to limitations identified in Phase II.  Applicability
accuracy  of  the  cut  parts  as  programmed  and
to  Navy  and  U.S.  Coast  Guard  shipbuilding  pro 
creates undue waste and scrap.
grams were identified, with potential early impact
The University of New Orleans, College of Engi 
on  the  Navy  DD(X)  program.  This  task  requires
neering (UNO COE) was asked to investigate this
considerable additional effort, but should provide
phenomenon and develop ways of mitigating the
some results that will be quite interesting to the
unwanted problems.  The research began with the
shipbuilding industry.
investigation of typical steel making processes in
In a related effort, the system is being applied
major steel mills.  The three steel making processes
to  the  specific  task  of  modeling  production  pro 
investigated were the reverse mill process, steckle
cesses  at  the  Northrop  Grumman  Ship  Systems
mill process, and hot strip mill process.  In each of
(NGSS) Avondale Operations shipyard panel line.
these processes, possible sources of residual stress
Simulations of the current line are being used to
were thoroughly investigated, researched, and ana 
test proposed modifications to the processes with
lyzed.  Mill temperature data for each step of the
the goal of improving throughput and the quality
steel making process was collected, and three di 
of the finished stiffened panel.  Expanded versions
mensional models were generated to analyze the
of these simulations are being used to analyze the
different rolling, leveling, and cooling processes (all
throughput and utilization of resources specified
possible sources of residual stress).
for a new panel line as well as to identify potential
Since there are many thermal and mechanical
bottlenecks.  Future steps envision the evaluation
parameters involved in steel plate making, many
of modifications to the NGSS Pascagoula Opera 
of  them  only  contribute  to  thermal  stress/strain
tions  panel  line,  analysis  of  a  new  line  at
development at high temperature and are washed
Pascagoula, and the distribution and sequence of
out by subsequent process steps at lower tempera 
products between the two lines at the two yards to
tures.  Leveling and cooling operational non uni 
optimize throughput and quality.
formity dominate the short range RS distribution
and do not affect long range stress factors.  Conse 
quently, it was determined that primary leveling
Modeling Residual Stress in Steel
does not contribute to the stress development in
Plate Making
plates. Below 1500
0
 F, cooling mechanisms domi 
nate the long range RS distributions, and for ship 
Eliminating residual stress or a means to iden 
yard cutting dimensional accuracy, it is the long
tify and predict the effects of the stress will enable
range RSs that are of concern.
shipbuilders to improve their usage of automated
The research team is now conducting a system 
part nesting and cutting of steel plates while mini 
atic parametric study on long range RS, and will
mizing material usage.  A team of researchers, in 
be developing a means to identify RS types (e.g.,
cluding researchers from the University of New Or 
distribution  characteristics  and  magnitude)  for
leans,  College  of  Engineering,  Bender  Shipyards,
cutting  optimizations.   This  information  will  as 
Battelle and Caterpillar, have undertaken a research
sist the shipbuilders in attaining their goals of high
project that will assist the shipbuilders and others.
accuracy, high material utilization, optimized cut 
ter path utilization, and low material scrap.  Final
The shipbuilding industry found that nesting
results  and  technical  papers  on  this  research
several different parts within the same sheet of
project should be available in late 2003.
material and then cutting the parts to near net
shape had some unexpected downfalls.  Typically,
cutter path movement is optimized to minimize
Shipboard Learning of Diesel Engine
cutter (laser or plasma) movement and maximize
Operating Characteristics
torch on time.  This process also ensures maxi 
mum  utilization  of  material.    Residual  Stress
Through the use of an artificial intelligence moni 
(RS) is created within the plates of steel during
toring system, the University of New Orleans, Col 
the steel making process.  This stress is relieved
lege of Engineering and MACSEA Ltd. developed a
during the cutting operation, resulting in move 
software system that performs shipboard learning
ment of the plates (e.g., walking, growth, shrink 
of diesel engine operating characteristics.
age and warping).   This movement negates the
14
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