Performances of the PIPER scalable child human body model in accident reconstruction

Biofidelity Investigation and Chest Structure Enhancement of Q3 Dummy Restrained in Impact Shield Child Restraint System

PURPOSE

The biofidelity of anthropomorphic test devices directly affects the evaluation of safety performance of child restraint systems. The purpose is to enhance the biofidelity of Q3 child dummy by chest structure reconstruction for the accurate prediction of the child injuries during a frontal crash.

METHODS

The finite element model of Q3 child dummy restrained in impact shield child restraint systems was validated through a frontal sled test. Based on the validated sled test simulation models, the comparative biofidelity analyses between Q3 model and PIPER 3-year-old human model were conducted by the quantitative kinematic and biomechanical analyses. The internal chest structure difference between Q3 and PIPER 3-year-old human model is discussed, and the absence of the heart, lungs, and great vessels in the Q3 dummy leads to the low biofidelity; therefore, the chest structure and cardiopulmonary model of Q3 dummy were reconstructed to enhance the biofidelity.

RESULTS

In comparison to the original Q3 model, the chest deflection, head forward displacement, and neck bending angle of the reconstructed Q3 model increased by 38.5, 2.2, and 17%, respectively, and the upward displacement of the hip decreased by 49%. The head swing degree of the reconstructed Q3 model is dramatically reduced during the rebound process, and the injury assessment criteria of the head, chest, and pelvis can reach more than 95% of the level of the PIPER 3-year-old human model.

CONCLUSIONS

This study shows that the chest reconstruction can significantly improve the biofidelity of the Q3 dummy, and future study is recommended to optimize the spinal structures of the Q3 model for further enhancement of biofidelity.

Oblique pole-side crash assessment using the six-year-old HBM PIPER

Side impact crashes are one of the most dangerous impact scenarios that a child can suffer. Studies by the National Highway Traffic Safety Administration (NHTSA) have shown that the head and Thorax regions are affected severely. The objective of this work is to perform a numerical evaluation of the oblique pole-side test considering the FMVSS 214-P standard to estimate the Head, Neck, and Thorax injuries for a six-year-old child positioned in the rear seat without any Child Restraint System, two configurations were performed for the oblique pole-side impact: a nearside and a far-side positioning configuration. A six-year-old Human Body Model (HBM) denominated Scalable PIPER Child Model, and the Ford Explorer 2003 were used to perform the test in the LS DYNA® software to assess the biomechanics involved in the crash scenarios. The approach considered a comparative case study with the baseline of the six-year-old child PIPER model to ensure that the positioning adjustment has not affected the mesh quality and interior components for the PIPER child model. The outcomes obtained in case 1 show that the modified PIPER child model has slight outcomes at the shoulder and pelvis zone due to the differences in the body positioning and not by the mesh or the interior interaction between the components. The outcomes obtained in case 2 reflect that the nearside setup obtained the higher measurements for the child occupant. TheA c 3 m s for Head at nearside test to overcome the Side Criteria established by the Assessment Protocol Child Occupant Protection by Euro NCAP, the kinematics behavior demonstrates the importance of researching children in side crashes to enhance child security, especially in the oblique pole side impact.

Evaluating child helmet protection and testing standards: A study using PIPER child head models aged 1.5, 3, 6, and 18 years

The anatomy of children's heads is unique and distinct from adults, with smaller and softer skulls and unfused fontanels and sutures. Despite this, most current helmet testing standards for children use the same peak linear acceleration threshold as for adults. It is unclear whether this is reasonable and otherwise what thresholds should be. To answer these questions, helmet-protected head responses for different ages are needed which is however lacking today. In this study, we apply continuously scalable PIPER child head models of 1.5, 3, and 6 years old (YO), and an upgraded 18YO to study child helmet protection under extensive linear and oblique impacts. The results of this study reveal an age-dependence trend in both global kinematics and tissue response, with younger children experiencing higher levels of acceleration and velocity, as well as increased skull stress and brain strain. These findings indicate the need for better protection for younger children, suggesting that youth helmets should have a lower linear kinematic threshold, with a preliminary value of 150g for 1.5-year-old helmets. However, the results also show a different trend in rotational kinematics, indicating that the threshold of rotational velocity for a 1.5YO is similar to that for adults. The results also support the current use of small-sized adult headforms for testing child helmets before new child headforms are available.

Personalization of human body models and beyond via image registration

Finite element human body models (HBMs) are becoming increasingly important numerical tools for traffic safety. Developing a validated and reliable HBM from the start requires integrated efforts and continues to be a challenging task. Mesh morphing is an efficient technique to generate personalized HBMs accounting for individual anatomy once a baseline model has been developed. This study presents a new image registration-based mesh morphing method to generate personalized HBMs. The method is demonstrated by morphing four baseline HBMs (SAFER, THUMS, and VIVA+ in both seated and standing postures) into ten subjects with varying heights, body mass indices (BMIs), and sex. The resulting personalized HBMs show comparable element quality to the baseline models. This method enables the comparison of HBMs by morphing them into the same subject, eliminating geometric differences. The method also shows superior geometry correction capabilities, which facilitates converting a seated HBM to a standing one, combined with additional positioning tools. Furthermore, this method can be extended to personalize other models, and the feasibility of morphing vehicle models has been illustrated. In conclusion, this new image registration-based mesh morphing method allows rapid and robust personalization of HBMs, facilitating personalized simulations.

Variation in Juvenile Long Bone Properties as a Function of Age: Mechanical and Compositional Characterization

Bone is a heterogeneous, hierarchical biocomposite material made of an organic matrix filled with a mineral component, which plays an important role in bone strength. Although the effect of the mineral/matrix ratio on the mechanical properties of bone during aging has been intensively investigated, the relationship between the mechanical properties and the chemical composition of bone with age requires additional research in juvenile individuals. In this study, bone coupons from bovine and ovine animal species were machined from cortical areas of long bones to quantify whether the variation in mechanical properties at different stages of development is related to the change in the composition of bone tissue. An energy-dispersive X-ray detector (EDX) attached to a scanning electron microscope (SEM) was used to perform a compositional analysis of the tissue. In addition, nanoindentation analyses were carried out to address how the elastic modulus changed with age. Nonparametric statistical analyses found significant differences (p < 0.05) in Ca content and elastic modulus between species, but no differences were found within each species with development. A multiple linear regression model found that the elastic modulus was significantly related to the decrease in P and C in the samples, to the animal species (larger in bovine), and development, although not linearly. This model also found an interaction between Ca and development that could explain the lack of significance of the relationship between the elastic modulus and development in the univariate models.

Mapping the knowledge of traffic collision Reconstruction: A scientometric analysis in CiteSpace, VOSviewer, and SciMAT

Traffic collisions are incidents with high fatality rate which generate billions of US dollars of loss worldwide each year. Post-collision scene reconstruction, which involves knowledge of multiple disciplines, is an important approach to restore the traffic collision and infer the cause of it. This paper uses software CiteSpace, VOSviewer, and SciMAT to conduct a visualization study of knowledge mapping on the literature of traffic collision scene reconstruction from 2001 to 2021 based on the Web of Science database. Knowledge mapping is a cutting-edge research method in scientometric, which has been widely applied in medicine and informatics. Compared with traditional literature review, knowledge mapping with visual techniques identifies hot keywords and key literature in the field more scientifically, and displays them in schematic diagrams intuitively which allows to further predict potential hotspots. A total of 803 original papers are retrieved to analyze and discuss the evolution of the field in the past 20 years, from macro to micro, in term of background information, popular themes, and knowledge structure. Results indicate the number of publications in this field is limited, and collaborations among authors and among institutions are insufficient. In the meantime, mappings imply the top three hot themes being scene reconstruction, computer technology, and injuries. The introduction of AI related technologies, such as neural networks and genetic algorithms, into collision reconstruction would be a potential research direction.

Effects of restraint parameters using PIPER 6y in reclined seating during frontal impact

OBJECTIVE

This study explores possible challenges for child occupants in reclined seating positions, applying current protection systems. Using PIPER 6 y in frontal impacts, the aim was to investigate the effect of restraint parameters in reclined seating positions, in addition to an upright position, varying booster design, shoulder belt outlet, and pretensioner activation.

METHOD

Eighteen full frontal impacts were simulated using the PIPER 6 y human body model restrained on a booster in a front passenger seat. The type of booster, pretensioner activation and shoulder belt outlet were varied with the vehicle seat in 'upright position' (25°) and 'reclined position' (40°). Three booster principles were used: booster seat (BoosterA), booster cushion (BoosterB) and representing properties of a vehicle built-in booster cushion (BoosterC). The two shoulder belt outlets include 'nominal D-ring' and 'rearward D-ring´.

RESULTS

Overall, activation of the pretensioner reduced the overall body displacement as well as the head and neck response in both seating positions. Submarining occurred only in the case of BoosterB in 'reclined position' without pretensioner. Some differences were observed for the lap belt interaction with pelvis in the non-submarining simulations. Greater pelvis displacement was observed in 'reclined position' as compared to 'upright position'. In both seating positions, greatest pelvis displacement was observed for BoosterB, due to relatively more forward initial lap belt position. While both provided favorable initial lap belt to pelvis contact, BoosterC offered more efficient lap belt restraint than BoosterA, since the lap belt remained lower on the pelvis and the vertical movement of the pelvis was more limited compared to BoosterA. When in 'reclined position', the 'rearward D-ring' position enabled earlier coupling of the torso due to initial shoulder belt to shoulder contact, resulting in lower head and neck responses as well as shorter head displacement compared to 'nominal D-ring'.

CONCLUSIONS

Submarining can be addressed in reclined seating positions using current booster design in combination with a seatbelt pretensioner. Lap belt routing was influenced by booster design and reclined seating, affecting the overall kinematics and responses of the PIPER 6 y. This study highlights the importance of including the whole context of child occupant protection when investigating reclined seating, such as the interaction and compatibility of booster, vehicle seat and seatbelt.

Analysis of 6YO pediatric human body model kinematics and kinetics to determine submarining across naturalistic seating postures

OBJECTIVES

The aim of this study was to analyze the kinematics and kinetics of a naturalistically seated 6-year-old (6YO) pediatric human body model and evaluate the metrics described by earlier studies for pediatric ATDs to indicate whether different postures and booster seats were more associated with submarining than others in a frontal impact.

METHODS

The PIPER 6YO pediatric human body model was restrained on a lowback (LBB) and a highback (HBB) booster child restraint seat (CRS) in four naturalistic seating postures: leaning-forward, leaning-inboard, leaning-outboard, and a pre-submarining posture, and a baseline reference seating position as per the FMVSS No. 213 protocol. A 2012 mid-size sedan finite element (FE) model was used as the vehicle environment. A standard 3-point lap-shoulder belt system was modeled to restrain the child and the CRS in the left-rear vehicle seat. Additionally, a No-CRS condition was modeled in a reference posture and pre-submarining posture in which the occupant's legs bent over the edge of the rear seat. 12 conditions were simulated in LS-DYNA R10.1.0, and kinematics and kinetics were compared to metrics as per prior literature: 1) maximum femur displacement and pelvis rotation, 2) maximum knee-head excursion and maximum change in torso angle, 3) lap belt trajectory relative to pelvis's coordinate frame.

RESULTS

The pre-submarining posture on the HBB depicted submarining in all metrics except for the lap belt trajectory. Only the pre-submarining posture in No-CRS depicted submarining through analysis of all metrics. For this pre-submarining No-CRS condition, the mid-abdominal compression was approximately 5 times greater than the average of the mid abdominal compression depths of all other cases and maximum abdominal pressure was at least 22.9 kPa higher than the rest of the conditions.

CONCLUSIONS

The results of this study suggest that metrics used to assess submarining for 6YO pediatric occupants in frontal impacts may need to be updated so that they are more accurate for both simulated and physical studies. In addition, the results of this study could be used to design booster seats that discourage postures that could lead to an increased likelihood of submarining-like characteristics in a frontal crash impact.

Evaluation of parental education using biomechanical visualization to increase child restraint use in China

INTRODUCTION

Despite demonstrated effectiveness of child restraint system (CRS), its use in China is extremely low due to the lack of national legislation requiring the use of CRS, as well as lack of child passenger safety knowledge among caregivers. Implementing an effective intervention is urgently needed to promote the use of CRS. In this study, we primarily evaluated the effectiveness of biomechanical visualization delivered in the context of CRS education to promote CRS use.

METHODS

We conducted a cluster randomised controlled trial to test the effects of educational intervention programs on increased use of CRS. Participants included caregivers from 8 pre-schools located in two cities (i.e., Chaozhou and Shantou) in China. Following a baseline survey, 8 pre-schools were randomly assigned into 1 of 4 groups with 2 schools in each group: 1) CRS education-only, 2) CRS education with behavioral skill training, 3) CRS education with biomechanical visualization, and 4) control. The primary outcome was CRS use, and the secondary outcomes included scores of child passenger safety-related knowledge and CRS use-related attitudes. The effect of the intervention was assessed among caregivers at two time points: baseline preintervention and 6 months postintervention.

RESULTS

More than 70% caregivers had never used CRS at baseline. No statistically significant between-group differences CRS use were observed at baseline preintervention (34.2%, 25.4%, 29.6% and 21.9%, respectively, P = 0.18). However, compared to the control group, odds of CRS non-use was significantly lower in caregivers assigned to the CRS education with biomechanical visualization (adjusted odd ratio (AOR) = 0.11, 95% confidence interval (CI) = 0.07-0.17), CRS education with behavioral skill training (AOR = 0.15, 95%CI = 0.10-0.24) and CRS education-only (AOR = 0.26, 95%CI = 0.17-0.41) groups, respectively. Statistically significant differences were also observed in the secondary outcomes postintervention across groups. Specifically, the CRS education with biomechanical visualization and CRS education with behavioral skill training groups had higher mean knowledge change scores than the CRS education-only group (3.3 ± 1.5 vs. 2.9 ± 2.2, p = 0.035 and 3.2 ± 1.9 vs. 2.9 ± 2.2, p = 0.039, respectively). We also observed a significantly higher increase in the attitudes scores in the CRS education with biomechanical visualization group compared with the CRS education-only group (4.7 ± 2.1 vs. 3.5 ± 2.8,p = 0.026).

CONCLUSIONS

This study shows that both biomechanical visualization and behavioral skill training supplements to education improved understanding of CRS knowledge compared to education only, and all three strategies led to increased CRS use. Importantly, CRS education with biomechanical visualization was shown to be more effective than CRS education alone in improving caregiver's knowledge and attitudes. The use of biomechanical visualization may be an effective supplement to traditional education programs.

Crash test-based assessment of injury risks for adults and children when colliding with personal mobility devices and service robots

Autonomous mobility devices such as transport, cleaning, and delivery robots, hold a massive economic and social benefit. However, their deployment should not endanger bystanders, particularly vulnerable populations such as children and older adults who are inherently smaller and fragile. This study compared the risks faced by different pedestrian categories and determined risks through crash testing involving a service robot hitting an adult and a child dummy. Results of collisions at 3.1 m/s (11.1 km/h/6.9 mph) showed risks of serious head (14%), neck (20%), and chest (50%) injuries in children, and tibia fracture (33%) in adults. Furthermore, secondary impact analysis resulted in both populations at risk of severe head injuries, namely, from falling to the ground. Our data and simulations show mitigation strategies for reducing impact injury risks below 5% by either lowering the differential speed at impact below 1.5 m/s (5.4 km/h/3.3 mph) or through the usage of absorbent materials. The results presented herein may influence the design of controllers, sensing awareness, and assessment methods for robots and small vehicles standardization, as well as, policymaking and regulations for the speed, design, and usage of these devices in populated areas.

Modeling small remotely piloted aircraft system to head impact for investigating craniocerebral response

Understanding small remotely piloted aircraft system (sRPAS) to human head impacts is needed to better protect human head during sRPAS ground collision accidents. Recent literature reported cadaveric data on sRPAS to human head impacts, which provided a unique opportunity for developing validated computational models. However, there lacks an understanding of skull stress and brain strain during these impacts. Meanwhile, how slight changes in sRPAS impact setting could affect human head responses remains unknown. Hence, a representative quadcopter style sRPAS finite element (FE) model was developed and applied to a human body model to simulate a total of 45 impacts. Among these 45 simulations, 17 were defined according to cadaveric setting for model validation and the others were conducted to understand the sensitivity of impact angle, impact location, and impacted sRPAS components. Results demonstrated that FE-model-predicted head linear acceleration and rotational velocity agreed with cadaveric data with average predicted linear acceleration 4.5% lower than experimental measurement and average predicted of rotational velocity 2% lower than experimental data. Among validated simulations, high skull stresses and moderate level of brain strains were observed. Also, sensitivity study demonstrated significant effect of impact angle and impact location with 3° variation inducing 30% changes in linear acceleration and 29% changes in rotational velocity. Arm-first impact was found to generate more than two times higher skull stresses and brain strains compared to regular body-shell-first impact.

Subject-Specific Head Model Generation by Mesh Morphing: A Personalization Framework and Its Applications

Finite element (FE) head models have become powerful tools in many fields within neuroscience, especially for studying the biomechanics of traumatic brain injury (TBI). Subject-specific head models accounting for geometric variations among subjects are needed for more reliable predictions. However, the generation of such models suitable for studying TBIs remains a significant challenge and has been a bottleneck hindering personalized simulations. This study presents a personalization framework for generating subject-specific models across the lifespan and for pathological brains with significant anatomical changes by morphing a baseline model. The framework consists of hierarchical multiple feature and multimodality imaging registrations, mesh morphing, and mesh grouping, which is shown to be efficient with a heterogeneous dataset including a newborn, 1-year-old (1Y), 2Y, adult, 92Y, and a hydrocephalus brain. The generated models of the six subjects show competitive personalization accuracy, demonstrating the capacity of the framework for generating subject-specific models with significant anatomical differences. The family of the generated head models allows studying age-dependent and groupwise brain injury mechanisms. The framework for efficient generation of subject-specific FE head models helps to facilitate personalized simulations in many fields of neuroscience.

Analysis of Kinematic Response of Pediatric Occupants Seated in Naturalistic Positions in Simulated Frontal Small Offset Impacts: With and Without Automatic Emergency Braking

Naturalistic driving studies have shown that pediatric occupants do not assume ideal seating positions in real-world scenarios. Current vehicle assessment programs and child restraint system (CRS) sled tests, such as FMVSS No. 213, do not account for a wide range of seating postures that are typically observed during real-world trips. Therefore, this study aims to analyze the kinematic and kinetic response of a pediatric human body model in various naturalistic seating positions in booster seats when subjected to a frontal offset impact in a full-vehicle environment, with and without the application of pre-crash automatic emergency braking (AEB). A 6YO (seated on a lowback and highback booster) and a 10YO (seated in no-CRS and on a lowback booster) PIPER pediatric human body model's response was explored in a reference, and two most commonly observed seating postures: forward-leaning and forward-inboard-leaning. The vehicle environment with a side-curtain airbag (SCAB) was subjected to a small offset barrier impact (25% overlap at 40MPH), with and without the application of a pre-crash automatic emergency braking (AEB). 24 conditions were simulated using finite element analysis. Cases with a pre-crash AEB resulted in relatively lower kinematic and kinetic values due to the occupant being in a more flexed position before impact compared to without-AEB cases, coupled with the increased ride-down effect due to AEB. Moreover, different seating postures resulted in substantially different kinematics and kinetics, the injury metrics crossing the injury assessment reference values in some cases. Therefore, to design a passive safety standard test for pediatric occupants, it is important to consider the possible postural changes that may occur.

Booster cushion design effects on child occupant kinematics and loading assessed using the PIPER 6-year-old HBM and the Q10 ATD in frontal impacts

OBJECTIVE

Our objective was to study the effect on child occupant kinematics and loading by differences in booster cushion designs and attachment in a frontal impact.

METHODS

Three different booster cushion designs were exposed to a frontal impact in vehicle rear seat interiors. The boosters were selected based on their difference in shape, stiffness, and guiding loop design. Tests were run varying the shoulder belt routing above or under the guiding loop, in addition to with or without attachment of the booster cushion to the vehicle ISOFIX anchorages. Eighteen simulations with the finite element PIPER 6-year-old human body model (HBM) were run investigating all combinations of parameters, in addition to 3 sled tests with a Q10 anthropomorphic test dummy (ATD).

RESULTS

Across 2 different child sizes, using an HBM and an ATD, respectively, consistent sensitivity to the booster design differences were seen. Boosters providing similar initial static belt fit can result in different occupant responses during a crash, due to the design of the boosters and their dynamic performance. Compression of the booster cushion resulted in a delayed pelvis restraint, influencing the upper body kinematics. The guiding loop design as well as the belt routing above or under the guide also influenced the upper body kinematics and shoulder belt interaction.

CONCLUSIONS

Early pelvis coupling to initiate torso pitch, and thereby an upper torso motion controlled by the shoulder belt, is the preferred occupant protection for booster-seated children. A stable mid-shoulder belt position centered over the chest initially is a prerequisite. Additionally, it was seen that the design of the guiding loops helps provide favorable interaction with the torso during the crash. The option to allow the shoulder belt to be placed above and under the guiding loops will accommodate a larger span of child sizes and adapt to more vehicle seat belt geometries. This study provides evidence that the design of the booster cushion plays an important role in creating an early pelvis coupling, as well as supporting favorable torso-shoulder belt interaction.

Biomechanical Comparison of Real World Concussive Impacts in Children, Adolescents, and Adults

Accidental falls occur to people of all ages, with some resulting in concussive injury. At present, it is unknown whether children and adolescents are at a comparable risk of sustaining a concussion compared to adults. This study reconstructed the impact kinematics of concussive falls for children, adolescents, and adults and simulated the associated brain tissue deformations. Patients included in this study were diagnosed with a concussion as defined by the Zurich Consensus guidelines. Eleven child, 10 adolescent, and 11 adult falls were simulated using mathematical dynamic models(MADYMO), with three ellipsoid pedestrian models sized to each age group. Laboratory impact reconstruction was conducted using Hybrid III head forms, with finite element model simulations of the brain tissue response using recorded impact kinematics from the reconstructions. The results of the child group showed lower responses than the adolescent group for impact variables of impact velocity, peak linear acceleration, and peak rotational acceleration but no statistical differences existed for any other groups. Finite element model simulations showed the child group to have lower strain values than both the adolescent and adult groups. There were no statistical differences between the adolescent and adult groups for any variables examined in this study. With the cases included in this study, young children sustained concussive injuries at lower modeled brain strains than adolescents and adults, supporting the theory that children may be more susceptible to concussive impacts than adolescents or adults.

Effect of anthropometry scaling on the response of the piper child scalable human body model subject to pelvic impact

The Open Source PIPER child scalable human body model was publicly released in April 2017 (www.piper-project.org) along with frontal and side impact validation conditions. The objective of this paper is to investigate the effect of anthropometry scaling on the response of the model in side pelvic impact. Three setups from two published studies were used: (1) a lateral drop test (2) a greater trochanter impact with a rigid pendulum (3) a pelvis side impact with a flat surface. The first study used scaling assumption developed for crash test dummy design (setups 1 and 2) and the second performed tests on post mortem human surrogates. The baseline 6 years old child model was scaled using a model morphing methodology to match the stature and weight of the surrogates used in the two published studies. Overall, the main trends observed in the three setups can be approached using the baseline model. Although the model morphing did not account for specific skeletal dimensions, it reduced some of the discrepancies between model response and reference for the drop test and flat plate impact. However, it had little effect on the pendulum test. In that case, the model response was in the corridor at low speed but above at higher speeds. Possible reasons for this difference should be further investigated.

Methods for fusing uncertain results obtained from different models in accident reconstruction

Considering that almost all existing solutions of fusing different reconstructed results require experts’ opinions and the issue of how to fuse probabilistic results and mixed results has not been discussed. Two solutions are proposed. The first is based on the Monte Carlo Method (FMCM), while the second is based on the Sub-Interval Technique (FSIT). The method based on FMCM generates sample points according to the distribution of each uncertain result firstly, and then gives out the cumulative distribution function of the final fused result by statistical analysis. The method based on FSIT gets the result fusion interval set according to lower and upper bounds of all interval results and a given length d of each sub-interval firstly, and then calculate the weighted matrix of the result fusion interval. As a result, the cumulative distribution function of the final fused result can also be given out by statistical analysis. Finally, three real accidents are given to demonstrate the methods of FMCM and FSIT, the results of which show that both work well in practice.

Improved safety standards are needed to better protect younger children at playgrounds

Playground-related traumatic brain injuries (TBIs) in children remain a considerable problem world-wide and current safety standards are being questioned due to historical reasons where the injury thresholds had been perpetuated from automobile industry. Here we investigated head injury mechanisms due to falls on playgrounds using a previously developed and validated age-scalable and positionable whole body child model impacted at front, back and side of the head simulating head-first falls from 1.59 meters (m). The results show that a playground material passing the current testing standards (HIC < 1000 and resultant linear acceleration <200 g) resulted in maximum strain in the brain higher than known injury thresholds, thus not offering sufficient protection especially for younger children. The analysis highlights the age dependence of head injuries in children due to playground falls and the youngest have a higher risk of brain injury and skull fracture. Further, the results provide the first biomechanical evidence guiding age-dependent injury thresholds for playground testing standards. The results also have direct implications for novel designs of playground materials for a better protection of children from TBIs. Only making the playground material thicker and more compliant is not sufficient. This study represents the first initiative of using full body human body models of children as a new tool to improve playground testing standards and to better protect the children at playgrounds.

Methods for describing different results obtained from different methods in accident reconstruction

There is always more than one method can be employed to reconstruct a traffic accident and then more than one result can be obtained. How to describe these different results becomes an issue. Two solutions were given, the first is to fuse different results to one result, while the other is to rank different results according to their credibility. Methods based on the Ordered Weighted Averaging (OWA) operator and Uncertain Ordered Weighted Averaging (UOWA) operator were proposed to fuse different certain results and different interval results to one result, respectively. And methods based on the Combination Weight Arithmetic Average (CWAA) and OWA operators were proposed to rank different certain or interval results. Finally, a true vehicle-motorcycle accident was given to demonstrate these proposed methods, results showed that all methods work well in practice. If the calculation uncertainty was not considered, the fused result 64.56km/h and a ranked vector can be obtained; if the calculation uncertainty was considered, the fused result [62.13, 68.13]km/h and a ranked interval number set can be obtained. Because that all final results were obtained by employing widely used mature operators, they deserve to be trusted. The research provides more reliable choices to describe different results obtained from different methods in accident reconstruction.

Evaluating the response of the PIPER scalable human body model across child restraining seats in simulated frontal crashes

OBJECTIVE

Booster seats ensure appropriate belt fit for children that a traditional vehicle seat belt cannot offer to small occupants. In this study, the responses of the PIPER 6-year-old human body model are compared to the traditional Q6 anthropomorphic test dummy (ATD).

METHODS

Eight frontal impact finite element simulations were run using 4 different child restraining systems on the FMVSS 213 test bench. Kinematics and kinetics were extracted and compared between the 2 child models.

RESULTS

The PIPER 6-year-old showed variation by 11.2 ± 14.1% (head resultant acceleration, G), 20.4 ± 50.3% (chest resultant acceleration, G), 272.9 ± 188.4% (chest displacement, mm), 24.8 ± 17.5% (maximum head excursion, mm), -31.5 ± 5.1% (neck force, F_z, N), -73.8 ± 2.8% (neck moment, M_y, N.m), and -60.4 ± 7.2% (N_ij) compared to the Q6. However, the kinematics of both models were nearly similar.

CONCLUSIONS

The PIPER model has a flexible neck and shows higher chest displacement compared to the Q6. We hypothesize that this is due to the inherent anatomical and mechanical differences between the human body model and the ATD model. More research is needed to explore these differences systematically.