sr 1460 effect of welded properties on aluminum structures
DESCRIPTION
SR 1460 Effect of welded properties on Aluminum Structures. Dr. Pradeep Sensharma & Joey Harrington BMT Designers & Planners [email protected] 703 920 7070 x 275 Dr. Matt Collette SAIC [email protected] (301) 352-4728. Agenda. Introduction Objective Background Tasks - PowerPoint PPT PresentationTRANSCRIPT
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Ship Structure Committee
SR 1460Effect of welded properties on Aluminum
Structures
Dr. Pradeep Sensharma & Joey HarringtonBMT Designers & [email protected]
703 920 7070 x 275
Dr. Matt ColletteSAIC
[email protected](301) 352-4728
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Ship Structure Committee
Agenda
• Introduction• Objective• Background• Tasks• Schedule• Progress
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Objective•The goal of this project is to provide a basis for design of aluminum structures that will minimize the penalty on scantling selection
– Study all possible methods of modeling aluminum stiffened plate structure– Provide basis for modification to existing design standard
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• The 5xxx-series (5083) and 6xxx-series(6082) aluminum alloys are extensively used for marine structures
• 5xxx-series alloys are used in deck and hull plating whereas 6xxx-series alloys are used as structural reinforcements, bulkheads, and stiffeners that do not come in direct contact with seawater.
• These Aluminum alloys suffer reduction in strength in the Heat Affected Zone (HAZ) of welds
Background
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• Reduction can be up to 50% of the strength of base material
Background (cont.)
PROOF STRESS (MPA)
ULTIMATE STRESS (MPA)
ALLOY
BASE WELDED BASE WELDED
5083-H116 214 165 303 276
5383-H321 220 165 305 290
6061-T6 (<3/8”) 241 138 290 165
Ref: ONR report on Aluminum Structure Reliability Program (ASRP), 2006
Ref: Paik et al.
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• The traditional approach to design has been using the minimum strength of the HAZ as the design strength
• This approach may seriously underestimate the strength of welded structure
• Imposes a significant weight penalty on the final design
Background (cont.)
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Tasks
• Task 1 - Develop Project Plan Based on the SOW•Task2 - Perform literature survey
–Review previous technical studies which address the impact of welds on the strength of aluminum structures–Review current aluminum design standards from the marine and civil engineering communities
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Tasks (cont.)• Task 3 - Develop Matrix of Plate-Stiffener Combinations to be analyzed
Model Plate Stiffener Weld Location1 Light (4mm)/ 5083 Light (60x3/30x6)/5083 Plate stiffeners connection2 Heavy (6mm)/ 5083 Light (60x3/30x6)/5083 Plate stiffeners connection3 Heavy (6mm)/ 5083 heavy (100x6/40x10)/5083 Plate stiffeners connection4 Light (4mm)/ 5083 heavy (100x6/40x10 )/5083 Plate stiffeners connection5 Light (4mm)/ 5083 Light (60x3/30x6)/6082 Plate stiffeners connection6 Heavy (6mm)/ 5083 Light (60x3/30x6)/6082 Plate stiffeners connection7 Heavy (6mm)/ 5083 heavy (100x6/40x10 )/6082 Plate stiffeners connection8 Light (4mm)/ 5083 heavy (100x6/40x10 )/6082 Plate stiffeners connection9 Light (4mm)/ 6082 Light (60x3/30x6)/6082 Weld between two extruded 10 Heavy (6mm)/ 6082 Light (60x3/30x6)/6082 Weld between two extruded 11 Heavy (6mm)/ 6082 heavy (100x6/40x10 )/6082 Weld between two extruded 12 Light (4mm)/6082 heavy (100x6/40x10 )/6082 Weld between two extruded
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Task3 (cont.)
Welded Stiffeners
Extruded panels
Ref: Rigo et al.
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Tasks (cont.)
• Task 4 - Develop Stress-Strain relationship–Develop stress-strain data for base metal and HAZ–Use Ramberg-Osgood relationship or use existing data
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Task4 (cont.)0.2% Proof Stress Alloy Ten. Comp.
Elastic Modulus
Elongation at failure
Ramberg Osgood Exponent
Calculated Tensile Failure Stress
Code Tensile Failure Stress
-- MPa MPa MPa % -- MPa MPa 5083-H116
215 180 70000 12 12 302 305
6082-T6 260 260 70000 8 30 294 290-310 Mild Steel 235 235 208000 20-30 Infinite --
Ref: ONR report on Aluminum Structure Reliability Program (ASRP), 2006
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Task 4 (cont.)– Existing Stress-strain data (Rigo et al.)
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Tasks (cont.)
• Task 5 – Develop & Analyze FE Models– Develop FE models using FEMAP– Use plate elements only– Model HAZ (3*thick.) for Plate & Stiffeners (4 or 5)–Welds will not be modeled–Model 3 bays or ½ + 1 + ½ bays
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Task 5 (cont.)
–Develop models for all the combinations of plate/stiffener/material discussed before–Model using Material properties of
•Only base metal•Only HAZ•Base metal and HAZ
– Model initial distortion by applying lateral pressure– Residual stress will not be modeled in this study
Ref: Rigo et al.
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Task 5 (cont.)– Use non-linear stress strain relationship– Analyze model for three load cases
•Compression•Tension•Bending
– Perform Non-linear FEA and check for Failure using load deflection curve fro compressive loading– Use max strain/max displacement for other two cases– Compare results
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• Task 6 – Volumetric Yield strength & ULSAP calculations– Perform volumetric yield strength calculations using
Dr. Paik’s close form solution
– Develop fine mesh models of same stiffener-plate combinations using MAESTRO (?)
– Perform limit state calculations using ULSAP (?)
Tasks (cont.)
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Task 6 (cont.)
– Check influence of HAZ, residual stress & initial distortion on Ultimate strength of a sample aluminum ship using ALPS/HULL(?)
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• Task 7 – Analyze results & Recommend changes to existing design standard
• Task 8 – Prepare Final report
Tasks (cont.)
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ScheduleTasks & Deliverable Expected Completion Date
Develop a work plan February 05, 2009(Deliverable 1)
Literature Survey March 31, 2009
Review of Current Design Standards April 30, 2009
Quarterly Progress Report/Review 1 May 15, 2009(Deliverable 2)
Model and Analyze FE Models November 15, 2009
Quarterly Progress Report/Review 2 (with interim results)
August 07, 2009(Deliverable 3)
Quarterly Progress Report/Review 3 (With Final FEA Results)
November 30, 2009(Deliverable 4)
Develop recommendations for changes in design standard
December 15, 2009
Draft Final Report January 05, 2010(Deliverable 5)
Final report that includes all activities and previous deliverables of this project including case studies.
February 05, 2010(Deliverable 6)
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Schedule (cont.)
ID Task Name1 Effect of Welded Properties on Aluminum Structure2 Kick - off Meeting3 Literature Survey4 Quarterly Progress Review 15 Review of Current Design Standards6 FE Modeling and Analysis7 Quarterly Progress Review 2 (Interim Results)8 Quarterly Progress Review 3 (Final FEA Results)9 Develop recommendations for Changes10 Draft Final Report11 Final Report12 Project Conclusion
2/5
5/15
8/7
11/30
2/5
February March April May June July August September October November December January February March
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Progress• Developed panel geometries for FEA
– Paik’s Panel test data (SSC-451)
Plate Slenderness ratio: 2.2 – 3.2
Column Slenderness ratio: 0.4 – 1.5
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Progress (Cont.)• Selected panel geometries
Model Plate Stiffener Weld Location1 Light (4mm)/ 5083 Light (60x3/30x6)/5083 Plate stiffeners connection2 Heavy (6mm)/ 5083 Light (60x3/30x6)/5083 Plate stiffeners connection3 Heavy (6mm)/ 5083 heavy (100x6/40x10)/5083 Plate stiffeners connection4 Light (4mm)/ 5083 heavy (100x6/40x10 )/5083 Plate stiffeners connection5 Light (4mm)/ 5083 Light (60x3/30x6)/6082 Plate stiffeners connection6 Heavy (6mm)/ 5083 Light (60x3/30x6)/6082 Plate stiffeners connection7 Heavy (6mm)/ 5083 heavy (100x6/40x10 )/6082 Plate stiffeners connection8 Light (4mm)/ 5083 heavy (100x6/40x10 )/6082 Plate stiffeners connection9 Light (4mm)/ 6082 Light (60x3/30x6)/6082 Weld between two extruded 10 Heavy (6mm)/ 6082 Light (60x3/30x6)/6082 Weld between two extruded 11 Heavy (6mm)/ 6082 heavy (100x6/40x10 )/6082 Weld between two extruded 12 Light (4mm)/6082 heavy (100x6/40x10 )/6082 Weld between two extruded
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Progress (Cont.)• Stiffener Spacing: 225mm• Plate Slenderness ratios:
5083_4 2.852
6082_4 3.428
5083_6 1.902
6082_6 2.285
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Progress (Cont.)• Stiffener Length: 1000 mm• Column Slenderness ratios:
5083_4_L 0.658
5083_6_L 0.723
6082_4_L 0.791
6082_6_L 0.869
Light Stiffener Heavy Stiffener
5083_4_H 0.36
5083_6_H 0.37
6082_4_H 0.432
6082_6_H 0.445
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Progress (cont.)• Literature Survey In-Process
– Experimental material properties• Base and HAZ measurements (6)
– Previous design studies• Experimental and numeric compression
collapse (8)• Plates and beam under lateral loads (5)• Detailed weld studies (3)
– Standards• Eurocode 9, Aluminum Association, ABS.
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Ship Structure Committee
Progress (cont.)• Started developing FE models
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Thank You
Any Questions?