Failure Analaysis

   Failure as a Design      Criterion

   Fracture Mechanics

 :: 
Tutorial Questions

 :: 
Griffith Equation


 :: 
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 16

The last question in this section of the tutorial illustrates the concept of superposition of stress intensity factors, which has already been invoked in dealing with pressure vessels. For internal defects in pressurised vessels, we had to take account of the stress intensity arising from the internal pressure on the crack faces, as well as that due to the membrane stresses in the shell.

This particular case also demonstrates the application of LEFM to ice, a glass-like material.

It should take around 10 minutes to complete.
The figure below shows stress intensity factors corresponding to two load cases for a vertical edge crack in an infinite body. Case A represents uniform tension, while Case B illustrates a linearly increasing tensile load with depth into the body. The two stress intensity equations are:

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Consider a surface crevasse in a wide, thick glacier, which is subject to a uniform longitudinal stress of 200 kN/m2. Determine the depth to which this vertical crack can grow, given that the density of ice is 0.92 x 103 kg/m3 and the gravitational constant is g = 9.81 m/s2.

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