact with other passengers, ability to see the road, and legroom/comfort. However, many participants disliked having some passengers not facing forward. Overall, parents liked facing their children, but several said that they would only be comfortable if they could see out of the front windshield; meanwhile, children liked seeing their parents’ faces but also preferred to face forward. Child restraint system and vehicle manufacturers could benefit from considering this study when designing new products