Head Injury Criterion Research Articles

A new approach for uncertainty analysis of ETW Rider Head Injury Reconstruction via Coupling Response Surface and Monte Carlo methodologies

Traditional vehicle accident reconstructions do not take into account all existing uncertainties and may over- or under-estimate the injury risk. The objective of this study was to introduce a new uncertainty analysis method by applying Response Surface-Monte Carlo Methods (RS-MCM) to predict head injury risk in real electric two wheelers (ETW) to vehicle accidents. Vehicle impact velocity ranges in three detailed ETWs accidents (including video records and injury reports) were estimated using direct linear transformation (DLT) or video frame (VF) methods. A response surface methodology (RSM) was used to obtain an approximate model of the each real ETW accident, and a vehicle impact velocity distribution was estimated by applying the Monte Carlo Method (MCM) to the resulting model. If the velocity distribution was in agreement with the initial estimated velocity, the reconstruction quality was deemed acceptable. The injury severity was then assessed using the initial conditions resulting from the range of potential head impact conditions identified in the reconstruction activities. The identified head linear and angular impact velocities were input to finite element analyses to the THUMS Ver4.02 pedestrian head model and resulting in head injury criteria (HIC). The HIC values were further explored using the same RSM method used earlier to establish impact conditions. The distribution of reconstructed AIS levels show good agreement with the injury results from forensic reports. The results illustrated that the RS-MCM enriches the information for head trauma injury mechanisms caused by the vehicle collisions or ground impact.

Feasibility Study on the Redesign of a Metallic Car Hood by Using Composite Materials

Nowadays, fuel consumption and exhaust emissions are topical issues in the automotive field, as environmental safeguard legislation constraints are going to get tougher. Indeed, one of the most efficient methods to contain fuel consumption and emissions is the weight reduction of the vehicle. In this paper, a feasibility study on the lightweight redesign of a metallic car hood by using composite materials is presented. In particular, two different configurations, employing composite laminates and sandwich structures, are investigated. The feasibility of each configuration is assessed in terms of stiffness specifications and pedestrian safety requirement. Hence, Head Injury Criteria are employed, according to regulations. Finally, an optimization procedure on the stacking sequence of the composite laminates is performed, to determine, among the feasible solutions, the one characterized by the minimum weight.

Complete Republication: Fall Injury while the Parent Is Operating a Bicycle with an Infant in a Baby Carrier.

Introduction: Pediatric emergency physicians commonly experience cases of infantile trauma as a result of a child falling from the arms or the back of a parent while the parent is operating a bicycle. Methods: 1. We conducted a retrospective case-series study which included children younger than 1 year who were injured after falling from the arms or the back of the parent while the latter was operating a bicycle. 2. We conducted a dynamics experiment by recreating the circumstances of the accident using dummies representing a 6-month-old infant being carried on the back of the mother. We assessed the score of the Head Injury Criterion (HIC) and the maximum impact load on the head of the dummy infant. Results: 1. We found eight injured patients, two of whom required intensive care. One of the latter experienced neurological sequelae. 2. The HIC score and the maximum impact load varied from 7.7 to 17.0 and 2.26 to 3.47 times the reference values for 6-month-old infants, respectively. Conclusions: Our study revealed that a strong impact on an infant’s head can result in severe head trauma due to the mechanics of the injury type studied. Preventive strategies for the safe transportation of infants are needed.

An In-silico Simulation of Pressure Wave Excursions after Impact to the Frontal Lobe of a Homogenous Model of the Brain

Traumatic impacts to the crania are known to have chronic effects on cerebral tissue and cognitive function. However, the inaccessibility of healthy brain tissue has limited studies of the mechanical behavior of the brain during impact. Consequently, it is uncertain how specific impacts lead to injury. The well-known Head Injury Criterion (HIC) metric is stochastic in nature. Therefore, it cannot provide deterministic indications of the severity of certain impacts and is ambivalent to trauma location.This research investigated an impact to the anterior region of an isomorphic model of intracranial tissue. The impact was 18 mm lateral of the sagittal plane. The impact propagation through the brain model was observed with a focus on the depth of wave penetration. The brain model was simplified by removing material property variations across white and grey matter and in the ventricles that contain cerebrospinal fluid regions. Ultimately, homogeneity of the simplified model was assumed to show more conservative results than what may be observed in practice.The simulation showed the significance of the initial impact magnitude and location with respect to any propagated wave. It was observed that despite minimizing the effect of damping in the model, pressure waves were not significant at the anterior of the brain. Thus, it was concluded that it is unlikely that secondary impact during TBI has a significant correlation to the location and severity of injury sustained.

Studying on the design and simulation of collision protection system between vehicle and pedestrian

Pedestrian protection technology has become the most important issue in the field of vehicle safety. The design and simulation method of pedestrian protection system for vehicles is studied based on the Teoriya Resheniya Izobreatatelskih Zadatch theory in this article. The optimal solution of a new type of all-around airbag system mounted to the front of vehicles is presented after performing some Teoriya Resheniya Izobreatatelskih Zadatch analysis tools, such as the component analysis, causal analysis, resource analysis, and contradiction analysis. The digital modeling is carried out on the airbag deployments by SolidWorks, and the simulation analysis is performed on the collision between vehicle and pedestrian head by HyperWorks and LS-DYNA. The results show that the vehicle equipped with the front-end all-around airbag than without can play a better role in pedestrian head protection during the collision, making the maximum value of head injury criterion decrease by 66.7%, effectively reducing the collision damage and verifying the feasibility of the solution.

Methodology for scaling finite element dummy and validation of a Hybrid III dummy model in crashworthiness simulation

For study of car-pedestrian crashes, it is two common methods that can be employed: conducting crash tests with mechanical dummies and simulating car crashes on computer. The former is a traditional way and gives good results compared with real life car impact; however, its disadvantage is very expensive test equipment and generally more time-consuming than the latter because after every crash test, experimental vehicles as well as dummies need repairing to be ready for the next experiments. Therefore, crash test simulation using finite-element method is more and more popular in the automobile industry because of its feasibility and cost saving. The majority of finite element dummy models used in crash simulation. Particularly, it is popular to use Hybrid III 50th dummy model which is built based on fiftieth percentile male (equal in height and weight of the average North American). Thus, it is necessary to develop a scaling algorithm to scale a reference dummy size into a desired one without rebuilding the entire model. In this paper, the Hybrid III dummy model provided by LS-DYNA software is scaled to suit Vietnamese biomechanical characteristics. Scaling algorithm comprises dummy geometry, inertial properties and joint properties is utilized. In order to estimate level of head injury – brain concussion by using numerical simulation, the correlation between Head Injury Criterion (HIC) and Abbreviated Injury Scale (AIS) is introduced. In addition, the Hybrid III dummy model in crashworthiness simulation is presented in key frame picture. Numerical simulation approach is validated by comparing results of head acceleration and HIC obtain from this study with experimental data and numerical simulation results in other publication

A parametric analysis of factors that determine head injury outcomes following equestrian fall accidents

This study examined the effects and interaction of four primary impact parameters (impact velocity, angle of impact relative to the ground, ground compliance and helmet impact location) on head kinematics and brain tissue response for falls that are most commonly associated with equestrian sports. A helmeted headform was subject to parametric tests using a rail guided launcher at three impact velocities (6, 9 and 12 m/s), four angles of incidence (15°, 30°, 45° and 60°), three ground compliance levels (High, Medium and Low) and three helmet locations (front, front-boss and rear-boss). Head kinematics were obtained from the headform and a finite element model was used to estimate brain tissue response. Velocity and angle had the largest effects on the risk of concussion, as measured by head kinematics and brain tissue response, while compliance and location were less influential. Interactions such as angle and compliance were found to greatly influence the risk of concussion. These findings suggest that an increased ground compliance can decrease linear acceleration and Head Injury Criterion (HIC) but not necessarily decrease rotational kinematics and brain tissue response. Consequently, the use of technological designs to attenuate rotational acceleration and decouple the helmet from that of the head may provide better safety than simply the addition of extra protective layers to the ground or a helmet liners.

Frontal crash seat belt restraint effectiveness and comfort accessories used by older occupants

Objective: Around a quarter of older occupants use some type of comfort or orthopedic aftermarket accessory on the vehicle seat while traveling in a vehicle. The aim of this study was to investigate the effect of comfort accessories on the performance of the seat belt restraint system in a frontal crash in terms of potential injury implications for older occupants.Methods: Eight frontal sled tests (43 km/h, 32 g) were carried out on a deceleration sled fitted with a three-point lap-sash seat belt and a front passenger seat from a common Australian passenger car for each test. A 5th percentile Hybrid III anthropometric test device (ATD) was positioned in the seat and measurements were recorded for head center of gravity acceleration, chest acceleration, neck forces and moments and sternal deflection. Tests were carried out in a baseline condition and with seven comfort accessories. Each comfort accessory was inserted between the ATD and vehicle seat as it is intended to be used, with the ATD otherwise positioned as close as possible to the baseline test position.Results: Initial distance between the seat belt anchor and ATD hip was associated with a statistically significant decrease in Head Injury Criterion and increase in sternal deflection. Submarining was related to the ATD torso recline angle and angle of the lap belt from the seat belt anchor.Conclusions: Accessories placed between the seat back and the lumbar region of an occupant have the potential to increase the risk of submarining due to a change in posture and should be avoided if such a change in posture when seated with an accessory is excessive. Sitting on seat cushions resulted in the greatest increase in seat belt anchor to hip distances and hence largest increase in sternal deflection. Given the fragility, frailty and particular importance of chest injuries among older vehicle occupants, further investigation is needed to determine whether these changes in ATD sternal deflection observed with seat cushion use results in injury threshold limits being exceeded and whether pretensioners and load limiters would ameliorate these effects without causing other negative changes in occupant response or kinematics.

Prediction of pedestrian brain injury due to vehicle impact using computational biomechanics models: Are head-only models sufficient?

Objectives: Accident reconstruction using computational biomechanics models plays an important role in research and prevention of human brain injury caused by car-to-pedestrian impacts. Finite element (FE) “head-only” models (that represent only the pedestrian head and brain) used in such reconstruction do not account for the influence of the rest of the pedestrian body on the head kinematics due to the accident and, consequently, on the brain injury risk prediction. Application of full-scale FE pedestrian models, on the other hand, is limited by their high computational cost and, more importantly, by the time-consuming preprocessing when repositioning the model to represent the pedestrian posture and location in relation to the impacting car. The objective of this study is to propose a computational biomechanics modeling approach to overcome these challenges.Methods: First, we couple a validated commercial FE head-neck complex model and a multibody (MB) pedestrian model. This coupled FE-MB model is evaluated through application in reconstruction of a real-world car-to-pedestrian impact accident and comparison of the pedestrian kinematics predicted using this model with the results obtained from the established full-scale MB pedestrian model. Finally, we compare the results obtained using the coupled FE-MB model proposed in this study and FE head-only model in terms of both the head kinematics and brain injury risk predicted using the two models.Results: The results of analysis of head injury criterion (HIC15) and brain deformation-based injury criteria (instantaneous value of cumulative strain damage measure iCSDM and maximum shear strain of the brain tissue) indicate substantial differences in the head kinematics and brain injury risk predicted using the two models. The coupled FE-MB model predicts a high risk of the brain injury which is consistent with the database record of the analyzed accident, in particular for the impact between the pedestrian head and road surface. In contrast, the head-only model did not predict that such impact can occur. The FE head head-only model with rigid skull and prescribed acceleration–time history of the head center of gravity determined from accident reconstruction using the purely MB pedestrian model, predicted appreciably lower iCSDM than the coupled FE-MB model that accounts for skull deformations using the linear elastic-plastic material model.Conclusions: This study suggests that the FE head-only models may be deficient for car-to-pedestrian impact accident reconstruction and estimation of risk of the pedestrian brain injury. In particular, this applies to the models that simplify the pedestrian skull as a rigid body.

Head injury metric response in finite element ATDs and a human body model in multidirectional loading regimes

Objective: The objective was to quantify head injury metric sensitivity of the 50th percentile male Hybrid III, THOR, and Global Human Body Models Consortium simplified occupant (GHBMC M50-OS) to changes in loading conditions in loading regimes that may be experienced by occupants of spaceflight vehicles or highly autonomous vehicles (HAVs) with nontraditional seating configurations.Methods: A Latin hypercube (LHD) design of experiments (DOE) was employed to develop boundary conditions for 455 unique acceleration profiles. Three previously validated finite element (FE) models of the Hybrid III anthropomorphic test device (ATD), THOR ATD, and GHBMC M50-OS were positioned in an upright 90°-90°-90° seat and with a 5-point belt. Acceleration pulses were applied to each of the three occupants in the ± X, +Y, and ± Z directions, with peak resultant acceleration magnitudes ranging from 5 to 20 G and times to peak ranging from 32.5 to 120.8 ms with duration 250 ms, resulting in 1,248 simulations. Head injury metrics included peak linear head acceleration, peak rotational head acceleration, head injury criteria (HIC15), and brain injury criteria (BrIC). Injury metrics were regressed against boundary condition parameters using 2nd order multiple polynomial regression, and compared between occupants using matched pairs Wilcoxon signed rank analysis.Results: Across the 416 matched-simulations that reached normal termination with all three models, HIC15 values ranged from 1.0–396.5 (Hybrid III), 1.2–327.9 (THOR), and 0.6–585.6 (GHBMC). BrIC ranged from 0.03–0.95 (Hybrid III), 0.03–1.21 (THOR), and 0.04–0.84 (GHBMC). Wilcoxon signed rank analysis demonstrated significant pairwise differences between each of the three occupant models for head injury metrics. For HIC15, the largest divergence between GHBMC and the ATDs was observed in simulations with components of combined underbody and rear impact loading. The three models performed most similarly with respect to BrIC output when loaded in a frontal direction. Both the GHBMC and the Hybrid III produced lower values of BrIC than the THOR on average, with the differences most pronounced in rear impact loading.Conclusion: In conclusion, observed differences between the occupant models’ head injury metric output were quantified. Loading direction had a large effect on metric outcome and metric comparability across models, with frontal and rear impacts with low vertical acceleration tending to be the most similar. One explanation for these differences could be the differences in neck stiffness between the models that allowed more rotation in the GHBMC and THOR. Care should be taken when using ATDs as human volunteer surrogates in these low energy events.

Frontal Crash Injury Metrics Are Below Mandated Limits for a Spica Casted Child Dummy in Currently Available Restraints.

There is a paucity of data defining safe transport protocols for children treated with hip spica casting. Although restraint devices for casted children are available, all federally mandated testing uses a noncasted anthropomorphic test device (ATD or crash dummy). The purpose of this study was to evaluate current restraint options in simulated frontal crash testing using a casted pediatric ATD to determine injury risk to the head, cervical spine, chest, and pelvis. Using a 3-year-old ATD, dynamic crash sled tests simulating frontal crash were performed in accordance with government safety standards. The ATD was casted in a double-leg spica and the following restraint devices were tested: a seat designed for spica casted children, a restraint vest-harness, a traditional booster seat, and 2 traditional forward-facing car seats. Although the presence of the cast increased many of the injury metrics measured, all seats passed current federal guidelines for the head and chest. No single seat performed best in all metrics. The greatest magnitude of neck loading and second-highest head injury criterion values were observed for the booster seat. The vest-harness produced the highest head injury criterion and the chest compression exceeded proposed federal limits. The results suggest safe transport in commercially available seats is possible with the child properly restrained in a correctly fitting seat. However, parents should not assume a child restraint system is appropriate for use just based on fit as, for example, seats with harnesses outperformed an easy to fit booster seat. Each child and the position of the child's cast are unique and discharge planning involves consideration of safe transportation. Although this study suggests several seats used to transport spica casted children pass the federal head and chest injury prevention requirements, it is important to recognize that some children may still require emergency vehicle transport.

Suitability of enhanced head injury criteria for vehicle rating

Objective: Euro NCAP is considering the implementation of a new head injury assessment with the introduction of THOR in the mobile progressive deformable barrier frontal impact crash test. The objective of this study is to assess the suitability of enhanced head injury criteria for practical application in consumer rating programs.Method: AIS2+ risk predictions from nine selected head injury criteria where calculated for 27 pairs of crash test results representing small and moderate overlap frontal crashes. The capability of each injury criteria to predict the real-world injury rates of these crash modes was evaluated. Next, the correlation coefficients between the head injury candidates were calculated and individual predictions were compared for all tests in scatter plots.Results: The results show that none of the crash tests head injury assessment predicted the four-times higher head injury rates observed in the accident data for small overlap crashes compared to moderate overlap crashes. Poor correlation was demonstrated between many leading brain injury metrics, and the risk predictions for individual vehicles differ quite substantially depending on the criterion considered. Conclusions: While preliminary, the results of this study demonstrate that more evaluation of the most suitable brain injury criteria is necessary before consideration into a consumer evaluation program. Convergence of the head injury criteria risks for individual cases should be part of the validation process for enhanced head injury criteria, since identical head signals should yield similar injury risks.

Responses of the scaled pediatric human body model in the rear- and forward-facing child seats in simulated frontal motor vehicle crashes

Objective: The study presents the first-ever endeavor at developing 18-, 24-, 30-, 36-, 42-, and 48-month-old pediatric finite element models from the 6-year-old PIPER human body model as a baseline and comparing their responses systematically in rear-facing and forward-facing simulations across similar boundary conditions.Methods: A 6-year-old PIPER model was scaled down to create anthropometric models of the 18-, 24-, 30-, 36-, 42-, and 48-month-old child using the PIPER scaling tool. The models were installed on a convertible car seat (rear-facing and forward-facing configurations) installed with a 3-point lap–shoulder belt in the rear outboard seat of a 2012 Toyota Camry vehicle model finite element model and setup for full-frontal crash simulation (24 G, 120 ms pulse).Results: The forward-facing models showed higher head resultant accelerations for 24-, 36-, 42-, and 48-month-old models (reduction for rear-facing seats ranging from 10% to 32%). For the 18- and 30-month-old models, the maximum head acceleration showed similar values (difference of less than 10%). Upper neck forces and moments were consistently lower for rear-facing models compared to forward-facing. The neck forces were reduced by 83%–90% and the neck moments were reduced by 63%–85% in the rear-facing models compared to their respective forward-facing configurations. The reduction in head injury criterion (HIC36) for rear-facing models ranged from 14% to 51%. The neck injury criterion (Nij) for all forward-facing models was 6 to 9 times the values of their rear-facing counterpart.Conclusions: The study shows the potential benefit of rear-facing orientation compared to forward-facing for children up to 4 years of age in a controlled environment.

Safe Transport of Spica Casted Children in Passenger Vehicles is Possible: A Frontal Crash Test Analysis of Child Restraint Systems Using Spica Casted Crash Test Dummies

Purpose: There is a paucity of data defining safe transport protocols for children treated with hip spica casting. No current restraint device has been tested using casted anthropomorphic test devices (ATDs). Our goal was to evaluate current restraint options in simulated frontal crash testing using a casted pediatric ATD.
 Methods: Using an ATD simulating a 3-year-old child, dynamic crash sled tests simulating a frontal crash were performed in accordance with Federal Motor Vehicle Safety Standards 213 (FMVSS 213). Sensors within the ATD recorded: HIC36 (Head Injury Criterion score; predictive of skull fracture), neck injury assessment (Nij), chest compression, chest acceleration, and pelvic injury assessment. Test crash video visual assessment was performed (Figures 1&2). The ATD was casted in a double-leg spica. Five restraint devices were tested: seat designed for spica-casted children (Merrit Wallenberg), modified restraint harness (Modified EZ-On-Vest), commercially available booster seat (Britax Parkway SGL Booster), and two commercially available forward-facing car seats able to accommodate the casted ATD (Diono Radian R100, Graco Nautilus 65 LX). One test was performed for each restraint system. All tests were performed at 30 MPH on a deceleration sled.
 Results: Although the presence of the cast increased many of the injury metrics measured, all 5 seats that were tested passed current FMVSS 213 federal guidelines for the head and chest. However, there were marked differences between the 5 restraint options (Figures 3-5). No single seat performed best in all metrics. Additionally, visual analysis of the video from the test crash of the EZ-On-Vest demonstrated that the face and upper extremities of the ATD are impacted during the crash. The ATD does not have a way to record injury to the extremities, thus this is not captured in the quantitative data.
 Conclusions: Per the FMVSS 213 standard, these results suggest safe transport in the five evaluated restraint systems is possible with the child properly fitted and restrained. However, the Nautilus and Diono were found to have both the lowest HIC36 and chest acceleration values, suggesting casted children may not need specially designed seats. Additionally, review of the video of the EZ-On Vest appears to demonstrate that the vest may expose the casted child to additional facial and extremity injuries compared to systems that allow the child to sit upright.
 Significance: Parents should not assume a restraint system is automatically appropriate for use with their child. While there were differences in the performances of the tested restraint systems, each child is unique and a trained healthcare provider should be consulted to ensure the child is properly restrained.

Prediction of impact response in construction safety helmet using FEA

PurposeThis paper aims to present 3D finite element (FE) simulations of impact loading on a construction safety helmet over a headform to improve the ventilation slots profile in helmet design.Design/methodology/approachImpact response on headforms in three different studies considering ventilation slots of varied profiles and dimensions in helmets with rectangular elliptical and circular slots is compared and analysed. Head injury criteria (HIC) and safety regulations from past literature have been considered to evaluate the impact responses.FindingsSimulation results show that a helmet with rectangular ventilation slots achieves a lowest peak impact force of 5941.3 N for a slot area of 170 mm2 as compared to elliptical and circular slots.Research limitations/implicationsVentilation slots of simple geometry (rectangular, elliptical and circular) have been considered in this work. Other/complex geometry slots can also be chosen to predict its effect during impact response on a helmet–headform model. Biofidelic head–neck FE model can be developed to achieve precise results.Practical implicationsThe presented work gives a clear idea to design engineers for the selection of ventilation slot profiles to design a construction safety helmet.Social implicationsConstruction safety (CS) helmets are used to reduce injuries on heads of workers at construction sites in the event of free-falling objects. Rectangular ventilation slots in CS helmets as suggested in the work may reduce the risk of injury.Originality/valueResults are found in good agreement with the past numerical simulation of impact response on a construction safety helmet over a validated biofidelic head FE model.

Sensitivity Analysis and Interval Multi-Objective Optimization for an Occupant Restraint System Considering Craniocerebral Injury

Abstract In vehicle collision accidents, an occupant restraint system (ORS) is crucial to protect the human body from injury, and it commonly involves a large number of design parameters. However, it is very difficult to quantify the importance of design parameters and determine them in the ORS design process. Therefore, an approach of the combination of the proposed approximate sensitivity analysis (SA) method and the interval multi-objective optimization design is presented to reduce craniocerebral injury and improve ORS protection performance. First, to simulate the vehicle collision process and obtain the craniocerebral injury responses, the integrated finite element model of vehicle-occupant (IFEM-VO) is established by integrating the vehicle, dummy, seatbelt, airbag, etc. Then, the proposed approximate SA method is used to quantify the importance ranking of design parameters and ignore the effects of some nonessential parameters. In the SA process, the Kriging metamodel characterizing the relationships between design parameters and injury responses is fitted to overcome the time-consuming disadvantage of IFEM-VO. Finally, according to the results of SA, considering the influence of uncertainty, an interval multi-objective optimization design is implemented by treating the brain injury criteria (BRIC, BrIC) as the objectives and regarding the head injury criterion (HIC) and the rotational injury criterion (RIC) as the constraints. Comparison of the results before and after optimization indicates that the maximum values of the translational and rotational accelerations are greatly reduced, and the ORS protection performance is significantly improved. This study provides an effective way to improve the protection performance of vehicle ORS under uncertainty.

Design and Modeling of a Continuously Tunable Stiffness Arm for Safe Physical Human–Robot Interaction

Abstract To reduce injury in physical human–robot interactions (pHRIs), a common practice is to introduce compliance to joints or arm of a robotic manipulator. In this paper, we present a robotic arm made of parallel guided beams whose stiffness can be continuously tuned by morphing the shape of the cross section through two four-bar linkages actuated by servo motors. An analytical lateral stiffness model is derived based on the pseudo-rigid-body model and validated by experiments. A physical prototype of a three-armed manipulator is built. Extensive stiffness and impact tests are conducted, and the results show that the stiffness of the robotic arm can be changed up to 3.6 times at a morphing angle of 37 deg. At an impact velocity of 2.2 m/s, the peak acceleration has a decrease of 19.4% and a 28.57% reduction of head injury criteria (HIC) when the arm is tuned from the high stiffness mode to the low stiffness mode. These preliminary results demonstrate the feasibility to reduce impact injury by introducing compliance into the robotic link and that the compliant link solution could be an alternative approach for addressing safety concerns of physical human–robot interactions.

Head and Neck Response of an Active Human Body Model and Finite Element Anthropometric Test Device During a Linear Impactor Helmet Test.

It has been proposed that neck muscle activation may play a role in head response resulting from impacts in American Football. The importance of neck stiffness and active musculature in the standard linear impactor helmet test was assessed using a detailed head and neck finite element (FE) model from a current human body model (HBM) compared to a validated hybrid III head and neck FE model. The models were assessed for bare-head and helmeted impacts at three speeds (5.5, 7.4, and 9.3 m/s) and three impact orientations. The HBM head and neck was assessed without muscle activation and with a high level of muscle activation representing a braced condition. The HBM and hybrid III had an average cross-correlation rating of 0.89 for acceleration in the primary impact direction, indicating excellent correspondence regardless of muscle activation. Differences were identified in the axial head acceleration, attributed to axial neck stiffness (correlation rating of 0.45), but these differences did not have a large effect on the overall head response using existing head response metrics (head injury criteria, brain injury criteria, and head impact power). Although responses that develop over longer durations following the impact differed slightly, such as the moment at the base of the neck, this occurred later in time, and therefore, did not considerably affect the short-term head kinematics in the primary impact direction. Though muscle activation did not play a strong role in the head response for the test configurations considered, muscle activation may play a role in longer duration events.

The effects of topology and relative density of lattice liners on traumatic brain injury mitigation

This paper evaluates the effects of topology and relative density of helmet lattice liners on mitigating Traumatic Brain Injury (TBI). Finite Element (FE) models of new lattice liners with prismatic and tetrahedral topologies were developed. A typical frontal head impact in motorcycle accidents was simulated, and linear and rotational accelerations of the head were recorded. A high-fidelity FE model of TBI was loaded with the accelerations to predict the brain response during the accident. The results show that prismatic lattices have better performance in preventing TBI than tetrahedral lattices and EPS that is typically used in helmets. Moreover, varying the cell size through the thickness of the liner improves its performance, but this effect was marginal. The relative density also has a significant effect, with lattices with lower relative densities providing better protection. Across different lattices studied here, the prismatic lattice with a relative density of 6% had the best performance and reduced the peak linear and rotational accelerations, Head Injury Criterion (HIC), brain strain and strain rate by 48%, 37%, 49%, 32% and 65% respectively, compared to the EPS liner. These results can be used to guide the design of lattice helmet liners for better mitigation of TBI.

Analysis and comparison of lateral head impacts using various golf discs and a Hybrid III head form

ABSTRACT The potential for head injuries from discs specifically designed for the sport of disc golf has increased as more disc golf courses are constructed in municipal parks where there is an inherent risk to park users of being struck by a golf disc. This study investigated the potential for head injury of various golf discs used in the sport of disc golf at 18 m/s (40 mph) and 27 m/s (60 mph) using a Hybrid III head form. A matrix of eight modern golf discs were tested to determine if velocity, mass, disc type, or flexibility has a significant effect on the potential for head injury as indicated by peak linear acceleration, peak angular acceleration, Head Injury Criteria (HIC) and Severity Index (SI) values. Regression analyses indicated peak linear acceleration, peak rotational acceleration, HIC, and SI varied by velocity, mass, type, and flexibility. The highest mean linear and rotational acceleration results, 38.5 g and 2512 rad/s2 respectively, both associated with a less than 10% likelihood of sustaining a concussion. The findings should be of interest to both researchers and practitioners who seek to balance use and safety of public parks.