MODULE DESCRIPTOR
MECH 2011 - Materials and Design Studies
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MECH2011
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Materials and Design Studies
2
0.5/7.5
September
June
Dr Adam Wojcik (100%)
Module Coordinator
Prerequisites
Students considering registering for this course would normally be expected to have completed
introductory courses in materials science and mechanics of materials.
This is a level 2 course and students are therefore expected to have a sound basis in materials science
as applicable to engineering contexts. This entails an understanding of the structure-property relationship
in materials and the way in which manufacturing methods affect the latter. A grasp of phase equilibria
and basic metallography is expected, as is an understanding of the way in which mechanical properties
are determined and how engineers utilize materials data to design with, and select, materials.
Additionally, an understanding and knowledge of polymer types and processing, how materials can be
strengthened, and how products and components are manufactured from materials, is of great utility to
this course.
Course Aims
This course is somewhat unique in materials teaching in that it delivers the required aspects of standard
materials theory for 2nd year engineers, but does so within a context of design and in particular, failure of
design to deliver the desired effect. In this respect, the course aims to educate and inform by bitter
experience as well as by the more conventional textbook approach.
Two main threads are explored in this course: Materials, and Failure of materials & how these aspects
link into product design and manufacturing technology. The main aims are as follows:
1.
To build upon the theory of materials given in Year 1 through a detailed
examination of the principal alloy systems employed in engineering, their main characteristics,
uses and heat treatments.
2.
To deliver a basic understanding of the theory of other classes of
material, including polymers, ceramics and composites, and their selection
in engineering design.
3.
To understand the modes and mechanisms by which materials and
components fail in service and the engineering and manufacturing
solutions available to combat such failure.
4.
To relate all such information to the design of components and products
and to illustrate the strong linkage between design and materials issues,
and to the way in which components are manufactured.
5.
To equip students with a sense that they have a responsibility to society
to produce products that are fit for use, safe and long lasting, as well as
cost effective and profitable for their employer.
Method of Instruction
The course is delivered using lectures, tutorials and weekly practical sessions which together service a
failure analysis case study (FACS).
Assessment
The course is assessed via a conventional unseen written exam of 3 hours duration. This covers both
major threads of the course. 75% of the credit for the course is predicated on this exam. The course
work (remaining 25%) consists of one short coursework question sheet, plus a major piece of project
work – the Failure Analysis Case Study (FACS). The FACS coursework is a highly novel aspect of the
course. Students work on the FACS in groups and it provides an opportunity to deal with practical
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aspects of engineering that feed off the theoretical side of the course, within a group context – much as
engineers conduct themselves in the “real” world.
Resources
General books on all materials including;
Materials Science & Engineering. (8th ed, 2010 or 7th ed). W. D. Callister, D. G. Rethwisch. Wiley
(hardback with good coverage of most topics, has either CD or web access).*
The Science and Engineering of Materials. (4th ed.) D. R. Askeland & P. P. Phule. Thompson/Brooks.
(hardback, covers more than Callister in places + CD).*
Introduction to Materials Science for Engineers. (7th, 2009 or 6th ed). J. F. Shackelford. Pearson
Education. (general text with emphasis on engineering applications, web access).
An additional bibliography covering detailed aspects such as corrosion and fracture is supplied to all
students.
Additional Information
This structure of the course is designed to divide into two distinct sections, which nevertheless cross over
at certain points. Students should treat each half as independent but note that in the end of year exam,
questions will often be mixed, and contain aspects of both materials theory and materials failure. Thus,
for example, the course has a section on stainless steels (see syllabus) but corrosion is also covered as a
separate topic within the failure section of the course. Stainless steels are usually employed in
engineering designs for their superior corrosion resistance over conventional carbon steels, but in some
cases they can corrode as fast, if not faster, than an “ordinary” steel, and engineers need to be aware of
this – so there is obvious overlap between both sections of the course. Manufacturing processes can
also strongly influence the choice of a material for an application – and the way in which it fails when in
service, so an understanding of some basic manufacturing techniques is also required. The course will
therefore touch on manufacturing issues, especially during the practical aspects involved in the
coursework.
Content
The lectures are supported by pictorial hand-outs and a weekly thought-provoking problem (the “TTT”)
with a detailed worked solution supplied the following week. The syllabus is as follows;
Steels:
The iron carbon system reviewed. Allotropes of iron. Definitions
of phases and basic steel types.
Typical microstructures and the nucleation and growth of pearlite.
Development and use of TTT and CCT diagrams.
Structural aspects of pearlite, bainite and martensite.
Heat treatment of steels, including types of annealing, normalising
hardening and tempering. Quench media and relationship to TTT
diagrams, effect of section size and hardenability. The Jominy end
quench test. Microstructure of tempering. Martempering and
ausforming. Case hardening procedures.
Alloy Steels:
Reasons for, types and effects of alloying additions. Effect on
hardenability and ductile to brittle transition. Impurities in steels.
Special steels (HSLA, high speed, Hadfield)
Stainless steels, details of types, properties and application areas.
Weld decay.
Cast Irons:
Introduction to types, microstructures and uses. Effect of cooling
rate on cast microstructure.
Al Alloys:
Types, designation and introduction to microstructure. The age
hardening process in detail and its influence on properties in Al-Cu
alloys. Uses of these alloys, problems with welding.
Cu Alloys:
Overview of brasses, bronzes and others in relation to relevant
phase diagrams.
Ni Alloys:
Overview of superalloys and monels.
Ti Alloys:
Overview of titanium alloy types, advantages and uses.
Microstructure and phase diagrams.
Ceramics:
A brief introduction to ceramics & glasses. Differences in structure
between glasses and ceramics, use of network modifiers, firing and
forming of engineering ceramics. Brief coverage of phase
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diagrams, applications and glass ceramics.
Composites:
A brief introduction to composites, types, definitions, uses and
advantages.
Fracture:
The concept of brittle and ductile fracture and degree of plasticity.
The theoretical strength of solids and the role of the defect in
premature failure. Stress concentrations.
Ductile tearing, microvoid coalescence and cleavage
as micromechanisms of fracture failure. The plastic zone.
Development of the Griffith theory and stress intensity factor.
Important consequences of the Griffith theory with respect to design.
Brief introduction to LEFM and K1C
Fatigue:
The concept of fatigue failure
Stress amplitude and fatigue life. Other definitions.
High cycle and low cycle fatigue and the effect of mean stress.
Coffin-Manson, Goodman and Miner's Rules etc. The importance
of probability in fatigue and the need for testing.
Fatigue of cracked components, the Paris Law and determining
remaining lifetime of components.
Fatigue micromechanisms, for initiation and propagation.
Coping with fatigue. Design considerations and manufacturing
methods to resist fatigue failure.
A fatigue failure design case study.
Corrosion:
Basic introduction to chemistry of corrosion and oxidation.
Types of chemical corrosion, idea of electrode potential and
importance of EMF series. Composition cells, stress cells as
sources of corrosion. Crevice corrosion. Stress Corrosion and
galvanic corrosion mechanisms.
Corrosion control. Use of inhibitor and galvanic protection methods.
Sacrificial anodes and impressed current methods. Types
and influence of coatings, from polymer & metallic to ceramic.
Designing out corrosion.
Creep:
The concept of time dependent deformation in metals under
constant load. Basic definitions. Influence of time and temperature
on creep. Mechanisms of creep in metals. Methods of dealing with
creep. A manufacture and design case study - gas turbine blades.
General Learning Outcomes
Knowledge and understanding
The properties of metals, polymers and composites and their common processing methods; appropriate
service conditions and long term performance of different materials; environmental issues associated with
different materials; an awareness of interactions between structure/processing/properties; an introduction
to fracture mechanics; integrate knowledge of engineering science, design, business context and
engineering practice, to solve product design and manufacture problems; design methods and their
application to manufacturing design.
Skills and attributes
(i) Intellectual
Select appropriate materials and processes for a given application; identify the engineering requirements
of a component and define how these can be achieved through processing and manufacture; the
application of fracture mechanics in the assessment of remnant life in metals.
(ii) Practical
Generate a case study through research and material investigation of a component failure; metallographic
and material testing.
(iii) Transferable
Report on an evaluation of the design and manufacturing problems clearly and concisely and provide a
solution, if feasible; work as part of a team.
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