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Design and Optimization of Aluminum Structures for the 21st Century Navy
Dr. Brett ConnerSegment Leader, Sea Systems
Alcoa Defense
June 15, 2010
Agenda
Meeting Challenges with Alcoa’s Collaborative Development Approach (ACDA)
Aluminum Design Innovation Leadership
Aluminum Design Development Approach
Design Challenges for the 21st Century Navy
2
Aluminum: What’s your reference point?
3
Legacy Current FutureAlloy Primarily 5456 5456, 5083, some 6xxx (not really
new alloys). 5454 in elevated service temperature areas
New alloys?
Product forms Plate, extruded stiffeners Plate, specialty extrusions including multi-hollows
Legacy + Current + Advanced Hybrid Materials?
Construction: Manual labor intensive “stickbuilding”
Panelization through the use of automated linear welding
Advanced lightweight panels?
Joiningtechnology
GMAW or GTAW. Mostly manual
GMAW, GTAW, FSW, HDGMAW, etc. More automation.
Legacy + Current + Adhesives? + Advanced fastening? + Laser weld?
Marine plate specs
AMS-QQ-250 or ASTM B209 ASTM B928 TBD?
Design tools Hand calculations, empiricism, global stress analysis
legacy tools + FEA (more localized stress analysis), Spectra Fatigue Analysis
Multiscale modeling? Time-stepmodeling? Prognosis?
The shape of the future for aluminum in ship
design and construction will depend on innovative
material and design solutions between the
shipbuilder, naval architect, the Navy and
Alcoa
Alcoa Technical and Parental Advantage
Alcoa Innovations for the Designer
4
Audi A8 Challenge:Rebranding for uncompromising performance and luxury
Airbus A380 Challenge:Product expansion: develop and product the largest commercial airliner in the world
LM F-35 Challenge:Develop and product the next generation tactical fighter for USAF, USN, USMC and allies
Solution: The Audi Spaceframe• Material development• Product forms• Fastening• Design simplification
Solution: 7085 Wing Spar Forging• Product form• Parts reduction• Strength
Solutions: Bulkhead and Lift Fan Forgings, Eddie Bolt fasteners, Engine components• Product forms• Fastening• Strength
5
The Audi Story
94 95 96 97 98 99 00 01 02 03 04 05 06 07 08
Audi A81st Generation
Audi A8 — 2nd Gen.
Alcoa Spaceframe Technology 10 Year Strategic Development
Partnership Co-developed new design
methods & capabilities 40 New Patents 7 New Aircraft Grade Aluminum
Alloys New Casting & Manufacturing
Processes & Factory
Repositions Audi as luxury brand
Rated safest car in its class Received
rating from insurance company for repairs
Reduced component and assembly costs by 50%
Major parts consolidation with large castings
More interior space than predecessor
Faster than its predecessor
6
6
Alcoa Collaborative Development Approach (ACDA)- Collaborative IPT Teams (OEM, Alcoa, Military) -
Phase I -Identify and Select Candidate Assemblies/ComponentsPhase II -Develop and Evaluate Conceptual DesignsPhase III -Finalize Conceptual Designs and AnalysesPhase IV -Develop and Evaluate PrototypesPhase V -Implement Designs in Production
4thgate
3rdgate
2ndgate
1stgate
PartID
ConceptDesign Prototyping ProductionFinal
DesignI II III IV V
Opportunity identification
Gather geometry, packaging, load req’s
Develop concept redesign options
Prelim. evaluation of conceptual redesigns
Down-select concepts for further development
Ex. Activities: Finalize part redesigns –
detailed CAD and analysis
Evaluate advanced design concepts
Finalize total costs and plans for prototyping
Develop prototype part fabrication and test plans
Produce prototype parts
Test prototypes and approve for production
ACDA
7
Phase II: Develop and Evaluate Conceptual Designs
Gather geometry, packaging, load req’s
Develop concept redesign options
Prelim. evaluation of conceptual redesigns
Down-select concepts for further development
Customer evaluation criteria
Phase I: Identify and Select Candidate Structures
Opportunity Identification with OEM
• What are the challenges?• What are the pain points?
Materials Data &
Development
Structural Design
Manufacturing Tech
Advanced Power & Energy
Design Rules & Tools
SolutionIdeation
Phase III: Final Design Analysis
Finalize part redesigns –detailed CAD and analysis
Evaluate advanced design concepts
Finalize total costs and plans for prototyping
Component testing
Phase IV: Develop and Evaluate Prototypes
Develop prototype part fabrication and test plans
Produce prototype parts
Test prototypes and approve for production
Product ManufacturingProduct Design and Development
ACDA can be implemented during trade studies, concept development, contract design or even detailed design
Agenda
Meeting Challenges with Alcoa’s Collaborative Development Approach (ACDA)
Aluminum Design Innovation Leadership
Aluminum Design Development Approach
Design Challenges for the 21st Century Navy
8
9
Customer Requirements Addressed by Alcoa Designers
Light weighting of structures
Structural analysis and design Cost reduction
– Materials, design, manufacturing, assembly
Alloy selection/recommendations– Structural, thermal, electrical, corrosion,
forming, cost
Fractures/Failures– Joints: Mechanical, Adhesives, Fusion
Welds, FSW, LSW– Product forms (castings, extrusions, sheet,
Plate): yielding, fracture, buckling, wear, corrosion
Material and Manufacturing Quality– Wrought, welded, extruded, cast
Fabrication and assembly recommendations and implementation
Corrosion issues and environmental durability
Repair methods
Mechanical testing and material performance
Prototype product manufacture
Surface management
No one knows aluminum structural design better than Alcoa
10
Alcoa Design Technologies
Alcoa’s design technologies have been successfully leveraged across multiple commercial and defense market segments– Passenger and bulk hauling rail cars– Transportation systems such as bulk trailers and intermodal
containers– Cars, trucks and busses– Commercial aerospace– Defense aerospace, sea and land systems
Design activities are driven by customer performance requirements and standards– Alcoa has found that its design competencies and toolkits are fully
transferable to other market segments once we learn a customer’s performance requirements and standards
11
Rail Car Design and Analysis Expertise
Cars made of 5XXX alloys
Designing to AAR (American Association of Rail Roads) standards– Static structural analysis– Dead load, live load, draft
load, buff load, compression end load, impact load
Shaker test simulation
Dynamic squeeze test simulation
Thermal buckling simulations
Manufacturing cost analysis/reduction
Alcoa has been building its rail car design and analysis expertise and
experience since early 1930s
12
Rail Car Design and Analysis Examples
Coal Car AAR Compressive End Loading
Lateral Deflection Von Mises Stress Plot
Coal Car Mode Frequency Analysis
Phase III: FEM Validates Concept - Confidence to go to Prototype
13
Transportation System Design and Analysis Expertise and Examples
Bulk Trailer Design Designing Intermodal Containers for ISO Standards
20ft Dry Tainer 40ft Dry Tainer
Internal Pressure Load Case
Deflections Stresses
14
Automotive Design and Analysis Expertise
15
Commercial Aerospace Design and Analysis Tools and Expertise
By working with customers, Alcoa’s rapid trade study tools and rapid testing help identify benefits of new materials and design concepts
Inboard stiffener view
2 - bay fatigue crack
exit skin crack
Outboard stiffener view
0.00
0.50
1.00
1.50
2.00
2.50
3.00
0 1000 2000 3000 4000 5000 6000 7000
Number of Flights
Hal
fC
rack
Len
gth
(inch
)
C47A - T8X
110% Load
C433 - T351
110% Load
MT Spec., W=7.8 inches, B=0.47 inchesRH > 90% Freq. = 10 Hz
C47A - T8X, 120% Load
C433 -T351
100% Load
2024 - T351
100% Load
7075 frame
16 in. spacing
2a
2524 - T3, or 2024 - T3 skin
• Fatigue crack grows due to
hoop pressurization stress
• Max cyclic stress ( σ max ) =
12 to 15 ksi , R = 0.1
• Initial damage 2ao = 2 in.
2
4
8
6
Hal
f cra
ck le
ngth
, a, (
in.)
0 84 12 16
No. flights (thousands)
2524 - T3
2024 - T3
σ max in
Ksi
13 12
15 14 13 12
0
Example: Predicted Longitudinal fuselage skin crack under intact frame
14
ASPAN-F Curved Panel Design SoftwareThe 2524-T3 toughness advantage considerably
increases the 2-bay crack residual strength
The 2524-T3 FCG advantage enables an operating stress
increase at lower weight, or longer periods between
inspections
Alcoa’s new materials show improvement in crack growth under lower wing spectrum
Residual strength and crack growth testing (integral panels shown)
root
tip
large
wing
root
tip
large
stabilizer
Load Intensities Typically found in
Upper Wing and Stabilizer Structure
root
tip
small
wing
large
fuselage
belly
large
fuselage
crown
Load IntensityCompression Design Stress Levels at Ultimate
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
3 5 7 9Stiffener Spacing (in.)
Max
imum
Allo
wab
le S
tres
s Le
vel a
t Ulti
mat
e (
psi)
7075 - T6xx
7150 - T61xx
7150 - T77xx
7055 - T77xx
5,000 lb/in.
2,000 lb/in.
10,000 lb/in.
15,000 lb/in.
35,000 lb/in
As load levels increase, Alcoa’s higher strength 7055 alloy shows
large weight savings potentialAlcoa Compression
Design Software
ASPAN-W Spar Design Software
[after T. Swift]
Predicted Failure
Skin / Frame at Limit Load % Improvement
2024 - T3 / 7075 - T651 18.2( ksi ) 125( Mpa )
2524 - T3 / 7150 - T7xx 21.2 ( ksi ) 146( Mpa ) 16.6%
2524 - T3 / 7055 - T7xx 21.2 ( ksi ) 146( Mpa ) 16.6%
Full 2 - Bay Longitudinal Crack with Central Broken Frame
Effects of bulging due to pressure & curvature
Localbending
Internalpressure
Crack length
[after T. Swift]
CrownAxial Stressat LimitLoad(ksi)
[after T. Swift]
2 - Bay Circumferential Crack with Central Broken Stringer
Failure Stress
Skin / Stringer @ Limit Load Failure % Improv
2x24 - T3 / 7075 - T6 30.5 ksi stringer
2x24 - T3 / 2024 - T3 18.3 ksi stringer ( - 40.0%)
2x24 - T3 / 7150 - T77511 34.4 ksi stringer 12.8%
2x24 - T3 / 7055 - T77511 42.5 ksi stringer 39.3%
Alcoa’s high strength 7xxx stringers significantly increase the 2-bay crack residual strength in the fuselage crown panel
Spar
CrownPanels
Side Panels
Upper Wing Cover
Lower Wing Cover
elasto - plastic
boundary
elasto - plasticboundary
C433 - T39 (panel 6) @ failure load
crack - tips
0.000
ASPAN-D Panel Design Software
16
Commercial Aerospace Design and Analysis Tools Example
2-Bay Circumferential Crack with Central Broken Stringer Failure Stress
Skin / Stringer @ Limit Load Failure % Improvement
2X24-T3 / 7075-T6511 30.5 ksi Stringer baseline2X24-T3 / 2024-T3511 18.3 ksi Stringer (-40%)2X24-T3 / 7150-T77511 34.4 ksi Stringer 12.8%2X24-T3 / 7055-T77511 42.5 ksi Stringer 39.3%
ASPAN -F Curved Panel Design Software
Output from Alcoa Stiffened Panel Analysis System (ASPAN), one of a suite of Alcoa-generated CAE tools, enables rapid design trade studies with new alloys,
materials & structural concepts
Alcoa’s 40 Year History with LNG Containers
Focus Areas:• 5000 Series Material Characterization
o Wrought and Welded Propertieso Static, Fatigue and Fracture o Room Temperature, -162C, -196C, 253C, and 269Co Corrosion and Sensitizationo Multiple Thickness’s ( 1” to 9”)o Crack Growth Rate Under Ship Spectrum Loadingo Leak Rates & Penetrated Crackso Residual Strength of Cracked Specimens
• Design and Manufacturing Studieso Welding, Forming, Handling, and Assembly Guidelineso Design Guidelines
Agenda
Meeting Challenges with Alcoa’s Collaborative Development Approach (ACDA)
Aluminum Design Innovation Leadership
Aluminum Design Development Approach
Design Challenges for the 21st Century Navy
18
Multiscale Design: Atoms to Ships
19
Requirements:• Mission• Cost• Operating environment• Rules
Production:• Capital • Sourcing• Efficiency• Cost
Grillage
Alloy composition and microstructure
Scantlings
Material:• Alloys/Tempers• Product form
Plate
Extrusions
PanelMechanical Behavior
20
Alcoa’s Integrated Approach to Design
Quality Process
Freq
uenc
y
Material Design
b b2R
InhomogeneityCrack
New Design
Manufacturing Process
PUMP
Functional Performance
Number of Cycles
Stre
ss L
evel
21
Quality-Performance Linkage
One important fundamental premise of this work is the existence of a quantifiable link(s) among material processing, microstructure and long-term structural
performance
Reduce initial flaw size population (initial quality)
Life
Economic Limit
Category I (black)
Category III (red)
Flaw
Siz
e
22
Use of Weld Specification Discontinuity Limits
Category I : Fatigue critical joints
Category II : Strength critical joints
Category III : Non Critical jointsFillet Weld Discontinuity Limits Determined by Metallographic Analysis
Item No.
Item DescriptionCategory I Category II Category III
1Weld Thickness (WT )
WT > 0.7t WT > 0.7t WT > 0.6t
2Fillet Leg Size (L)
L > 1.5 t L > 1.5 t L > t
3Weld Convexity (CV)
CV < 3 mm andα > 110 degrees
CV < 4 mm andα > 100 degrees
CV < 4 mm
23
Examples of ALCOA’s Fatigue Design Capability
Pressurized Truck Container
Problem Cracking in weld area Very expensive repair
SolutionHigh strains in area of crackingFatigue life similar to actual lifeMultiple solutions proposedLow cost solution implemented
24
Importance of Baseline Weld Specification
• Links All Product Development/Production Components (Design, Manufacturing, Quality)
• Design Process Improvements (More systematic/rule based; Links design/mfg to structural performance)
• Manufacturing Process Improvements (More traceability/monitoring world wide)
• Quality Assurance Improvement (Consistent/Relevant Measurement methods & traceability)
• Consistency/Reliability
• Enables Systematic Continuous Improvement
25
Importance of Coupon and Substructure Testing
• Simplified Tests Can Be Very Helpful and Timely (Instead of Waiting for the Finished Product. Always look to anchor analyses with reality as early as possible)
• Account for Tests in Original Development Plan
• Both Coupon Level Tests and Subscale Tests
• Be Very Careful How Tests Are Designed, Executed, Evaluated & Used for Correlation
Naval Structures Initiative (NSI)
26
First formal engagement and contract activity (in recent history) between Alcoa and the Navy.
Support research and development of improved lightweight aluminum structures for LCS and other HSVs. Applied research Develop conceptual and advanced concepts Develop engineering designs Fabricate prototype hardware Perform laboratory and field tests
Alcoa and the Navy created IPTs with members from PEO Ships, NAVSEA 05, NSWCCD, ABS, Primes, Shipyards, and Naval Architects: IPTs were setup in March 2008 sub-IPTs for each LCS
Collaboration: Who should be involved?
PrimeShipbuilder
Naval Architects
Program Office
Technical WarrantHolders
ABS NSWC
Ship Design
Managers
28
Meeting the Ship Construction Challenge with Alcoa Expertise
elasto - plastic
boundary
Alcoa can provide the innovations in ship design and construction required by the Navy and industry to create more affordable vessels that will meet mission requirements
Design Rules & Tools Manufacturing Knowledge
Structural DesignMaterial Knowledge
Alcoa is a leader in aluminum alloy research and development
Alcoa is a proven industry partner for aluminum design solutions and can deliver trade studies for alternative designs to the Navy addressing
With decades of design and production experience in aluminum, Alcoa has a breadth of knowledge that can be applied to the optimization of naval design rules and tools
Alcoa’s advances in next-generation manufacturing technology
Design for Cost
Once structures are identified as opportunities for cost savings, Alcoa can begin to develop concepts
Collaboration with the customer(s) identifies requirements and targets
The baseline structure or component must be defined and agreed upon
The baseline is then cost modeled
As concepts are developed they are cost modeled
The concepts are then evaluated for the above criteria
This process continues as concepts are downselected and refined
29
ACDA Results for Naval Platforms
30
Solutions to reduce the shipbuilding costs and reduce the weight of the ship Each opportunity identified that required a solution in cost has resulted
in 50-70% savings in recurring manufacturing cost
Each opportunity identified that required a solution in weight has received between 15-60% savings in weight
Immediate payoffs: solutions are being inserted into LCS and JHSV
Results:• 50% lighter than steel alternative• Nearly half the cost• Rapid development cycle and delivered on time
Phase I Opportunity identified (April 2009):• Need for lightweight cargo tie down• Must be ready for JHSV-1: Dec 2009
Phase V Production (December 2009 -Present):• Contract award• ABS approval for JHSV• ABS Type Approval
ACDA
Example: JHSV structural fitting
First prototype tested within 90 days
31
Aluminum Design Development Approach
Alcoa uses design in support of – Alcoa-OEM application engineering activities– Design and material trade studies– Joint concept development programs– Integrated product development teams– Alloy/product development activities– New Test Development for Coupons and Substructures
Designing from Publicly Available Handbooks and Design Tools is Not Enough– A much deeper view of the material properties and design options are
required to optimize structure– The tools and material data for aluminum that many OEMs are designing
with are not as sophisticated as those Alcoa can offer– What you know is not the limit to what is out there
Agenda
Meeting Challenges with Alcoa’s Collaborative Development Approach (ACDA)
Aluminum Design Innovation Leadership
Aluminum Design Development Approach
Design Challenges for the 21st Century Navy
32
Design Challenges for the 21st Century Navy
• Green Navy• Total Ownership Cost: Life Cycle vs Acquisition Costs• Power Demand• Unmanned systems
Green Navy
• The Great Green Fleet– Fuel efficiency– Alternative fuels– Reducing the fleet’s carbon footprint
• Finding solutions:– Lightweight structure:
• Keane, Scher, Piskorski (2006) show weight savings factor of 0.47 for aluminum decking over steel baseline for a High Speed Sealift vessel
• Aluminum sandwich panels are 20% lighter than conventional aluminum decking
– Power generation: gas turbines– New materials
“By 2016, we are going to deploy the Great Green Fleet which is going to be powered entirely by alternative fuels. And by 2020 the Navy and Marine Corps will produce half of all our energy from alternative sources.” Honorable Ray Mabus, Secretary of the Navy, January 21, 2010
$, $ everywhere and not a buck to spend
• “"Total Ownership Cost includes all costs associated with the research, development, procurement, operation, and disposal of an individual weapon system over its full life.“ –NAVAIR Total Ownership Cost website
• Finding solutions:– ACDA: 50-70% savings in recurring manufacturing
cost– Design for Producibility– Fatigue properties in spectrum loading (both
initiation and propagation)– Design and material selection for corrosion control– Effect of lean manning on ship reliability,
maintainability and availability
Power: The Joules to Victory
• Sensors to find and track the threat: cruise missiles, ballistic missiles
• Power to fight: lasers and rail guns• Keys:
– Stiff aluminum structures:• Sandwich panels• Multi-hollow extrusions• I-core type structures
– Use aluminum’s conductive properties for power generation, storage, transmission
– Thermal management– Lightweight aluminum mounts
Unmanned systems
• Advances in unmanned systems are leading to the point where a surface combatant can project for far- reaching sea control and power projection
• The key for design:– The need to maximize the
unmanned systems carried per volume and minimizing weight impact
– The ability to quickly deploy these systems
– This is beyond modularity• Key challenges:
– Collaborative design approaches for modular systems
– Alternative joining: fastening and adhesives
ACDA developed marine solutions providing 40% cost reduction
38
Alcoa’s Aluminum Structural Design Potential
Alcoa Can:
• Optimize the performance of cost effective lightweight aluminum structures through its deep expertise in aluminum structural design and internally developed design tools
Leverage its proven integrated design approach to optimize aluminum designs from the material microstructure through fabrication and assembly to lifecycle management
Address aluminum marine structure design challenges such as stiffness and buckling, fatigue crack initiation and propagation, structural health monitoring, fire protection, corrosion, and fabrication while maintaining performance benefits
Design optimized aluminum structures enabled by new technologies in the areas of GMAW, FSW, Coatings, and Alloys and Alloy Processing.
39
Collaboration Challenge for Alcoa’s Aluminum Structural Design
Aluminum structural design competencies and design tools are a significant enablers for cost effective weight reduction
Alcoa has significant resources and expertise for developing optimized aluminum structures
Achieving next-generation breakthroughs in aluminum vessel designs will require significant collaboration with the ship builders, researchers and certification agencies
Alcoa stands ready to be a full partner in bringing its cutting-edge research capabilities to bear on current and future structural design challenges