Customisation of nCode DesignLife to model fatigue of ... · 2 Summary • Introduction to nCode...
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Customisation of nCode DesignLife to model fatigue of engineered polymers Peter Heyes, Jeff Mentley and Stephan Vervoort HBM UK Ltd
Transcript of Customisation of nCode DesignLife to model fatigue of ... · 2 Summary • Introduction to nCode...
Customisation of nCode DesignLife to model fatigue of engineered polymers
Peter Heyes, Jeff Mentley and Stephan VervoortHBM UK Ltd
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Summary
• Introduction to nCode DesignLife• Customisation capability using Python• Application example: life prediction process for composite component
made from SMC (sheet moulding compound)• Concluding remarks and further work
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Introduction to nCode DesignLife
• General purpose FE based fatigue analysis tool4Stress-life (SN)4Local strain approach (EN)4Multiaxial fatigue4Welds and spotwelds4High temperature fatigue4Quasi-static, dynamic, non-
linear, vibration
• Supports common FE codes
• Intuitive, flow based graphical user interface• Integrated postprocessing and reporting• Knowledge capture and process encapsulation• Fast, flexible and efficient (parallel processing etc)• Available in Hyperworks
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Fatigue analysis process
DYNAMICSTRESSES
FE
LIFE
Damage Modelling
LOADS
ANALYSIS /TEST
Static superposition Modal superposition Transient Non-linear time stepRandom vibration
SN Plot of : Z-Specimen
Database :nmats
Mean Type :R-ratio
Stress type: RANGE
Stress Units: MPa
UTS:1030.00000
E value:1.17000e+005
-0.5
0.1
0.5
0.9
Cycles
Str
es
s
1000 1E4 1E5 1E6 1E7
200
400
600
800
S-N (Stress-Life)Local strain approachWelds and spot weldsMultiaxial fatigueHigh temperatures
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Customisation of nCode DesignLife using Python
• Allowing custom algorithms to be incorporated in the software based on some simple configuration files and Python scripting
• New requirements can be implemented rapidly outside normal software development cycle
• Implement proprietary methods in production software environment• Research – test new theories with realistic FE data and loading• Custom methods appear on interface and work in the same way as
standard methods (some speed penalty)• SN and Spot Weld methods exposed so far• Example applications…
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Python extension to SN capability
Simple S-N process
Custom SN method
Mat Db(MXD)
Customxdef
Customnpd
Custom.sysfile
Pythonscript
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Use to support aerospace specific SN curve formulation
ABNC
SS
)(1
++=
∞
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Python extension to spot weld capability
Simple spotweld process
Load provider
Force and moment
Fxyz(t),Mxyz(t)
Sheet and nugget stresses
σ(t,θ,loc)
Rainflowcount
(Δσ,σm)n
Damage
Custom SN method
Mat Db(MXD)
Customxdef
Customnpd
Custom.sysfile
Pythonscript
Custom stress calculation
Custom.sysfile
Pythonscript
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Used to predict life of Self-Piercing Rivets
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Customisation of nCode DesignLife for life prediction of composite parts
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Example application: tyre fit made from sheet moulding compound (SMC)
SMC – randomly oriented chopped glass fibre strands in polypropylene
Hot pressing process results in alignment of fibres – properties of formed part will in general be anisotropic
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Forming simulation
Simulation of Pressing Technique (GMT)
• Flow Simulation• Fibre Orientation• Shrinkage and Shape Distortion• Anisotropic Material Properties • Generate properties for structural
model
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FlowSimulation
FEMSimulation
FatigueSimulation Life
Geometry
MaterialProperties
Loading
PressureTemperature
Rheological properties
Durability process
Physical test
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Wöhler Curves
Tensile Strength
Fibre Angle [° degree]
UTS
[MPa
]Life [cycles]
Stre
ss R
ange
[MPa
]
Material test – anisotropic fatigue properties
Fatigue and tensile properties strongly depend on orientation of fibres relative to loading direction
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Python extension to SN capability
Custom SN method
Mat Db(MXD)
Customxdef
Customnpd
Custom.sysfile
Pythonscript
Static superposition
Modal superposition
Transient
Non-linear Critical Plane Method
fibreangles(csv)
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Analysis summary
• Structural analysis uses orthotropic properties • Material angle set on each shell element• Top and bottom surface stresses used• Family of fatigue curves corresponding to different fibre orientations• Fatigue analysis: 9 loadcases with corresponding displacement-time
histories• Critical plane analysis considers plane angle relative to material orientation
and interpolates the SN parameters
G1
G2G3Critical plane angle
θ
x
G4
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Graphical view of process – correlation with test
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Concluding remarks
• Customisation capability in nCode DesignLife permits rapid exploration and deployment of new or proprietary algorithms
• System has potential for life prediction of composite structures, particularly short fibre moulded composites
• Further work - composites:43D elements4Multi-ply laminate models4Fibre density and other processing parameters4More sophisticated fatigue damage criteria
• Further work - general:4Open up other areas of software to customisation
