reasons-as-to-why-cracks-stopWhy do cracks stop? 1. Drop in frequency due to cross-section weakening 2. Damping due to rubbing of the crack edges 3. Suitable stress gradient in the direction of growth 4. Loss of stress in strain-controlled processes 4. Rounding of the crack tip 5. Structural hindrance 6. Residual stresses 7. Increase in the crack toughness of the material 8. Loss of external loads 9. Increase in strength10. Drop in the E modulus11. Transverse hindrance12. Fiber reinforcementDynamic fatigue crackShaft under circumferentialflexural loadsSurface with increaseddynamic strength- tempered (steel)- coated- hardenedThermal fatigue crackHigh-strength base materialCrack in the coatingSoft coating and/orpoor bondingTough base material Crack in the coatingpasses into the base materialHard, brittle coatingwith good bonding Gaping crack due to oxidation at the crack tipRubbing process