Failure Analysis

   Failure as a Design      Criterion

   Fracture Mechanics


Tutorial Questions


Griffith Equation


Stress Intensity Factor and Fracture Toughness Testing


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


Theory Resource

These are designed to test your knowledge of the principles contained in the lecture course, through practice in typical engineering applications. By putting them on the internet, you are enabled to work at your own pace and hence maximise the benefit obtained form the relatively few formal sessions on problem solution.

Most of the questions require reasonable engineering assumptions to be made in arriving at a solution, e.g. whether plane stress or plane strain conditions are valid, or whether a plastic zone correction needs to included in crack length. This development of 'engineering commonsense' in assessing typical assumptions and their limitations, is crucial to the examination and to your progress in tackling real engineering problems. Part of this development also entails a feel for engineering units, so be aware that units have to be consistent in the problems, but are not necessarily given as such! Over a number of years, I have learnt which areas in the tutorial questions give problems to students, hence you can access hints on-line if you are stuck. The learning process, however, will only be effective if you have thought about the question before requesting a hint. The hint then reinforces the learning process, instead of bypassing it.

The tutorial questions fall into a number of sub-sections, as shown below. Note that a number of different theory cards are hyperlinked from the questions. If a question introduces a new topic, check the theory card to see if it contains relevant information. There is a search engine attached to the bottom of the page, which can be used to search the tutorial for specific topics and words. This might be useful if, for example, you wished to look up 'plane stress' or 'plane strain', or look for questions dealing with specific hardware. Other on-line resources which can be accessed from the questions are a scientific calculator and graph plotting facilities.

A number of the questions deal with specific engineering materials, for instance maraging steels. If you are interested in learning more about why such alloys are specified, there are several internet sites which provide information on properties, applications, composition and trade names of engineering alloys and materials. One such site, which is hyperlinked from this page, is Matweb, the Online Materials Information Resource. This is a very well structured site which can be searched for information and would be generally useful to engineering undergraduates.

Hopefully, you will enjoy working through this tutorial as much as I have enjoyed putting it on the internet!

Each question has online resources to support its solution; these comprise a 'normal' scientific calculator, a Reverse Polish Notation RPN calculator, a graph package and an appropriate theory box.  RPN calculators operate the way that many engineers think, n that they load numbers up a stack and then progressively perform arithmetic or trigonometric calculations on them.  Information on the origin of the RPN notation and using RPN calculators can be found at the Calculator Home Page website and at the HP website.  There are many other RPN calculator programs available on the web.


Failure Analysis  -  Fracture Mechanics  -  Failure As A Design Criterion