SAMPE Journal - May/June 2017 - 37

Feature Article
J. Wang1,3, P. Simacek1,3, S. Yarlagadda2,3, S.G. Advani1,3
1
Dept. of Mechanical Engineering; 2Dept. of Electrical & Computer Engineering; 3Center for Composite Materials
University of Delaware, Newark, DE

Integration of Composite Part Design and
Processing Simulation in Liquid
Composite Molding (LCM)
Abstract
In Liquid Composite Molding (LCM) processes, processing simulations are necessary to virtually execute the manufacturing
steps to verify the design. Processing parameters, such as infusion/venting plan, should be optimized and the process simulation
results should provide accurate feedback to designers suggesting necessary design modifications. It is highly desirable to couple
the manufacturing process design with the part design cycle, so that the designer can modify the part to meet the design
requirements, include manufacturing constraints and maximize part yield simultaneously. However, the inherent material
variability and geometry features designed for mechanical requirements may introduce processing variations (for example flow
disturbances) that introduce variability in the manufacturing process and require hundreds of simulations to capture the effect
of the stochastic nature. This also requires large amount of highly specialized pre-and post-processing analysis and consequently,
it prevents the designers from using processing simulation tools effectively. In this paper, a set of new tools are developed and
integrated with part design software to provide automated support for analyzing process variability. Three levels of process
simulations are developed, automated and integrated with optimization algorithms to generate robust processing feedback to the
designer. With these tools interfaced with CAD design software, the designer is provided with both accurate manufacturability
analysis and suggested geometry modifications for the part.
Introduction
In Liquid Composite Molding
(LCM)
processes,
dry
fiber
reinforcement is placed within a
mold cavity, which is then infused
with catalyzed liquid resin until it
is completely saturated. Once the
resin cures the part is de-molded.
Two most common variations of
LCM processes are Resin Transfer
Molding (RTM) and Vacuum
Assisted Resin Transfer Molding
(VARTM). RTM uses a rigid mold so
that highly pressurized resin can be
injected, whereas VARTM uses onesided mold and a vacuum bag to seal
the mold, and atmospheric pressure
is used as the driving force. There are
other techniques such as RTM-Light
which uses a compliant mold. LCM
is widely used because it allows one
to manufacture complex net-shaped
parts with good structural properties
and surface finish1.
Mold filling simulation describes
flow of resin through fiber preforms
which are modeled as porous
continuum.
Many
numerical
simulations have been developed to
forecast the mold filling patterns2-10.
SAMPE Journal, Volume 53, No. 3, May/June 2017

We have also developed a three
dimensional Finite Element/Control
Volume (FE/CV) based simulation
called "Liquid Injection Molding
Simulation" (LIMS)2,11 which can
predict the flow patterns once the
geometric and local permeability
information is provided as input. For
perfectly deterministic, repeatable
process in which the permeability
may vary from location to location
but will not change from one part
to the next, only one simulation

is necessary to identify the vent
locations for desired inlet location(s)
to fill the mold without any dry
regions or voids.
These mold filling simulation tools
can provide the user an estimation of
the manufacturing design of the part.
However, the functional design of a
composite part is usually addressed
separately and well in advance of
the design of the manufacturing
process, keeping with the tradition
of first ensuring functional design.

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Table of Contents for the Digital Edition of SAMPE Journal - May/June 2017