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

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