Anthropomorphic Test Device Research Articles

Simulated single-bicycle crashes in the VTI crash safety laboratory

Objective: The objective of this study was to examine the influence of bicycle design and speed on the head impact when suffering from a single-bicycle crash, and the possibility to study this using crash tests.Methods: Simulations of single-bicycle crashes were performed in the VTI crash safety laboratory. Two bicycle crash scenarios were simulated: “a sudden stop” and “sideways dislocation of the front wheel”; using four different bicycle types: a “lady’s bicycle”, a commuter bicycle, a recumbent bicycle and a pedelec; at two speeds: 15 and 25 km/h. In addition, sideway falls were performed with the bicycles standing still. All tests were done with a Hybrid II 50th percentile crash test dummy placed in the saddle of the bicycles, with acceleration measurements in the head.Results: The crash tests showed that a sudden stop, e.g. a stick or bag in the front wheel, will result in a falling motion over the handle bars causing a forceful head impact while a sideways dislocation of the front wheel will result in a falling motion to the side causing a more moderate head impact. The falling motion varies between the different bicycle types depending on crash test scenario and speed. The pedelec had a clearly different falling motion from the other bicycle types, especially at a sudden stop.Conclusions: The study implies that it is possible to examine single-bicycle crashes using crash tests, even though the setup is sensitive to minor input differences and the random variation in the resulting head impact values can be large. Sideway falls with the bicycles standing still were easier to perform with a good repeatability and indicated an influence of seating height on the head impact.

Collision between a Pedestrian and Tram - Pilot Experiment

This article intends to present the first results of a long-term research project, which will result in developing a validated model of a pedestrian for the simulation of crash tests involving tram fronts and, where applicable, the fronts of other urban rail vehicles. The current phase of research includes results of the pilot experiment with a crash-test dummy, and these results supplement the results from simulations, thus demonstrating how important it is to pay special attention to the individual stages of a collision event and how important the localisation of and moulding by an individual tram's front panels are for the nature of the monitored stages. In the first stage, inertia of individual body segments plays a significant role, with the primary contact taking place between the tram's bumper and dummy's thigh. The dummy subsequently takes the shape of the tram's front with progressive bumps to shoulders and head following. At that moment, the tram brakes, and the dummy begins to disentangle from the front panel. The friction force between the dummy's soles and the surface of the rail track is very significant for the nature of this second stage of the collision event .The dummy then hits the ground. It is an accelerated fall, and under the given conditions, it is the stage that has the most devastating impact on the dummy. The simulation made shows the way to modify this dangerous stage to be less harmful to a pedestrian involved in a tram collision.

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.

Pelvis injury risk curves in side impacts from human cadaver experiments using survival analysis and Brier score metrics

Objectives: Post Mortem Human Surrogate (PMHS) experiments are used for describing tolerance and improve safety. For nearside impacts, the United States Standard Federal Motor Vehicle Safety Standards (FMVSS-214) used PMHS tests and binary regression methods to achieve these goals. Since this promulgation, Parametric Statistical Survival Modeling (PSSM) has become a de facto standard for developing injury risk curves (IRCs). This study is focused on pelvic injuries from side impacts. The objectives are as follows. Analyze impactor-based intact PMHS tests and develop IRCs at different AIS levels using the force metric and examine the effectiveness of other force-related variables on IRCs.Methods: Impactor-driven pelvic tests conducted using whole body PMHS were selected from published studies. The dataset had 63 tests. Peak force, 3-ms clip force, and impulse were used to develop IRCs for Abbreviated Injury Scores (AIS) AIS2+ and AIS3+, i.e., groups A and B. Brier Score Metric (BSM) was used for ranking metrics. 95% confidence intervals were computed, Normalized Confidence Interval Sizes (NCIS) were determined, and quality of the IRCs were obtained.Results: Impulse best described the underlying response of the pelvis. BSMs were the lowest for the impulse for both groups. At 10% and 50% probabilities, impulses were 71 Ns and 125 Ns for group A and 79 Ns and 160 Ns for group B; peak forces were 3.8 kN and 7.1 kN and 4 kN and 10 kN for groups A and B; and clip forces were 2.7 kN and 6.5 kN and 3.6 kN and 8.6 kN, for groups A and B. NCIS at discrete probability levels, qualities of risk curves, and individual IRCs are given.Conclusion: This study underscores the importance of using impulse to describe pelvis injury criteria in lateral impacts. These findings are applicable to anthropomorphic test devices, as matched pair tests are done to determine dummy-based injury criteria/injury assessment risk curves (IARCs). Although IRCs have been developed for WorldSID, it may be appropriate to use impulse-based IARCs. Because THOR is a potential device for automated vehicle environments, it may be appropriate to develop THOR-based IARCS. The present IRCs act as fundamental human-based injury criteria. These responses can also be used in human body and subsystem computational models.

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.

Traction load, tong position, and head support significantly influence cervical spine loading during traction.

Some cervical dislocation injuries may be acutely treated with traction via Gardner-Wells tongs, which are attached to the skull via two pins. While a variety of techniques have been proposed and utilized in the literature and clinical practice to use the tongs, these techniques have not been methodically studied to confirm how they transmit loads to the cervical spine. The current study investigated the mechanical effect of different traction techniques in a laboratory setting. A 50th male Hybrid anthropomorphic test device was used as a human surrogate to represent an average male in height and weight was modified to represent a patient with a unilateral facet dislocation injury. Electronic sensors at the atlanto-occipital joint recorded the loading delivered to the superior cervical spine by traction loading. Combinations of the following variables were evaluated as traction loads were progressively increased to one-third of body weight: tong pin position in the skull (anterior-posterior and superior-inferior to the recommended neutral position), traction cable angle in the sagittal plane (elevated, horizontal, declined), and presence or absence of an occipital support. Analysis of the cervical axial traction loads showed that the only significant predictor of cervical tension was the magnitude of the traction load. Anterior-posterior changes in the pin positions in the skull significantly influenced the cervical flexion-extension moment and anterior-posterior (AP) shear. The data show that a combined cervical tension, flexion moment, and anterior shear force can be achieved with posteriorly biased pins and a bolster behind the head. Increasing the angle of traction cable increased the cervical flexion moment and anterior shear force. The following variables should be carefully considered when applying cervical traction since they significantly affect cervical loading: magnitude of the hanging traction load, anterior-posterior pin position, use of an occipital bolster, and traction load angle.

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.

Feasibility study of a safe sled environment for reclined frontal deceleration tests with human volunteers

Objective: The goal of the study was to assess the feasibility of a safe crash environment for volunteer tests in reclined seating positions. An iterative multimodal approach was chosen, consisting of full-body human body model (HBM) simulations, anthropomorphic test device (ATD) physical testing, and volunteer testing.Methods: To estimate a noninjurious deceleration pulse, the iterative inclination of the seat was supported through HBM simulations and physical ATD testing. One male volunteer was exposed to 5 low-speed frontal sled impacts with stepwise reclined seat angles. The volunteer was restrained with a non-pretensioned 3-point seat belt. All procedures were approved by the relevant ethics boards.Results: Volunteer sled tests in 3 different seat configurations were performed with one volunteer at noninjurious deceleration levels. Inclination of the seat and the absence of a footrest resulted in elevated axial seat reaction forces and almost pure translational motion of the human body.Conclusions: A maximum speed of 7.1 km/h and peak deceleration of 3.0 g was found to be a safe pulse for volunteer testing in frontal impacts with a rigid reclined seat. Larger soft tissue deformations were observed when reclined, possibly associated with higher shear loads within the soft tissue. Preliminary results highlight trade-offs between the degree of seat angulation, friction force, and restraint capability of a 3-point seat belt, thus causing forward translation and/or axial spinal compression of the occupant that may need to be addressed in the future.

Effects of child restraint misuse on dynamic performance

Objective: Estimates of child restraint misuse rates in the United States range from 49% to 95%, but not all misuse modes have similar consequences in terms of restraint effectiveness. A series of laboratory sled tests was conducted to determine the effects of common misuses and combinations of misuses, including loose harness, loose installation, incorrect installation angle, incorrect belt path, loose/no tether, and incorrect harness clip usage.Methods: Three commercial convertible child restraint models were loaded with the Hybrid III 3-year-old anthropomorphic test device (ATD) and secured by either LATCH or seat belt on a modified FMVSS No. 213 bench. Tests were conducted in forward-facing (FF) and rear-facing (RF) modes. The response variables included ATD accelerations, excursions, and restraint kinematics. Belt/LATCH loads, tether loads, ATD kinematics, and restraint structural response data were also documented. A fractional factorial test design on 8 factors was used to define an initial series of 32 tests. The first series also included 4 tests of correct CRS, 2 forward facing and 2 rearward facing. The analysis of those data determined the selection of conditions for the remaining 20 tests to focus on factors and interactions of high interest and significance.Results: In the RF condition, misrouting the LATCH belt or seat belt through the incorrect belt path was the only misuse that significantly affected outcomes of interest and was associated with high levels of undesirable CRS rotation. In FF tests, loose installation and tether misuse had large adverse effects on 3 of 4 key response variables.Conclusion: The study provides strong evidence for prioritizing tight restraint installation and proper tether use for FF restraints. In particular, use of the tether helped offset the adverse effects of loose installation or loose harness. Because the results show that performance of a RF child restraint system (CRS) installation is less affected by user error, they also provide support for extended RF restraint use. In addition, packaging convertible child restraints with the LATCH belt routed through the RF belt path could help prevent the most consequential RF CRS misuse.

ATD Biodynamics During Lateral Impact for USAF Neck Injury Criteria

Research was conducted involving a series of lateral impact tests on a horizontal sled facility by scientists at the Air Force Research Laboratory (AFRL). The purpose of the research was to conduct an assessment of the biodynamic response of an anthropomorphic test device (ATD) to support the development of AFRL neck injury criteria. Impacts were completed using a 50th male Hybrid III aerospace ATD due to this ATD being used by the USAF to qualify and evaluate ejection systems. A test matrix was developed to assess ATD response as a function of various seat configurations which were an approximation of the seat configurations used by the Medical College of Wisconsin (MCW) for previously conducted lateral impact tests of PMHS subjects (post-mortem human subjects). The specially fabricated seat configurations were a rigid seat fixture with a 5-point harness and a padded rigid seat with a 3-point harness. The input acceleration pulses were trapezoidal in shape and varied in peak magnitude from 8.5 to 17 G. The rigid and padded seat configurations both generated fairly linear ATD responses across the input acceleration range. The ATD’s response with the padded seat and the 3-point restraint was greater than the ATD’s response with the rigid seat and the 5-point restraint with the upper neck. The My torque showed the greatest increase from the rigid seat configuration to the padded seat configuration. This highlights the importance of a proper restraint and the importance of controlling the motion of the torso since it could reduce the loads and torques of the unrestrained head and neck, resulting in a lower probability of injury. The lateral impact program with the ATD provided critical impact data to fill data gaps that support the development of the ATD-to-human transfer functions for AFRL’s Multi-Axial Neck Injury Criteria (MANIC) for lateral impact or MANICy calculation. The program also highlighted gaps in human and PMHS head response data in identical lateral impact configurations that would not only improve the current MANICy transfer function but would allow the investigation of the efficacy of using the 6F-MANICy to replace the current MANICy.

Experimental assessment of vehicle performance and injury risk for cutaway buses using tilt table and modified dolly rollover tests

BackgroundRollover crashes of buses occur less frequently than do those involving passenger cars; however, they are associated with higher fatality rates. During rollover crashes, a vehicle experiences multidirectional acceleration and multiple impacts, yielding a complex interaction between structural components and its occupants. A better understanding of vehicle and occupant’s motion, structural deformation, and vehicle and road interactions are necessary to improve the safety of the occupants during this event. One of the key factors in rollover crashworthiness assessment is to investigate the relationship between the strength of the vehicle’s structure and the risk of injury outcomes. However, rollover crashes involving buses have received less research attention than have those involving passenger cars. Experimental studies in bus rollover safety have mainly focused on the structural integrity of the passenger compartment without considering the occupant responses. The main goal of this research is to evaluate the rollover mechanism and associated injury risk during two experimental rollover tests for a paratransit cutaway bus that is commonly used by transit agencies. MethodsThe modified dolly rollover (MDR) and tilt table (TT) tests were conducted using a similar bus and anthropomorphic test device (ATD) configurations. In each test, a 2-point and 3-point belted Hybrid III 50th percent male ATDs were used to quantify the kinematics of the occupants. The deformation index (DI), accelerations and angular velocities of the bus’s CG were measured as vehicle responses. The collected data were then calibrated and filtered to assess the effects of the test procedure on kinematic responses of the vehicle and occupants. Next, the effectiveness of the 2-point vs 3-point seatbelt to reduce or prevent the injuries, the vulnerable body regions and corresponded injury risk were evaluated. ResultsThe residual space remained intact (DI < 1) during both rollover tests, however, the ATD responses were quite different. The results of the injury assessment indicate that the risk of the injuries in the MDR test was significantly higher than the TT test. The highest risk of injuries was identified for the head, neck, and shoulder of 2-point belted ATD during the MDR test. Also, the main source of injuries during the MDR test was partial ejection due to the shattered side window, whereas for the TT test impacts between the ATDs and the side window and/or window frame were the injury causes. From the vehicle point of view, the total energy produced in the MDR was 3.5 times higher than the TT test, but the overall structural deformation in the TT test was higher than MDR test. Overall, the tilt table test provides a more severe scenario compared to the MDR test for the assessment of structural strength. Considering the limited real-world injury data in rollover crashes of buses, the MDR test presented the more realistic occupant responses.

Developing a custom Anthropomorphic Test Device for measuring blast effects on occupants inside armored vehicles

This work represents our first step at forming the concept of a measuring system of blast effects on humans inside armored vehicles.We present our initial attempts at developing a custom anthropometric test device (ATD) for measuring blast effects on human occupants in armored vehicles. It was designed to mimic the body of a 50th percentile human male in shape, weight and size. A drop tower was specifically built to simulate dynamic loads resulting from the explosion of improvised explosive devices under vehicle structures. The custom ATD was dropped from a 10 m height and the results were used to verify its design using published data. The ATD was then used to validate the effectiveness of the design of an armored vehicle that was equipped with passive blast protection devices. Useful information was derived from test results and design improvements were suggested. Future experiments are planned to improve the design of the next version of the custom ATD.

Cross-chest clips in child restraints: A crash testing study

Objective: Cross-chest clips are widely used in North American child restraints but are less common in other countries, partially due to concerns over anterior neck contacts in frontal crashes. They have recently been reported to be associated with lower odds of injury in real-world crashes, but there is a paucity of crash test performance information. This study aimed to compare the dynamic performance of a small child occupant in frontal crash tests with and without cross-chest clips in place.Methods: Frontal sled tests at 49 km/h were conducted to compare 2 cross-chest clip designs to nonuse of a chest clip. Tests using a P3/4 anthropomorphic test device (ATD) to represent the smallest occupant in a forward-facing child restraint were conducted with the chest clips in the recommended position and also in an incorrect lower position and with and without additional harness slack present.Results: Though contacts were observed between the chest clips and the base of the ATD’s neck, there was little difference observed in head excursion or ATD sensor loads in the presence of the chest clips. No detectable change in the neck forces or moments was detected at the time of the neck contacts. The position of the clips did not affect the results. Harness slack increased head excursion, as expected, but this effect did not differ between the tests with and without the clips.Conclusions: Cross-chest clips do not appear to greatly influence the dynamic performance of a forward-facing child restraint in a simulated frontal crash. Taken together with recent research suggesting a potential benefit in injury reduction from the clips in the real world, possibly due to maintaining the harness straps in place on a child’s shoulders, it may be appropriate to re-evaluate safety standards that prevent their use.

Multibody system modelling of unmanned aircraft system collisions with the human head

Understanding the impact severity of unmanned aircraft system (UAS) collisions with the human body remains a challenge and is essential to the development of safe UAS operations. Complementary to performing experiments of UAS collisions with a crash dummy, a computational impact model is needed in order to capture the large variety of UAS types and impact scenarios. This article presents the development of a multibody system (MBS) model of a collision of one specific UAS type with the human body as well with a crash dummy. This specific UAS type has been chosen because data from experimental drop tests on a crash dummy is available. This allows the validation of the MBS model of UAS impacting a crash dummy versus experimental data. The validation shows that the MBS model closely matches experimental UAS drop tests on a crash dummy. Subsequently, the validated UAS MBS model is applied to predict human body injury using a biomechanical human body model. Head and neck injury from the frontal, side and rear impact on the human head are predicted at various elevation angles and impact velocities. The results show that neck injury is not a concern for this specific UAS type, but a serious head injury is probable.

Implications of head and neck restraint test repeatability for specification improvement

Objective: Since 2005, National Association for Stock Car Auto Racing, Incorporated (NASCAR) drivers have been required to use a head and neck restraint system (HNR) that complies with SFI Foundation, Inc. (SFI) 38.1. The primary purpose of the HNR is to control and limit injurious neck loads and head kinematics during frontal and frontal oblique impacts. The SFI 38.1 performance specification was implemented to establish a uniform test procedure and minimum standard for the evaluation of HNRs using dynamic sled testing. The purpose of this study was to evaluate the repeatability of the current SFI 38.1 test setup and explore the effects of a polyester seat belt restraint system.Method: Eight sled tests were conducted using the SFI 38.1 sled test protocol with additional test setup constraints. Four 0° frontal tests and 4 30° right frontal (RF) oblique tests were conducted. The first 3 tests of each principal direction of force (PDOF) used nylon SFI 16.1 seat belt restraint assemblies. The fourth test of each PDOF used polyester SFI 16.6 seat belt restraint assemblies. A secondary data set (Lab B Data) was also supplied by the HNR manufacturer for further comparisons. The International Organization for Standardization (ISO) 18571 objective comparison method was used to quantify the repeatability of the anthropomorphic test device (ATD) resultant head, chest, and pelvis acceleration and upper neck axial force and flexion extension bending moment time histories across multiple tests.Results: Two data sets generated using the SFI 38.1 test protocol exhibited large variations in mean ISO scores of ATD channels. The 8 tests conducted with additional setup constraints had significantly lower mean ISO score coefficients of variation (CVs). The Lab B tests conducted within the current specification but without the additional test setup constraints had larger mean ISO score standard deviation and CV for all comparisons. Specifically, tests with the additional setup constraints had average CVs of 3.3 and 2.9% for the 0° and 30° RF orientations, respectively. Lab B tests had average CVs of 22.9 and 24.5%, respectively. Polyester seat belt comparisons had CVs of 5.3 and 6.2% for the 0° and 30° RF orientations, respectively.Conclusion: With the addition of common test setup constraints, which do not violate the specification, the SFI 38.1 test protocol produced a repeatable test process for determining performance capabilities of HNRs within a single sled lab. A limited study using polyester webbing seat belt assemblies versus the nylon material called for in SFI 38.1 indicates that the material likely has less effects on ATD upper neck axial force and flexion extension bending moment time histories than the test setup freedom currently available within the specification. The additional test setup constraints are discussed and were shown to improve ATD response repeatability for a given HNR.

The response of the pediatric head to impacts onto a rigid surface

The study of pediatric head injury relies heavily on the use of finite element models and child anthropomorphic test devices (ATDs). However, these tools, in the context of pediatric head injury, have yet to be validated due to a paucity of pediatric head response data. The goal of this study is to investigate the response and injury tolerance of the pediatric head to impact.Twelve pediatric heads were impacted in a series of drop tests. The heads were dropped onto five impact locations (forehead, occiput, vertex and right and left parietal) from drop heights of 15 and 30 cm. The head could freely fall without rotation onto a flat 19 mm thick platen. The impact force was measured using a 3-axis piezoelectric load cell attached to the platen.Age and drop height were found to be significant factors in the impact response of the pediatric head. The head acceleration (14%–15 cm; 103–30 cm), Head Injury Criterion (HIC) (253%–15 cm; 154%–30 cm) and impact stiffness (5800%–15 cm; 3755%–30 cm) when averaged across all impact locations increased with age from 33 weeks gestation to 16 years, while the pulse duration (66%–15 cm; 53%–30 cm) decreased with age. Increases in head acceleration, HIC and impact stiffness were also observed with increased drop height, while pulse duration decreased with increased drop height.One important observation was that three of the four cadaveric heads between the ages of 5-months and 22-months sustained fractures from the 15 cm and 30 cm drop heights. The 5-month-old sustained a right parietal linear fracture while the 11- and 22-month-old sustained diastatic linear fractures.

The Effectiveness of Protective Headgear in Attenuating Ball-to-Forehead Impacts in Water Polo.

Recent reports have demonstrated that there is a serious risk of head impact and injury in water polo. The use of protective headgear in contact sports is a commonly accepted strategy for reducing the risk of head injury, but there are few available protective headgears for use in water polo. Many of those that are available are banned by the sport's governing bodies due to a lack of published data supporting the effectiveness of those headgears in reducing head impact kinematics. To address this gap in knowledge, we launched a water polo ball at the forehead of an anthropomorphic testing device fitted with either a standard water polo headgear or one of two protective headgears. We selected a range of launch speeds representative of those observed across various athlete ages. Mixed-model ANOVAs revealed that, relative to standard headgear, protective headgears reduced peak linear acceleration (by 10.8–21.6%; p < 0.001), and peak rotational acceleration (by 24.5–48.5%; p < 0.001) induced by the simulated ball-to-forehead impacts. We discuss the possibility of using protective headgears in water polo to attenuate head impact kinematics.

DCE-MRI protocol for constraining absolute pharmacokinetic modeling errors within specific accuracy limits.

To quantify the effects of DCE acquisition and pharmacokinetic modeling processing methodologies on the absolute accuracy and precision of derived pharmacokinetic (PK) parameter values using a novel anthropomorphic phantom test device in which "ground truth" values were known a priori. Ground truth arterial input function (AIF), tumor, and healthy tissue contrast agent concentration-time curves (CTCs) were established within the phantom and repeatedly measured on a 3T MRI scanner with varying temporal resolution (Tres =1.22-30.6s). Ground truth CTCs, Ktrans , ve , and kep values were directly compared to measured values as a function of Tres , with and without the application of voxel-wise flip-angle corrections applied to the data and PK modeling performed using linear and nonlinear forms of the standard Tofts model. Measurement of the AIF was strongly affected by the Tres used (AIF curve-shape feature errors: 3%-222% for Tres : 1.22-30.6s), which directly translated to errors in the derived Ktrans , ve , and kep values of 1%-24%, 2%-5%, and 1%-26% respectively across this Tres range (flip-angle correction applied). Further appreciable improvements in accuracy and precision arising from the use of flip angle corrections and nonlinear least squares fitting were quantified and used to identify optimal acquisition and analysis methodologies for which measurement errors could be constrained below threshold levels. This quantitative study provides insight into how errors in AIF measurement propagate to errors in PK parameter outputs. Absolute quantification of the accuracy and precision of MR-measured CTCs, and resultant PK parameter values, allowed for an optimal temporal resolution to be defined commensurate with maintaining Ktrans , ve , and kep measurement errors below 5% and 10% levels. An appreciable gain in PK parameter estimation accuracy at the analysis stage was also demonstrated using flip-angle corrections and a linear approach to PK model fitting.

A priori prediction of the probability of survival in vehicle crashes using anthropomorphic test devices and human body models

Objective: In the development of restraint systems, anthropomorphic test devices (ATDs) and human body models (HBMs) are used to estimate occupant injury risks. Due to conflicting objectives, this approach limits an injury severity risk tradeoff between the different body regions. Therefore, we present and validate a protocol for the aggregation of injury risks of body regions to a probability of survival (PoS).Methods: Injuries were clustered in regions similar to ATD or HBM investigations and the most severe injury as rated by the Maximum Abbreviated Injury Scale (MAIS) per body region was determined. Each injury was transformed into a dichotomous variable with regard to the injury severity level (e.g., MAIS 3+) whose injury risk was computed using the German In-Depth Accident Study (GIDAS) and NASS-CDS databases. Without loss of generality, we focus on 2 body regions—Head/face/neck (HFN) and chest (C)—at the MAIS 3+ level. The PoS was calculated using injury outcomes from the databases. The method of predicting PoS was validated by stratifying the database by crash type and technical crash severity.Results: The PoS of occupants injured in both HFN and C at the AIS 3+ level was found to be lower, at a statistically significant level, than that of occupants with AIS 3+ injuries to just one of the body regions. Focusing on occupants with only one body region injured at the AIS 3+ level, HFN injuries tended to decrease PoS more than chest injuries. For the validation cases, observed PoS could be reproduced in the majority of cases. When comparing predicted to observed values, a correlation of = 0.92 was observed when not taking the restraint system into account. Focusing on frontal crashes, the correlation was = 0.89. Considering only belted occupants, increased to 0.93, whereas for cases with deployed airbag systems the decreased to 0.68. The PoS for side crashes is reproduced with 0.97 independent of the restraint system; it was 0.95 with belted occupants and 0.55 when also factoring in airbag deployment.Conclusions: The method showed an excellent predictive capability when disregarding the restraint system, or restraint-specific subgroups, for the considered validation cases.

Frontal crash simulations using parametric human models representing a diverse population

Objective: Analyses of crash data have shown that older, obese, and/or female occupants have a higher risk of injury in frontal crashes compared to the rest of the population. The objective of this study was to use parametric finite element (FE) human models to assess the increased injury risks and identify safety concerns for these vulnerable populations.Methods: We sampled 100 occupants based on age, sex, stature, and body mass index (BMI) to span a wide range of the U.S. adult population. The target anatomical geometry for each of the 100 models was predicted by the statistical geometry models for the rib cage, pelvis, femur, tibia, and external body surface developed previously. A regional landmark-based mesh morphing method was used to morph the Global Human Body Models Consortium (GHBMC) M50-OS model into the target geometries. The morphed human models were then positioned in a validated generic vehicle driver compartment model using a statistical driving posture model. Frontal crash simulations based on U.S. New Car Assessment Program (U.S. NCAP) were conducted. Body region injury risks were calculated based on the risk curves used in the US NCAP, except that scaling was used for the neck, chest, and knee–thigh–hip injury risk curves based on the sizes of the bony structures in the corresponding body regions. Age effects were also considered for predicting chest injury risk.Results: The simulations demonstrated that driver stature and body shape affect occupant interactions with the restraints and consequently affect occupant kinematics and injury risks in severe frontal crashes. U-shaped relations between occupant stature/weight and head injury risk were observed. Chest injury risk was strongly affected by age and sex, with older female occupants having the highest risk. A strong correlation was also observed between BMI and knee–thigh–hip injury risk, whereas none of the occupant parameters meaningfully affected neck injury risks.Conclusions: This study is the first to use a large set of diverse FE human models to investigate the combined effects of age, sex, stature, and BMI on injury risks in frontal crashes. The study demonstrated that parametric human models can effectively predict the injury trends for the population and may now be used to optimize restraint systems for people who are not similar in size and shape to the available anthropomorphic test devices (ATDs). New restraints that adapt to occupant age, sex, stature, and body shape may improve crash safety for all occupants.