Showing papers by "Jason R. Kerrigan published in 2009"

Pediatric thoracoabdominal biomechanics

Abstract: No experimental data exist quantifying the force-deformation behavior of the pediatric chest when subjected to non-impact, dynamic loading from a diagonal belt or a distributed loading surface. Kent et al. (2006) previously published juvenile abdominal response data collected using a porcine model. This paper reports on a series of experiments on a 7-year-old pediatric post-mortem human subject (PMHS) undertaken to guide the scaling of existing adult thoracic response data for application to the child and to assess the validity of the porcine abdominal model. The pediatric PMHS exhibited abdominal response similar to the swine, including the degree of rate sensitivity. The upper abdomen of the PMHS was slightly stiffer than the porcine behavior, while the lower abdomen of the PMHS fit within the porcine corridor. Scaling of adult thoracic response data using any of four published techniques did not successfully predict the pediatric behavior. All of the scaling techniques intrinsically reduce the stiffness of the adult response, when in reality the pediatric subject was as stiff as, or slightly more stiff than, published adult corridors. An assessment of age-related changes in thoracic stiffness indicated that for both a CPR patient population and dynamic diagonal belt loading on a PMHS population, the effective stiffness of the chest increases through the fourth decade of life and then decreases, resulting in stiffness values approximately the same for children and for elderly adults. Additional research is needed to elucidate the generality of this finding and to assess its significance for scaling adult data to represent pediatric responses.

Pedestrian Head Impact Dynamics: Comparison of Dummy and PMHS in Small Sedan and Large SUV Impacts

Abstract: This study compares head impact dynamics between post mortem human surrogates (PMHS) and the Polar- II pedestrian crash dummy in vehicle-pedestrian impacts with a small sedan and a large SUV. A total of fifteen (8 sedan, 7 SUV) full-scale vehicle pedestrian impact tests were performed at 40 km/h. For each vehicle, two (SUV) or three (sedan) PMHS tests and five dummy tests were performed, with three of the dummy tests in the same configuration to show repeatability, and the other two tests utilizing slightly different configurations. Head linear and angular kinematics were captured from PMHS and dummy head instrumentation, and dummy neck forces and impact forces were calculated from the upper neck load cell data. Differences in head impact locations, timing, and kinematics between the dummy and PMHS were minimized when the dummy was positioned higher above the ground reference level to match the pelvis height of the PMHS. On average, the dummy recorded higher resultant impact forces (2930 N vs. 1862 N) in windshield impacts to the sedan than in hood impacts to the SUV, which resulted in higher HIC15 values and higher peak and averaged angular accelerations. While differences in dummy injury risk metrics both the dummy and PMHS data show that the difference in injury risk metrics predicted by the dummy can be explained by the variation in impact velocity between the sedan (14.1 ± 1.2 m/s) and the SUV (10.7 ± 2.3 m/s), the differences in injury risk predicted by the PMHS is not as clear due to confounding factors. The data and analyses presented in this study also show that neck forces during head impacts contribute a substantial and additive effect to the head impact accelerations (and thus HIC15 values) measured in the dummy, and that for the SUV, neck forces affect head accelerations more than impact forces. Despite analyzing only lateral impacts with two vehicle geometries at 40 km/h, this study provides the only comparison of PMHS and dummy pedestrian head impact kinematics data available. The full text of this paper may be found at: http://www-nrd.nhtsa.dot.gov/pdf/esv/esv21/09-0127.pdf For the covering abstract see ITRD E145407.

Frontal impact pmhs sled tests for fe torso model development

Abstract: This study evaluated the response of PMHS in 40 km/h frontal sled tests.Three male PMHS were restrained on a rigid planar seat by a custom 3-point shoulder and lap belt. Ribcage deformation was comprehensively quantified using three-dimensional trajectories of multiple skeletal sites on the torso provided using a motion tracking system. The motion of the lower ribcage up and away from the spine may have contributed to sternal fractures early in the event and suggests that fracture risk may not be fully described solely by anterior ribcage displacement toward the spine. The tests produced valuable kinematic data that will be useful in developing a more biofidelic human model. For the covering abstract see ITRD E143807.

An Analysis of Injury Type and Distribution of Belted, Non-Ejected Occupants Involved in Rollover Crashes

Abstract: Previous research has described the frequency of injuries to body regions suffered by belted, non-ejected occupants of vehicles involved in rollover crashes. While these studies have characterized the crash and occupant outcomes based on contact of the belted occupant with the vehicle interior, these studies have not delved into the specific types of injuries within the body regions. Atkinson et al. (2000) described in detail head and neck injury types resulting from rollover crashes in order to determine what injuries should be predicted in rollover simulations. Ridella and Eigen (2008) investigated injury mechanisms in belted, rollover-involved occupants from the NHTSA’s Crash Injury Research Engineering Network (CIREN) database, but could not project their conclusions to the national level. The aim of this study is to determine distributions of specific injury types in rollover crashes of belted, non-ejected occupants from recent years of the National Automotive Sampling System - Crashworthiness Data System (NASS-CDS) database.

Experimental and computational investigation of human clavicle response in anterior-posterior bending loading - biomed 2009.

Abstract: Clavicle fractures are common injuries in three-point belt restrained occupants involved in frontal and lateral car collisions Therefore, better understanding of clavicle loading which occurs during an impact and clavicle structural/material properties could help in the optimization of seatbelt restraint systems Six clavicles from three post mortem human subjects were tested in a three point -bending test setup with pinned-pinned boundary conditions The clavicle extremities were fixed into potting cups which were able to rotate freely about a single rotational axis (inferior-superior axis) and then, were loaded in the anterior-posterior direction by an impactor at the middle shaft level Two tests were performed on each clavicle: a) A noninjurious quasi-static test (1mm/s impactor rate) up to approximately 400 N b) A dynamic test (1m/s impactor rate) to failure Reaction forces and moments were measured at both clavicle supports The results showed an averaged clavicle stiffness of 211+/-30 N/mm in the quasi-static tests Concerning the dynamic tests to failure, the average maximum force was 1159+/-133 N, the average maximum deflection was 49+/-07 mm, the average clavicle stiffness was 237+/-64 N/mm, and the average maximum strain was 1+/-02% The most common failure location was the middle third of the bone, which is consistent with literature data A finite element model of a human clavicle was developed and used to simulate the tests The optimization of the elastic parameters of clavicle finite element model during the simulations of quasi-static tests provided an 81 GPa Young modulus for cortical bone In addition to providing validation data for computational human models and dummies, the results of this study may lend insight into the development of advanced belt restraint systems

Biomechanical response of the clavicle under bending

Abstract: Over 90% of the clavicle fractures occurring during frontal car impacts are caused by the seat-belt webbing (Kemper et al. 2006; Hynd et al. 2007). Clavicle fractures are not considered as severe but they can cause long-term impairment. To develop and validate accurate models of human thorax for crash simulation and restraint development, previous studies have investigated the response and failure properties of clavicle under bending loading (Kemper et al. 2006). This study aims to augment the existing data set with the response and failure properties of clavicles from relatively young cadavers.