Objective To investigate the injury mechanisms of three-year-old child occupants by reconstructing a real traffic accident.Methods A traffic accident case from the CIREN database was reconstructed using a vehicle finite element model and a three-year-old child occupant injury bionic model(TUST IBMs 3YO-O).The Δv,mass of the vehicle,and deformation energy were comprehensively analyzed to calculate the collision velocity of the vehicle.This accident was simulated to present injuries to a child occupant,and the injury mechanisms were analyzed in depth.Results The TUST IBMs 3YO-O fully reconstructed the injuries of the child occupant in this case.The kinematic and biomechanical responses of the children's heads differed.The biomechanical response of the internal tissues and organs in the chest cavity showed no injury,however,the result ant chest acceleration at 3 ms reached 54 g,which exceeded the threshold.Conclusions In the future,it will be necessary to adopt biomechanical parameters for occupant safety evaluations.The application of human biomechanical models with high biofidelity to reconstruct occupant injuries in traffic accidents can not only be used to observe the kinematic responses of the occupant in the accident and analyze the injury mechanisms in depth,but also to provide references for virtual testing,as well as for the research and development of child occupant protection devices and the formulation of safety regulations.

The study presents a method for the personalized biomechanical modeling of the human head and validates the generated model.Based on the TUST 50th percentile head biomechanical model,the method utilizes head CT data of the target model,and employs three-dimensional point cloud registration and free-form deformation techniques to rapidly develop a personalized head finite element model with detailed brain tissue structures.By reconstructing classic cadaver tests,it is found that the personalized head biomechanical model created by the proposed method shows a good consistency with the results of cadaver tests in kinematic and biomechanical responses.Furthermore,no significant differences are observed when compared with the head biomechanical model developed using reverse engineering method,thus verifying the effectiveness of the developed model.Consequently,the proposed method can be used to quickly construct personalized head biomechanical models with detailed anatomical structures,providing a fundamental computational analysis tool for researches in injury biomechanics,clinical medicine,and forensic identification.

Objective To predict and assess biomechanical responses and injury mechanisms of the thorax and abdomen for small-sized females in vehicle collisions. Methods The accurate geometric model of the thorax and abdomen was constructed based on CT images of Chinese 5th percentile female volunteers. A thoracic-abdominal finite element model of Chinese 5th percentile female with detailed anatomical structure was developed by using the corresponding software. The model was validated by reconstructing three groups of cadaver experiments (namely, test of blunt anteroposterior impact on the thorax, test of bar anteroposterior impact on the abdomen, test of blunt lateral impact on the chest and abdomen). Results The force-deformation curves and injury biomechanical responses of the organs from the simulations were consistent with the cadaver experiment results, which validated effectiveness of the model. Conclusions The model can be used for studying injury mechanisms of the thorax and abdomen for small-sized female, as well as developing small-sized occupant restraint systems and analyzing the forensic cases, which lays foundation for developing the whole body finite element model of Chinese 5th percentile female.

The finite element method is a new method to study the mechanism of brain injury caused by blunt instruments. But it is not easy to be applied because of its technology barrier of time-consuming and strong professionalism. In this study, a rapid and quantitative evaluation method was investigated to analyze the craniocerebral injury induced by blunt sticks based on convolutional neural network and finite element method. The velocity curve of stick struck and the maximum principal strain of brain tissue (cerebrum, corpus callosum, cerebellum and brainstem) from the finite element simulation were used as the input and output parameters of the convolutional neural network The convolutional neural network was trained and optimized by using the 10-fold cross-validation method. The Mean Absolute Error (MAE), Mean Square Error (MSE), and Goodness of Fit ( R ²) of the finally selected convolutional neural network model for the prediction of the maximum principal strain of the cerebrum were 0.084, 0.014, and 0.92, respectively. The predicted results of the maximum principal strain of the corpus callosum were 0.062, 0.007, 0.90, respectively. The predicted results of the maximum principal strain of the cerebellum and brainstem were 0.075, 0.011, and 0.94, respectively. These results show that the research and development of the deep convolutional neural network can quickly and accurately assess the local brain injury caused by the sticks blow, and have important application value for understanding the quantitative evaluation and the brain injury caused by the sticks struck. At the same time, this technology improves the computational efficiency and can provide a basis reference for transforming the current acceleration-based brain injury research into a focus on local brain injury research.
Brain ; Brain Injuries ; Computer Simulation ; Finite Element Analysis ; Humans ; Neural Networks, Computer

Objective To study influencing factors of renal blunt impact injury by using finite element (FE) method. Methods Based on CT images of the kidney, the kidney FE models for different age groups were constructed. The renal blunt impact test was reconstructed, and the influence of kidney material constitutive parameters, kidney tissue structure, kidney size, impact position and impact velocity on injury severity were analyzed. Results Under the same impact condition, the stress of renal cortex decreased with the kidney mass increasing, and increased with the impact velocity of the hammer increasing. The renal capsule had a certain energy absorption effect, so as to reduce the kidney stress. When the kidney was impacted, the stress of renal cortex under side impact was significantly higher than that under frontal impact. Conclusions Compared with viscoelastic constitutive model, Mooney Rivlin material constitutive model is more suitable for FE evaluation on renal injury severity. The renal injury decreases with the kidney mass increasing. The increase of impact velocity will intensify the renal injury severity. Renal capsule will reduce renal injury to a certain extent, so the existence of renal capsule structure must be considered in FE modeling of the kidney. Compared with frontal and rear impact, the renal injury severity is greater when the kidney is impacted from the lateral side.

Objective To explore the influence of child head injury under different impact angles by applying the finite element model of six-year-old child pedestrian as specified in the European New Car Assessment Programme (Euro NCAP). Methods Based on the finite element model of 6-year-old pedestrian with detailed anatomical structure as specified by the Euro NCAP (TB024), four groups of simulation experiments were set up to explore the mechanism of head injury in children under different impact angles. The initial position for head mass center was on the longitudinal center line of the car. The initial speed of the car was 40 km/h. The car contacted with the model from the direction of the right (0°), the front (90°), the left (180°) and the back (270°). The kinematics differences and head impact responses were compared, and injuries of the facial bone and skull were analyzed. Results Through the analysis of head contact force, acceleration of head mass center, resultant velocity of head mass center with the vehicle, head injury criterion (HIC15), facial bone fracture and skull stress distribution, it was found that the risk of head fracture and brain contusion under back impact and front impact was higher than that under side impact. The risk of head fracture and brain contusion was highest under back impact, while the lowest under side impact. Conclusions Child pedestrian head injury was the largest under back impact. The results have important application values for the assessment and development of car-pedestrian collision protection device.

Objective To study the influence of skull thickness on intracranial biomechanical parameters by finite element method. Methods The female head at 5th percentile was selected for CT scanning to construct finite element model of the head with high biofidelity,and the model was verified by reconstructed cadaver test. The finite element model of the head with different skull thickness was established, and multiple groups of tests were carried out to compare the intracranial mechanical parameters. Results The negative value of intracranial pressure was significantly affected by the decrease in skull thickness under the same head size, while the negative value of intracranial pressure was slightly affected, with an increasing trend. The shear stress and von Mises stress of brain tissues were significantly increased with skull thickness increasing. Conclusions Under the same head size, the skull thickness will affect head injury to a certain extent, and people with small skull thickness are more likely to be injured than those with large skull thickness.

Objective To study the constitutive model of adipose tissue at medium strain rate and its parameter inversion. Methods Based on experiments of adipose tissue mechanical properties, the compression experiment of adipose tissues was reconstructed by finite element method, and the parameters for characterizing constitutive models of adipose tissues were screened. Combined with the method of feasible direction (MFD) in optimization method, the reverse calculation for parameters of fat tissue constitutive model at medium strain rate was conducted. ResultsCompared with Ogden constitutive model, the viscoelastic constitutive model was more suitable for characterizing the mechanical response at medium strain rate (260 s-1). The parameters of the constitutive model suitable for simulation were obtained using the reverse method. Conclusions The viscoelastic constitutive model was more suitable for characterizing the mechanical response at medium strain rate. The results provide references for studying the influence of human adipose tissues on body injury in finite element simulation of vehicle collisions.

Objective To explore the effect of restraint system misuse on head-neck injuries for rear occupant of 6-year-old children in frontal impact crashes. Methods Based on the previously validated 6-year-old child occupant finite element model, in terms of ECE R44 testing regulations, the impact crash under right and wrong use of restraint system was simulated in Pam-Crash software. Results The force and moment of the neck were the minimum by merely using booster seat, but the maximum intracranial pressure, the maximum stress and the maximum principal strain were larger than their damage threshold and would cause fatal brain damage in child head. The only use of adult safety belt would cause more serious damage in child neck with larger force and moment. Conclusions Two ways of misusing the restraint system would aggravate head-neck injuries of the 6-year-old child. The proper use of the restraint system can provide the best protective effect for head and neck of the 6-year-old child occupant.

Objective To study the effect of neck restrain on traumatic brain injury during airbag inflation in traffic accidents. Methods Based on the previously validated 3-year-old child head finite element (FE) model, the impact on out-of-position (OOP) child occupant during airbag inflation was simulated by FE method, so as to investigate the effects of neck restraint on intracranial response and injury mechanism in traffic accidents. Results The head kinematics with neck restrain was different from that without neck restrain under the impact of airbag inflation. The neck restraint would obviously decrease the maximum Von Mises stress of pediatric brain. When airbag-head distance was 20 cm or 25 cm, the neck restraint would obviously decrease the maximum intracranial pressure. Conclusions Neck restraint had a relatively large influence on pediatric intracranial response. When the FE method is used to predict pediatric craniocerebral injury, consideration of neck restrain on child brain response is necessary.