Binhui Jiang

Development of a 10-year-old paediatric thorax finite element model validated against cardiopulmonary resuscitation data

Thoracic injury in the paediatric population is a relatively common cause of severe injury and has an accompanying high mortality rate. However, no anatomically accurate, complex paediatric chest finite element (FE) component model is available for a 10-year old in the published literature. In this study, a 10-year-old thorax FE model was developed based on internal and external geometries segmented from medical images. The model was then validated against published data measured during cardiopulmonary resuscitation performed on paediatric subjects.

Blast effect on the lower extremities and its mitigation: a computational study.

A series of computational studies were performed to investigate the response of the lower extremities of mounted soldiers under landmine detonation. A numerical human body model newly developed at Wayne State University was used to simulate two types of experimental studies and the model predictions were validated against test data in terms of the tibia axial force as well as bone fracture pattern. Based on the validated model, the minimum axial force causing tibia facture was found. Then a series of parametric studies was conducted to determine the critical velocity (peak velocity of the floor plate) causing tibia fracture at different upper/lower leg angles. In addition, to limit the load transmission through the vehicular floor, two types of energy absorbing materials, namely IMPAXX(®) foam and aluminum alloy honeycomb, were selected for floor matting. Their performances in terms of blast effect mitigation were compared using the validated numerical model, and it has been found that honeycomb is a more efficient material for blast injury prevention under the loading conditions studied.

Computational modeling of traffic related thoracic injury of a 10-year-old child using subject-specific modeling technique

Traffic injuries have become a major health-related issue to school-aged children. To study this type of injury with numerical simulations, a finite element model was developed to represent the full body of a 10-year-old (YO) child. The model has been validated against test data at both body-part and full-body levels in previous studies. Representing only the average 10-YO child, this model did not include subject-specific attributes, such as the variations in size and shape among different children. In this paper, a new modeling approach was used to morph this baseline model to a subject-specific model, based on anthropometric data collected from pediatric subjects. This mesh-morphing method was then used to rapidly morph the baseline mesh into the subject-specific geometry while maintaining a good mesh quality. The morphed model was subsequently applied to simulate a real-world motor vehicle crash accident. A lung injury observed in the accident was well captured by the subject-specific model. The findings of this study demonstrate the feasibility of the proposed morphing approach to develop subject-specific human models, and confirm their capability in prediction of traffic injuries.

Numerical simulations of the occupant head response in an infantry vehicle under blunt impact and blast loading conditions.

This article presents the results of a finite element simulation on the occupant head response in an infantry vehicle under two separated loading conditions: (1) blunt impact and (2) blast loading conditions. A Hybrid-III dummy body integrated with a previously validated human head model was used as the surrogate. The biomechanical response of the head was studied in terms of head acceleration due to the impact by a projectile on the vehicle and intracranial pressure caused by blast wave. A series of parametric studies were conducted on the numerical model to analyze the effect of some key parameters, such as seat configuration, impact velocity, and boundary conditions. The simulation results indicate that a properly designed seat and internal surface of the infantry vehicle can play a vital role in reducing the risk of head injury in the current scenarios. Comparison of the kinematic responses under the blunt impact and blast loading conditions reveals that under the current loading conditions, the acceleration pulse in the blast scenario has much higher peak values and frequency than blunt impact case, which may reflect different head response characteristics.

Numerical simulations of the 10-year-old head response in drop impacts and compression tests

BACKGROUND AND OBJECTIVE Studies on traumatic injuries of children indicate that impact to the head is a major cause of severe injury and high mortality. However, regulatory and ethical concerns very much limit development and validation of computer models representing the pediatric head. The purpose of this study was to develop a child head finite element model with high-biofidelity to be used for studying pediatric head injury mechanisms. METHODS A newly developed 10-year-old (YO) pediatric finite element head model was limitedly validated for kinematic and kinetic responses against data from quasi-static compressions and drop tests obtained from an experimental study involving a child-cadaver specimen. The validated model was subsequently used for a fall accident reconstruction and associated injury analysis. RESULTS The model predicted the same shape of acceleration-time histories as was found in drop tests with the largest discrepancy of -8.2% in the peak acceleration at a drop height of 15 cm. Force-deflection responses predicted by the model for compression loading had a maximum discrepancy of 7.5% at a strain rate of 0.3 s(-1). The model-predicted maximum von Mises stress (σv) and principal strain (εp) in the skull, intracranial pressure (ICP), maximum σv and maximum εp in the brain, head injury criterion (HIC), brain injury criterion (BrIC), and head impact power (HIP) were used for analyzing risks of injury in the accident reconstruction. CONCLUSIONS Based on the results of the injury analyses, the following conclusions can be drawn: (1) ICP cannot be used to accurately predict the locations of brain injury, but it may reflect the overall energy level of the impact event. (2) The brain regions predicted by the model to have high σv coincide with the locations of subdural hematoma with transtentorial herniation and the impact position of an actual injury. (3) The brain regions with high εp predicted by the model coincide with locations commonly found where diffuse axonal injuries (DAI) due to blunt-impact and rapid acceleration have taken place.

Application of an anatomically-detailed finite element thorax model to investigate pediatric cardiopulmonary resuscitation techniques on hard bed

OBJECTIVES Improved Cardiopulmonary Resuscitation (CPR) approaches will largely benefit the children in need. The constant peak displacement and constant peak force loading methods were analyzed on hard bed for pediatric CPR by an anatomically-detailed 10 year-old (YO) child thorax finite element (FE) model. The chest compression and rib injury risk were studied for children with various levels of thorax stiffness. METHODS We created three thorax models with different chest stiffness. Simulated CPR׳s in the above two conditions were performed. Three different compression rates were considered under the constant peak displacement condition. The model-calculated deflections and forces were analyzed. The rib maximum principle strains (MPS׳s) were used to predict the potential risk of rib injury. RESULTS Under the constant peak force condition, the chest deflection ranged from 34.2 to 42.2mm. The highest rib MPS was 0.75%, predicted by the compliant thorax model. Under the normal constant peak displacement condition, the highest rib MPS was 0.52%, predicted by the compliant thorax model. The compression rate did not affect the highest rib MPS. CONCLUSIONS Results revealed that the thoracic stiffness had great effects on the quality of CPR. To maintain CPR quality for various children, the constant peak displacement technique is recommended when the CPR is performed on the hard bed. Furthermore, the outcome of CPR in terms of rib strains and total work are not sensitive to the compression rate. The FE model-predicted high strains were in the ribs, which have been found to be vulnerable to CPR in the literature.

Computational Study of Fracture Characteristics in Infant Skulls Using a Simplified Finite Element Model

Skull fracture characteristics are associated with loading conditions (such as the impact point and impact velocity) and could provide indication of abuse or accident‐induced head injuries. However, correlations between fracture characteristics and loading conditions in infant and toddler are ill‐understood. A simplified computational model representing an infant head was built to simulate skull responses to blunt impacts. The fractures were decided through a first principal strain‐based element elimination strategy. Simulation results were qualitatively compared with test data from porcine heads. This simplified model well captured the fracture pattern, initial fracture position, and direction of fracture propagation. The model also very well described fracture characteristics found in studies with human infant cadaveric specimens. A series of parametric studies was conducted, and results indicated that the parameters studied had substantial effects on fracture patterns. Additionally, the jagged shapes of sutures were associated with strain concentrations in the skull.