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Technical Paper

Foot and Ankle Finite Element Modeling Using Ct-Scan Data

1999-10-10
99SC11
Although not life threatening in most cases, victims of lower extremity injuries frequently end up living with a poor quality of life. The implementations of airbag supplement restraint systems significantly reduce the incidence of head and chest injuries. However, the frequency of leg injuries remains high. Several finite element models of the foot and ankle have been developed to further the understanding of this injury mechanism. None of those models employed accurate geometry among various bony segments. The objective of this study is to develop a foot and ankle finite element model based on CT scan data so that joint geometry can be accurately represented. The model was validated against experimental data for several different configurations including typical car crash situations.
Technical Paper

Brain/Skull Relative Displacement Magnitude Due to Blunt Head Impact: New Experimental Data and Model

1999-10-10
99SC22
Relative motion between the brain and skull may explain many types of brain injury such as intracerebral hematomas due to bridging veins rupture [1] and cerebral contusions. However, no experimental methods have been developed to measure the magnitude of this motion. Consequently, relative motion between the brain and skull predicted by analytical tools has never been validated. In this study, radio opaque markers were placed in the skull and neutral density markers were placed in the brain in two vertical columns in the occipitoparietal and temporoparietal regions. A bi-planar, high-speed x-ray system was used to track the motion of these markers. Due to limitations in current technology to record the x-ray image on high-speed video cameras, only low- speed (﹤ 4m/s) impact data were available.
Technical Paper

Determination of Impact Responses of ES-2re and SID-IIs - Part III: Development of Transfer Functions

2018-04-03
2018-01-1444
An understanding of stiffness characteristics of different body regions, such as thorax, abdomen and pelvis of ES-2re and SID-IIs dummies under controlled laboratory test conditions is essential for development of both compatible performance targets for countermeasures and occupant protection strategies to meet the recently updated FMVSS214, LINCAP and IIHS Dynamic Side Impact Test requirements. The primary purpose of this study is to determine the transfer functions between the ES-2re and SID-IIs dummies for different body regions under identical test conditions using flat rigid wall sled tests. The experimental set-up consists of a flat rigid wall with five instrumented load-wall plates aligned with dummy’s shoulder, thorax, abdomen, pelvis and femur/knee impacting a stationary dummy seated on a rigid low friction seat at a pre-determined velocity.
Technical Paper

Determination of Impact Responses of ES-2re and SID-IIs – Part II: SID-IIs

2018-04-03
2018-01-1448
The main purpose of this study was to determine the impact responses of the different body regions (shoulder, thorax, abdomen and pelvis/leg) of the ES-2re and SID-IIs dummies using rigid wall impacts under different initial test conditions. The experimental set-up consisted of a flat rigid wall with five instrumented load-wall plates aligned with dummy’s shoulder, thorax, abdomen, pelvis and knee impacting a stationary dummy seated on a rigid seat at a pre-determined velocity. The relative location and orientation of the load-wall plates was adjusted relative to the body regions of the ES-2re and SID-IIs dummies respectively.
Technical Paper

Determination of Impact Responses of ES-2re and SID-IIs - Part I: ES-2re

2018-04-03
2018-01-1449
The main purpose of this study was to determine the impact responses of the different body regions (shoulder, thorax, abdomen and pelvis/leg) of the ES-2re and SID-IIs dummies using rigid wall impacts under different initial test conditions. The experimental set-up consisted of a flat rigid wall with five instrumented load-wall plates aligned with dummy’s shoulder, thorax, abdomen, pelvis and knee impacting a stationary dummy seated on a rigid seat at a pre-determined velocity. The relative location and orientation of the load-wall plates was adjusted relative to the body regions of the ES-2re and SID-IIs dummies respectively.
Technical Paper

Reconstruction of Pediatric Occupant Kinematic Responses Using Finite Element Method in a Real-World Lateral Impact

2017-03-28
2017-01-1462
Computational human body models, especially detailed finite element models are suitable for investigation of human body kinematic responses and injury mechanism. A real-world lateral vehicle-tree impact accident was reconstructed by using finite element method according to the accident description in the CIREN database. At first, a baseline vehicle FE model was modified and validated according to the NCAP lateral impact test. The interaction between the car and the tree in the accident was simulated using LS-Dyna software. Parameters that affect the simulation results, such as the initial pre-crash speed, impact direction, and the initial impact location on the vehicle, were analyzed. The parameters were determined by matching the simulated vehicle body deformations and kinematics to the accident reports.
Technical Paper

Study on the Key Preload Performance Parameters of an Active Reversible Preload Seatbelt (ARPS)

2018-04-03
2018-01-1175
In order to provide an improved countermeasure for occupant protection, a new type of active reversible preload seatbelt (ARPS) is presented in this paper. The ARPS is capable of protecting occupants by reducing injuries during frontal collisions. ARPS retracts seatbelt webbing by activating an electric motor attached to the seatbelt retractor. FCW (Forward Collision Warning) and LDW (Lane Departure Warning) provide signals as a trigger to activate the electric motor to retract the seatbelt webbing, thus making the occupant restraint system work more effectively in a crash. It also helps reduce occupant’s forward movement during impact process via braking. Four important factors such as preload force, preload velocity and the length and timing of webbing retraction play influential roles in performance of the ARPS. This paper focuses on studying preload performance of ARPS under various test conditions to investigate effects of the aforementioned factors.
Technical Paper

Study on the Step by Step Energy Absorption Method Based on the Theory of Reverse Design

2007-08-05
2007-01-3685
As the length of the frontal structure of the minibus can't be as long as cars, some new methods have to be developed to maximum the effect of the energy absorption. In this paper, a step-by-step energy absorption method which based on reverse design was proposed. Two plates with different size and different thickness which can take part in the energy absorption step by step were added in each of the rectangular longitudinal beams. Finite element models were developed both for rectangular beam and minibus. Multi-body model was also developed for the restraint system. The validation of the rectangular beam model was done by sled test, and the minibus model was done by minibus crash test. The computational results matched well with the test results. Then, orthogonal experimental method was used to find the most effective parameters for the energy absorption. These parameters were optimized in the simulation of minibus crash.
Technical Paper

Finite Element Modeling of Hybrid III Head-Neck Complex

1992-11-01
922526
A three-dimensional finite element model of the Hybrid III dummy head-neck complex was created to simulate the Amended Part 572 Head-Neck Pendulum Compliance Test, of the Code of Federal Regulations. The model consisted of a rigid head and five circular aluminum disks joined together by butyl elastomer rubber. Contact surfaces were defined to allow the anterior neck to separate upon an application of extension moments. Two mounting positions, one for flexion and the other one for extension, were used to simulate the head-neck calibration tests. An explicit finite element code PAM-CRASH was utilized to simulate the model dynamic responses. Simulation results were compared to experimental data obtained from First Technology Safety Systems Inc. Model predictions agreed well in both flexion and extension. This model can be used to study the head-neck biomechanics of the existing dummy as well as in the development of new dummies.
Technical Paper

Experimental Validation of Pediatric Thorax Finite Element Model under Dynamic Loading Condition and Analysis of Injury

2013-04-08
2013-01-0456
Previously, a 10-year-old (YO) pediatric thorax finite element model (FEM) was developed and verified against child chest stiffness data measured from clinical cardiopulmonary resuscitation (CPR). However, the CPR experiments were performed at relatively low speeds, with a maximum loading rate of 250 mm/s. Studies showed that the biomechanical responses of human thorax exhibited rate sensitive characteristics. As such, the studies of dynamic responses of the pediatric thorax FEM are needed. Experimental pediatric cadaver data in frontal pendulum impacts and diagonal belt dynamic loading tests were used for dynamic validation. Thoracic force-deflection curves between test and simulation were compared. Strains predicted by the FEM and the injuries observed in the cadaver tests were also compared for injury assessment and analysis. This study helped to further improve the 10 YO pediatric thorax FEM.
Technical Paper

Analysis of a Real-World Crash Using Finite Element Modeling to Examine Traumatic Rupture of the Aorta

2005-04-11
2005-01-1293
One of the leading causes of death in automotive crashes is traumatic rupture of the aorta (TRA) or blunt aortic injury (BAI). The risk of fatality is high if an aortic injury is not detected and treated promptly. The objective of this study is to investigate TRA mechanisms using finite element (FE) simulations of reconstructed real-world accidents involving aortic injury. For this application, a case was obtained from the William Lehman Injury Research Center (WLIRC), which is a Crash Injury Research and Engineering Network (CIREN) center. In this selected crash, the case vehicle was struck on the left side with a Principal Direction of Force (PDoF) of 290 degrees. The side structure of the case vehicle crushed a maximum of 0.33 m. The total delta-V was estimated to be 6.2 m/s. The occupant, a 62-year old mid-sized male, was fatally injured. The occupant sustained multiple rib fractures, laceration of the right ventricle, and TRA, among other injuries.
Technical Paper

Frontal Crash Protection Performance of Integrated Child Safety Seat

2013-04-08
2013-01-1160
Child Restraint Systems (CRS), when used properly, can effectively avoid or reduce injury for children in motor vehicle crashes. To deal with the problems of the high rate of misuse of the CRS and submarining in frontal crashes when child occupants using traditional vehicle seat belts, a novel integrated child safety seat (ICSS) with a four-point seat belt and a ring-shaped lap belt was developed in this study. It is easy to operate and has lower rate of misuse. To study the protection performance of the newly developed ICSS in frontal crashes, a sled test and a series of simulations were conducted. The frontal impact sled test was conducted according to the European regulation ECE R44, which includes a Q6 anthropomorphic test device (ATD) and the impact velocity is 50 km/h. The simulation model included the ICSS model and the Q6 ATD model was developed in the MADYMO software, and the simulation model was validated by the sled test.
Technical Paper

Foot and Ankle Injuries to Drivers in Between-Rail Crashes

2013-04-08
2013-01-1243
The research question investigated in this study is what are the key attributes of foot and ankle injury in the between-rail frontal crash? For the foot and ankle, what was the type of interior surface contacted and the type of resulting trauma? The method was to study with in-depth case reviews of NASS-CDS cases where a driver suffered an AIS=2 foot or ankle injury in between-rail crashes. Cases were limited to belted occupants in vehicles equipped with air bags. The reviews concentrated on coded and non-coded data, identifying especially those factors contributing to the injuries of the driver's foot/ankle. This study examines real-world crash data between the years 1997-2009 with a focus on frontal crashes involving 1997 and later model year vehicles. The raw data count for between-rail crashes was 732, corresponding to 227,305 weighted, tow-away crashes.
Technical Paper

Development of an FE Model of the Rat Head Subjected to Air Shock Loading

2010-11-03
2010-22-0011
As early as the 1950's, Gurdjian and colleagues (Gurdjian et al., 1955) observed that brain injuries could occur by direct pressure loading without any global head accelerations. This pressure-induced injury mechanism was "forgotten" for some time and is being rekindled due to the many mild traumatic brain injuries attributed to blast overpressure. The aim of the current study was to develop a finite element (FE) model to predict the biomechanical response of rat brain under a shock tube environment. The rat head model, including more than 530,000 hexahedral elements with a typical element size of 100 to 300 microns was developed based on a previous rat brain model for simulating a blunt controlled cortical impact. An FE model, which represents gas flow in a 0.305-m diameter shock tube, was formulated to provide input (incident) blast overpressures to the rat model. It used an Eulerian approach and the predicted pressures were verified with experimental data.
Technical Paper

Mechanisms of Traumatic Rupture of the Aorta and Associated Peri-isthmic Motion and Deformation

2008-11-03
2008-22-0010
This study investigated the mechanisms of traumatic rupture of the aorta (TRA). Eight unembalmed human cadavers were tested using various dynamic blunt loading modes. Impacts were conducted using a 32-kg impactor with a 152-mm face, and high-speed seatbelt pretensioners. High-speed biplane x-ray was used to visualize aortic motion within the mediastinum, and to measure deformation of the aorta. An axillary thoracotomy approach was used to access the peri-isthmic region to place radiopaque markers on the aorta. The cadavers were inverted for testing. Clinically relevant TRA was observed in seven of the tests. Peak average longitudinal Lagrange strain was 0.644, with the average peak for all tests being 0.208 ± 0.216. Peak intraluminal pressure of 165 kPa was recorded. Longitudinal stretch of the aorta was found to be a principal component of injury causation. Stretch of the aorta was generated by thoracic deformation, which is required for injury to occur.
Technical Paper

Effect of Vehicle Front End Profiles Leading to Pedestrian Secondary Head Impact to Ground

2013-11-11
2013-22-0005
Most studies of pedestrian injuries focus on reducing traumatic injuries due to the primary impact between the vehicle and the pedestrian. However, based on the Pedestrian Crash Data Study (PCDS), some researchers concluded that one of the leading causes of head injury for pedestrian crashes can be attributed to the secondary impact, defined as the impact of the pedestrian with the ground after the primary impact of the pedestrian with the vehicle. The purpose of this study is to understand if different vehicle front-end profiles can affect the risk of pedestrian secondary head impact with the ground and thus help in reducing the risk of head injury during secondary head impact with ground. Pedestrian responses were studied using several front-end profiles based off a mid-size vehicle and a SUV that have been validated previously along with several MADYMO pedestrian models.
Technical Paper

Biomechanical Response of the Bovine Pia-Arachnoid Complex to Tensile Loading at Varying Strain Rates

2006-11-06
2006-22-0025
The pia-arachnoid complex (PAC) covering the brain plays an important role in the mechanical response of the brain due to impact or inertial loading. However, the mechanical properties of the pia-arachnoid complex and its influence on the overall response of the brain have not been well characterized. Consequently, finite element (FE) brain models have tended to oversimplify the response of the pia-arachnoid complex, possibly resulting in a loss of accuracy in the model predictions. The aim of this study was to determine, experimentally, the material properties of the pia-arachnoid complex under quasi-static and dynamic loading conditions. Specimens of the pia-arachnoid complex were obtained from the parietal and temporal regions of freshly slaughtered bovine subjects with the specimen orientation recorded. Single-stroke, uniaxial quasi-static and dynamic tensile experiments were performed at strain-rates of 0.05, 0.5, 5 and 100 s-1 (n = 10 for each strain rate group).
Technical Paper

Application of a Finite Element Model of the Brain to Study Traumatic Brain Injury Mechanisms in the Rat

2006-11-06
2006-22-0022
Complete validation of any finite element (FE) model of the human brain is very difficult due to the lack of adequate experimental data. However, more animal brain injury data, especially rat data, obtained under well-defined mechanical loading conditions, are available to advance the understanding of the mechanisms of traumatic brain injury. Unfortunately, internal response of the brain in these experimental studies could not be measured. The aim of this study was to develop a detailed FE model of the rat brain for the prediction of intracranial responses due to different impact scenarios. Model results were used to elucidate possible brain injury mechanisms. An FE model, consisting of more than 250,000 hexahedral elements with a typical element size of 100 to 300 microns, was developed to represent the brain of a rat. The model was first validated locally against peak brain deformation data obtained from nine unique dynamic cortical deformation (vacuum) tests.
Technical Paper

Development of Numerical Models for Injury Biomechanics Research: A Review of 50 Years of Publications in the Stapp Car Crash Conference

2006-11-06
2006-22-0017
Numerical analyses frequently accompany experimental investigations that study injury biomechanics and improvements in automotive safety. Limited by computational speed, earlier mathematical models tended to simplify the system under study so that a set of differential equations could be written and solved. Advances in computing technology and analysis software have enabled the development of many sophisticated models that have the potential to provide a more comprehensive understanding of human impact response, injury mechanisms, and tolerance. In this article, 50 years of publications on numerical modeling published in the Stapp Car Crash Conference Proceedings and Journal were reviewed. These models were based on: (a) author-developed equations and software, (b) public and commercially available programs to solve rigid body dynamic models (such as MVMA2D, CAL3D or ATB, and MADYMO), and (c) finite element models.
Technical Paper

High-Speed Seatbelt Pretensioner Loading of the Abdomen

2006-11-06
2006-22-0002
This study characterizes the response of the human cadaver abdomen to high-speed seatbelt loading using pyrotechnic pretensioners. A test apparatus was developed to deliver symmetric loading to the abdomen using a seatbelt equipped with two low-mass load cells. Eight subjects were tested under worst-case scenario, out-of-position (OOP) conditions. A seatbelt was placed at the level of mid-umbilicus and drawn back along the sides of the specimens, which were seated upright using a fixed-back configuration. Penetration was measured by a laser, which tracked the anterior aspect of the abdomen, and by high-speed video. Additionally, aortic pressure was monitored. Three different pretensioner designs were used, referred to as system A, system B and system C. The B and C systems employed single pretensioners. The A system consisted of two B system pretensioners. The vascular systems of the subjects were perfused.
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