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Raytron Technical Review RESEARCH ARTICLE WP-06-03

Fatigue Performance of CCAA Conductors

RAYTRON Technical Team1

1RAYTRON Group, China

Published: March 2026 Version: 1.0
DOI: 10.1000/raytron.WP-06-03

1. Introduction

1.1 Fatigue Importance

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Figure fig1 Figure 1: Fatigue cycle requirements across different industries
ApplicationFatigue Cycles/YearCriticality
Automotive10⁶-10⁸High
Industrial10⁷-10⁹High
Aerospace10⁸-10¹⁰Very high

1.2 CCAA Fatigue Advantage

MaterialEndurance Limit (MPa)Improvement vs CCA
Cu70-90Baseline
CCA-135040-60Lower
CCAA-505280-100+60% vs CCA
CCAA-6061100-130+100% vs CCA

2. Fatigue Fundamentals

2.1 Fatigue Mechanism

  1. Crack initiation at surface defect
  2. Crack propagation under cyclic stress
  3. Final fracture

2.2 Key Parameters

ParameterSymbolDescription
Stress amplitudeσaHalf stress range
Mean stressσmAverage stress
Stress ratioRσmin/σmax
Cycles to failureNfFatigue life

2.3 S-N Curve

3. CCAA Fatigue Characteristics

3.1 S-N Data

CCAA-5052 (70% Cu cladding):

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Figure fig2 Figure 2: S-N curve for CCAA-5052 conductor
Stress (MPa)Cycles to Failure
2005×10⁴
1502×10⁵
12010⁶
1005×10⁶
8510⁷ (runout)

3.2 Comparison with Other Conductors

At 100 MPa stress amplitude:

ConductorNfRelative Life
Cu10⁶1.0
CCA-13502×10⁵0.2
CCAA-50522×10⁶2.0
CCAA-60615×10⁶5.0

3.3 Effect of Temperature

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Figure fig3 Figure 3: Temperature effect on CCAA-5052 fatigue life
TemperatureCCAA-5052 Life Factor
25°C1.0
100°C0.7
150°C0.4

3.4 Effect of Mean Stress

R RatioEndurance Limit Factor
-1 (fully reversed)1.0
00.8
0.50.6

4. Testing Methods

4.1 Standard Tests

TestStandardApplication
Axial fatigueASTM E466Material property
Bending fatigueCustomWire-specific
Flex testSAE AS4373Qualification

4.2 Test Setup

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Figure fig4 Figure 4: Fatigue test apparatus for conductor samples
ParameterTypical Value
Frequency5-50 Hz
Stress ratioR = 0.1 or -1
Samples6-10 per stress level

4.3 Data Analysis

  • S-N curve fitting
  • Statistical analysis
  • Endurance limit determination

5. Design Approaches

5.1 Safe-Life Design

Design for infinite life at operating stress:

5.2 Finite-Life Design

For known cycle requirements:

5.3 Example Calculation

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Video 1: Fatigue design calculation example for CCAA conductors

Given:

  • Required life: 10⁷ cycles
  • Application: Automotive engine bay
  • Temperature: 100°C

For CCAA-5052:

  • Endurance limit at RT: 85 MPa
  • At 100°C: 85 × 0.7 = 60 MPa
  • With SF = 2: Allowable = 30 MPa

5.4 Design Recommendations

ApplicationMax Stress (MPa)CCAA Grade
High vibration, high temp<305052 or 6061
Moderate vibration<605005 or 5052
Low vibration<100Any CCAA

6. Conclusion

6.1 Summary

PropertyCCAA-5052CCAA-6061
Endurance limit85 MPa110 MPa
vs CuSimilarBetter
vs CCA-1350+60%+100%
Best forVibrationHigh stress

6.2 Design Implications

  • CCAA significantly improves fatigue life over CCA
  • Proper grade selection critical for fatigue applications
  • Temperature effects must be considered

7. References

  1. ASTM E466. (2021). Fatigue Testing.
  2. Suresh, S. (1998). Fatigue of Materials.

Frequently Asked Questions

How is fatigue life predicted for CCAA conductors?

Fatigue life is predicted using S-N curves (stress vs. cycles to failure) following the Basquin equation: σa = σf'(2Nf)^b. For CCAA-5052, at 100 MPa stress amplitude, expected life is 5×10⁶ cycles; at 85 MPa, runout (>10⁷ cycles) is achieved.

What safety factor should be used for fatigue design?

For safe-life design, a safety factor of 2-4 is recommended depending on application criticality. Aerospace applications typically use SF=4, automotive SF=2-3, and industrial SF=2. The safety factor accounts for material variability and environmental effects.

How does temperature affect CCAA fatigue performance?

Elevated temperature reduces fatigue life. At 100°C, CCAA-5052 retains about 70% of room-temperature fatigue life. At 150°C, only 40% remains. Design for high-temperature applications must apply appropriate derating factors.

Which CCAA grade is best for fatigue-critical applications?

For maximum fatigue resistance, CCAA-6061 offers the highest endurance limit (110 MPa) and longest fatigue life. For balanced performance with lower cost, CCAA-5052 (85 MPa endurance limit) provides excellent value for most vibration applications.

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