BSc Materials Science and Engineering

The unit provides a development of knowledge on the mechanical behaviour of materials acquired during the first year of the course and extends it to deformations in 2- and 3-Dimensions. It also extends the simple introduction to fracture, covered in the first year, to a more formal fracture mechanics approach. The course also provides an introduction to macroscopic plasticity, hardness, friction and wear.

The unit aims to:

• Introduce the representation of stress and strain as 2nd rank tensors and their relation via the compliance and stiffness tensors.
• Explain the methods used to measure strain in a body and how these are used in practical engineering situations.
• Introduce the concepts of a stress distribution and a stress concentration. Explain how stress distributions lead to a resistance to twisting and bending and how the shape of a material influences this resistance.
• Introduce the concept of fracture mechanics, fracture resistance and critical stress intensity.
• Introduce simple statistical concepts for the prediction of failure in brittle materials.
• Introduce the mechanisms for fatigue failure in terms of crack initiation and crack growth.
• Introduce simple descriptions of macroscopic plastic deformation, hardness, friction and wear.

A greater depth of the learning outcomes are covered in the following sections:

• Knowledge and understanding
• Intellectual skills
• Practical skills
• Transferable skills and personal qualities

• Define stress and strain in 3-dimensions and represent them in the form of a tensor in Cartesian and cylindrical co-ordinates. Understand how to manipulate these tensors to represent a state of stress or strain in different spatial orientations of the axes.
• Determine the principal stresses and strains of a tensor and their invariant values.
• Identify the relationship of the shape and composition of a beam and rod control their resistance to bending and twisting.
• Explain the concept of a stress distribution and a stress concentration.
• Explain the relation between the Griffiths model of fracture and that proposed by Irwin and Orowan.
• Demonstrate an understanding of the mechanisms that dissipate energy during fracture and now these can lead to size effects in the measurement of fracture toughness.
• Demonstrate an understanding of the need to use statistical methods for the description of the strength of highly brittle materials.
• Construct the description of fatigue based on descriptive simple models for fatigue life prediction.
• Predict macroscopic plasticity and be able to relate materials hardness and flow strength.
• Demonstrate an understanding of simple models for friction and wear.

• Show improved logical reasoning, problem solving and ability in applied mathematics.
• Show an improved understanding and spatial awareness through solving problems in 2- and 3-dimensions. 

• Perform simple matrix manipulation and calculations.
• Quantify the stress intensity factor from measurements made from fracture mechanics specimens.
• Use photoelastic effect to understand stress concentrations in real materials  

• Convert problems described using text into equations to provide numerical answers.
• Use spreadsheets to analyse data
• Work effectively in a group to solve problems.
• Compose simple technical reports on laboratory tests. 

Written and verbal

• Mechanical Metallurgy: G Dieter, 3rd edition or later
• Deformation and Fracture Mechanics of Engineering Materials: R W Hertzberg, 5th edition or later
• Mechanical Behavior of Materials: Engineering Methods for Deformation, Fracture, and Fatigue: N E Dowling, 3rd edition or later
• Continuum Mechanics by George E. Mase