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Car accidents are amongst the most common causes of fatalities for a younger population in developed countries and world-wide. While research using Anthropometric Test Devices (ATDs) has led to improvements in frontal impact occupant protection, epidemiological data on the effectiveness of devices for side impact protection remains inconclusive. Current regulatory physical side impact tests are limited to standardized full-vehicle Moving Deformable Barrier and rigid pole impacts, only one seating position of the occupant, and a unidirectional occupant surrogate (side impact ATD). To address some limitations of the existing research methods, and expand the understanding of the occupant response and potential for injury, numerical Human Body Models (HBMs) have been developed as repeatable, biofidelic, omni-directional, and frangible occupant surrogates. The overall goal of this study was to improve the understanding of the underlying sources of conflicting epidemiological and physical test data on thoracic response in side impacts. This study applied two highly detailed HBMs in parametric investigations with simple to complex impact scenarios ranging from a pendulum, rigid-wall side sled, to a full-vehicle lateral impact and an accident reconstruction. Subsequently, a thoracic side airbag and three-point seatbelt models were developed and integrated with the vehicle model to study the effect of occupant pre-crash position on the potential for injury. Occupant response assessment included global criteria (chest deflection and viscous criterion), local measurements at different thorax levels, spine kinematics, and prediction of rib fracture locations and lung response. This research identified limitations in current analysis methods, demonstrating effects on occupant response of pre-crash arm position, which is known to vary widely among occupants. The magnitude of the arm effect was dependent on the lateral impact scenario, where the occupant response demonstrated the highest sensitivity to arm orientation in the full vehicle impact. The arm position effect was more significant than changes in response to four restraint combinations, where the assessment of the restraint performance was also dependent on the thoracic response measurement locations and method. A parametric study using detailed HBM, vehicle and restraint models provided new understanding of occupant response in side impact crash scenarios.
Occupant thoracic injury incurred during side impact automotive crashes constitutes a significant portion of all fatal and non-fatal automotive injuries. The limited space between the impacting vehicle and occupant can result in significant loads and corresponding injury prior to deceleration of the impacting vehicle. Within the struck vehicle, impact occurs between the occupant and various interior components. Injury is sustained to human structural components such as the thoracic cage or shoulder, and to the internal visceral components such as the heart, lungs, or aorta. Understanding the mechanism behind these injuries is an important step in improving the side impact crash safety of vehicles. This study is focused on the development of a human body numerical model for the purpose of predicting thoracic response and trauma in side impact automotive crash. The human body model has been created using a previously developed thoracic numerical model, originally used for predicting thoracic trauma under simple impact conditions. The original version of the thorax model incorporated three-dimensional finite element representations of the spine, ribs, heart, lungs, major blood vessels, rib cage surface muscles and upper limbs. The present study began with improvements to the original thorax model and furthered with the development of remaining body components such that the model could be assessed in side impact conditions. The improvements to the thoracic model included improved geometry and constitutive response of the surface muscles, shoulder and costal cartilage. This detailed thoracic model was complimented with a pelvis, lower limbs, an abdomen and a head to produce the full body model. These components were implemented in a simplified fashion to provide representative response without significant computational costs. The model was developed and evaluated in a stepwise fashion using experimental data from the literature including side abdominal and pelvic pendulum impact tests. The accuracy of the model response was investigated using experimental testing performed on post mortem human subjects (PMHS) during side and front thoracic pendulum impacts. The model produced good agreement for the side thoracic and side shoulder pendulum impact tests and reasonable correlation during the frontal thoracic pendulum impact test. Complex loading via side sled impact tests was then investigated where the body was loaded unbelted in a NHTSA-type and WSU-type side sled test system. The thorax response was excellent when considering force, compression and injury (viscous criterion) versus time. Compression in the thorax was influenced by the arm position, which when aligned with the coronal plane produced the most aggressive form of compressive loading possible. The simplified components provided good response, falling slightly outside experimental response corridors defined as one standard deviation from the average of the experimental PMHS data. Overall, the predicted model response showed reasonable agreement with the experimental data, while at the same time highlighting areas for future developments. The results from this study suggested that the numerical finite element model developed herein could be used as a powerful tool for improving side impact automotive safety.
Although there have been tremendous improvements in crash safety there has been an increasing trend in side impact fatalities, rising from 30% to 37% of total fatalities from 1975 to 2004 (NHTSA, 2004). Between 1979 and 2004, 63% of AIS[greq]4 injuries in side impact resulted from thoracic trauma (NHTSA, 2004). Lateral impact fatalities, although decreasing in absolute numbers, now comprise a larger percentage of total fatalities. Safety features are typically more effective in frontal collisions compared to side impact due to the reduced distance between the occupant and intruding vehicle in side impact collisions. Therefore, an increased understanding of the mechanisms governing side impact injury is necessary in order to improve occupant safety in side impact auto crash. This study builds on an advanced numerical human body model with focus on a detailed thoracic model, which has been validated using available post mortem human subject (PMHS) test data for pendulum and side sled impact tests (Forbes, 2005).
Thoracic injury is the most dominant segment of automotive side impact traumas. A numerical model that can predict such injuries in crash simulation is essential to the process of designing a safer motor vehicle. The focus of this study was to develop a numerical model to predict lung response and injury in side impact car crash scenarios. A biofidelic human body model was further developed. The geometry, material properties and boundary condition of the organs and soft tissues within the thorax were improved with the intent to ensure stress transmission continuity and model accuracy. The thoracic region of the human body model was revalidated against three pendulum and two sled impact scenarios at different velocities. Other body regions such as the shoulder, abdomen, and pelvis were revalidated. The latest model demonstrated improvements in every response category relative to the previous version of the human body model. The development of the lung model involved advancements in the material properties, and boundary conditions. An analytical approach was presented to correct the lung properties to the in-situ condition. Several injury metric predictor candidates of pulmonary contusion were investigated and compared based on the validated pendulum and sled impact scenarios. The results of this study confirmed the importance of stress wave focusing, reflection, and concentration within the lungs. The bulk modulus of the lung had considerable influence on injury metric outcomes. Despite the viscous criterion yielded similar response for different loading conditions, this study demonstrated that the level of contusion volume varied with the size of the impact surface area. In conclusion, the human body model could be used for the analysis of thoracic response in automotive impact scenarios. The overall model is capable of predicting thoracic response and lung contusion. Future development on the heart and aorta can expand the model capacity to investigate all vital organ injury mechanisms.
A systematic treatment of current crashworthiness practice in the automotive, railroad and aircraft industries. Structural, exterior and interior design, occupant biomechanics, seat and restraint systems are dealt with, taking account of statistical data, current regulations and state-of-the-art design tool capabilities. Occupant kinematics and biomechanics are reviewed, leading to a basic understanding of human tolerance to impact and of the use of anthropometric test dummies and mathematical modelling techniques. Different types of restraining systems are described in terms of impact biomechanics. The material and structural behaviour of vehicle components is discussed in relation to crash testing. A variety of commonly used techniques for simulating occupants and structures are presented, in particular the use of multibody dynamics, finite element methods and simplified macro-elements, in the context of design tools of increasing complexity, which can be used to model both vehicles and occupants. Audience: An excellent reference for researchers, engineers, students and all other professionals involved in crashworthiness work.
Although there have been tremendous improvements in crash safety there has been an increasing trend in side impact fatalities, rising from 30% to 37% of total fatalities from 1975 to 2004 (NHTSA, 2004). Between 1979 and 2004, 63% of AIS[greq]4 injuries in side impact resulted from thoracic trauma (NHTSA, 2004). Lateral impact fatalities, although decreasing in absolute numbers, now comprise a larger percentage of total fatalities. Safety features are typically more effective in frontal collisions compared to side impact due to the reduced distance between the occupant and intruding vehicle in side impact collisions. Therefore, an increased understanding of the mechanisms governing side impact injury is necessary in order to improve occupant safety in side impact auto crash. This study builds on an advanced numerical human body model with focus on a detailed thoracic model, which has been validated using available post mortem human subject (PMHS) test data for pendulum and side sled impact tests (Forbes, 2005).
Contents include: Abdominal Injury and Response in Side Impact Parametric Finite Element Studies of the Human Pelvis: The Influence of Load Magnitude and Duration on Pelvic Tolerance During Side Impact Instrumentation of Human Surrogates for Side Impact Side Impact Countermeasure Study Using A Hybrid Modeling Technique Numerical Analysis of Side Impact Phenomena Using MADYMO-3D DOT-SID Dummy Influence of the NHTSA and EEVC Side Impact Barriers on Various Dummy Responses: Evaluation by Mathematical Simulations Proposed Provisional Reference Values for the Humerus for Evaluation of Injury Potential Hybrid III Dummy Instrumentation and Assessment of Arm Injuries During Air Bag Deployment Impact Response of Foam: The Effect of the State of Stress A NASS-Based Investigation of Pelvic Injury within the Motor Vehicle Crash Environment Influence of Test Conditions on Protection Criteria in Side Impact Age Effects on Thoracic Injury Tolerance The Effects of Subfracture Impact Loading on the Patellofemoral Joint in a Rabbit Model Experimental and Analytical Study of Knee Fracture Mechanisms in a Frontal Knee Impact Biomechanical Response and Physical Properties of the Leg, Foot, and Ankle Biomechanics of Lower Limb Injuries of Belted Car Drivers and the Influence of Intrusion and Accident Severity Dynamic Axial Tolerance of the Human Foot-Ankle Complex A Three-Dimensional Finite Element Model of the Human Ankle: Development and Preliminary Application to Axial Impulsive Loading A Numerical Model of the Human Ankle/Foot under Impact Loading in Inversion and Eversion An Analysis of Injury Mechanisms for Ankle/Foot Region in Frontal Offset Collisions A Global and a Detailed Mathematical Model for Head-Neck Dynamics Validation Study of a 3D Finite Element Head Model Against Experimental Data Human Subject Kinematics and Electromyographic Activity During Low Speed Rear Impacts Neck Injuries in the UK Co-operative Crash Injury Study Effect of Seat Stiffness in Out-of-Position Occupant Response in Rear-End Collisions Optimised Restraint Systems for Low Mass Vehicles A Study of Motor Vehicle Accidents Involving Children Comparison of the Six-Year-Old Hybrid III, Part 572 and TNO P6 Child Dummies Air Bags and Children: Results of a National Highway Traffic Safety Administration Special Investigation into Actual Crashes Performance of Child Restraint Systems in Real-Life Lateral Collisions.
Safety of the car occupant is given foremost importance by the consumers, federal regulatory agencies, and automobile manufacturers. Many techniques and new technologies are proposed every year and implemented for the enhancements of the safety and crashworthiness of the vehicles. More efforts are still needed to make the cars safer, which in turn reduces the risk of fatal injuries to the occupants. In this study, a typical compact-sized sedan model is analyzed for the Federal Motor Vehicle Safety Standards (FMVSS) 214 Moving Deformable Barrier (MDB) and, Side Pole impact collisions, via numerical simulations. In particular, the effect of placement of the driver's seat laterally inward is investigated. A methodology is presented in this thesis to examine the structural damage experienced by the car when it is engaged in side collision with a rigid pole and the MDB barrier, and also to assess the injuries sustained by the driver in both scenarios. In order to delay the contact, a seat position is modified to provide during a side impact with an additional 18mm clearance between the seat and struck door. The National Crash Analysis Center (NCAC)'s Toyota Yaris finite element (FE) model have been utilized in this thesis to analyze the structural side impact responses of this compact sedan. The EuroSID-2re 50th percentile adult male side impact crash test dummy has been as the car occupant. The critical injury parameters of the dummy and the vehicle deformation are evaluated and compared. This study indicates that a small inward lateral displacement of the driver's seat towards the interior of the car can significantly reduce the potential injuries to the occupant. This is due to the fact that most of the energy of impact is absorbed by the vehicle side structure instead of the seat structure and the occupant.
Over the last two decades, there has been extensive research work carried out on the dynamics and potential injuries to the occupants positioned at the struck-side in automobile side impact accidents. With the development of strong vehicle body structures and other passive safety systems, these advances have been proven to effectively reduce probability of injuries and deaths to these "nearside" occupants. The advancement of airbag technologies, seatbelts, side impact door beams etc., have reduced the severity of injuries to the driver during any side impact accidents. The regulation on automotive safety and occupant protection in side impacts require only to examination of the nearside occupant/driver. Real world data has shown that occupants seated away from the nearside called as "far-side" occupants, could also be subjected to serious injuries as well. Hence, it is important to investigate the crash responses and injury potential of far-side occupants individually along with the occupants on the nearside for body-to-body contacts in side impact accidents. The main objective of this research is to examine side impact epidemiology from an injury perspective to far-side occupants. Effort is made here to examine the thorax and pelvic injuries and the role of seatbelts as per FMVSS 214 test conditions. The simulations are carried out with nearside and the far-side impacts by using finite element models of a typical compact car, a moving deformable barrier (MDB), a EuroSID-2 dummy with rib extensions (ES-2RE) and a three-point seatbelt. Occupant kinematics and injury parameters are then compared for both unbelted and belted passengers to investigate the significance of the seatbelts. The results from this study demonstrates and quantifies the differences in the dynamics and injury potential to the nearside and the far-side occupants individually, and their interactions when both are present.