Browse Topic: Injury causation
The research on connected vehicles has attracted much interest of governments and research institutions in these days. As researchers who have been deeply intrigued, we are particularly interested in investigating the lane changing issues of connected buses when exiting bus stops. In order to examine the utilities of both the buses and social vehicles in a connected environment, we employ the game theory to analyze the interactions between them. A two-player, non-cooperative, non-zero-sum game model was built in this paper. We analyzed 5 different scenarios for bus exiting at bus bay stops and curbside bus stops. The payoffs considered in the game model were mainly from the perspective of safety and time. Besides the commonly studied safety issues caused by collisions, we supplement the existing literature by adding on non-collision injuries caused by improper driving behaviors (e.g. excessive acceleration). Moreover, unlike the lane changing game between two social vehicles, bus, as one of the dominant players in the game, carry more passengers and its impact on traffic delays cannot be neglected in the payoff of the time. According to the payoff functions, we deduced the Nash equilibrium solutions for the game between the connected bus and the connected social vehicle. The Nash equilibria in different conditions are analyzed. It is verified that the Nash equilibrium solutions obtained with the changes in parameters in the model is in accordance with the logic of rational players. The model proposed in this paper can provide reliable supports in terms of the lane changing behaviors for bus exiting in a connected environment.
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. Combat boot usage reduced the peak force by 36% experimentally (32% in simulation) by compressing the sole and insole with similar mitigations for calcaneus strain. The simulated Von Mises stress contours showed the boot both mitigating and shifting stress concentrations from the calcaneus in unbooted impacts to the talus-tibia joint in the booted impacts, which may explain why some previous studies have observed shifts to tibia injuries with boot or padding usage.
Unmanned aircraft systems (UAS), commonly known as drones, are part of a new and budding industry in the United States. Economic and public benefits associated with UAS use across multiple commercial sectors are driving new regulations which alter the stringent laws currently restricting UAS flights over people. As new regulations are enacted and more UAS populate the national airspace, there is a need to both understand and quantify the risk associated with UAS impacts with the uninvolved public. The purpose of this study was to investigate the biomechanical response and injury outcomes of Post Mortem Human Surrogates (PMHS) subjected to UAS head impacts. For this work, PMHS were tested with differing UAS vehicles at multiple impact angles, locations and speeds. Using a custom designed launching device, UAS vehicles were accelerated into the frontal, parietal, or vertex portions of subjects’ craniums at speeds up to 22 m/s. Of the 35 UAS impacts carried out, one AIS 2+ injury was observed: a 13 cm linear skull fracture resulting from a Phantom 3 impact. Additionally, injury risk curves used in automotive testing were found to over predict the risk of injury in UAS impact scenarios. Finally, localized skull deformation was observed during severe impacts; the effect that this deformation had on measured kinematics should be further evaluated. Overall, the study found that AIS 2+ head injuries may occur as a result of UAS impacts and that automotive injury metrics may not be able to accurately predict head injury risk in UAS impact scenarios.
An anatomically detailed rhesus monkey brain FE model was developed to simulate in vivo responses of the brain of sub-human primates subjected to rotational accelerations resulting in diffuse axonal injury (DAI). The material properties used in the monkey model are those in the GHBMC 50th percentile male head model (Global Human Body Model Consortium). The angular loading simulations consisted of coronal, oblique and sagittal plane rotations with the center of rotation in neck to duplicate experimental conditions. Maximum principal strain (MPS) and Cumulative strain damage measure (CSDM) were analyzed for various white matter structures such as the cerebrum subcortical white matter, corpus callosum and brainstem. The MPS in coronal rotation were 45% to 54% higher in the brainstem, 8% to 48% higher in the corpus callosum, 13% to 22% higher in the white matter when compared to those in oblique and sagittal rotations, suggesting that more severe DAI was expected from coronal and oblique rotations as compared to that from sagittal rotation. The level 1+ DAI was associated with 1.3 to 1.42 MPS and 50% CSDM (0.5) responses in the brainstem, corpus callosum and cerebral white matter. The mass scaling method, sometimes referred to as Holbourn's inverse 2/3 power law, used for development of human brain injury criterion was evaluated to understand the effect of geometrical and anatomical differences between human and animal head. Based on simulations conducted with the animal and human models in three different planes - sagittal, coronal and horizontal - the scaling from animal to human models are not supported due to lack of geometrical similitude between the animal and human brains. Thus, the scaling method used in the development of brain injury criterion for rotational acceleration/velocity is unreliable.
Crash safety researchers have an increased concern regarding the decreased thoracic deflection and the contributing injury causation factors among the elderly population. Sternum fractures are categorized as moderate severity injuries, but can have long term effects depending on the fragility and frailty of the occupant. Current research has provided detail on rib morphology, but very little information on sternum morphology, sternum fracture locations, and mechanisms of injury. The objective of this study is two-fold (1) quantify sternum morphology and (2) document sternum fracture locations using computed tomography (CT) scans and crash data. Thoracic CT scans from the University of Michigan Hospital database were used to measure thoracic depth, manubriosternal joint, sternum thickness and bone density. The sternum fracture locations and descriptions were extracted from 63 International Center for Automotive Medicine (ICAM) crash cases, of which 22 cases had corresponding CT scans. The University of Michigan Internal Review Board (HUM00043599 and HUM00041441) approved the use of crash cases and CT scan data. The sternum morphomics data showed the thoracic depth increased, except for the 60-74-year-old age group. The average sternum thickness was greater in the older age groups. The sternum bone density decreased from youngest to oldest age groups. The angle between the manubrium and the sternum body decreased by 5.6° between the youngest and oldest age groups. The frequency of sternum fractures increased after age 45. Fractures were most frequent in the sternum body. The seat belt webbing was coded as the source of 54% of the sternum fractures.
Road accident between pedestrian and motor vehicle causes severe injuries and even death of pedestrian. The accident statistics show that the possibility of injury to pedestrian is higher in case of collision with car on busy roads. In car and pedestrian collisions, the pedestrian’s head hits with car bonnet and suffer from multiple injuries such as skull fractures and brain injury. The role of car bonnet structural strength plays an important role in pedestrian head injury level. To provide enough structural strength the high bonnet thickness is provided with under bonnet stiffeners, however thick bonnet and stiffeners reduces deformation of the bonnet during collision and increases injury level to pedestrian. Hence optimum bonnet thickness, least number and geometry of stiffeners and enough structural strength is important for bonnet to reduce injury level. The aim of this study is to analyse the effect of car bonnet thickness, number and arrangement of under bonnet stiffeners on head injury levels with the help of head injury criteria (HIC). Head Injury Criteria (HIC) is a measure of the likelihood of head injury arising from an impact during a car crash. It indicatesthe level of injury caused during a particular crash. A typical modern car bonnet is selected for investigation with variety of bonnet material thickness and different configurations of under bonnet stiffeners and head injury criteria (HIC) is computed with the help of computer modelling. Further, head linear velocity, acceleration and head injury risk are predicted for probability of skull fracture. The geometry of bonnet is optimized with the help of optimization technique and optimized bonnet geometry is validated experimentally by designing a bonnet test facility and head form imparter.
The interior components of a passenger vehicle are designed to provide comfort and safety to its occupants. In the event of accident, vehicle interiors are primary source of injuries when occupants interact with them. Vehicle interiors consists of Instrument panel (IP), center console, seats and controls in front of seating position etc. Severity of the injuries depends on the energy dissipating characteristics, profiles, projections of different interior components. These are assessed by ECE R21 and IS12553 head form impact tests. To evaluate the Head form impact performance on Interior components, Computer Aided Engineering (CAE) simulations are extensively used during the vehicle development. In order to predict failure of plastic components and snap joints which might lead to expose sharp edges, it is critical to model plastic material and snap joint. Vehicle interiors are certified for head form impact requirements based on physical testing where dashboard samples from productions tools are used. At this stage of development, if any failure occurs then changes in interior design becomes very expensive and time consuming. To avoid this situation, CAE based failure predictions and injury performance evaluations are done during initial design phase of product development when changes are easily implemented without time and cost penalties. This paper describes the development of vehicle interior using CAE based head form impact simulations and predicting the failures like sharp edges exposure, structural integrity or joint failures. For accurate prediction of these failures in CAE based vehicle interior development, plastic material characterization and snap joint failure characterization are done.
In 2010, the UN General Assembly proclaimed the period 2011-2020 as the Decade of Action for Road Safety, with a goal to stabilize and then reduce the forecast level of road traffic fatalities around the world. Road traffic accidents are the 8th cause of death in Brazil, according to World Health Rankings. There are few studies around the world with respect to cost due to traffic accidents, however a study performed in 2011 estimates that were spent R$ 44.6 billion in Brazil. So, the recent Brazilian regulations updates have enforced the automakers to develop vehicles safer to passengers and pedestrians. These regulations focus on prevent, reduce or minimize the traumas and injuries caused by different types of vehicular accidents. The present work was developed to optimize the driver restraint system, while focusing on minimizing the trauma during a vehicle frontal impact. The driver restraint system was optimized considering the complex interaction between the ATD and the different components that assemble the restraint system, like airbag, safety belts with/without pre-tensioners, seatbelt load limiting devices and steering column stroke. The numerical computational simulations were performed based on Design of Experiments (DOE), which is a powerful tool that allows for multiple input factors to be manipulated determining their effect on a desired output. The numerical computational model created was initially correlated with a physical test, and then 36 numerical simulations were performed in order to create the optimization matrix. The optimized parameters provided by the analysis of the DOE orthogonal matrix were simulated and showed a significant reduction at probability of injuries due to vehicle frontal impact. The computational numerical optimization tool helped to reduce the cost and time development of a safer vehicle that satisfies the current Brazilian regulations, focusing on driver performance. The results presented excellent correlation and the goals of the optimization were achieved showing that this tool is reliable and helpful for current and future developments.
ABSTRACT A full-scale crash test of a USMC CH-46 helicopter airframe was conducted at NASA-Langley Research Center. One of the internal experiments was an assessment of mobile aircrew restraint concepts. Two Hybrid III Pedestrian Anthropomorphic Test Devices (ATD's) were positioned in a standing position, just aft of the crew door. On the left side, a traditional gunner's belt was employed. On the right side, the Mobile Aircrew Restraint System (MARS) was employed with the Aircrew Endurance vest. The motivation behind this experiment was based on several mishap-based injuries of mobile aircrew that were using traditional gunner's belts. However, correlation of presumed injury causes with equipment deficiencies was difficult because of a near total void of mobile aircrew restraint testing data in a system-level environment. For the condition tested, the measured results for the two ATD's indicated a dramatic reduction in injury probability when employing the MARS. In contrast, the ATD equipped with the gunner's belt experienced accelerations and forces that could generally be considered lethal.
This work is based on a current project funded by the United States Army Small Business Innovation Research (SBIR) Program and is being conducted with the Tank Automotive Research, Development and Engineering Center (TARDEC) Ground Systems Survivability (GSS) Team and Paradigm Research and Engineering. The focus of this project is to develop an advanced and novel sensing and activation strategy for Pyrotechnic Restraint Systems, Air Bags and other systems that may require activation. The overriding technical challenge is to activate these systems to effectively protect the Soldier during blast events in addition to Crash, Rollover and Other Injury Causing events. These activations of Pyrotechnic systems must occur in fractions of milliseconds as compared to typical automotive crashes. By investigating systems outside of typical accelerometer based applications and activations, the potential exists to exploit systems that require little power, are self-contained and provide the required output for the desired result. As such Constant-Flux Magnetostrictive Sensors shall be evaluated in a self-contained environment to provide the output during these events. By activating the Pyrotechnic Restraint Systems and Air Bag Systems early in Blast Events, the systems can Restrain the Occupant and provide flail protection from surfaces within the vehicle. As the system is developed various test scenarios will be introduced to activate these systems and design a robust sensing and activating strategy.
A considerable number of victims in the traffic are originated by some kind of side collisions. Around 30% of the fatalities occur due to these kinds of accidents [1][2]. Due to this fact, the development of the occupant protection for this kind of load cases becomes indispensable. For this, different kinds of crash tests were and are being developed around the world according to the characteristics inherent of each market. Barrier weight, impact angle, barrier type (pole or movable deformable barrier) and dummy types are some of the variations observed. The severity of injuries caused by side crashes is very high as the occupant is very close to the impacting object and the crush space is almost nothing when compared to frontal impact. To decrease these injuries the following features of the vehicle must be developed: structure (high strength materials, reinforcements, etc), restraint system (side airbags, curtain airbags, pre-tensioners, seats, etc), design and package (distances between occupant and interior parts, flat surfaces, etc), high speed sensing systems (accelerometers, pressure sensors, etc). This paper will present a comparative analysis between these different types of tests and demonstrate future tendencies and the challenges for the Brazilian market and the technologies available during the vehicle development capable of making the products safer when it comes to side impact collisions.
The FMVSS 208 advanced air bag rule has brought new technologies into the automotive industry. Low Risk Deployment, Suppression, or a combination of both, have prevailed in the industry to meet the right front passenger requirements for FMVSS 208 compliance. This rule provides the options to conduct low risk deployment (LRD) airbag tests with a 12-months-old infant dummy riding in a rear facing child seat and child dummies representing 3 years and 6 years old children. If the LRD tests do not meet the injury criteria set by NHTSA, vehicle manufacturers have to choose the another option for the suppressing airbag system when infants or children are present at the passenger seat. But this suppressing systems is not the cost effective method, also, contains potential quality problem such as misrecognition passenger age. Thus, the car makers start to choose LRD requirement option and develop new LRD passenger airbag system. A low risk deployment passenger airbag system has been developed to reduce the risk of injuries caused by airbag inflation to small size occupants and improve the restraint of adult occupants in high speed crashes as well. The new passenger airbag system has mounted on the instrument panel in such a way to reduce the inflator outputs. This paper presents a new methodology for improvement of airbag deployment using experimental and analytical research. The significant parameters were determined from screening process of the experiment data. As a result of the number of tests conducted at different conditions, this study was able to determine the range of relevant parameters. Additionally, using simulation model, a parametric study was done. It make to figure out main design factors of low risk deployment of the passenger airbag
A large study of rear-end collisions was conducted for the neck injury indicators and test procedures. Neck injury in low-speed rear-end collisions is a big issue because there are a lot of patients despite low-speed rear-end collisions. Europe, Korea and Japan introduced the specific part in the New Car Assessment Program to reduce whiplash injury in low-speed rear-end collisions. From the legal point of view, to reduce the frequency and severity of injuries caused by rearward displacement of the head in rear-end collision, USA, EC, Korea, Japan and others internationally cooperated to make the global technical regulation (GTR) in UNECE/WP29. In 2008, after much meandering, GTR No. 7 head restraints were established. However the GTR No.7 is not a unique regulation because many countries had their own opinions and domestic regulations, and many questions related to injury criteria and biomechanical issues of dummy remain unresolved. The Biofidelic Rear Impact Dummy II (BioRIDII) is regarded as possessing the most similar characteristics to human volunteers and Post-mortem Human Subjects(PMHS) in terms of its response to low-speed rear impacts. Although a great amount of research was conducted for repeatability and reproducibility on the BioRIDII, the research results did not directly suggest the neck injury criteria and limit values for the regulation. The purpose of this research is to review the proper neck injury indicators for the BioRID-II through the low-rear sled test on the 3set BioRIDII ver-g. A series of sled tests were conducted to assess the adequacy of neck injury indicators for the repeatability and reproducibility of results obtained on the 3set BioRIDII. The sled tests were performed according to the test procedure proposed by the Korea New Car assessment Program (KNCAP). Neck injury indicators including NIC, Nkm, upper & lower Fx, upper & lower Fz, T1 X acc, Head X acc, were analysed for each dummy. The results show that some criteria, such as the neck shear force, exhibit coefficient variation (CV) up to 20.
Worldwide, 1.2 million people die in road crashes yearly; 43,000 just in Europe. This implies a cost to the European society of approximately 160 billion euro, making use of 10% of all health care resources. Sharp objects like crash barriers may lead vulnerable road users into serious injuries. Different road restraint system designs have been developed in recent years to improve vulnerable road users' safety. SMART RRS is an FP7 SST 2007 RTD1 European collaborative project funded by the EC with the participation of 10 institutions from 5 countries. The project aims to develop a new smart road restraint system that will reduce the number of deaths and injuries caused in road traffic accidents by integrating primary and tertiary sensor systems in it, providing greater protection to all road users, warning motorists and emergency services of danger for prevention purposes and alerting emergency teams of accidents as they happen to minimize response time to the exact location of the incident. This new smart restraint system will: - Reduce the number of accidents through better information on the actual state of the road and traffic flow (climatic conditions, traffic flow, obstructions, hazards, accidents). - Eliminate dangerous profiles from road restraint systems (crash barriers) that currently endanger vulnerable road users. - Optimize road safety by providing exact information of where and when accidents happen in real time. The project obtained interesting results from an in-depth review of motorcycle accidents, showing that the most aggressive elements for riders are protection systems installed on roadsides (continuous, punctual, rigid, wire rope). Also the accidents involving roadside protective systems include high speeds and the rider commonly impacts the barrier in an upward position, with severe outcome. Some of the most important injuries received by riders are blunt impacts to the head, member amputation and severe thoracic intrusion.
Optical based sensor systems for vehicle based detection and warning systems are under development to reduce accidents and limit injuries caused by accidents. (1, 2, 3) In order to validate these types of detection systems, it is necessary to perform real world tests. In the case of pedestrian detection systems, this is very difficult in the field for safety reasons. Instead, simulated tests are more desirable. This paper describes work to understand the effectiveness of using virtual pedestrians as surrogates for real world pedestrian detection.
Children who are too large for harness restraints but too small to obtain good restraint from a vehicle seatbelt alone should be seated in a belt-positioning booster. Boosters have been shown to significantly reduce abdominal injuries caused by seatbelts. This effectiveness may be due in part to the fact that boosters reduce the effective seat cushion length, allowing children to sit more comfortably without slouching. NHTSA recommends that children who do not use harness restraints use boosters until they are at least 145 cm tall. In this paper, data from several sources were combined to assess how well children fit on rear seat cushions. Data from NASS-GES were analyzed to determine the age distribution of rear-seat occupants. Anthropometric data from several sources were analyzed to determine the distribution of buttock-popliteal length, a measure of thigh length that is a key determinant of seat fit, as a function of age and gender. Second- and third-row cushion lengths were measured on a convenience sample of 56 late-model vehicles. Comparing the distribution of body size for rear-seat occupants with the seat cushion lengths showed that most cushions are too long for most rear-seat occupants, using commonly applied standards of seat fit. Given that most rear-seat occupants in the U.S. are children, rear-seat design standards should consider the smaller body dimensions and different restraint needs of this population.
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