CSAR Seminar
SPEAKER: Jie Wan, Rensselaer Polytechnic Institute
TITLE:
Adaptive Mesh Control for Evolving Geometry Problems
DATE: Wednesday, May 3, 2006
TIME: 12:00 Noon
PLACE: 2240 DCL
1304 W. Springfield Ave., Urbana, IL
ABSTRACT
In 3D simulations of large deformations, the geometries of deformable
objects evolve to represent material flow. The meshes of the deforming
objects typically must be updated frequently to continue the analysis
due to large mesh-associated errors, including mesh discretization
errors, geometric approximation errors, and element distortions.
Historically, the approach taken to address the need for updating once
a mesh becomes unsatisfactory is to perform a full remeshing of the
entire domain even though the mesh may contain only a limited number of
distorted elements. More importantly, remeshing process imposes the
need for transferring history-dependent solution data globally from old
mesh to new mesh, which tends to diffuse the transferred solution
variables numerically. To achieve satisfactory solution accuracy and
computational efficiency, an automated simulation process based on
simulation monitoring and adaptive mesh control executed through the
application of local mesh modifications is developed. The adaptive mesh
control procedure is coupled with FEM engines for automated finite
element simulations of various types of 3D problems with evolving
geometry.
The decision on the need for adaptive mesh enrichment is based on
monitoring the errors associated with the mesh during the analysis
increments. When the errors become too large, the analysis is stopped
and adaptive mesh control is triggered to perform the needed localized
mesh improvements and incremental solution transfer. The topological
description of the object boundary is properly updated to reflect the
current deformation configuration and geometry features before the mesh
enrichment process is applied. A posteriori error indicators based on
plastic deformation related quantities are used to control the mesh
discretization errors through an h-adaptive procedure. The mesh size
field is further processed to control the geometric approximation
errors in the critical portions of the object boundary. The mesh of
the deformed object is then modified through controlled application of
local mesh modifications to meet both the needs of mesh discretization
and element quality. The history dependent solution fields are locally
and incrementally transferred from the old mesh to the updated mesh as
mesh modifications are applied, based on local mesh modification driven
solution transfer operators. A set of industrially relevant problems
is investigated to demonstrate the capabilities developed.
BIOGRAPHY
After graduating with B.E. in mechanical engineering from National
University of Defense Technology in 1989 and M.E. in computer
engineeing from Chinese Academy of Space Technology (CAST) in 1992, Jie
Wan worked as a project manager and a senior CAE engineer in CAST for
more than 4 years. He then received his M.S. from University of
Massachusetts at Amherst and Ph.D. from Rensselaer Polytechnic
Institute, both in mechanical engineering. His current research
interests include finite element methods, automatic mesh generation,
adaptive mesh control, large deformation simulation automation,
advanced geometric modeling, computer aided design, interactive 3D
computer graphics, and reverse engineering.