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Technical Paper

Occupant Kinematics and Shoulder Belt Retention in Far-Side Lateral and Oblique Collisions: A Parametric Study

2013-11-11
2013-22-0014
In far-side impacts, head contact with interior components is a key injury mechanism. Restraint characteristics have a pronounced influence on head motion and injury risk. This study performed a parametric examination of restraint, positioning, and collision factors affecting shoulder belt retention and occupant kinematics in far-side lateral and oblique sled tests with post mortem human subjects (PMHS). Seven PMHS were subjected to repeated tests varying the D-ring position, arm position, pelvis restraint, pre-tensioning, and impact severity. Each PMHS was subjected to four low-severity tests (6.6 g sled acceleration pulse) in which the restraint or position parameters were varied and then a single higher-severity test (14 g) with a chosen restraint configuration (total of 36 tests). Three PMHS were tested in a purely lateral (90° from frontal) impact direction; 4 were tested in an oblique impact (60° from frontal). All subjects were restrained by a 3-point seatbelt.
Technical Paper

The Effect of Pretensioning and Age on Torso Rollout in Restrained Human Volunteers in Far-Side Lateral and Oblique Loading

2012-10-29
2012-22-0012
Far-side side impact loading of a seat belt restrained occupant has been shown to lead to torso slip out of the shoulder belt. A pretensioned seat belt may provide an effective countermeasure to torso rollout; however the effectiveness may vary with age due to increased flexibility of the pediatric spine compared to adults. To explore this effect, low-speed lateral (90°) and oblique (60°) sled tests were conducted using male human volunteers (20 subjects: 9-14 years old, 10 subjects: 18-30 years old), in which the crash pulse safety envelope was defined from an amusement park bumper-car impact. Each subject was restrained by a lap and shoulder belt system equipped with an electromechanical motorized seat belt retractor (EMSR) and photo-reflective targets were attached to a tight-fitting headpiece or adhered to the skin overlying key skeletal landmarks.
Journal Article

Headform Impact Tests to Assess Energy Management of Seat Back Contact Points Associated with Head Injury for Pediatric Occupants

2012-04-16
2012-01-0561
Head injuries are the most common injuries sustained by children in motor vehicle crashes regardless of age, restraint and crash direction. Previous research identified the front seat back as relevant contact point associated with head injuries sustained by restrained rear seated child occupants. The objective of this study was to conduct a test series of headform impacts to seat backs to evaluate the energy management characteristics of relevant contact points for pediatric head injury. A total of eight seats were tested: two each of 2007 Ford Focus, Toyota Corolla, 2006 Volvo S40, and 2008 Volkswagen Golf. Five to six contact points were chosen for each unique seat model guided by contact locations determined from real world crashes. Each vehicle seat was rigidly mounted in the center track position with the seatback angle adjusted to 70 degrees above the horizontal.
Technical Paper

Comparison of Kinematic Responses of the Head and Spine for Children and Adults in Low-Speed Frontal Sled Tests

2009-11-02
2009-22-0012
Previous research has suggested that the pediatric ATD spine, developed from scaling the adult ATD spine, may not adequately represent a child's spine and thus may lead to important differences in the ATD head trajectory relative to a human. To gain further insight into this issue, the objectives of this study were, through non-injurious frontal sled tests on human volunteers, to 1) quantify the kinematic responses of the restrained child's head and spine and 2) compare pediatric kinematic responses to those of the adult. Low-speed frontal sled tests were conducted using male human volunteers (20 subjects: 6-14 years old, 10 subjects: 18-40 years old), in which the safety envelope was defined from an amusement park bumper-car impact.
Technical Paper

Biomechanical Response of the Pediatric Abdomen, Part 2: Injuries and Their Correlation with Engineering Parameters

2008-11-03
2008-22-0006
This paper describes the injuries generated during dynamic belt loading to a porcine model of the 6-year-old human abdomen, and correlates injury outcomes with measurable parameters. The test fixture produced transverse, dynamic belt loading on the abdomen of 47 immediately post-mortem juvenile swine at two locations (upper/lower), with penetration magnitudes ranging from 23% – 65% of the undeformed abdominal depth, with and without muscle tensing, and over a belt penetration rate range of 2.9 m/s – 7.8 m/s. All thoracoabdominal injuries were documented in detail and then coded according to the Abbreviated Injury Scale (AIS). Observed injuries ranged from AIS 1 to AIS 4. The injury distribution matched well the pattern of injuries observed in a large sample of children exposed to seatbelt loading in the field, with most of the injuries in the lower abdomen.
Technical Paper

Neck Pendulum Test Modifications for Simulation of Frontal Crashes

2008-04-14
2008-01-0518
Pediatric Anthropomorphic Test Devices (ATDs) are valuable tools for assessing the injury mitigation capability of automotive safety systems. The neck pendulum test is widely used in biofidelity assessment and calibration of the ATD neck, and neck moment vs. angle response requirements are the metrics typically derived from the test. Herein, we describe the basis and methods for modifying the neck pendulum such that it more closely reflects base of the neck accelerations observed by a restrained three-year old ATD in a frontal crash. As a measure of base of the neck acceleration, the x-direction chest acceleration from thirty-one restrained Hybrid III three-year-old ATDs in vehicle frontal crash tests were analyzed. The standard neck pendulum yielded a mean peak acceleration that is 1.2x the peak of vehicle base of the neck accelerations, 1.6x the average, and 0.24x the duration.
Technical Paper

Anterior-Posterior Thoracic Force-Deflection Characteristics Measured During Cardiopulmonary Resuscitation: Comparison to Post-Mortem Human Subject Data

2006-11-06
2006-22-0006
Comparative data of thoracic compression response between live vs. post mortem human subjects (PMHS) has been reported, but the live subject tests are often at low deflections and include the effects of muscle tensing. Novel technology has been developed that overcomes several of these limitations. Specifically, a load cell and accelerometer has been integrated into a clinical monitor-defibrillator to measure chest compression and applied force during live human cardio-pulmonary resuscitation (CPR). The sensor is interposed between the hands of the person administering CPR and the sternum of the patient. The objective of this study was to compare the thoracic force-deflection measured during adult CPR to that measured during hub-based loading of adult PMHS. CPR represents a unique setting in which to study the mechanics of the chest as the thorax is loaded to a maximum chest deflection similar to that seen in a frontal crash environment and the effects of muscle tensing are minimized.
Technical Paper

Biomechanical Response of the Pediatric Abdomen, Part 1: Development of an Experimental Model and Quantification of Structural Response to Dynamic Belt Loading

2006-11-06
2006-22-0001
The abdomen is the second most commonly injured region in children using adult seat belts, but engineers are limited in their efforts to design systems that mitigate these injuries since no current pediatric dummy has the capability to quantify injury risk from loading to the abdomen. This paper develops a porcine (sus scrofa domestica) model of the 6-year-old human's abdomen, and then defines the biomechanical response of this abdominal model. First, a detailed abdominal necropsy study was undertaken, which involved collecting a series of anthropometric measurements and organ masses on 25 swine, ranging in age from 14 to 429 days (4-101 kg mass). These were then compared to the corresponding human quantities to identify the best porcine representation of a 6-year-old human's abdomen. This was determined to be a pig of age 77 days, and whole-body mass of 21.4 kg.
Technical Paper

Pediatric Facial Fractures: Implications for Regulation

2002-03-04
2002-01-0025
On-site, in-depth investigations were conducted on 14 crashes involving 15 children who sustained facial fractures. Of the 23 facial fractures documented, the most frequent were the nose (n=8), orbit (n=6), zygoma/maxilla (n=6), and mandible (n=3). The most frequent contact point of those seated in the rear was the rear of the front seat; of those seated in the front, the instrument panel. 11/15 had sub-optimal torso restraint resulting from placing the shoulder belt behind their back or sitting in a position only equipped with a lap belt. The data suggest that these injuries resulted from high-energy impact with interior vehicle components. Revision to FMVSS 201 to account for vehicle interior structures typically contacted by child occupants and enhancement of pediatric dummies to measure facial impact forces should be considered.
Technical Paper

Regional Differences in Mechanical Properties of the Porcine Central Nervous System

1997-11-12
973336
Computational modeling is a potentially powerful tool to provide information about the mechanisms of traumatic brain injury. In order to ensure that the estimates calculated by these computer models provide the most useful information, it is essential that these models contain accurate central nervous system (CNS) tissue properties. Previous material property measurements lack strict control over crucial experimental parameters that may influence material properties and tail to examine any regional variation in the measured response. To address these issues, we measured the material response of two regions of the CNS, the brainstem and the cerebrum. Specifically, adult porcine tissue was subjected to high loading rate mechanical deformation using a custom designed oscillatory shear device. Complex shear moduli were calculated over a range of frequencies (20-200 Hz) at two engineering strain amplitudes (2.5%, and 5.0%).
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