ABSTRACT
OBJECTIVES@#To analyze and predict the striking velocity range of stick blunt instruments in different populations, and to provide basic data for the biomechanical analysis of blunt force injuries in forensic identification.@*METHODS@#Based on the Photron FASTCAM SA3 high-speed camera, Photron FASTCAM Viewer 4.0 and SPSS 26.0 software, the tester's maximum striking velocity of stick blunt instruments and related factors were calculated and analyzed, and inputed to the backpropagation (BP) neural network for training. The trained and verified BP neural network was used as the prediction model.@*RESULTS@#A total of 180 cases were tested and 470 pieces of data were measured. The maximum striking velocity range was 11.30-35.99 m/s. Among them, there were 122 female data, the maximum striking velocity range was 11.63-29.14 m/s; there were 348 male data, the maximum striking velocity range was 20.11-35.99 m/s. The maximum striking velocity of stick blunt instruments increased with the increase of weight and height, but there was no obvious increase trend in the male group; the maximum striking velocity decreased with age, but there was no obvious downward trend in the female group. The maximum striking velocity of stick blunt instruments has no significant correlation with the material and strike posture. The root mean square error (RMSE), the mean absolute error (MAE) and the coefficient of determination (R2) of the prediction results by using BP neural network were 2.16, 1.63 and 0.92, respectively.@*CONCLUSIONS@#The prediction model of BP neural network can meet the demand of predicting the maximum striking velocity of different populations.
Subject(s)
Male , Humans , Female , Neural Networks, Computer , Software , Wounds, Nonpenetrating , Forensic MedicineABSTRACT
OBJECTIVES@#To reconstruct the cases of acceleration craniocerebral injury caused by blunt in forensic cases by finite element method (FEM), and to study the biomechanical mechanism and quantitative evaluation method of blunt craniocerebral injury.@*METHODS@#Based on the established and validated finite element head model of Chinese people, the finite element model of common injury tool was established with reference to practical cases in the forensic identification, and the blunt craniocerebral injury cases were reconstructed by simulation software. The cases were evaluated quantitatively by analyzing the biomechanical parameters such as intracranial pressure, von Mises stress and the maximum principal strain of brain tissue.@*RESULTS@#In case 1, when the left temporal parietal was hit with a round wooden stick for the first time, the maximum intracranial pressure was 359 kPa; the maximum von Mises stress of brain tissue was 3.03 kPa at the left temporal parietal; the maximum principal strain of brain tissue was 0.016 at the left temporal parietal. When the right temporal was hit with a square wooden stick for the second time, the maximum intracranial pressure was 890 kPa; the maximum von Mises stress of brain tissue was 14.79 kPa at the bottom of right temporal lobe; the maximum principal strain of brain tissue was 0.103 at the bottom of the right temporal lobe. The linear fractures occurred at the right temporal parietal skull and the right middle cranial fossa. In case 2, when the forehead and left temporal parietal were hit with a round wooden stick, the maximum intracranial pressure was 370 kPa and 1 241 kPa respectively, the maximum von Mises stress of brain tissue was 3.66 kPa and 26.73 kPa respectively at the frontal lobe and left temporal parietal lobe, and the maximum principal strain of brain tissue was 0.021 and 0.116 respectively at the frontal lobe and left temporal parietal lobe. The linear fracture occurred at the left posterior skull of the coronary suture. The damage evaluation indicators of the simulation results of the two cases exceeded their damage threshold, and the predicted craniocerebral injury sites and fractures were basically consistent with the results of the autopsy.@*CONCLUSIONS@#The FEM can quantitatively evaluate the degree of blunt craniocerebral injury. The FEM combined with traditional method will become a powerful tool in forensic craniocerebral injury identification and will also become an effective means to realize the visualization of forensic evidence in court.
Subject(s)
Humans , Finite Element Analysis , Biomechanical Phenomena , Wounds, Nonpenetrating , Head , Craniocerebral TraumaABSTRACT
Objective To explore the brain injury mechanism and enrich the database of human finite element (FE) biomechanical model by developing the FE model of one-year-old toddler head. Methods Based on CT data from Chinese one-year-old toddler head with substantial and detailed information, the head model with detailed anatomical structure was constructed by using the medical software Mimics to get the head geometry data, as well as the reverse engineering software to divide NURBS surface and build the geometric model. Finally, the FE pre-processing software was used mesh the model. The FE model of one-year-old toddle head was validated by data from anatomic and cadaver experiments, and was used for preliminary analysis on damage mechanism of one-year-old toddler head. Results The FE model of Chinese one-year-old male toddler head was developed, which included and distinguished the gray matter and white matter of brain and cerebellum, hippocampus, fontanel, sagittal suture, coronal suture, brainstem and ventricles. The cadaver head static compression experiments and drop experiments were reconstructed by using this head model, and the results showed that the FE model of head had similar mechanical properties with the cadaver, which proved the validity of the FE model. Simulation results showed that skull stiffness and skull injury severity varied with different compression rates. Conclusions The FE model of one-year-old toddler head with detailed anatomical structures is of great biofidelity. The FE head model can be used to further investigate the detailed injury mechanism of deep brain tissues, especially for the closed craniocerebral injury, which provides an effective way and tool for the related research and clinical application.
ABSTRACT
Objective To develop the finite element model of six-year-old child occupant lower extremity with higher biofidelity and validate the model of knee joints, as well as analyze the biomechanical responses of growth plate under frontal impact load and injury mechanisms of the knee joint by using this model. Methods The six-year-old child occupant lower extremity with growth plate was modeled based on children’s anatomy and CT images, and corresponding material properties of the lower extremity model were assigned．The model was validated according to biomechanical experiments by Kerrigan et al. and Haut et al. and then was used to analyze the injury results of growth plate with different material properties. Results The model validation was qualified by comparing the curves from the experimental and simulation results．The growth plates at knee regions could change injury patterns of the child occupant lower extremity fracture. The material properties of growth plate could affect threshold of axial damage of the femur as well as relative position of the fracture． Conclusions The validated model can be used for related study and application on biomechanical responses and injury mechanisms of six-year-old child occupant lower extremities．
ABSTRACT
Objective To develop the finite element model of six-year-old child occupant lower extremity with higher biofidelity and validate the model of knee joints,as well as analyze the biomechanical responses of growth plate under frontal impact load and injury mechanisms of the knee joint by using this model.Methods The sixyear-old child occupant lower extremity with growth plate was modeled based on children's anatomy and CT images,and corresponding material properties of the lower extremity model were assigned.The model was validated according to biomechanical experiments by Kerrigan et aL and Haut et aL and then was used to analyze the injury results of growth plate with different material properties.Results The model validation was qualified by comparing the curves from the experimental and simulation results.The growth plates at knee regions could change injury patterns of the child occupant lower extremity fracture.The material properties of growth plate could affect threshold of axial damage of the femur as well as relative position of the fracture.Conclusions The validated model can be used for related study and application on biomechanical responses and injury mechanisms of sixyear-old child occupant lower extremities.
ABSTRACT
Objective To develop the finite element model of six-year-old child occupant lower extremity with higher biofidelity and validate the model of knee joints,as well as analyze the biomechanical responses of growth plate under frontal impact load and injury mechanisms of the knee joint by using this model.Methods The sixyear-old child occupant lower extremity with growth plate was modeled based on children's anatomy and CT images,and corresponding material properties of the lower extremity model were assigned.The model was validated according to biomechanical experiments by Kerrigan et aL and Haut et aL and then was used to analyze the injury results of growth plate with different material properties.Results The model validation was qualified by comparing the curves from the experimental and simulation results.The growth plates at knee regions could change injury patterns of the child occupant lower extremity fracture.The material properties of growth plate could affect threshold of axial damage of the femur as well as relative position of the fracture.Conclusions The validated model can be used for related study and application on biomechanical responses and injury mechanisms of sixyear-old child occupant lower extremities.
ABSTRACT
Objective In view of the uncertainties of material parameters for child craniocerebral tissues, the effects of such parameters on responses of child head under direct impact loads were investigated. Methods The impact simulation experiments were conducted under direct impact loads by using a validated finite element model of 3-year-old child head. Taguchi orthogonal method and variance analysis were performed to analyze the material properties of craniocerebral tissues in child head. Results Elastic modulus of the skull had statistically significant effects on impact responses of child head. With the skull elastic modulus increasing, the coup pressure decreased significantly (P=0.000), whereas the contrecoup pressure (P=0.000) and maximum Von Mises stress of the skull increased significantly (P=0.000). The linear viscoelastic material parameters of brain tissues also had statistically significant effects on impact responses of child head. With the increase of the short-time shear modulus of brain tissues, the maximum shear stress of brain tissues increased significantly (P=0.000) whereas the maximum principal strain decreased significantly (P=0.000). Conclusions These statistical analysis results can provide references for selecting material parameter of craniocerebral tissues in finite element model of child head, which will be helpful to improve diagnosis accuracy of brain injuries such as concussion difficult to be definitely diagnosed when using brain CT images in clinic.
ABSTRACT
Objective To predict biomechanical responses of neck injuries under different loading conditions based on the finite element model of the 6-year-old pediatric neck. Methods The finite element model of the 6-year-old pediatric neck with real anatomical structural muscles was developed, according to the CT images. The model was verified by reconstructing the dynamic tensile test of different cervical spine segments, the tensile test of full cervical spine and the low speed impact experiment of the pediatric volunteers. Results The force-displacement curves, obtained from the simulations on tensile test of different cervical spine segments and tensile test of full cervical spine, were in good agreement with the experimental curves. The head angular velocity-time curve obtained from simulations on pediatric volunteer was consistent with the corridor obtained from experimental data. Conclusions The model is validated and can be used for studying the biomechanical responses and injury mechanism of pediatric neck under different loading conditions.
ABSTRACT
Objective To investigate brain responses from children during traffic accident and drop impact by developing a 3-year-old child head finite element (FE) model. Methods Based on the CT data from a 4-year-old child head, the FE child head model with detaile
ABSTRACT
Brain injury has become the most severe injury in traffic accident due to its high incidence and high fatality rate. The brain injury model plays a critical role in researches on brain injury. The constitutive model and the material properties used in the model are key factors in determining the accuracy of injury prediction. The present paper aims to review the application of constitutive models and material properties in brain simulation so as to better understand biomechanical properties of brain and provide references for finite element researches on brain injury.
ABSTRACT
Objective To construct and validate the 95th percentile finite element model of Chinese human head, evaluate the relative displacement between the skull and brain according to four types of skull brain relative displacement experiments as references, and investigate the shear strain distributions on the brain. Methods By comparing the relative displacement curve derived from the experiment and simulation and referring to conclusions from animal and physical experiments, the position of higher shear strain was investigated. Results High correlations could be found between the simulated and experimental results for skull brain relative displacement. Peaks and troughs could always appear in curves of skull brain relative displacement due to the fact that the brain tissue tended to return to its initial state. The results that higher strain could occur at temporal lobe of the brain, corpus callosum and brain surface were consistent with conclusions from the animal and physical experiments. ConclusionsT he 95th percentile finite element model of Chinese human head is validated with good biofidelity. Due to the rotational motion of human head, higher shear strain will occur on brain surface and in deep brain, leading to injuries, which provids a scientific theoretical basis for the study on injury mechanism of human head in traffic accidents.