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3/8/2002, Friday Toughness.

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Presentation on theme: "3/8/2002, Friday Toughness."— Presentation transcript:

1 3/8/2002, Friday Toughness

2 Fracture Modes

3 Stress Field Around Crack Tip

4 Stress Concentration

5 Crack Tip Stress Distribution

6 Stress Intensity Factor, K

7 Fracture Toughness, KIC

8 Crack Tip Plastic Zone

9 Fracture Process Zone

10 Concrete

11 Polymer Fracture - Craze

12 Polymer Yielding

13 Atomistic fracture pattern at different loading rate
H. Tan and W. Yang, Acta Mechanica Sinica co-existence of dislocations and cleavage embryo dislocation cleavage We established a critical rate theory for the competition between dislocation emission and cleavage. If the dynamic strain rate is slow, the crack tip has enough time to generate dislocations. The ductility of the material is reduced when higher loading rates are imposed. The center figure shows the co-existence of dislocations and cleavage embryos. If the loading rate is even higher, the right figure shows that crack cleaves before a dislocation has time to emit from the crack tip. High strain rate Low strain rate

14 Fiber Composite

15 Stress-Strain Curve

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