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Engineering Materials I (ENME502)
Laboratory
WZ325, Weeks 3-4, July/August 2024
(Please see the attached for grouping and the time for each group to attend)
Title: Mechanical Properties of Materials
Objective: Firstly, conducting this laboratory tests and the analysis of the data obtained serve
to develop a good understanding on:
a. how strength of materials is determined,
b. how elastic modulus maybe estimated,
c. how tough (or brittle) materials maybe evaluated.
Secondly, this laboratory is for students to obtain firsthand property data and, being equally important, to obtain the property values determined from the laboratory tests to support the learning in this course/paper on:
a. what elastic modulus values of materials depend on,
b. what affect the strength and fracture strain of materials,
c. what are the methods of strengthening of metallic alloys,
d. what properties are important for forming in solid state.
Specimen: To serve the above objective, testing will be conducted using six (6) samples
from selected materials: one (1) each low strength and medium strength aluminium alloy sample, one (1) each low strength (mild) and medium strength steel sample, one (1) thermoset and one (1) thermoplastic polymer sample.
In the gauge length section of the samples: gauge length is 31 mm, width (machined to be) is 6 mm, thickness is nominally 3 mm, The exact values of the thickness of the samples and widths will be measured during the tests.
Equipment: Tensile testing machine and the associated displacement measurement (a. cross head and b. using an extensometer) and data acquisition facility/software.
Procedures: Tensile testing will be conducted with the cross head speed at 3 mm/min
(viscoelastic/plastic behaviours not considered in this lab). Load and extension (both cross head and clip edge displacement) will be recorded during each test thus students will be provided with the full sets oftest data.
Note: Students will come one group after another to the lab during the lab time so each student can come and take part in at least one test. Testing of samples will be recorded and the recording will be made available in Canvas.
Analyzing and writing a formal report including:
Background information
Procedures
Results
Discussion
Conclusion
References
General information about tensile testing and data analysis will be discussed in class and the lecture notes will be provided. Using the testing data, students will analyse the data and plot tensile curves and determine various property values. Students will write a formal report (15% weighting of the paper) including:
a. Introduction (information on strength of materials, their measurement/estimation, and what this lab is about) – aparagraph of 6-8 lines with an engineering illustration [ 1.5 marks]
b. Experimental Procedures (what materials and testing machine were used, size of each sample, how tests are conducted and how the property values are determined or estimated) – using a table, 3-4 images, relevant formulas, 4-5 paragraphs to illustrate/explain [4 marks]
c. Results (plotting curves and reporting the values determined) – 12 curves and a table (of values determined: modulus, yield strength, UTS, and fracture strain) to report, 4-5 paragraphs to explain [4 marks]
d. Discussion – from the tensile curves and determined values, ~4 paragraphs to explain
- the various structure-property relationships (methods of strengthening in metallic alloys, ductility),
- why elastic modulus is difficult to be precisely determined using tensile testing [4 marks]
e. General presentation – Write the report following the required technical reporting
sequence, describing/explaining properly (not just bullet points) and presenting data using figures and tables properly numbered and referred to in text and with self-explanatory captions, referencing properly. [ 1.5 marks]