Factors influencing the effectiveness of occupant retention under far-side impacts: A parametric study.

The occupant retention and injuries under far-side impact are invariably dependent upon the effectiveness of the seatbelt restraint system, which is largely driven by parameters such as seatbelt pre-tensioner limiting load, D-ring position above and behind the shoulder, and friction coefficient between the torso and the seatbelt. The cumulative effect of systematic variation of these parameters on occupant kinematics under far-side is rarely studied in the literature. In this study, a systematic and detailed analysis was performed to understand the effect of these parameters on occupant retention.

Influence of morphological variations on cervical spine segmental responses from inertial loading.

Objectives: The objective of this study was to investigate the influence of morphological variations in osteoligamentous lower cervical spinal segment responses under postero-anterior inertial loading.

Methods: A parametric finite element model of the C5-C6 spinal segment was used to generate models. Variations in the vertebral body and facet depth (anteroposterior), posterior process length, intervertebral disc height, facet articular process height and slope, segment orientation ranging from lordotic to straight, and segment size were parameterized.

Biomechanics of Lumbar Motion-Segments in Dynamic Compression.

Recent epidemiology studies have reported increase in lumbar spine injuries in frontal crashes. Whole human body finite element models (FEHBM) are frequently used to delineate mechanisms of such injuries. However, the accuracy of these models in mimicking the response of human spine relies on the characterization data of the spine model.

Normalized frontal impact biofidelity kinematic corridors using post mortem human surrogates.

Due to reducing cost and powerful computing resources and the ability of finite element human body models (FEHBM) to predict human body response more realistically, they are gaining acceptance to be a substitute for mechanical surrogates. Unlike mechanical surrogates, FEHBM can realistically simulate human kinematics and kinetics. Moreover, an array of quantities can be directly measured from FEHBMs.

Evaluation of kinematics and injuries to restrained occupants in far-side crashes using full-scale vehicle and human body models.

Objective: The objective of the current study was to perform a parametric study with different impact objects, impact locations, and impact speeds by analyzing occupant kinematics and injury estimations using a whole-vehicle and whole-body finite element-human body model (FE-HBM). To confirm the HBM responses, the biofidelity of the model was validated using data from postmortem human surrogate (PMHS) sled tests.

Methods: The biofidelity of the model was validated using data from sled experiments and correlational analysis (CORA).

Oblique Loading in Post Mortem Human Surrogates from Vehicle Lateral Impact Tests using Chestbands.

While numerous studies have been conducted to determine side impact responses of Post Mortem Human Surrogates (PMHS) using sled and other equipment, experiments using the biological surrogate in modern full-scale vehicles are not available. The present study investigated the presence of oblique loading in moving deformable barrier and pole tests. Threepoint belt restrained PMHS were positioned in the left front and left rear seats in the former and left front seat in the latter condition and tested according to consumer testing protocols.

Dynamic Responses of Intact Post Mortem Human Surrogates from Inferior-to-Superior Loading at the Pelvis.

During certain events such as underbody blasts due to improvised explosive devices, occupants in military vehicles are exposed to inferior-to-superior loading from the pelvis. Injuries to the pelvis-sacrum-lumbar spine complex have been reported from these events. The mechanism of load transmission and potential variables defining the migration of injuries between pelvis and or spinal structures are not defined.

Lower Leg Injury Reference Values and Risk Curves from Survival Analysis for Male and Female Dummies: Meta-analysis of Postmortem Human Subject Tests.

Objective: Derive lower leg injury risk functions using survival analysis and determine injury reference values (IRV) applicable to human mid-size male and small-size female anthropometries by conducting a meta-analysis of experimental data from different studies under axial impact loading to the foot-ankle-leg complex.

Methods: Specimen-specific dynamic peak force, age, total body mass, and injury data were obtained from tests conducted by applying the external load to the dorsal surface of the foot of postmortem human subject (PMHS) foot-ankle-leg preparations. Calcaneus and/or tibia injuries, alone or in combination and with/without involvement of adjacent articular complexes, were included in the injury group.

Military boot attenuates axial loading to the lower leg.

Biomechanical tests to understand injury mechanisms and derive injury tolerance information using Post-Mortem Human Subjects (PMHS) have not used foot protection and they have primarily focused on civilian environments such as automotive and athletic- and sports-related events. As military personnel use boots, tests with the boot are required to understand their effect on attenuating lower leg loads. The purpose of this study was therefore, to determine the modulation of human lower leg kinematics with boot compressions and share of the force absorbed by the boot from underbody blast loading.

Sensitivity and stability analysis of a nonlinear material model of cervical intervertebral disc under cyclic loads using the finite element method.

It is known that the human spine exhibits non-linear behavior, and its intervertebral discs play a role in the mechanism of internal load transfer. It is important to simulate its nonlinear behavior in computational models for better delineation of intrinsic responses, especially during cyclic loading activities, a mode pertinent to civilian and military populations. For developing a robust “material model” of the disc, this study used experimental tensile-compressive cyclic loading responses from four human cadaver cervical functional spinal units.

Crash characteristics and injury patterns of restrained front seat occupants in far-side impacts.

Objective: The study was conducted to determine the association between vehicle-, crash-, and demographic-related factors and injuries to front seat far-side occupants in modern environments.

Methods: Field data were obtained from the NASS-CDS database for the years 2009-2012. Inclusion factors included the following: adult restrained front outboard-seated occupants, no ejection or rollovers, and vehicle model years less than 10 years old at the time of crash.

Optimized lower leg injury probability curves from postmortem human subject tests under axial impacts.

Objective: Derive optimum injury probability curves to describe human tolerance of the lower leg using parametric survival analysis.

Methods: The study reexamined lower leg postmortem human subjects (PMHS) data from a large group of specimens. Briefly, axial loading experiments were conducted by impacting the plantar surface of the foot.

A methodology to condition distorted acoustic emission signals to identify fracture timing from human cadaver spine impact tests.

While studies have used acoustic sensors to determine fracture initiation time in biomechanical studies, a systematic procedure is not established to process acoustic signals. The objective of the study was to develop a methodology to condition distorted acoustic emission data using signal processing techniques to identify fracture initiation time. The methodology was developed from testing a human cadaver lumbar spine column.

Deflection corridors of abdomen and thorax in oblique side impacts using equal stress equal velocity approach: comparison with other normalization methods.

The first objective of the study was to determine the thorax and abdomen deflection time corridors using the equal stress equal velocity approach from oblique side impact sled tests with postmortem human surrogates fitted with chestbands. The second purpose of the study was to generate deflection time corridors using impulse momentum methods and determine which of these methods best suits the data. An anthropometry-specific load wall was used.

Normalizing and scaling of data to derive human response corridors from impact tests.

It is well known that variability is inherent in any biological experiment. Human cadavers (Post-Mortem Human Subjects, PMHS) are routinely used to determine responses to impact loading for crashworthiness applications including civilian (motor vehicle) and military environments. It is important to transform measured variables from PMHS tests (accelerations, forces and deflections) to a standard or reference population, termed normalization.

Biomechanics of human thoracolumbar spinal column trauma from vertical impact loading.

Recent studies suggest that dorsal spine injuries occur in motor vehicle crashes to restrained occupants. Compression/compression-flexion injuries occur in frontal crashes due to seat pan and vertical loading. While injuries, mechanisms and tolerances for neck injuries have been determined, thoraco-lumbar spine data are very limited.