National Diploma in Engineering
Properties and Applications of Engineering Materials
Assignment booklet
Don’t forget that when submitting work you must declare which outcome you are claiming. (P1, M3, D2, for example)
Don’t forget to put your name on all submitted work.
When requested, work must be submitted with the assignment facing sheet, signed.
Make sure that you understand the work you have submitted. You may be asked questions upon submission.
Work which is not reasonably presented might not be accepted.
P1 describe the structure (including the atomic structure) associated with a given metal, polymer, ceramic, composite and smart material
Describe the structure (including the atomic structure) associated with each of the following materials. Identify the nature of the bonds between atoms and molecules, in particular identifying where you will find covalent, ionic and metallic bonds.
(i) With reference to tin-lead solder, explain what a eutectic mixture is. Show a phase diagram and explain what it shows.
(ii) With reference to a suitable micrograph or sketch, including the scale, show the typical granular structure of typical plain carbon steel.
Explain how the grains form from the melt.
Identify and describe the lattice structure associated with the ferrite.
The pearlite is a layered structure. What are the layers?
Identify and describe the lattice structure associated with the cementite.
What effect does increased carbon content have on the number of pearlite grains?
Explain what you would expect to see at the microscopic level as the carbon content exceeds 1.7%
(iii) With reference to the molecular bonds and cross links, explain why it is possible to melt and reuse a thermoplastic polymer, but not a thermosetting polymer. Show a polymer molecule, for example a polythene polymer, and identify the elements and bonds it contains.
(iv) Explain what is meant by the glass transition temperature in polymers.
(v) Using examples explain how ceramics can have an amorphous structure, a crystalline structure or a combination.
(vi) Using examples of composite materials describe what the matrix is and what the reinforcement is. Explain how a composite can be particulate, fibrous or laminated.
(vii) With reference to piezoelectric materials, electro-rheostatic or magneto-rheostatic materials, and shape memory alloys, explain how smart materials can have crystalline, amorphous or metallic structures.
P2 classify given engineering materials as either metals or non-metals according to their properties.
The list of engineering materials below contains materials from the following categories:-
i) Ferrous alloy.
ii) Non-ferrous metal.
iii) Non-ferrous alloy
iv) Thermoplastic polymer
v) Thermosetting polymer
vi) Elastomer
vii) Ceramic
viii) Composite
ix) Smart material
x) Natural material.
Link each of the materials below to one or more categories and say why the material belongs in those categories. The materials are:-
a) Latex
b) Copper
c) Stainless steel
d) Brass
e) Fibre glass
f) PVC
g) Piezoelectric crystal
h) Bakelite
i) Concrete
j) Wood
P3 describe mechanical, physical, thermal and electrical and magnetic properties and state one practical application of each property in an engineering context.
The mechanical properties you need to describe are: tensile strength, shear strength, compressive strength; hardness; toughness; ductility; malleability; elasticity; brittleness.
The physical properties are: density; melting temperature.
The thermal properties are: expansivity; conductivity.
The electrical and magnetic properties are: conductivity; resistivity; permeability; permittivity.
P4 (See also M1) describe the effects on the properties and behaviour of processing metals, polymers, ceramics and composites and of post-production use of smart materials.
(i) Describe how the cooling rate of bronze when cast for a bearing can affect the distribution of the constituent elements, and describe what effect this has on the properties of the bearing material. What can be done to control the cooling process?
(ii) Describe how processing temperature and evenness of cooling affect the properties of thermoplastic polymers in service
(iii) Explain why curing is important in thermosetting polymers and describe the effects of incomplete curing.
(iv) Describe what is meant by sintering in the context of ceramic processing and its importance to the finished product.
P5 (See also D1) use information sources to select a different material for two given applications, describing the criteria considered in the selection process.
(i) With reference to BS EN 13261:2009 describe the principal selection criteria for a railway carriage axle.
(ii) Select a suitable material for the mass production of sports drink bottles, based on a variety of information sources. Among the criteria you should consider are safety (e.g. toxicity), cost, availability, recyclability, material properties such as strength, weight and elasticity, and other criteria you may consider important.
P6 describe the principles of the modes of failure known as ductile/brittle fracture, fatigue and creep.
(i) Compare the processes of ductile and brittle fracture. Describe the appearance of the fracture surfaces in each case.
Explain, with a relevant diagram, the transition temperature for steel.
(ii) Explain, with a relevant diagram, for example an S-N curve, what is meant by fatigue in the context of cyclic loading in components. Describe the appearance of the fracture surfaces that would indicate fatigue stress. What are the stress concentrators that will promote fatigue stress?
(iii) Explain, with a suitable diagram, such as a strain versus time curve, what is meant by creep in the context of components subjected to constant stress. Describe the processes of primary, secondary and tertiary creep. How is the rate of creep affected by temperature, grain size and the magnitude of the applied stress?
P7 (See also M2 and D2) perform and record the results of one destructive and one non-destructive test method using one metal and one non-metallic material.
Write a report based on the following two tasks. In addition to the report you will be observed performing the test and a witness statement will be signed.
Task 1: Use the tensile testing machine and the associated computer software to produce a graph of stress against strain for a given polymer sample. Ascertain Young`s modulus, ultimate tensile strength and the yield stress of the sample.
Task 2: Conduct a visual inspection of a galvanised steel crash barrier and lamp post and record the results. State what processes of degradation might occur in these items and report your findings.
P8 (See also M3) describe a different process of degradation associated with each of metals, polymers and ceramics.
Describe the processes of galvanic corrosion, erosion and stress corrosion in metals, solvent attack and radiation effects on polymers, and thermal shock in ceramics.
M1 explain how the properties and structure of different given engineering materials affect their behaviour in given engineering applications.
This is an extension of the work you will do for P1 and P4. For example, when a force is applied to a piezoelectric material it produces an electric charge which can be used to trigger a car`s airbag in the event of an accident.
You have also studied how the quality of steels affects their behaviour in service, for example how this affects the transition temperature in steels that have been used in shipbuilding.
It is the internal structure of metals which determines their resistance to fatigue stress in service.
In rubber it is the arrangement of the polymer molecules which allow considerable reversible extension and make it a suitable material for car tyres.
M2 (See P7, D2) explain how one destructive and one non-destructive test procedure produces useful results.
This will follow on from the work you did for P7.
Task 1. Explain the relevance of tensile testing to the real life application of materials, for example in components that will be subjected to loads in service.
Task 2. Explain the importance of visual inspection in ensuring that street furniture is fit for purpose. Consider, for example, the safety implications and the costs of not maintaining these items.
M3 explain how two given degradation processes affect the behaviour of engineering materials.
This will be an extension of the work you did for P8. For example, how does the corrosion of a component experiencing a tensile or compressive load affect the stress in the component?
D1 justify your selection of an engineering material for one given application describing the reasons the selection meets the criteria.
This will follow on from your work for P5. This can be an example from your project. In particular, you need to give reasons for selecting a particular material and why other materials considered for the application were not selected. For example, if you chose to talk about a steel beam in your answer to P5 you could go on to say what other materials you considered and why you chose steel and not the alternatives. You need to consider the service environment, loads, forces, design life, relative cost, safety and efficiency among other factors.
D2 evaluate the results of one test procedure.
This will follow on from the work you did for P7 and M2. You need to write a report which evaluates the results of one of the tests you carried out for P7 and M2. For example, when carrying out a tensile test on various polymers, you could explain how the value you obtain for Young`s modulus is dependant on the internal structure and the strength of the internal bonds.