Influence of stiffness and shape of contact surface on skull fractures and biomechanical metrics of the human head of different population underlateral impacts (original) (raw)
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Assessment of head injury risk caused by impact using finite element models
Impact loading is the primary source of head injuries and can result in a range of trauma from mild to severe. Because of the multiple environments in which impact-related injuries can take place (automotive accidents, sports, accidental falls, violence), they can potentially affect the entire population regardless of their health conditions. Despite the increasing research effort on the understanding of head impact biomechanics, accurate prediction and prevention of traumatic injuries has not been completely achieved.
Dynamic biomechanics of the human head in lateral impacts
Annals of advances in automotive medicine / Annual Scientific Conference ... Association for the Advancement of Automotive Medicine. Association for the Advancement of Automotive Medicine. Scientific Conference, 2009
The biomechanical responses of human head (translational head CG accelerations, rotational head accelerations, and HIC) under lateral impact to the parietal-temporal region were investigated in the current study. Free drop tests were conducted at impact velocities ranging from 2.44 to 7.70 m/s with a 40 durometer, a 90 durometer flat padding, and a 90 durometer cylinder. Specimens were isolated from PMHS subjects at the level of occipital condyles, and the intracranial substance was replaced with brain simulant (Sylgard 527). Three tri-axial accelerometers were instrumented at the anterior, posterior, and vertex of the specimen, and a pyramid nine accelerometer package (pNAP) was used at the contra-lateral site. Biomechanical responses were computed by transforming accelerations measured at each location to the head CG. The results indicated significant "hoop effect" from skull deformation. Translational head CG accelerations were accurately measured by transforming the pN...
Journal of the Mechanical Behavior of Biomedical Materials, 2016
The objective of this study was to enhance an existing finite element (FE) head model with composite modeling and a new constitutive law for the skull. The response of the state-ofthe-art FE head model was validated in the time domain using data from 15 temporoparietal impact experiments, conducted with postmortem human surrogates. The new model predicted skull fractures observed in these tests. Further, 70 well-documented head trauma cases were reconstructed. The 15 experiments and 70 real-world head trauma cases were combined to derive skull fracture injury risk curves. The skull internal energy was found to be the best candidate to predict skull failure based on an in depth statistical analysis of different mechanical parameters (force, skull internal energy), head kinematicbased parameter, the head injury criterion (HIC), and skull fracture correlate (SFC). The proposed tolerance limit for 50% risk of skull fracture was associated with 453 mJ of internal energy. Statistical analyses were extended for individual impact locations (frontal, occipital and temporo-parietal) and separate injury risk curves were obtained. The 50% risk of skull fracture for each location: frontal: 481 mJ, occipital: 457 mJ, temporo-parietal: 456 mJ of skull internal energy.
Numerical Model of the Human Head under Side Impact
2013
Head injury constitutes approximately 50 percent of all injuries sustained in transition and it is a common injury in sport and other human activities. Mathematical models provide powerful tool in the analysis of the mechanics of head impact. In particular the finite element method lends itself for the construction of a mathematical head model because of its capability to describe complex geometries. In this study human head dynamic response to side impact is consider with finite element method. A two dimensional model of coronal section of human head has been designed using the actual human anatomy. The reference model consisting of the three layer of skull (inner layer and outer layer are compact bone and mid layer is spongy bone), cerebral spinal fluid (CSF), brain membranes (falx cerebri and tentorium) and brain tissue. The model is loaded by a sinusoidal pulse with a peak pressure of 40 kPa. Finite element analysis was conducted using Ansys software. Time-pressure history in th...
Investigating the effects of impact directions to improve head injury index
Scientia Iranica, 2019
Traumatic Brain Injury (TBI) is one of the most important causes of death and disability. The objective of this study was to develop new Head Injury Criteria (HIC), which could predict the Maximum Principal Strain (MPS) and shear stress in the brain considering the impact directions and magnitudes. Accordingly, 150 head impact simulations were performed with three magnitudes and 50 directions of impact using head Finite Element Model (FEM). Simulations were performed in order to assess the strain and shear stress in the brain tissues due to di erent impact directions and magnitudes. Next, new HIC were developed through performing statistical analysis. The simulation results showed that TBI risks in the sagittal and frontal planes were higher than those in transverse plane. Furthermore, new brain injury indices were developed to predict MPS and shear stress in the brain, which had correlation coe cients of 0.85 and 0.89 with the head FEM responses, respectively. The ndings of the present research showed the e ects of impact directions on TBI risks. They also demonstrated that impact magnitude, direction, and duration should be used to develop a brain injury index.
The creation of three-dimensional finite element models for simulating head impact biomechanics
International Journal of Crashworthiness, 2003
Decay factor λ X , λ Y , λ Z X, Y and Z dimension length scale factors C 10 , C 01 Temperature dependent coefficients G 0 Short term shear modulus G ∞ Long term shear modulus t Time Abstract: A new 3 dimensional finite element representation of the human head complex has been constructed for simulating the transient occurrences of simple pedestrian accidents. This paper describes the development, features and validation of that model. When constructing the model, emphasis was placed on element quality and ease of mesh generation. As such, a number of variations of the model were created. The model was validated against a series of cadaveric impact tests. A parametric study (a High/Low study) was performed to investigate the effect of the bulk and shear modulus of the brain and cerebrospinal fluid (CSF). The influence of different mesh densities on the models and the use of different element formulations for the skull were also investigated. It was found that the short-term shear modulus of the neural tissue had the predominant effect on intracranial frontal pressure, and on the predicted Von-Mises response. The bulk modulus of the fluid had a significant effect on the contre-coup pressure when the CSF was modelled using a coupled node definition. Differences of intracranial pressure were reported that show the sensitivity of the method by which the skull is modelled. By simulating an identical impact scenario with a range of different finite element models it has been possible to investigate the influence of model topologies. We can conclude that careful modelling of the CSF (depth/volume) and skull thickness (including cortical/ trabecular ratio) is necessary if the correct intracranial pressure distribution is to be predicted, and so further forms of validation are required to improve the finite element models' injury prediction capabilities.
Influence of the head shape variation on brain damage under impact
2005
The influence of the head shape on intracranial responses under impact was investigated by using Finite Element Method. Head shape models of 52 young adult male Japanese were analyzed by Multi Dimensional Scaling (MDS), and a 2 dimensional distribution map of head ...