PALESTRAS - Modelação Computacional de Problemas de Engenharia


8 de Julho de 2014 | 14h30 – 16h30
Sala 4.17, Ed. IX

Elson Magalhães Toledo, Professor Universidade Federal de Juiz de Fora
Laboratório Nacional de Computação Cientifica


Efficient Explicit Finite Difference Method for Acoustic Wave Using Locally Adjustable Time-Steps

Finite difference methods (FDM) are often used to find numerical solution of seismic
wave problem and it has been widely used in seismic modeling and the accuracy of these
methods depends on the operators approximation order and grid spacing.

In heterogeneous media with strong discontinuities in physical properties, as it
happens in these applications, conventional finite-difference modelling are based on a
time-stepping scheme with a constant (global) time step, determined by the medium with
higher wave velocity propagation. This cause oversampling in time for some domain
regions and the use of different temporal discretization for each region can greatly
reduce the computational cost involved when solving this kind of problem.

In this seminar we discuss an adaptive local temporal discretization algorithm for the
explicit finite difference method applied to acoustic wave equation showing some
numerical results to illustrate its application.

Modeling Experiments in the Biomechanical study of dental implants

The large use of computational approximated methods in the solution of continuum
mechanics problems particularly as it occurs in solid mechanics, has driven its
application to involve a diversity of areas such as biomechanics. Such is the case of
the stress analysis, by finite element method, around osseointegrated (endosseous)
dental implants.

In this seminar we show how a 3-D model for one mandible was used, based on a
reconstruction from a computerized tomography, with the loading simulating the
masticatory actions equilibrated by a set of muscles actions, and with the support at
the Temporo Mandibular Joint.

Elastic linear behavior is assumed for the constitutive material of the implant -
titanium - and of the two kinds of bone: cortical and trabecular. Comparisons are shown
in terms of principal and von-Mises stresses in the bone near the implant and a
discussion is made about this kind of modeling.