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Leading car manufacturer Renault
solves unwanted engine noise and vibration using Maple |
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When an engine stops, several
engine components take part in the process. Components can
produce unwanted |
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noise and vibrations when the
engine slows
down, which
can lead to their deterioration. Jean-Louis Ligier, a
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Research and Development manager
at Renault, and his team were tasked with determining
the sources of these
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noises and vibrations in a 2.2
liter 4-cylinder turbo diesel engine.
They found Maple™ to be
the most efficient tool |
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to model the engine and
determine the source of the unwanted noise. More importantly,
they also used Maple to |
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determine a solution to the
problem. |
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Ligier, who
has a Ph.D. in Mechanical Engineering, has been using Maple
for over 20 years. He has used the software in several applied
research projects, such as time-varying thermal analysis in
gearbox components, engine friction optimization, and
vibration analysis. He has been with Renault for over 12
years, managing thermal behaviors and mechanic fatigue on
engine components, as well as determining new simulation
methodology for them. His primary goal in using Maple was to
write equations that control the engine components very
easily. |
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When creating
mathematical models of various components, different software
can be implemented. Ligier has found through his experiences
that Maple is the easiest and fastest software for his tasks.
"In comparison with others, Maple can do in a couple of hours
what other software can take days to compute," he said. "The
natural math notation allows me to enter the equations as if I
were writing them by hand. The fact that I can do symbolic
calculations allows me to do optimizations that are virtually
impossible with other software. What’s more, the results are
extremely accurate." |
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When speed
decreases in an engine, several mechanical resonances are
generated. If there is too much movement within the engine,
not only do the components create noises disturbing to the
driver, but they also begin to wear out prematurely. The goal
of the study was to model and understand the cause for the
vibrations. The modeled engine was a 4-cylinder from Renault’s
Laguna line of cars. The model of the engine was a system of
five differential equations and focused primarily on the
crankshaft, the dual mass flywheel (DMF), as well as the whole
power train. From these equations, Ligier could estimate the
level of vibration created during the deceleration of the
engine. After plotting the results of the simulation, it
became apparent that the vibrations were primarily occurring
from shocks inside the DMF. To rectify the problem, a rather
simple solution was implemented, which involved modifying the
air intake while decelerating. |
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Discovering the exact cause of
the problem led to a substantial cost-saving benefit to
Renault because it meant that the problem was fixed with a
simple solution—only a slight modification of the engine was
required |
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By analyzing
the simulation results, Ligier reduced the noise by as much as
30%. Modeling the engine in Maple allowed him to analyze the
symbolic equations, which enabled a more in-depth
understanding of the system. The numeric results were plotted
and the location of the unwanted vibrations was discovered. By
using Maple, was able to create and run his model in one day,
which was a substantial time saver in comparison to other
software, which took over a week for the same task. “I have
been using Maple for over 20 years. I have always liked how
easy it is to use, and how powerful it is. The ability to
perform both symbolic and numeric computations is a huge time
saver for me, allowing me to get results in a day, instead of
weeks with other software,” concluded Ligier. |
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Exploring Chaos and Dynamical
Systems with MapleSim |
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Dr. Stephen Lynch is a world
class leader in the use of mathematical software in teaching
and learning, and a |
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renowned expert on dynamical
systems and their applications. He teaches a
range of courses at Manchester
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Metropolitan University in the
UK,
and has been
nominated for a second time by MMU for a National Teaching
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Fellowship in recognition of his
excellence in teaching at the higher education level. |
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Dr. Lynch has
chosen to feature MapleSim in the second edition of his
best-selling book, Dynamical Systems and Applications
using Maple. Due to be published in the summer of 2009,
the book introduces readers to the theory of dynamical systems
through theoretical and practical examples, all illustrated
with programs created with software tools from Maplesoft.
These programs model phenomena such as chemical kinetics,
electrical circuits, mechanical systems, and fractals. |
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In a chapter devoted to
continuous and discrete simulation, Dr. Lynch presents
MapleSim as a tool for exploring chaos and the dynamical
behavior of real systems without the complexity of more
traditional simulation and modeling packages. The chapter
introduces simulation concepts with the signal-flow solution
of a resistor-inductor circuit modeled in Simulink. This is
then contrasted with an acausal model of the same system using
MapleSim. Dr. Lynch comments, “MapleSim is fantastic. Its
representation looks a lot better. Students and scientists
alike are more at home with the acausal representation of a
circuit, and find it easier to pick up”. He says that MapleSim
enables students to model real-life chaotic and dynamical
systems at the physical component level and delivers an
environment in which the parameter space can be explored
rapidly and efficiently. This gives students greater
appreciation of the mathematics that defines the dynamical
behavior of everyday systems. |
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Dr. Lynch
also introduces readers to the MapleSim
Connectivity Toolbox. This newly released add-on product
enables engineers and students to model systems at the
physical component level in MapleSim, and then automatically
generate a highly optimized S-function for instant use in
Simulink.
The chapter then continues
with models that explore the limit cycle of an underdamped
oscillator, a periodically forced pendulum, and ends with a
discussion of chaos control and synchronization. |
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