Fatigue life prediction in the

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Fatigue life prediction in the STAMPING process
Montecarlo, Junio, 2000
Presented by Luis Saracho Senior Applications
Engineer Análisis y Simulación S.L.
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Contents

• Aim of the project
• Softwares - Integration
• Traditional calculation

• New approach
• Problems
• Results

• Conclusion

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Aim of the Project

• Life Calculation of a STAMPED component due to
  Fatigue.
• Account for life on the stamping process.
• Asses life by REAL usage load data.

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Aim of the Project

• Before Simplicity
• NO DAMAGE is calculated during the STAMPING
  process.

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Software - Integration

• Stamping Simulation
• MSC/Dytran
• Pam-Stamp
• LS Dyna
• Autoform

• Static Calculations
• MSC/Nastran
• Ansys
• Abaqus
• SDRC-IDEAS
• Cosmos

• Life Predictions
• MSC/Fatigue

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MSC / FATIGUE
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Traditional Calculation
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New Approach
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Fatigue Calculation

• Transient Analysis
• Remesh Static Analysis

• Fatigue on Stamping process
• Fatigue due to real use

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FE Model I

• Stamping Process on a FE Model.

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FE Model II
RE - MESH
Optimisation of the FE MODEL for the
STATIC ANALYSIS
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FE Model III
Results Extrapolation
Thickness of Stamped Model
Residual Stresses
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FE Model III
FE Model for REAL USAGE Fatigue Calculation
Stress results
LBCs
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Materials I - EN Curves

• Material Database
• Creation
• Characterisation Test

MSC/Fatigue provides a library of up to 200
materials within the software
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Real Usage Loads
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Equivalent Stresses

• Principal of linear Superposition

• In order to combine all load cases together to
  determine the strain variation at each node due
  to the combination of all loads.

For EACH node at t1
For all ti
?eq
( Abs. Max. Principal )
P1(t1)
X ? ij 1
? eq (t1)
?
? eq (t2)
X ? ij 2
P2(t1)

• .
• .
• .

• .
• .
• .

? eq (tn)
Pn(t1)
X ? ij n
LIFE
secs x Sample rate
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Results I

• A (0-1) Stamping
• B (1-2) Real Usage

 
Total Life Life B x ( 1 damage A )
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Results I

• Damage on Stamping

• Total Damage

Life A 12 cycles
Life B 63.100 cycles
Total Life Life B x ( 1 1/Life A )
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TOTAL LIFE of the Component
63.100 54.500 Cycles reduction
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Results III
Sensitivity Analysis - Back Calculations
What happens if ?
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CONCLUSION
Account for damage during the stamping process
provides better life results !!
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Merci beaucoup par votre attention
Luis Saracho Análisis y Simulación / MSC Agent