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Journal ArticleDOI

Generation of geometry of closed human head and discretisation for finite element analysis

01 May 1995-Medical & Biological Engineering & Computing (Med Biol Eng Comput)-Vol. 33, Iss: 3, pp 349-353
TL;DR: The experiment used four acid dyes, three basic dyes and two solvents, ethanol and toluene to create spots that cured under pressure, preventing bubbles appearing in the spots as a result of the contraction of the rubber during cure.
Abstract: The experiment used four acid dyes, three basic dyes and two solvents, ethanol and toluene. The procedure was to stir a very small quantity 1 mm 3) o f powdered dye into 2 ml of the selected solvent and then to mix this with 2 ml o f D e 3140. The mixture was deposited as 'spots,' about 1.5 cm in diameter, on to clean microscope slides, which were then cured in moist air in a pressure chamber at 2 bar. Curing under pressure prevents bubbles appearing in the spots as a result of the contraction of the rubber during cure. The spot colours noted were those seen after 24 h; in most cases, however, the colour developed within a few minutes and was stable therafter, 48 h were allowed for cure.
Citations
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Journal ArticleDOI
TL;DR: The results indicate that, despite the fundamental differences between these six model formulations, the comparisons with the experimentally measured pressures and relative displacements were largely consistent and in good agreement and may prove useful for those attempting to model real life accident scenarios.
Abstract: In order to create a useful computational tool that will aid in the understanding and perhaps prevention of head injury, it is important to know the quantitative influence of the constitutive properties, geometry and model formulations of the intracranial contents upon the mechanics of a head impact event. The University College Dublin Brain Trauma Model (UCDBTM) [1] has been refined and validated against a series of cadaver tests and the influence of different model formulations has been investigated. In total six different model configurations were constructed: (i) the baseline model, (ii) a refined baseline model which explicitly differentiates between grey and white neural tissue, (iii) a model with three elements through the thickness of the cerebrospinal fluid (CSF) layer, (iv) a model simulating a sliding boundary, (v) a projection mesh model (which also distinguishes between neural tissue) and (vi) a morphed model. These models have been compared against cadaver tests of Trosseille [2] an...

209 citations


18


01 Jan 2000-
Abstract: The main objectives of the present thesis were to define the dimension of head injuries in Sweden over a longer period and to present a Finite Element (FE) model of the human head which can be used ...

108 citations


Journal ArticleDOI
Abstract: This paper is devoted to review the current status related to motorcycle helmet crash studies from biomechanics and computational point of view. The importance of motorcycle helmet performance on statistical background was reviewed. The paper is divided into two main sections: in the first section, the biomechanics issues are highlighted and the head injury classifications are presented. The injury mechanisms for different injury types are analyzed and the related helmeted-head impacts were identified. The injury tolerances for the head main components presented with an insight into the current controversies among the different limits particularly rotational acceleration effects on the brain and the DAI brain damage type. In the second section, insights into the computational issues that are critical to the understanding of the helmet safety are presented. Some recent examples in which computational techniques used are also reviewed. Finally, directions for future research are also highlighted.

50 citations


Journal ArticleDOI
TL;DR: Three-dimensional finite-element analysis is carried out to investigate the influence of the partitioning membranes of the brain and the neck in head injury analysis through free-vibration analysis and transient analysis.
Abstract: A head injury model consisting of the skull, the CSF, the brain and its partitioning membranes and the neck region is simulated by considering its near actual geometry. Three-dimensional finite-element analysis is carried out to investigate the influence of the partitioning membranes of the brain and the neck in head injury analysis through free-vibration analysis and transient analysis. In free-vibration analysis, the first five modal frequencies are calculated, and in transient analysis intracranial pressure and maximum shear stress in the brain are determined for a given occipital impact load.

44 citations


Journal ArticleDOI
TL;DR: Shear strain theory appears to better account for the clinical findings in head injury when the head is subjected to an indirect impact, and predictions of cavitation theory that a pressure gradient develops in the brain during indirect impact are supported.
Abstract: The mechanism of brain contusion has been investigated using a series of three-dimensional (3D) finite element analyses. A head injury model was used to simulate forward and backward rotation around the upper cervical vertebra. Intracranial pressure and shear stress responses were calculated and compared. The results obtained with this model support the predictions of cavitation theory that a pressure gradient develops in the brain during indirect impact. Contrecoup pressure-time histories in the parasagittal plane demonstrated that an indirect impact induced a smaller intracranial pressure (-53.7 kPa for backward rotation, and -65.5 kPa for forward rotation) than that caused by a direct impact. In addition, negative pressures induced by indirect impact to the head were not high enough to form cavitation bubbles, which can damage the brain tissue. Simulations predicted that a decrease in skull deformation had a large effect in reducing the intracranial pressure. However, the areas of high shear stress concentration were consistent with those of clinical observations. The findings of this study suggest that shear strain theory appears to better account for the clinical findings in head injury when the head is subjected to an indirect impact.

41 citations


References
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01 Jan 1990-
Abstract: The dynamic response of the human head to side impact was studied by 2-dimensional finite element modeling. Three models were formulated in this study. Model I is an axisymmetric model. It simulated closed shell impact of the human head, and consisted of a single-layered spherical shell filled wiht an inviscid fluid. The other two models (Model II and III) are plane strain models of a coronal section of the human head. Model II approximated a 50th percentile male head by an outer layer to simulate cranial bone and an inviscid interior core to simulate the intracranial contents. The configuration of Model III is the same as Model II but more detailed anatomical features of the head interior were added, such as, cerebral spinal fluid (CSF); falx cerebri, dura, and tentorium. Linear elastic material properties were assigned to all three models. All three models were loaded by a triangular pulse with a peak pressure of 40 kPa, effectively producing a peak force of 1954 N (440 lb). The purpose of this study was to determine the effects of the membranes and that of the mechanical properties of the skull, brain, and membrane on the dynamic response of the brain during side impact, and to compare the pressure distributions from the plane strain model with the axisymmetric model. A parametric study was conducted on Model II to characterize fully its response to impact under various conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

163 citations


Journal ArticleDOI
TL;DR: The purpose of this study was to determine the effects of the membranes and that of the mechanical properties of the skull, brain, and membrane on the dynamic response of the brain during side impact, and to compare the pressure distributions from the plane strain model with the axisymmetric model.
Abstract: The dynamic response of the human head to side impact was studied by 2-dimensional finite element modeling. Three models were formulated in this study. Model I is an axisymmetric model. It simulated closed shell impact of the human head, and consisted of a single-layered spherical shell filled wiht an inviscid fluid. The other two models (Model II and III) are plane strain models of a coronal section of the human head. Model II approximated a 50th percentile male head by an outer layer to simulate cranial bone and an inviscid interior core to simulate the intracranial contents. The configuration of Model III is the same as Model II but more detailed anatomical features of the head interior were added, such as, cerebral spinal fluid (CSF); falx cerebri, dura, and tentorium. Linear elastic material properties were assigned to all three models. All three models were loaded by a triangular pulse with a peak pressure of 40 kPa, effectively producing a peak force of 1954 N (440 lb). The purpose of this study was to determine the effects of the membranes and that of the mechanical properties of the skull, brain, and membrane on the dynamic response of the brain during side impact, and to compare the pressure distributions from the plane strain model with the axisymmetric model. A parametric study was conducted on Model II to characterize fully its response to impact under various conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

154 citations


Journal ArticleDOI
TL;DR: The results revealed that the load spatial distribution strongly influenced skull and, consequently, the load required to initiate skull fracture, and the other parameters produced small effects on the models' responses.
Abstract: An investigation utilizing the finite element technique was performed to study the human head response to impact loading. Three axisymmetric head model configurations were selected where the human skull was represented by a single-layer spherical shell, an oval shell consisting of two spherical caps and a cone frustum, and a three-layer spherical shell. For all models the interior cavity was filled by an inviscid fluid representing the cranial vault contents, and the exterior shell surface was encased by a skin-flesh layer corresponding to the scalp. The skull and scalp materials were characterized by an elastic representation. For each configuration, an axisymmetric force history was assumed to act over one of the polar cap areas. Of particular interest were the levels of strain produced in the skull and stress in the fluid interior. Theoretical load levels required to produce skull fracture and/or brain damage by cavitation were predicted. A parametric study was conducted to determine the sensitivity of the response of the model to changes in the spatial and temporal distributions of the applied load, the head dimensions, and the material properties of skull representation. The results revealed that the load spatial distribution strongly influenced skull strains and, consequently, the load required to initiate skull fracture. The other parameters produced small effects on the models' responses.

119 citations


Proceedings ArticleDOI
01 Feb 1974-
Abstract: Crash test dummies serve as human surrogates in automotive crash simulations, and accelerations monitored in the heads of these dummies are used for assessment of human head injury hazard. For these acceleration measurements to be meaningful indicators of head injury, the impact response of the human head must be a part of dummy head design. This paper describes the conception, design and development of a crash test dummy head. Geometric, inertial, and performance requirements based on biomechanical information are presented and discussed. The head design concept is compatible with current head injury assessment procedures, and the configuration is based on the GM Research skull and head geometry models. The manufacture and development are described, and the test procedures and results are presented and discussed with reference to the biomechanical and functional requirements. The resulting dummy head is shown to comply with these requirements.

96 citations


Journal ArticleDOI
Abstract: : A finite element elastic analysis is made of a skull. Measurements were made of the geometry and thickness of a skull. The skull was then idealized with a doubly curved and arbitrary triangular shell element. Results suggest that the skull is well built for resistance to front loads. The importance of using a composite material through the thickness of the shell was established. On the basis of tensile cracking at maximum elastic stress, loads of 3,500 lbs. and 1,400 lbs. were predicted for the first cracking of the skull due to front and side loading respectively.

51 citations


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