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Fatigue Growth Behaviour of Two Interacting Cracks with Different Crack Offset
Huijin Jin1, Bing Cui2, Ling Mao3
1State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China. jinhuijin863@163.com.
Materials (Basel, Switzerland)
|October 31, 2019
Summary
Multiple cracks significantly reduce component lifespan due to interaction effects. This study reveals crack offset influences fatigue growth, with overlapping cracks causing mode transfer and growth retardation, especially at smaller offsets.
Area of Science:
- Materials Science
- Mechanical Engineering
- Fracture Mechanics
Background:
- Component service life is significantly reduced by multiple cracks compared to single cracks due to crack interaction.
- Understanding crack interaction is crucial for predicting fatigue behavior and ensuring structural integrity.
Purpose of the Study:
- To investigate the impact of crack interaction on fatigue crack growth behavior in an aluminum-lithium alloy.
- To analyze the effect of varying crack offsets on the interaction phenomena.
Main Methods:
- Experimental fatigue crack growth tests on samples with single and non-collinear cracks.
- Finite element modeling to calculate stress intensity factors (K) for different crack offsets.
Main Results:
- Non-collinear cracks shifted growth direction upon overlap, transitioning from Mode I to Mode I + II mixed mode.
- Overlapping cracks exhibited a shielding effect, decreasing stress intensity factor (K) and retarding crack growth, particularly with small offsets.
- The interaction effect varied from positive to negative during crack growth, influencing acceleration or deceleration.
Conclusions:
- Crack interaction significantly alters fatigue crack growth, with offset being a critical parameter.
- The shielding effect from overlapping cracks can retard growth, but this effect is dependent on the crack offset and growth stage.
- The dynamic nature of interaction effects necessitates considering different growth stages for accurate fatigue life prediction.
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