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Fracture

Fracture. Liberty Ships in WWII. Fracture. Quebec Bridge - August 29, 1907. Quebec Bridge - Sept. 11, 1916. Tacoma Narrows Bridge Failure. Tacoma Narrows Bridge Failure. Tacoma Narrows Bridge Failure. Tacoma Narrows Bridge Failure. Basis for Fracture Mechanics.

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Fracture

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  1. Fracture Liberty Ships in WWII

  2. Fracture

  3. Quebec Bridge - August 29, 1907

  4. Quebec Bridge - Sept. 11, 1916

  5. Tacoma Narrows Bridge Failure

  6. Tacoma Narrows Bridge Failure

  7. Tacoma Narrows Bridge Failure

  8. Tacoma Narrows Bridge Failure

  9. Basis for Fracture Mechanics  ( c )1/2= (2 s E )1/2 Stress Intensity Factor K geometrical loading Fracture Toughness KIc Material Parameters

  10. Stress Intenisty Factors K = f (,c) Infinite plate; through crack Semi-infinite plate; through crack K =  (c)1/2 Y = 1 K = Y (c)1/2 Y = 1.12 2c c Finite plate; through crack Penny crack K = Y (c)1/2 w K = Y  (c)1/2 Y = 2/ 2.2 2.0 1.8 Y 2c .1 .5 2c/w

  11. Typical Values for GIC ; KIC

  12. Ductile Fracture • local > yield • dislocation motion blunts the crack tip !!! • harder for crack to propagate  r

  13. Ductile Fracture

  14. Brittle Fracture  r local < yield No dislocation motion !!! Atoms cleave

  15. Brittle Fracture

  16. DBTT Ductile Brittle Transition Temperature BCC yield  fracture fast fracture yielding DBTT T

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