A large-strain, transient dynamic analysis of head injury problems by the finite element method.

摘要

The deformation of brain tissue in the human head, subjected to a rotational impact is analyzed numerically using a finite element model to understand the head injury problems. This model consists of eight noded hexahedron and four noded quadrilateral isoparametric elements. This finite element model uses an updated Lagrangian approach and a weak form of governing equations based on the alternative measures of stress and strain to solve the finite deformation problem of head-injury.;In this investigation, the cylindrical, half-cylindrical, and skull models used in the experiments of Margulies, are employed for numerical study. Parametric studies are conducted varying the amplitude and the peak change of velocity of impact, and also varying the size and material properties of the brain in the cylindrical and half-cylindrical models. In the skull model, the influence of the falx cerebri and cerebrospinal fluid, which circulates within the lateral ventricles and subarachnoid space, on the shear deformation of brain tissue under rotational impact, is studied.;The phenomenon of large strains near the periphery of the cylindrical shell, in the prototype material, under intense rotational acceleration is captured well in the computations. The rigid body motions of core region also predicted well in the simulation, and the time lag between the displacement of brain material and the input angular displacement is in good agreement with the experimental results of Margulies. The parametric studies show patterns similar to those of the experimental, clinical, and analytical studies of other head-injury investigations.;The results in this numerical simulation using the skull model show that the falx cerebri produces the intensified strain near the falx due to the combined effect of the subarachnoid space and lateral ventricles. The distribution of the shear strain also shows the diffuse pattern which is also good enough to explain a diffuse axonal injury. These results agree well with those of many clinical tests.