Transcript Project No. and Title - Ship Structure Committee

Ship Structure Committee
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
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Ship Structure Committee
Agenda
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Introduction
Objective
Background
Tasks
Schedule
Progress
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Ship Structure Committee
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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Ship Structure Committee
Background
• 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
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Ship Structure Committee
Background (cont.)
• Reduction can be up to 50% of the strength of
base material
ALLOY
PROOF
STRESS (MPA)
ULTIMATE
STRESS (MPA)
BASE WELDED BASE WELDED
Ref: Paik et al.
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
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Ship Structure Committee
Background (cont.)
• 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
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Ship Structure Committee
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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Ship Structure Committee
Tasks (cont.)
• Task 3 - Develop Matrix of Plate-Stiffener
Combinations to be analyzed
Model
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2
3
4
5
6
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8
9
10
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Plate
Light (4mm)/ 5083
Heavy (6mm)/ 5083
Heavy (6mm)/ 5083
Light (4mm)/ 5083
Light (4mm)/ 5083
Heavy (6mm)/ 5083
Heavy (6mm)/ 5083
Light (4mm)/ 5083
Light (4mm)/ 6082
Heavy (6mm)/ 6082
Heavy (6mm)/ 6082
Light (4mm)/6082
Stiffener
Light (60x3/30x6)/5083
Light (60x3/30x6)/5083
heavy (100x6/40x10)/5083
heavy (100x6/40x10 )/5083
Light (60x3/30x6)/6082
Light (60x3/30x6)/6082
heavy (100x6/40x10 )/6082
heavy (100x6/40x10 )/6082
Light (60x3/30x6)/6082
Light (60x3/30x6)/6082
heavy (100x6/40x10 )/6082
heavy (100x6/40x10 )/6082
Weld Location
Plate stiffeners connection
Plate stiffeners connection
Plate stiffeners connection
Plate stiffeners connection
Plate stiffeners connection
Plate stiffeners connection
Plate stiffeners connection
Plate stiffeners connection
Weld between two extruded
Weld between two extruded
Weld between two extruded
Weld between two extruded
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Ship Structure Committee
Task3 (cont.)
Welded Stiffeners
Extruded
panels
Ref: Rigo et al.
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Ship Structure Committee
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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Ship Structure Committee
Task4 (cont.)
Alloy
-5083H116
6082-T6
Mild Steel
0.2%
Stress
Proof
Ten.
Comp.
MPa
215
MPa
180
Calculated
Ramberg
Elastic
Elongation
Tensile
Osgood
Modulus at failure
Failure
Exponent
Stress
MPa
%
-MPa
70000
12
12
302
260
235
260
235
70000
208000
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20-30
30
Infinite
294
--
Code
Tensile
Failure
Stress
MPa
305
290-310
Ref: ONR report on Aluminum Structure
Reliability Program (ASRP), 2006
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Ship Structure Committee
Task 4 (cont.)
– Existing Stress-strain data (Rigo et al.)
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Ship Structure Committee
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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Ship Structure Committee
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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Ship Structure Committee
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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Ship Structure Committee
Tasks (cont.)
• 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 (?)
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Ship Structure Committee
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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Ship Structure Committee
Tasks (cont.)
• Task 7 – Analyze results & Recommend
changes to existing design standard
• Task 8 – Prepare Final report
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Ship Structure Committee
Schedule
Tasks & Deliverable
Develop a work plan
Expected Completion Date
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
Quarterly Progress Report/Review 2 (with interim
results)
November 15, 2009
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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Ship Structure Committee
Schedule (cont.)
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Ship Structure Committee
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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Ship Structure Committee
Progress (Cont.)
• Selected panel geometries
Model
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2
3
4
5
6
7
8
9
10
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Plate
Light (4mm)/ 5083
Heavy (6mm)/ 5083
Heavy (6mm)/ 5083
Light (4mm)/ 5083
Light (4mm)/ 5083
Heavy (6mm)/ 5083
Heavy (6mm)/ 5083
Light (4mm)/ 5083
Light (4mm)/ 6082
Heavy (6mm)/ 6082
Heavy (6mm)/ 6082
Light (4mm)/6082
Stiffener
Light (60x3/30x6)/5083
Light (60x3/30x6)/5083
heavy (100x6/40x10)/5083
heavy (100x6/40x10 )/5083
Light (60x3/30x6)/6082
Light (60x3/30x6)/6082
heavy (100x6/40x10 )/6082
heavy (100x6/40x10 )/6082
Light (60x3/30x6)/6082
Light (60x3/30x6)/6082
heavy (100x6/40x10 )/6082
heavy (100x6/40x10 )/6082
Weld Location
Plate stiffeners connection
Plate stiffeners connection
Plate stiffeners connection
Plate stiffeners connection
Plate stiffeners connection
Plate stiffeners connection
Plate stiffeners connection
Plate stiffeners connection
Weld between two extruded
Weld between two extruded
Weld between two extruded
Weld between two extruded
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Ship Structure Committee
Progress (Cont.)
• Stiffener Spacing: 225mm
• Plate Slenderness ratios:
5083_4 2.852
5083_6 1.902
6082_4 3.428
6082_6 2.285
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Ship Structure Committee
Progress (Cont.)
• Stiffener Length: 1000 mm
• Column Slenderness ratios:
Light Stiffener
Heavy Stiffener
5083_4_L 0.658
5083_4_H 0.36
5083_6_L 0.723
5083_6_H 0.37
6082_6_L 0.869
6082_4_H 0.432
6082_4_L 0.791
6082_6_H 0.445
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Ship Structure Committee
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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Ship Structure Committee
Thank You
Any Questions?
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