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Unit information: Failure of Materials in 2015/16

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Unit name Failure of Materials
Unit code MENG33112
Credit points 10
Level of study H/6
Teaching block(s) Teaching Block 2 (weeks 13 - 24)
Unit director Dr. Velichko
Open unit status Not open

MENG11100 or MENG21100 or equivalent



School/department Department of Mechanical Engineering
Faculty Faculty of Engineering


Failure of Materials and Structures is divided into two equal components.

First the failure of un-cracked bodies is considered, where the classes of failure mechanisms are defined and examined in detail. This section compares brittle and ductile failure, plastic instability, probability based failure criteria, failure in composites and failure criteria in complex stress conditions. All these fracture and failure mechanisms are relevant to many practical engineering components.

The second set of lectures on fracture mechanics considers the failure of materials that contain pre-existing cracks. The fundamental concept of the stress intensity factor is introduced and discussed both under linear elastic and elastic -plastic conditions. Its measurement and application to fracture and fatigue problems is defined as the pre-eminent quantity in fracture mechanics. Fracture mechanics is presented within a framework of structural integrity assessments, with a particular focus on real-life problems.


The objective of this course is to understand:

  • The difference between material failure and structural failure
  • The impact of state of stress on material failure
  • The philosophy and application of fracture mechanics.
  • The importance of the stress intensity factor and its relation to the fracture toughness of materials.

Intended learning outcomes

On completion of the course the student should be able to:

  • Predict material failure for any combination of applied stresses.
  • Estimate failure conditions of a structure
  • Determine the stress intensity factor for simple components of simple geometry
  • Predict the likelihood of failure of a structure containing a defect

Teaching details

Students receive a 1-hour lecture each week for 20 weeks. Notes will be handed out as appropriate and note taking will also be required. Example questions will be given out; some examples will be solved during the lectures and the lecturer will state times and dates following the lecture course when he/she will be available to discuss any further problems.

Assessment Details

The lecture course will be assessed by a 2 hour written examination.

Reading and References

  • Mechanical Behaviour of Materials, 2nd ed. N.E. Dowling, (Prentice-Hall), 1998
  • Elementary Engineering Fracture Mechanics, 4th ed., D. Broek, (Kluwer), 1982