Bao Wierzbicki
Transcript of Bao Wierzbicki
Fracture Prediction of Navy SteelsFracture Prediction of Navy SteelsA System ApproachA System Approach
Tomasz WierzbickiPresentation at the NNR Review Meeting, St. Louis, June 2nd, 2004
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
MIT team members: Professor Frank McClintockDr. Yingbin BaoMr. Young-Woong LeeMr. Xiaoqing TengMr. Yuanli Bai
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Damaged Area as a Measure of Ships SurvivabilityDamaged Area as a Measure of Ships Survivability
USDHUSDH
x
y
L0
0.0 0.1 0.2 0.3 0.4 0.50.0
0.1
0.2
0.3
0.4
0.5
Water rushes into the hole
Adpative (ηcb = 0.0002)
USDH (ηcb = 0.0761)
ηcb : Normalized cracked area of bottom plate
ξ0 = 0.5; V = 1.14; τ = 0.55; Bottom face plate; 1/4 model
Nor
mal
ized
dis
tanc
e ζ
= y
/ L0
Normalized distance ξ = x / L0
MIT Simulation
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Fracture at Six Different LevelsFracture at Six Different Levels
5. Bay
4. Stiffeners & Panels
1. Microvoids
3. Specimens & Weldment
2. Unit Cube with defects
6. Ship
VirginiaTech/MIT
MIT
Michigan/MIT
5. Bay
4. Stiffeners & Panels
1. Microvoids
3. Specimens & Weldment
2. Unit Cube with defects
6. Ship
VirginiaTech/MIT
MIT
Michigan/MIT
MURI project : Development of blast resistance adaptive ship structures (Harvard University and MIT)Level 3 & 4
NNR project : Fracture prediction of navy steels (MIT through ATI )Level 2 & 3
NNR Project : Design of ships for survivability (jointly between Virginia Tech., UMich and, MIT )Level 1, 2, 5, & 6
ONR Project : DURIP instrumentation grant (awarded to MIT)Level 3
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Deliverables under NNR Funding Deliverables under NNR Funding through ATI ( 7/03through ATI ( 7/03--6/04)6/04)
Five technical reports (out of which, three have been submitted to major international journals)
Installation of three new pieces of equipment in the Impact and Crashworthiness Lab for fracture testing (3-D optical strain measuring device, Instron 9250NH DynatupDrop Tower, Zeiss microscope for fracture surface examination)
Completion of the design of 50 kN biaxial testing machine (joint project with Instron)
Design and manufacture of a universal specimen for fracture testing under combined loading
Study of physical aspects of ductile fracture (Report #112, 120)Study of numerical aspects of ductile fracture (Report # 114,
127)
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Deliverables under NNR Funding through ATI ( 7/03-6/04) (cont.)
Presentations and discussions of the industrial approach to fracture at :•Sandia National Labs Albuquerque and Livermore •Stanford Research Institute •Applied Research Associates •Weidlinger Associates•Earnst Mach Institute in Freiburg, Germany•BMW R&D Center in Munich, Germany•EuroPAM Conference in Mainz, Germany•AmeriPAM Conference in Warren, MI•ABAQUS User Meeting in Cambridge, MA
Two new US citizen graduate students admitted
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Publications of the MIT Team Completed for NNR Funding through ATI ( 7/03-6/04)
Necking, Fracture Initiation, and Crack Propagation in Flat Tensile Specimen, Y.W. Lee, T. Wierzbicki and Y. Bao, February, 2004, Impact andCrashworthiness Lab., Report #114 (to be submitted to Mechanics of Materials)
Bridgman Revisited: On the History Effects on Ductile Fracture, T. Wierzbicki and Y. Bao, January, 2004, Impact and Crashworthiness Lab., Report #112 (Submitted to Journal of the Mechanics and Physics of Solids)
Evaluation of the Wilkins (and other) Fracture Model, Y. Bao, Y.W. Lee and T. Wierzbicki, May 2004 Impact and Crashworthiness Lab., Report #120 (Submitted to Engineering Fracture Mechanics)
A Comparative Study of Shell Element Deletion and Element Split, H. Alsos, June, 2004, Impact and Crashworthiness Lab., Report #127 (MS Thesis)
Prediction of High Velocity Impact Fracture of Large Structural Systems, T. Wierzbicki, March, 2004, Impact and Crashworthiness Lab., Report #118 (Summary Report)
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Equipment Recently Purchased under DURIPEquipment Recently Purchased under DURIPInstrumentation Grant to ICLInstrumentation Grant to ICL
Zeiss microscope
Instron 9250NH Dynatup Drop
Tower
3-D optical strain
measuring device
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Custom Made 50 Custom Made 50 kNkN Biaxial Testing RigBiaxial Testing Rig
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
New Types of Specimens for Biaxial TestingNew Types of Specimens for Biaxial Testing
2nd generation 3rd generation
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Testing to FractureTesting to Fracture
Steel specimen under tension
Al 2024 in combined shear/compression
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Fracture vs. No FractureFracture vs. No Fracture
Round specimens subjected to hydrostatic pressure and tension
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Experimentally Determined Fracture LocusExperimentally Determined Fracture Locus
12 34 5
6 7 8
9 10 11
Bao-Wierzbicki fracture locus
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Calibration of BW ModelCalibration of BW ModelEvaluation of Calibration Constant Evaluation of Calibration Constant DDc c (high stress triaxiality)(high stress triaxiality)
Stre
ss tr
iaxi
ality
σm / σ
Equivalent strain ε
diffuse necking localized necking fracture initiation Critical
damage parameter
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Comparison of Seven Fracture Envelopes
-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0
FFLD
Johnson-Cook T-criterion
FLD: Storen/Rice
εf = const.
FLD: Hill
Wilkins
(1/3, b)
(0, a)
0.8
0.4
Maximum shear stress τmax = const.
Bao-Wierzbicki
Al2024-T351; a = 0.205; b = 0.54; n = 0.15
σm/σ
εf
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Comparison of Seven Fracture Envelopes
FFLD
T-criterion
Johnson-Cook
FLD: Hill
εf = const.
τmax = const.
Bao-Wierzbicki
FLD: Storen and Rice
0.5
0.5-0.5
Al2024-T351; a = 0.205; b = 0.54; n = 0.15
Wilkins
α = dε2 / dε1
α = -2compression
0.0
α = -1 shear
α = -0.5 uni-axial tension
α = 0 plane strain
α = 1 equi-biaxial tension
ε2
ε1
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Application of BaoApplication of Bao--Wierzbicki Fracture LocusWierzbicki Fracture Locus
Bao-Wierzbicki’s Constant fracture strain
An aluminum beam impacted by a round-nosed mass at V0 =300 m/s
Johnson-Cook’s • Large differences among three fracture loci;
• BW’s fracture criterion gives realistic results.
Eroded elements
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Double Hulls under Localized Impulsive Loading
outer hull
inner hull
initial
deformed
adaptive core
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Crack Formation and Propagation(Adaptive Sandwich Core Strucutre)
Initial FE mesh (1/2 model)Initial FE mesh (1/2 model)Onset of fracture(top face plate) Stress triaxialityStress triaxiality
Equivalent strainEquivalent strainFinal FE mesh (1/2 model)Final FE mesh (1/2 model)
Dimensionless loading area ξ0 = 0.5Dimensionless applied impulse V = 1.14
τ = 0.0
τ = 0.5
τ = 0.05
τ = 0.05
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
USDHUSDH NavtrussNavtruss
Y-webY-web AdaptiveAdaptive
Fracture Patterns of Inner Hull with Four Different Core Arrangements
Dimensionless loading area ξ0 = 0.5Dimensionless applied impulse V = 1.14
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Comparison of Damaged Area
USDH Navtruss Y-web Adaptive0.00
0.05
0.10
0.15
η0 = 0.25; V = 1.14
Nor
mal
ized
cra
ck a
rea η cb
Type of Core Structures
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Effect of Intensity of Applied Impulse (USDH)
USDH: V = 0.93USDH: V = 0.93
Dimensionless loading area ξ0 = 0.5
USDH: V = 1.14USDH: V = 1.14 USDH: V = 1.8USDH: V = 1.8
Outer hull (top), Inner hull (bottom)
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Damaged Area with Varying Intensity of Applied Impulse (USDH)
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
V = 1.14 (ηcb = 0.0761)
V = 1.05 (ηcb = 0.0196)
ξ0 = 0.5; USDH (Bottom face plate)
Nor
mal
ized
dis
tanc
e ζ
= y
/ L0
Normalized distance ξ = x / L0
V = 1.7 (ηcb = 0.2178)
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.00.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40ξ0 = 0.5; USDH (Bottom face plate)
Nor
mal
ized
cra
ck a
rea η cb
Normalized impulse V
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Distribution of Stress Triaxiality
Stress triaxialityStress triaxiality
Dimensionless loading area ξ0 = 0.5Dimensionless applied impulse V = 1.14
τ = 0.5
AdaptiveAdaptive
USDHUSDH
Impact & Crashworthiness Lab, MITImpact & Crashworthiness Lab, MIT
Future Work
lling
Fracture calibration of two or three types of Navy steel
Cooperation with the Bath Iron Shipyard and NSWC to acquire suitable material samples
Validation on the component level
Implementation into commercial FE codes in cooperation with the developers of LS-DYNA, ABAQUS and, PAM-CRASH
Application to several types of weapon threats.
Transfer of new technology to the Navy labs and Shipyards