Hubert Lobo, Matereality LLC, Ithaca, NY, USA
Hubert Lobo is the founder of DatapointLabs,
a testing laboratory specialized in generating representative properties
for CAE. He has been working in the area of material characterization
and modeling for CAE since 1986, first with the Cornell Injection Molding
Program and then with C-Mold, where he developed their material modeling
test protocols.
His company, DatapointLabs is the primary source of material properties
for structural analysis, process simulations such as injection molding,
extrusion, and blow molding offering analysis ready material models
for over a dozen major CAE programs. Matereality is his new company
bringing tools to manage the growing pool of material property data
available for virtual product development.
In 2002, the Society of Plastics Engineers honored Mr. Lobo as one of
its youngest Fellows, recognizing his pioneering work in quantification
of material behavior for CAE. Mr. Lobo actively participates in testing
standardization efforts within the US and internationally at ISO. He
has a Masters degree in Engineering from Cornell University.
Quantification of Material Behavior for Simulation
Material modeling is a key aspect of successful CAE with non-linear
materials such as plastics, rubber and foams. After the right material
model is selected, the properties of these complex materials need to
be determined with precision and in conformance with the needs of the
CAE application. Properties needed vary depending on the task at hand
and the material model parameters are often difficult to obtain. It
is therefore quite a complex matter to prepare material models for CAE.
In the finite element analysis (FEA) of plastics, analysts are now migrating
to non-linear and multi-physics applications. Successful implementation
of these simulations require the understanding and use of a variety
of material models for elastic-plastic behavior, rate dependency, temperature
dependency, creep, stress relaxation and fatigue. We examine these effects
and look at limitations of existing material models for plastics.
FEA of rubber is typically handled using hyperelastic models. The challenge
here is to obtain the right kind of data and to transform it into one
of several available material models. Issues discussed will include
the Mullens effect, strain range effects and problems related to visco-elastic
behavior.
Foam modeling is complex because each class of foams has a particular
kind of behavior. The discussion will focus on the different types of
foams and the kind of material models most appropriate for each. The
particular case of foams in impact situations, including non-linear
rate dependency, will be discussed.
Process simulation including injection mold analysis, thermoforming
and extrusion simulation require sophisticated are non-linear, non-isothermal
material models. Pros and cons of some of these modeling strategies
will be presented.
Finally, we consider the challenges that need to be addressed in the
future as simulation progresses to higher levels of sophistication:
the need for multi-dimensional material modeling and most crucially,
the desire to digitally store this complex expensive information so
it is always available to those who need it and not lost over time.
Visit the TCN CAE 2005 Website
http://tcncae05.consorziotcn.it/index.php
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