30 September 2016 1
A Farewell to the Design SpiralA Farewell to the Design Spiral
Horst Nowacki,
Technische Universität Berlin
Invited Note Presented at the
Mini-Symposium on
Ship Design, Ship Hydrodynamics
&Maritime Safety
Athens, September 30, 2016
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ContentsContents
1. Introduction
2. Early History of the Design Spiral
3. Innovation in Ship Design Methodology
4. Modern Concepts of Ship Design
5. Comparison Sequential vs. Concurrent
Engineering
6. Achievements and Contributions
7. Conclusions and Congratulations
References
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1. Introduction1. Introduction
My note will actually combine three farewells:
Farewell to the design spiral
(from sequential to concurrent design)
Farewell to 20th century design methodology
(abandoning single ship viewpoint)
Farewell to Prof. Papanikolaou after more than
30 years of research and teaching at NTUA
(1985-2016)
1. Introduction (cont.)1. Introduction (cont.)
I claim the design spiral is an incomplete,
inflexible, misleading and hence obsolete paradigm
of the design process.
It ought to be replaced by a systems analysis
based, concurrent engineering, team work
oriented paradigm.
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2. Early 2. Early HistoryHistory ofof thethe Design Spiral: Evans (1959) Design Spiral: Evans (1959)
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J. Harvey Evans: 1958, 1959, 1963,
[1] ,[2], [3].
„Optimized Design of Midship
Section“.
Spiral depicts sequential, cyclical
decision process . Purpose: Optimal,
low weight midship section structure.
Basis: Class rules.
At every intersection of a spoke with
a spiral a calculation task is
performed to update the structure.
Result: Low weight, feasible design.
2. Early 2. Early HistoryHistory ofof thethe Design Spiral: Design Spiral: MarAdMarAd (1965) (1965)
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Murphy, Sabat, Taylor,
MarAD, 1965: „Low cost ship
design.“
Scope: Preliminary design
cycles up to reliable cost
estimate.
Sequential, cyclical approach
in rigid sequence.
Univariate systematic
variation with constraints.
Rules based.
Result: Single feasible ship
with lowest building and fuel
cost.
2. Early 2. Early HistoryHistory ofof thethe Design Spiral: BSRADesign Spiral: BSRA
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Hurst, Buxton, BSRA,
1991/92.
Design spiral for
preliminary design up to
shipyard tender.
Elaborate sequence of
design steps. Basis of
software system
BRITSHIPS. Sequential,
cyclical approach with
increasing complexity.
Result: Single feasible ship
with economically reliable
tender.
2. Early 2. Early HistoryHistory ofof thethe Design Spiral: SDC (1980)Design Spiral: SDC (1980)
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Ship Design and Construction,
Kiss, Taggart (1980)
Gale, Lamb (2003)
Both editions drawn from Evans.
Sequential, cyclical approach.
Preliminary design up to contract
design. Subdivision into 4 design
phases.Result: Single feasible design
of low cost. Used in parametric design
studies.
2. Early 2. Early HistoryHistory ofof thethe Design Spiral: Design Spiral: ComparisonComparison
No. Author(s) Date Criterion Scope Basis Objective
1 J.H. Evans [1], [2], [3] 1959 Weight or
Cost Midship Section
Structure Class. rules
Cheapest or lightest
structure
2 MarAd
(Murphy et al.) [4]
1965 Least Cost Prelim. Design Rules Least cost
ship
3 BSRA (Hurst,
Buxton) [5], [6]
1971 RFR, NPV, Tradeoffs
Design up to tender Rules Best tenders
4 SDC (Kiss,
Gale) [7], [8]
1980 Cost Prelim. Design Rules Economic,
feasible design
5 Papanikolaou
[9]
2014 Same as in No. 4 From
rules to goals
Basis for optimization
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Design Spirals
3. Innovation in 3. Innovation in ShipShip Design Design MethodologyMethodology
Innovative Elements:
• Systems Engineering (1950)
• Computer Aided Design (1965)
• Optimization (1965)
• Economization (1967)
• Parametric Design (1970)
• Discretized Analysis Tools (1980)
• Concurrent Engineering (1985)
• Probabilistic Risk Analysis (2000)
• Globalization (2000)
• Open Systems Communication (2000)
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3. Innovation in 3. Innovation in ShipShip Design Design MethodologyMethodology ((contcont.).)
R = Requirements
S = Solution Space
D = Design variables
P = Parameters
M = Measure of merit
C = Constraints
The Systems Approach
4. Modern 4. Modern ConceptsConcepts in in ShipShip DesignDesign
• The Product Model
• The Process Model
• The Concurrent Engineering Approach
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4. Modern 4. Modern ConceptsConcepts in in ShipShip Design: The Design: The ProductProduct ModelModel
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The Product Model contains all the data
describing the ship in its design,
production and potentially operating
phases (Life Cycle Product Model).
The Product Model is built up step by
step by synthesis actions and is
analyzed at each stage by analytical
methods. Thus it is gradually
completed.
The sequence of steps in developing the
product model is in principle arbitrary.
Whenever the information is incomplete
for performing a certain step, it must be
substituted by provisional, assumed or
approximated data. Thus the product
model is open to overlapping
concurrent engineering actions.
4. Modern 4. Modern ConceptsConcepts in in ShipShip Design: The Design: The ProcessProcess ModelModel
The Product Model ought be supplemented by a
Process Model, which describes all the activities
that lead to the completion of the product and
potentially in its operation throughout its life.
The Process Model is formulated in terms of the
network of activities in the product lifecycle or at
least to its delivery. This activity model is
expressed by a set of transactions and events.
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4. 4. Modern Modern ConceptsConcepts in in ShipShip DesignDesign: : ConcurrentConcurrent EngineeringEngineering
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In Concurrent Engineering
the activities of several team
members may deal with
several overlapping phases
simultaneously and need not
await the completion of the
preceding phases. See
Figure. Whenever infor-
mation from other phases is
missing, it may be
substituted by provisional
assumptions and approxi-
mations. This saves time
toward earlier completion.
Earlier product delivery is a
competitive advantage.
On the other hand parallel work on related
design phases requires close control of
mutual dependencies, careful coordination
and good team work. Such close control
causes extra efforts and cost. Thus labor cost
may not diminish.
5. 5. ComparisonComparison ofof SequentialSequential vs. vs. ConcurrentConcurrent Engineering Engineering
Subject Approach ca. 1970 Modern approach
Paradigm Design spiral paradigm Systems paradigm
Sequence Consecutive steps Overlapping design phases
Design process Sequential engineering Concurrent engineering
Responsibilities Single persons, one after another
Several persons in design team
Regulatory basis Rule based design New IMO approach
Design logic Rule based design Goal based design (IMO)
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Trends in Ship Design Methodology (ca. 1970-2016)
5. 5. ComparisonComparison ofof SequentialSequential vs. vs. ConcurrentConcurrent Engineering (Engineering (contcont.).)
Subject Approach ca. 1970 Modern approach
Decision basis Semi-empirical Rational
Uncertainty Treatment Deterministic model Probabilistic model
Treatment of Parameters Several univariate passes Multivariate continuum
Solution search Trial and error Optimization with constraints
Criteria Single objective function and multiple constraints
Multiple measures of merit and constraints
Scope of goals Favorable tender by builder Owner’s life cycle cost
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Trends in Ship Design Methodology (ca. 1970-2016)
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66. Achievements and Contributions. Achievements and Contributions
Ship design in the past three or four decades has experienced
many new achievements. Prof. Papanikolaou and his team at
NTUA have made significant contributions to most of them.
To mention only a few top areas of innovation:
In design methodology:
Economic efficiency (quantification)
Safety and risk assessment (probabilistic models)
Rationality (measures of merit, cause and effect)
Optimality (unified format, multimodality, MCO)
Versatility (greater scope and depth, many new ship types)
Accounting for environmental safety
Risk Based Ship Design
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6. Achievements and 6. Achievements and Contributions (cont.)Contributions (cont.)
In computer technology:
Integration (neutral interfaces)
Open communication (data sharing and exchange)
Longevity (neutral archiving)
Man-machine interaction (simulation, visualization)
Process management (modeling of time depen-
dence, queueing models, process optimization)
Life cycle services (Product Lifecycle Management)
Probabilistic modeling of risks and uncertainties
Simulation and queueing theory
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LiteratureLiterature
1. J. Harvey Evans: “A Structural Analysis and Design Integration with Application to
the Midship Section Characteristics of Transversely Framed Ships”, Trans. SNAME, vol. 66,
1958.
2. J. Harvey Evans: ”Basic Design Concepts“, J. American Society of Naval Engineers,
1959.
3. J. Harvey Evans, D. Khoushy: “Optimimal Design of Midship Section”, Trans.
SNAME, 1963.
4. R. Murphy, D.J. Sabat, R.J. Taylor: “Least Cost Ship Characteristics by Computer
Techniques”, Marine Technology, SNAME, April 1965,
5. R. Hurst: “Advanced Techniques in Ship Design and Construction”, Lloyd’s List,
December 1971.
6. Ian L. Buxton: “Engineering Economics and Ship Design”, British Ship Research
Association, Wallsend, 2nd ed., 1976.
7. Ronald K. Kiss: “Mission Analysis and Basic Design”, 1st ch. in Robert Taggart, ed.,
“Ship Design and Construction”, SNAME, New York, 1980.
8. Peter A. Gale: “The Ship Design Process”, Ch. 5 in Thomas Lamb, ed.: “Ship Design
and Construction”, SNAME, Jersey City, NJ, 2003.
9. Apostolos D. Papanikolaou: “Ship Design”, Springer Science + Business Media,
Dordrecht Heidelberg New York London, 2014.
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7. Conclusions and Congratulations7. Conclusions and Congratulations
Ship design in the course of five decades of computer
use has become more rational, more systematic and
analytical, more transparent in its justifications.
The quality and safety of the product ship have
benefitted from this.
Ships have remained a foundation of global trade and
of worldwide standards of living.
Much work lies ahead of us. The past record of
marine design and Computer Aided Ship Design
encourages us to look confidently ahead at future
challenges to be faced.
77. . CongratulationsCongratulations
Today we are together here to
express our gratitude and
appreciation to Prof.
Papanikolaou, also on behalf
of his colleagues, team mates
and students, for his personal
contributions and his strong
commitment to ship design!
Congratulations and thank
you, Apostolos!
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Computer Aided
Flower (Bézier)
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