Failure Analaysis

   Failure as a Design      Criterion

   Fracture Mechanics

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Tutorial Questions

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Griffith Equation


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Stress Intensity Factor and Fracture Toughness Testing
- Stresses Close to a Crack Tip
- Fracture of Glass
- High Strength Versus high Toughness
- Quenching and Residual Stress
- Missile Motor Case Fracture
- Fracture Toughness Tests
- Plastic Zone Effect
- Specimen Thickness Effect
- Growth of Semi-Elliptic Flaws
- Leak-Before-Break Concept
- Pressurised Vessels
- Fracture of a Beer Barrel
- Pin-Loaded Lug
- Materials Selection and Temperature
- Chemical Reactor Vessel
- Fracture of Ice

 :: 
Characterising Sub-Critical Growth
 -  Fatigue Life Prediction
 -  Stress Corrosion Cracking

 :: 
Theory Resource



Problem 7

This question illustrates the iterative approach to determining K1C when account has to be taken of Irwin's plastic zone correction to crack length. It should take about 15 minutes to complete
A thin plate of steel contains a central through-thickness flaw of length 16 mm, which is subjected to a stress of 350 MPa applied perpendicularly to the flaw plane. The 0.2% flow stress of the material is 1400 MPa.

Calculate the plastic zone size and the effective stress intensity level at the crack tip, making reasonable assumptions about the state of stress.

If, after heat treatment, the flow stress of the steel dropped to 385 MPa, what would the plastic zone size be under the applied stress of 350 MPa, and what conclusions would you draw about the use of LEFM?

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