3/8/2002, Friday Toughness

Fracture Modes

Stress Field Around Crack Tip

Stress Concentration

Crack Tip Stress Distribution

Stress Intensity Factor, K

Fracture Toughness, KIC

Crack Tip Plastic Zone

Fracture Process Zone

Concrete

Polymer Fracture - Craze

Polymer Yielding

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

Fiber Composite

Stress-Strain Curve