Child Dummy Research Articles

An analysis of the length of hospital stay for cataract patients in Japan using the discrete-type proportional hazard model

We analyze the length of hospital stays of patients hospitalized for cataract and related diseases (Diagnosis Related Groups (DRG) 2041) in Japan, utilizing the data pertaining to 3436 patients on whom one-eye lens operations are performed. We use the discrete-type proportional hazard model to analyze variables that may affect the length of stay. We find that estimates of the Child and Other Facility Dummies are negative and significant. These variables affect the leaving rate and the length of stay. The length of stay also changes at age 40. With regard to the types of affiliated operations and treatments, the estimates of dummy variables are negative and significant at the 1% level. We also find large differences in the length of stay among hospitals, despite eliminating the influence of both the characteristics of the patient and the types of affiliated operations and treatments. The longest average length of stay is over 3.5 times as long as the shortest average length of stay. Finally, we analyze the factors pertaining to hospitals that may affect the length of stay. The estimates of the Profit and Cold Region dummies are negative and significant; in other words, the leaving rate is reduced and the length of stay is increased if the hospital becomes more profitable and is located in the cold regions of Hokkaido and Tohoku.

Load Limiting Behavior in CRS Tether Anchors as a Method to Mitigate Head and Neck Injuries Sustained by Children in Frontal Crash

Objective. This study focuses on methods to reduce injuries, specifically in the head and neck region, sustained by children seated in forward-facing child restraint system during a frontal vehicle crash. The main objective of this research was to implement load-limiting behavior into the upper tether and lower LATCH anchors of the CRS in order to reduce the neck injury criteria by increasing forward head excursion. Methods. Federal Motor Vehicle Safety Standard 213 outlines that the maximum limit for head excursion of the child dummy should be 720 mm, and the neck injury criteria should be less than 0.33 beyond the first 30 ms of the impact. Working within these limits, a fully deformable finite element model of a child restraint seat incorporating a Hybrid III 3-year-old dummy has been previously developed that has been validated for frontal impacts under CMVSS 208 and FMVSS 213 testing conditions. Observations from this previous work have illustrated that despite the head excursion being significantly less than the proposed limit of 720 mm, values of the neck injury criteria exceeded the protection reference values. Values of the load limits for both upper tether and lower LATCH anchors were calculated based on two approaches, initially based upon neck injury criteria and then an energy-based approach. Three numerical models were developed incorporating a Hybrid III 3-year-old dummy, Q3 child dummy, and a child finite element model. Numerical simulations, utilizing the identical 213 testing conditions, were completed incorporating load-limiting capabilities of the upper tether and lower LATCH anchors. Results. Evaluation of injury criteria based on the quantitative analysis of the simulations yielded that the implementation of load-limiting behavior in the upper tether and lower LATCH anchors was effective in reducing the head injury criteria by approximately 60 to 70%. Conclusion. Implementation of load-limiting behavior in the upper tether and lower LATCH anchors of the child restraint system effectively reduces the head and neck injuries sustained by toddlers in a frontal vehicle crash while controlling forward head excursion within the limits as defined by NHTSA.

A Study of the Rear Seat Occupant Safety using a 10-Year-Old Child Dummy in the New Car Assessment Program

This paper describes how the National Highway Traffic Safety Administration (NHTSA) conducted a total of 28 frontal crashes in the New Car Assessment Program (NCAP) involving the 10-year-old child Hybrid III dummy. The 10-year-old child dummy was in the rear seat. All types of vehicles (passenger cars, sport utility vehicles, vans and pick-up trucks) were tested to assess the effect of restraint systems such as booster and pretensioner on the rear seat occupant. In this study, the readings of the 10-year-old child dummy in rear-left and rear-right seat positions are examined. This paper applies a possible 5 star rating system, based on head and chest readings of the 10-year-old dummy. The paper also assesses the safety performance of rear seat occupants and the effect of the restraint systems on a child in the rear seat. This paper suggests that a star rating for rear seat occupants is independent of the present ratings for the driver and front adult passenger in NCAP. This paper examines the dynamic signals of the vehicle and the child dummy in the 28 NCAP crashes. The examination figured out the relationship between vehicle pulse and dummy pulse compared with 5-4 star-rated vehicles or 3-1 star-rated vehicles based on the rear seat occupant responses. The child dummy signals are compared for different passenger vehicles. For example, the comparison of high head acceleration and low chest acceleration case to low head acceleration and high chest acceleration case is performed for vans.

Occupant responses in child restraint systems in side impact tests

Accident data show that the injury risks to children seated in Child Restraint Systems (CRSs) are higher in side collisions than any other type. To investigate this, it is necessary to understand the occupant responses in various CRSs. While a sled test procedure has been discussed by the International Organisation for Standardisation for evaluating CRS performance, for which full car side impact tests were conducted with a Q3s child dummy seated in a Forward-Facing (FF) CRS, and a CRABI Six-Month-Old (6MO) infant dummy seated in a Rear-Facing (RF) CRS and also placed in car-bed restraint. In FF and RF CRS tests, the chest was loaded by an intruding door and the resulting chest deflection of the Q3s child dummy in the FF CRS was comparable with the Injury Assessment Reference Value (IARV). In tests with the FF and RF CRSs, the dummy heads were contained within the CRS shell during the entire impact event; and the HICs were small. Although all injury criteria of the CRABI 6MO infant dummy in the car-bed restraint were smaller than the IARVs, a calculated crotch harness force was large.

Child restraint seat design considerations to mitigate injuries to three-year-old children in side impact crashes

This research focuses on the injury potential of children seated in forward-facing child safety seats during side impact crashes in a far-side seated position. Side impact dynamic sled tests were conducted by Transportation Research Center Inc. (TRC) using two Hybrid III 3-year-old child dummies in convertible forward/rearward child safety seats. The seats were equipped with a LATCH and a top tether and the dummies were positioned in forward-facing/far-side configuration. The tests were completed using an acceleration pulse with a closing speed of 32.8 km/h, and the seat fixture with vehicle body oriented at 270° relative to the motion of the sled. A fully deformable finite element model of a child restraint seat, for side impact crash investigations, has been developed which has also been previously validated for frontal impacts. A numerical model employing a similar set-up as the experimental sled test was generated and simulated using LSDYNA. The numerical model was validated by comparing the head and the chest accelerations, resultant upper and lower neck forces and moments from the experimental and numerical tests. The simulation results were observed to be in good agreement to the experimental observations. Further studies were conducted to confine lateral movement of the dummy's head by adding energy absorbing foam on the side wings in the vicinity of the contact region of the CRS. It was observed from the simulation results that the addition of foam padding and foam blocks was effective in reducing the head injury criteria of the Hybrid III 3-year-old dummy by approximately 30%, and the upper neck lateral shear and lateral bending by approximately 45%.

Reconstruction of Crashes Involving Injured Child Occupants: The Risk of Serious Injuries Associated with Sub-Optimal Restraint Use May Be Reduced by Better Controlling Occupant Kinematics

Objective. To determine whether injuries to sub-optimally restrained child occupants in real-world crashes were likely to be preventable by alternative restraint usage practices and to assess the usefulness of crash reconstruction for exploring injury mechanisms in child occupants. Methods. Real-world crashes in which child occupants sustained significant injuries were reconstructed on a laboratory crash sled using the Hybrid III family of child dummies. Alternative restraint scenarios and cases in which children were not seriously injured were also simulated to compare dummy kinematics and dynamic responses in optimal restraint configurations. Results. Restraint misuse was associated with greater motion of the dummy torso and head during crashes, often allowing contact between the child and the vehicle interior, resulting in injury. Poor pre-crash posture for a child inappropriately restrained in an adult belt appeared to worsen the geometry of the sash (shoulder) belt, resulting in a cervical injury due to direct interaction with the belt. Dynamic dummy data did not appear to discriminate between injury and non-injury cases. Conclusions. Dummy kinematics suggest that injuries in which inappropriate use and misuse were a factor were less likely if the most appropriate restraint was used correctly. Adequately controlling the head and upper body of the child occupant was seen to prevent undesirable interactions with the vehicle interior and restraint system, which were associated with injury in the real world. Neck forces and moments and injury criteria calculated from these did not predict injury reliably.

154 衝撃応答解析における3歳児有限要素人体モデルと幼児ダミーモデルの応答比較

In recent years, the safety of children in car crashes has been mainly evaluated using child dummies. However, their body shapes and mechanical characteristics are different from an actual human body. Therefore, it is difficult to reproduce detailed injury of an actual human body. Consequently, the 3YO FE human model was developed based on the adult FE human model. The biofidelity of the 3YO FE human model were evaluated by simulating of the Hybrid III 3YO calibration test. And the impact responses of the 3YO FE human model were compared with impact responses of a Hybrid III 3YO child dummy model and a Q3 dummy model. From the results of the simulations, the impact responses of the 3YO FE model were mostly satisfied with the performance requirements of the Hybrid III 3YO calibration test.

Injury potential of a three-year-old Hybrid III dummy in forward and rearward facing positions under CMVSS 208 testing conditions

This research focuses on the injury potential of children in forward and rearward facing child restraint seats in frontal collisions. Vehicle crash tests were completed following the guidelines outlined in the Canadian Motor Vehicle Safety Standard 208 using a Hybrid III three-year-old dummy in a convertible forward/rearward facing child restraint seat. The seat was equipped with a five-point restraining system and the experimental test was completed in the forward facing configuration. A numerical model employing a similar set-up as the experimental crash test was developed and numerically simulated using LS-DYNA. To verify the numerical simulations, the head and chest accelerations as well as neck loads and moments were compared to the experimental findings and it was observed that a reasonable correlation between the experimental and numerical observations existed. Further numerical simulations were completed to investigate the influence of positioning the three-year-old dummy in the rearward configuration on the head and neck injury potential during frontal crash. Through an analysis of injury criteria, using neck loads and head accelerations, it was observed that the rearward facing child dummy sustained significantly lower levels of neck injury criteria while exhibiting similar levels of the head injury criteria as the forward facing child dummy.

Integration of Scientific Visualization With Physical and Digital Modeling for Improved Child Restraint System Safety

Computational modeling continues to play an increasingly significant role in the design of more effective vehicle crash safety systems. Researchers now frequently exercise models formulated with sophisticated computer analyses to supplement empirically generated results and conduct extensive what-if exploratory studies for information formerly available solely from costly and time-consuming physical testing. Our research team is developing a modeling and analysis capability that features a scientific visualization toolkit called NYSCEDII CRS visualization module (NCVM). NCVM post-processes conventional crash simulation imagery, enabling modelers to visualize aspects of both the digital model and the sled-test simulation in an immersive visual environment. This paper describes NCVM’s design and development in detail and illustrates its application to a series of sled tests conducted with a recent-production child restraint system and dummy occupant.

Sled tests and CIREN data illustrating the benefits of booster seats

Booster seats are recommended for children approximately 4 to 10 years old, with more specific recommendations according to their size. The booster seat improves the geometry of the lap and shoulder belts, and allows the child's lower limbs to bend at the knees eliminating the need to slouch. Without a booster seat, children will also often place the shoulder belt under their arm or behind their back. This paper presents sled tests with a 6-year old child dummy in several restraint conditions. In addition to correct booster seat use, the dummy is restrained with a three-point belt, and with the shoulder belt either behind the back or under the arm. Dummy injury measures illustrate the increased injury risk due to misuse of the shoulder belt. In support of the sled test findings, data from the CIREN (Crash Injury Research and Engineering Network) database illustrate injury trends resulting from these misuse scenarios.

A study of injury parameters for rearward and forward facing 3-year-old child dummy using numerical simulation

More children die of road traffic injuries than of any other cause. Nonuse and misuse of child restraints is common and leads to preventable severe injuries or deaths. Furthermore, many children graduate to inappropriate restraint systems or switch from rearward to forward facing prematurely. Facing rearward is intrinsically safer, provided the head is supported, and the reasons for seating a child in the opposite position relate to convenience, not safety. With heavy heads and weak necks, children are vulnerable to catastrophic traction injuries to the cervical cord, and children older than 1 year retain this vulnerability. Most studies have estimated that rearward facing restraints reduce the risk of serious injury by about 80–90%. A recent analysis of the Swedish Volvo crash database reported that the injury reducing effect of rearward facing child restraints might be as high as 96%. However, the age at which children should start sitting in a forward-facing position is controversial. The American Academy of Pediatrics has recently advised that children should be seated facing the rear of the vehicle for as long as possible and at least until 1 year of age. Both Transport Canada and the US National Highway Traffic Safety Administration (NHTSA) currently suggest having children face forward from about 1 year of age or once they reach 10 kg (22 lb), while Australian children are often turned around to forward facing at 5 to 6 months of age. In this paper a multi-body dynamic simulation MADYMO model is developed for rearward and forward facing 3-year-old child dummy. The reasonable correlation between the developed forward facing numerical simulation results and the experimental results indicates that the model is robust. Simulation for both facing configurations is conducted using an experimental moderate frontal crash pulse. The study indicates that the upper neck forces, and the neck injury criteria can be greatly reduced by keeping the child in the rearward facing position. For children safety, parents and caregivers should seriously consider keeping children rearward facing for as long as possible. Moreover, manufacturers should be encouraged to develop car safety seats that accommodate children rear facing up to 4 years of age.

Development of a mathematical model for evaluating child occupant behaviour in the case of a vehicle side impact simulation

The effectiveness of child restraint systems has been well proven for frontal collisions but the performances of the protective devices in side-impact situations were not, as yet, clearly demonstrated. This research programme was aimed at the development of a numerical method to simulate the behaviour of a child passenger, restrained in a protective device, in the case of a vehicle side impact. The MADYMO software was chosen to build the model using finite element and multi-body methods. The side wings of the child restraint system and the vehicle body have been modelled by the finite-element technique, to allow for a better representation of the contacts and to allow the simulation of the vehicle body deformation. The model has been evaluated against similar test data. The simulation results were generally very close to the experimental data but differences could be observed for some injury criteria, mainly due to a different initial position of the child dummy. The model exploitation aims to assess different installation configurations, dummy model influence and consequences of vehicle intrusion.

An investigation into the head and neck injury potential of three-year-old children in forward and rearward facing child safety seats

This research focuses on the injury potential of children in forward and rearward facing child restraint seats in frontal collisions. Experimental sled tests were completed following the guidelines outlined in the Federal Motor Vehicle Safety Standard 213 using a Hybrid III 3-year-old dummy in a convertible forward/rearward facing child restraint seat. The seat was equipped with a five point child safety belt and the experimental test was completed in the forward facing configuration. The Hybrid III 3-year-old dummy was equipped with three uniaxial accelerometers arranged in mutually perpendicular directions in the head and chest. A numerical model employing a subset of the apparatus used in the forward facing experimental sled test was developed and numerically simulated using LSDYNA. To verify the numerical simulations, the head and chest accelerations were compared to the experimental findings and it was observed that a reasonable correlation between the data existed. Further numerical simulations were completed to investigate the influence of positioning the 3-year-old dummy in the rearward configuration on the head and neck injury potential during frontal crash. Through an analysis of injury criteria, using neck loads and head accelerations, it was observed that the rearward facing child dummy sustained significantly lower levels of neck injury criteria while exhibiting similar levels of the head injury criteria as the forward facing child dummy.

Influence of crash severity and contact surfaces characteristics on the dynamic behavior of forward facing child occupants

The safety of children as occupants, in the event of vehicle collisions, is a pressing issue demanding more research and investigation to reduce harm and minimize injuries. Statistics show that motor vehicle crashes are the leading cause of death and injury for children, despite improved crashworthiness of vehicles and effective child restraint systems (CRS). Studies indicate that during a collision, children develop injury patterns, which are not fully understood. These child injury patterns are different from those experienced by adults due to differences in weight, height, and body proportions. Infants and young children have a disproportionately large head, with a high center of gravity and a weaker neck structure resulting in relatively poor head support. Vehicle speed, weight, impact mode (full-frontal, front offset, angled, side, or rear), type and location of the child restraint system and the interior design of the occupant compartment are some of the important factors that influence injury patterns and degree of harm in a child occupant. In this paper, a multi-body dynamic simulation model is developed, using MADYMO software, to investigate the behavior of a TNO-P3/4 9-month-old forward facing child dummy in a four-point convertible child safety seat. The reasonable correlation between the developed model simulations and experimental results from a CRABI 12-month child dummy sled test indicates that the model is robust. Simulations using three crash pulses, soft, moderate, and severe, are conducted to investigate the influence of crash severity on the child dummy head and thorax accelerations, upper neck forces, and injury parameters. The influence of contact surfaces characteristics is also investigated to shed some light on ways to improve child occupant kinematics during vehicle collisions. The study indicates that dynamic simulation is efficient, cost effective, and viable tool for vehicle occupant protection studies, policy change recommendations, and vehicle design modifications.

Influence of crash severity and contact surfaces characteristics on the dynamic behavior of forward facing child occupants

Abstract The safety of children as occupants, in the event of vehicle collisions, is a pressing issue demanding more research and investigation to reduce harm and minimize injuries. Statistics show that motor vehicle crashes are the leading cause of death and injury for children, despite improved crashworthiness of vehicles and effective child restraint systems (CRS). Studies indicate that during a collision, children develop injury patterns, which are not fully understood. These child injury patterns are different from those experienced by adults due to differences in weight, height, and body proportions. Infants and young children have a disproportionately large head, with a high center of gravity and a weaker neck structure resulting in relatively poor head support. Vehicle speed, weight, impact mode (full-frontal, front offset, angled, side, or rear), type and location of the child restraint system and the interior design of the occupant compartment are some of the important factors that influence injury patterns and degree of harm in a child occupant. In this paper, a multi-body dynamic simulation model is developed, using MADYMO software, to investigate the behavior of a TNO-P3/4 9-month-old forward facing child dummy in a four-point convertible child safety seat. The reasonable correlation between the developed model simulations and experimental results from a CRABI 12-month child dummy sled test indicates that the model is robust. Simulations using three crash pulses, soft, moderate, and severe, are conducted to investigate the influence of crash severity on the child dummy head and thorax accelerations, upper neck forces, and injury parameters. The influence of contact surfaces characteristics is also investigated to shed some light on ways to improve child occupant kinematics during vehicle collisions. The study indicates that dynamic simulation is efficient, cost effective, and viable tool for vehicle occupant protection studies, policy change recommendations, and vehicle design modifications.

1464 交通事故時の運転者と子供乗員の挙動解析

The kinematics and injury risks of occupants who are not standard size, such as small female driver and children were examined by using MADYMO. The child in the child restraint system with passenger airbag, and female on the driver seat were analyzed. The three-year-old child dummy, AM50th% dummy and AF5th% dummy were used in this study. The results show that when the child seat is attached correctly, the passenger airbag does not show clear difference of kinematics and injury risk of the child at impact of 50 km/h. In analyses of female driver model, since the female position is near the steering wheel, due to airbag deployment the kinematics of the female was different from those of male. For the female, the flexion of the neck occurred and ribs of female contacted steering wheel.

Dynamic response of the Hybrid III three year old dummy head and neck during side air bag loading

This paper presents the results from 14 tests designed to evaluate the response and injury potential of a Hybrid III three year old dummy subject to loading by a deploying seat mounted side air bag. An instrumented Hybrid III three year old dummy was used for tests in two different occupant positions chosen to maximize head and neck loading. Four seat mounted thoracic side air bags were used that varied only in the level of inflator output. The National Highway Traffic Safety Administration's neck injury criteria for complex loading were modified to include moment values for both anterioposterior and lateral directions. The results indicate that side air bags may be designed so that the forces and moments in the child dummy's neck are below injury threshold values during a side air bag deployment. While there is considerable uncertainty as to the validity of published injury criteria owing to the lack of child biomechanical data, this study demonstrates the sensitivity of child response to initial position which provides insight into placement and geometry of side airbag systems. Furthermore, the data indicate a relationship between airbag inflator properties and child dummy response for a given airbag geometry.

A Study of Standards for Child Restraint System Sled Tests

A method is developed for finding the best and worst possible responses of a child dummy in a child seat sled test where the sled deceleration pulse must follow a prescribed corridor. Constrained optimization techniques are applied to a two-degree-of-freedom lumped mass model of the sled test to determine the best and worst sled deceleration pulses, within the prescribed corridor, that produce the minimum and maximum child chest decelerations. A three-dimensional multi-body model is used to predict the values of the peak child chest g's in sled tests with the best and worst sled deceleration pulses. The results are useful as a measure of the variability of child dummy response that can be expected for a prescribed sled deceleration corridor. The standards for child seat safety testing can be evaluated and compared quantitatively using this sensitivity information. Results indicate that some prescribed sled deceleration corridors are too wide, allowing extreme variations in occupant responses, and some are too narrow, or perhaps unnecessarily complex.

CAD modelling of a human 3D child body

The CAD program RAMSIS was developed for ergonomic formation of car packages. This computer aided resource made it possible to create a real geometric and kinematic model of the human body. By using this model, the designer does not have to think about the posture of a person in a certain situation, because RAMSIS is able to prognosticate the natural estimated posture automatically. Furthermore, it is possible to rate the posture under comfort and health aspects. The research could be made with the male and female body types including the individual adjustment of body height, corpulence and proportion. In addition to this male and female model the body of a child, subdivided in different age groups, was developed and designed. In developing the child model, the first question that has to be clarified is the one about a suitable database. One problem is that most databases provide just values of 50% body segments. And those values are not suited to build a dummy of a real person. On the other hand, the measurement of a survey that is big enough to get a sound statement would have been too expensive. So it was decided to use the following procedure: First by making a literature enquiry the found values of a 50% child were transferred onto the model to get a first impression of a child dummy. By doing this, we formed dummies in the age of 3–12 yr. It was decided to build a unisex model due to the fact that differences between boys and girls bodies are not so significant up to the age of 12. Another database that was found is the Tanner study (Atlas of children's growth, 1982). In this book the author documents the growth of 54 children by measuring and taking 2 pictures of them each year from the age of 3 and up to the age of 18. Those pictures were scanned into the computer and we imposed the above-mentioned 50 percentile child dummy of the corresponding age. This was done using the stereophotogametric anthropometric measuring program PCMAN which was developed at the institute. In the end those anthropometric data were worked up statistically, so that the reproduction of a real test person was found that was nearly similar to the 50 percentile child. Those measurements were made, as mentioned above, for the age between 3 and 12 yr. In order to provide a 3D child dummy to the constructor to shape the interior of cars ergonomically for children meeting their demands. Relevance to industry RAMSIS is a CAD-tool for ergonomic analysis of vehicles developed for the German automotive industry. Up to now the different RAMSIS types were adults, so it was not possible to make statements on the quality of a car interior from the point of view of children. It was necessary to develop a realistic 3D child model which could be used by the designers for seat and safety analysis on a CAD-system

Paediatric Neck Modelling using Finite Element Analysis

This study investigated the external and internal biomechanical responses of the segmented paediatric human cervical spine using the finite element modelling approach. The three-dimensional model of the paediatric cervical spine was obtained by modifying our existing finite element model of the adult spine which was derived from computed tomography and cryomicrotomy. The C4-C5-C6 spine simulated the three vertebrae, the anulus fibrosus and the nucleus pulposus of the interconnecting intervertebral discs, and the ligaments. Appropriate anatomical and material property changes were incorporated to include the paediatric components such as the growth plates and the disc nucleus characteristics. The models were exercised under flexion, extension, lateral bending, and axial torsion load vectors. The responses of the paediatric neck model were compared with the adult neck model responses under these loadings. The external response results indicated the paediatric cervical spine to be more flexible than the adult cervical spine under all four modes; in particular, it was most flexible in the axial torsion mode. In addition, the internal stress responses demonstrated increasing magnitudes. While similar increases were found in the external angular flexibilities and the internal disc stresses between the two models, the vertebral body stresses indicated considerably higher relative changes in the paediatric spine, suggesting a higher role for this component under these vectors. These findings highlight the local component mechanics and the variations in the structural behaviours between the adult and paediatric human cervical spines. The present results are a first step in the analysis of the human paediatric cervical spine biomechanical response and will assist in the design of anthropomorphic child dummies for trauma assessment.