Evaluation of lap belt-pelvis load transfer in frontal impact simulations using finite element occupant models.

Objective: The goal of this study was to examine the relationship between lap belt tension and force measured at the iliac wing and the effects of model type and torso posture on this relationship. From this analysis, preliminary transfer functions were developed to predict loads applied to the iliac wing as a function of lap belt tension at magnitudes typically measured in sled and vehicle crash tests.

Methods: A DOE study was conducted to provide a robust assessment of the lap belt-pelvis load relationship under various conditions.

Cervical vertebral and spinal cord injuries in rollover occupants.

Background: Rollover crashes continue to be a substantial public health issue in North America. Previous research has shown that the cervical spine is the most injured spine segment in rollovers, but much of the past research has focused on risk factors rather than the actual cervical spine injuries. We sought to examine how different types of cervical spine injuries (vertebral and/or cord injury) vary with different occupant-related factors in rollovers and to compare these with non-rollovers.

Knockout of formyl peptide receptor 1 reduces osteogenesis and bone healing.

Aims: Formyl peptide receptor 1 (FPR1), from a G-protein coupled receptor family, was previously well-characterized in immune cells. But the function of FPR1 in osteogenesis and fracture healing was rarely reported. This study, using the FPR1 knockout (KO) mouse, is one of the first studies that try to investigate FPR1 function to osteogenic differentiation of bone marrow-derived stem cells (BMSCs) in vitro and bone fracture healing in vivo.

CCR2 monocytes as therapeutic targets for acute disc herniation and radiculopathy in mouse models.

Objective: Back pain and radiculopathy caused by disc herniation are major health issues worldwide. While macrophages are key players in disc herniation induced inflammation, their roles and origins in disease progression remain unclear. We aim to study the roles of monocytes and derivatives in a mouse model of disc herniation.

The Effects of Recline Angle and Restraint Geometry on Lap Belt-Pelvis Interaction for Above-Normal BMI Motor Vehicle Occupants.

The interaction of the three-point seat belt with the occupant, particularly the lap belt with the pelvis, is affected by a multitude of intrinsic and extrinsic factors, including the torso recline angle, lap belt angle, and occupant body mass index (BMI). While field data analyses have shown the strong safety benefit for seat belt use regardless of occupant size or crash direction, the term "submarining" historically has been used to describe a scenario in which the lap belt loads the abdominal soft tissue and organs, superior and posterior to the pelvic bone. While contemporary restraint systems work to effectively address the risk of submarining in occupants properly seated and properly belted, scenarios in which the lap belt may not properly engage the load-bearing pelvis remain.

Effect of axial compression on stiffness and deformation of human lumbar spine in flexion-extension.

Objective: The goal of this study was to evaluate the effect of axial compression, employed with a follower-load mechanism, on the response of the lumbar spine in flexion and extension bending. Additional goals include measurement of both the kinetic (stiffness) and kinematic (deformation distribution) responses, evaluating how the responses vary across specimens, and to develop response corridors that can be used to evaluate human body models (HBMs) and anthropomorphic test devices (ATDs).

Methods: Seven mid-sized male adult lumbar spines (T12-S1) from postmortem human surrogates were tested in subinjurious flexion and extension bending with 0, 900, and 1800 N of superimposed axial compression.

Human Lumbar Spine Injury Risk in Dynamic Combined Compression and Flexion Loading.

Anticipating changes to vehicle interiors with future automated driving systems, the automobile industry recently has focused attention on crash response in novel postures with increased seatback recline. Prior research found that this posture may result in greater risk of lumbar spine injury in the event of a frontal crash. This study developed a lumbar spine injury risk function (IRF) that estimated injury risk as a function of simultaneously applied compression force and flexion moment.

Failure tolerance of the human lumbar spine in dynamic combined compression and flexion loading.

Vehicle safety systems have substantially decreased motor vehicle crash-related injuries and fatalities, but injuries to the lumbar spine still have been reported. Experimental and computational analyses of upright and, particularly, reclined occupants in frontal crashes have shown that the lumbar spine can be subjected to simultaneous and out-of-phase combined axial compression and flexion loading. Lumbar spine failure tolerance in combined compression-flexion has not been widely explored in the literature.

Effect of Temperature and Freezing on Human Adipose Tissue Material Properties Characterized by High-Rate Indentation: Puncture Testing.

The characterization of human subcutaneous adipose tissue (SAT) under high-rate loading is valuable for development of biofidelic finite element human body models (FE-HBMs) to predict seat belt-pelvis interaction and injury risk in vehicle crash simulations. While material characterization of SAT has been performed at 25 °C or 37 °C, the effect of temperature on mechanical properties of SAT under high-rate and large-deformation loading has not been investigated. Similarly, while freezing is the most common preservation technique for cadaveric specimens, the effect of freeze-thaw on the mechanical properties of SAT is also absent from the literature.

Is optimized restraint system for an occupant with obesity different than that for a normal BMI occupant?

Objective: To optimize the components of restraint systems for protecting obese (BMI = 35 kg/m) and normal BMI (BMI = 25) human body models (HBMs) in frontal crash simulations, and to compare the two optimized designs.

Methods: The Life Years Lost metric, which incorporates the risk of injury and long-term disability to different body regions, was used as the optimization objective function. Parametric simulations, sampled from a 15-parameter design space using the Latin Hypercube technique, were performed and metamodels of the HBM responses were developed.

Effect of various restraint configurations on submarining occurrence across varied seat configurations in autonomous driving system environment.

Objective: Self-driving technology will bring novelty in vehicle interior design and allow for a wide variety of occupant seating choices. Previous studies have shown that the increased risk of submarining exhibited by reclined occupants cannot be fully mitigated by changes in the seat configuration alone. This study aims to investigate the effects of three restraint countermeasures on cases with marginal submarining events and estimate their effect on submarining risk and injury prediction metrics.

Multidirectional mechanical properties and constitutive modeling of human adipose tissue under dynamic loading.

The mechanical behavior of subcutaneous adipose tissue (SAT) affects the interaction between vehicle occupants and restraint systems in motor vehicle crashes (MVCs). To enhance future restraints, injury countermeasures, and other vehicle safety systems, computational simulations are often used to augment experiments because of their relative efficiency for parametric analysis. How well finite element human body models (FE-HBMs), which are often used in such simulations, predict human response has been limited by the absence of material models for human SAT that are applicable to the MVC environment.

Comparison of injuries in multiple and single event crashes.

Compare injuries for occupants in multiple event (ME) crashes where a less severe event preceded a more severe event to occupants in similar single event (SE) crashes. Occupants in ME crashes from NASS-CDS years 2000-2015 where the most severe event occurred subsequent to a less severe event were matched to occupants in SE crashes where the SE was similar to the most severe event in the ME crash. Occupants were matched based on occupant, vehicle, and crash characteristics and were compared across 21 detailed body regions using conditional logistic regression.

In Vitro Mechanical Characterization and Modeling of Subcutaneous Adipose Tissue: A Comprehensive Review.

Mechanical models of adipose tissue are important for various medical applications including cosmetics, injuries, implantable drug delivery systems, plastic surgeries, biomechanical applications such as computational human body models for surgery simulation, and blunt impact trauma prediction. This article presents a comprehensive review of in vivo experimental approaches that aimed to characterize the mechanical properties of adipose tissue, and the resulting constitutive models and model parameters identified. In particular, this study examines the material behavior of adipose tissue, including its nonlinear stress-strain relationship, viscoelasticity, strain hardening and softening, rate-sensitivity, anisotropy, preconditioning, failure behavior, and temperature dependency.

Leveraging machine learning for predicting human body model response in restraint design simulations.

The objective of this study was to leverage and compare multiple machine learning techniques for predicting the human body model response in restraint design simulations. Parametric simulations with 16 independent variables were performed. Ordinary least-squares (OLS), least absolute shrinkage and selection operator (LASSO), neural network (NN), support vector regression (SVR), regression forest (RF), and an ensemble method were used to develop response surface models of the simulations.

Sensitivity of scale factor choice on injury response for equal-stress equal-velocity scaling.

Objective: This study aims to evaluate the assumption of geometric similitude inherent to equal-stress equal-velocity scaling by determining if scale factors created with different anthropometry metrics result in different scaled injury tolerance predictions. This assumption will be evaluated when equal-stress equal-velocity scaling is employed across dissimilar (e.g.

Comparison of porcine and human adipose tissue loading responses under dynamic compression and shear: A pilot study.

Understanding the mechanical properties of human adipose tissue, and its influence on seat belt-pelvis interaction is beneficial for computational human body models that are developed for injury prediction in the vehicle crashworthiness simulations. While various studies have characterized adipose tissue, most of the studies used porcine adipose tissue as a surrogate, and none of the studies were performed at loading rates relevant for motor vehicle collisions. In this work, the mechanical response of human and porcine adipose tissue was studied.

Submarining sensitivity across varied seat configurations in autonomous driving system environment.

Objective: Self-driving technology will bring novelty in vehicle interior design and allow for a wide variety of occupant seating choices. Thus, vehicle safety systems may be challenged to protect occupants over a wider range of potential postures. This study aims to investigate the effects of the seat cushion angle on submarining risk, lumbar spine loads and pelvis excursion for reclined occupants in frontal crashes.

Kinematics of inboard-leaning occupants in frontal impacts.

Up to one-half of drivers swerve before a crash, which may cause vehicle motions that displace an occupant from a normal seated position. How these altered postures affect occupant restraint in a crash is unknown. The goal of this study was to quantify the effect of an initial inboard lean on occupant kinematics in a frontal impact.