UNIVERSITY OF SUNDERLAND
FACULTY OF ENGINEERING AND ADVANCED MANUFACTURING

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This coursework assignment carries 50% of the marks available for this module.
Assignment 2 (Manufacturing) will carry the remaining 50%.
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EAT104: COURSEWORK 2016/2017 SESSION: MATERIALS ASSIGNMENT
Materials Properties and Materials Selection
Introduction
Engineers design and make things. Let’s assume we’re talking about engineering
components. These components are made of MATERIALS (metal, plastic, ceramic,
composite etc.). The best material from which to make any given component
depends on a number of factors (e.g. mechanical, thermal or electrical properties,
density, cost, environmental impact etc.) and the process by which the final material
is chosen is MATERIALS SELECTION. In this module we use a well-established
graphical methodology for materials selection based on quantitative measures of
performance called PERFORMANCE INDICES. This methodology is the one
employed within the CES 2016 software – and part of the aim of this assignment is
that you become familiar with the use of this software. You will be using it in all 3
years of your degree.
1. Materials Selection Charts
A materials selection chart is a 2-D plot of one material property (or combination of
properties) against another. A simple example might be a plot of Young’s Modulus
(y-axis) v Density (x-axis). Such a plot can be generated via CES (Figure 1):
Figure 1. Young’s Modulus -v- Density Materials Selection Chart.
Any given unique material would occupy a single point on the above chart. Because
a material such as cast iron or PVC is, in reality, a family of materials, then it
occupies a “bubble” or “island” on the chart as indicated in Figure 1 above.
Density (kg/m^3)
10 100 1000 10000
Young’s modulus (GPa)
1e-4
0.001
0.01
0.1
1
10
100
1000
Rigid Polymer Foam (MD)
Softwood: pine, along grain
CFRP, epoxy matrix (isotropic)
Polyvinylchloride (tpPVC)
Cast iron, gray
Young’s Modulus v Density (Level 2 Database)
TASK 1
Using CES software (using Level 2 Database, Edu Level 2 Materials subset),
prepare the following materials selection charts (y-axis variable listed first):
1.1 Yield Strength -v- Density: (σy -v- ρ)
1.2 Yield Strength -v- (Price x Density): (σy -v- Cm ρ)
1.3 (Young’s Modulus)1/2 / Density -v- (Yield Strength)2/3 / Density:
[(E1/2/ρ) -v- (σy 2/3/ρ)]
Copy/Paste your charts from CES into your report. Label and format the charts in
your chosen style. Give a full commentary on your work.
2. Performance Indices
In order to be able to select the “best” or “optimum” material for a particular
component we need to understand what we’re trying to optimise. Essentially, what is
needed is a material which will meet all of the mechanical / electrical / thermal
requirements of the component. These requirements are COMPULSORY and are
called CONSTRAINTS. The best material is the one which meets all of these
compulsory needs at (say) minimum mass, minimum cost or minimum environmental
impact. This optimisation is termed the OBJECTIVE.
The constraint and objective factors dictate the selection methodology. Hence we
find materials which are capable of meeting all compulsory performance
requirements and then find the one that achieves this at (e.g.) minimum mass.
This selection methodology should be quantitative to work effectively. A quantitative
measure will allow us to shortlist materials and then rank them from best (lightest
component) to worst (heaviest component). This ranking is done via the
PERFORMANCE INDEX. Here are some common performance indices (Table 1):

Table 1: Some common performance indices for minimum weight design.
In class you have learned to take a given performance index (M) and use this:
(i) to plot the appropriate selection chart, and
(ii) apply a selection line of given gradient to allow the selection process to
proceed
[In essence, if a performance index, M, is given by: