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 6

This question illustrates the application of constraints on determining valid K1C values from fracture toughness tests, according to BS 7448 : Part 1 : 1991. It should take about 15 minutes to complete.
The figure below shows the load line displacement trace recorded from a standard sized compact tension fracture toughness specimen. Specimen thickness was 25 mm, the crack length at fracture was 25 mm and the steel alloy had a yield strength of 650 MPa.

a) Calculate FQ and hence KQ. Apply the required checks on plastic zone size, stress state and plasticity during the test to determine whether KQ is a valid plane strain fracture toughness value.

b) What is the maximum K1C value that can be determined for this steel using 25 mm thick specimens?

Note that:


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