EL3147 Digital Signal & Image Processing A Assessment: Non-Destructive Identification of Mechanically Stronger Composite Plates
School of Engineering
UCLan Coursework Assessment Brief
Module Title: Digital Signal & Image Processing A Module Code: EL3147
Academic Year
2022/23
Non-Destructive Identification of Mechanically Stronger Composite Plates
This assessment is worth 25% of the overall module mark
In this assessment, the student will demonstrate the ability to:
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Demonstrate an understanding of, and an ability to use, appropriate analysis techniques for digital signals and images.
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Apply and assess 1-D digital filters and their design, analysis, representation and implementation using appropriate methods including computer-based simulations.
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Appraise an appropriate fast prototyping software development platform to analyse digital signals and/or images and thereby specify processing requirements for particular practical applications.
Assessment Elements
Task 1: Signal Analysis
Task 2: Noise Reduction
Task 3: Attenuation Estimation
Task 4: Part Sentencing
Aim
Total
Weighting (%)
24 36 20 20 100
Assessment Brief
This assignment is designed to give students an introduction to digital signal and image processing (DSIP) through their applications in ultrasonic non-destructive evaluation of engineering structures. You are required to use the Matlab software package to design and implement a DSIP system to identify a mechanically stronger plate manufactured using composite carbon fibre materials.
Background and Problem
In a carbon fibre composite part, porosity is a defect that appears as small interlaminar voids. As the level of porosity increases, the mechanical strength of the composite part decreases. To evaluate the porosity level non- destructively, ultrasonic measurement is commonly employed. The process involves transmission of high-intensity ultrasonic waves through the component part under measurement and assessment of the relative amplitude values of the echoes reflected respectively from the front wall and the back wall of the composite part. A higher ultrasonic attenuation indicates a less dense composite part with higher porosity.
Two ultrasonic data files obtained from two laminated composite material plates with 3 mm thickness are provided as "Composite1.mat" and “Composite2.mat”. The data was acquired with a sampling frequency at 100 MHz over an area of 40 mm x 20 mm with 1 mm resolution. You are asked to produce a Matlab program to process the ultrasonic data and to identify which composite plate has the stronger mechanical strength overall.
Relevant files for the assignment are provided as email attachment together with this assignment brief and marking scheme for report writing.
Requirements
Task 1: Signal analysis
Ultrasonic signals are noisy in nature due to the back scattering phenomenon produced by the inherent
microstructure of the material. The first step is to extract a typical ultrasonic signal from each composite part under
test, and to carry out detailed signal analysis in the time and frequency domains to identify key signal features
such as locations, magnitudes and frequencies for ultrasonic echoes and noise.
Task 2: Noise reduction
With the ultrasonic measurement operating at a particular frequency band, the second step is to implement a
suitable digital filtering system to reduce the impact of out-of-band noise on ultrasonic echoes, and to demonstrate
the effectiveness of the filter by comparing the output with respect to input in the time and frequency domains. A
good filter should yield an output signal that is as similar to the original signal as possible in the two ultrasonic
echo intervals (with minimum amplitude distortion) and as near to zero as possible outside the two ultrasonic echo
intervals.
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Task 3: Attenuation estimation
The fourth step is to estimate the attenuation of the back wall echo with respect to the front wall echo. This involves
application of the filter developed in the second step to the whole ultrasonic record of each composite plate,
extraction of the two peak values from the front wall and back wall echoes in each ultrasonic signal, and calculation
of the echo attenuation at each ultrasonic measurement point. The results should lead to two echo attenuation
images for comparative visualisation of two composite plates.
Task 4: Part sentencing
The final step is to show the two distributions of the echo attenuation values obtained from the third step, to
compute basic statistics for the two distributions, and to use the results to determine which composite plate has
the stronger mechanical strength overall.
Submission details:
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A full report including the program code to perform non-destructive identification should be submitted via Turnitin on Blackboard.
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The report should be structured according to the above requirements based on the detailed marking scheme provided.
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The report length is expected to be around 15 pages (indicative). RELEASE DATES AND HAND IN DEADLINE
Assessment Release date: 23/11/2022 Assessment Deadline Date and time: 24/03/2023 (11:59pm)
Please note that this is the final time you can submit – not the time to submit!
Your feedback and mark for this assessment will be provided within 15 working days via email.Late work
Work submitted electronically may be submitted after the deadline to the same Turnitin assignment slot and will be automatically flagged as late.
Penalties for late submission
Unless an extension of the hand-in deadline date has been approved in due time, lateness penalties will be applied in accordance with University policy as follows:
(Working) Days Late
1 - 5
more than 5
Penalty
maximum mark that can be achieved: 40% 0% given
Plagiarism will be penalized as per the University rules. For detailed information on the procedures relating to plagiarism, please see the current version of the University Academic Regulations.
HELP AND SUPPORT
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For support of the coursework, please contact Lik-Kwan Shark (LShark@uclan.ac.uk).
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For support with using library resources, please contact Neil Marshall (NMarshall7@uclan.ac.uk). You will
find links to lots of useful resources in the My Library tab on Blackboard.
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If you have not yet made the university aware of any disability, specific learning difficulty, long-term health or
mental health condition, please complete a Disclosure Form. The Inclusive Support team will then contact to discussreasonableadjustmentsandsupportrelatingtoanydisability. Formoreinformation,visittheInclusive Support site.
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To access mental health and wellbeing support, please complete our online referral form. Alternatively, you can email wellbeing@uclan.ac.uk, call 01772 893020 or visit our UCLan Wellbeing Service pages for more information.
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If you have any other query or require further support you can contact The <i>, The Student Information and Support Centre. Speak with us for advice on accessing all the University services as well as the Library services. Whatever your query, our expert staff will be able to help and support you. For more information , how to contact us and our opening hours visit Student Information and Support Centre.
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If you have any valid mitigating circumstances that mean you cannot meet an assessment submission deadline and you wish to request an extension, you will need to apply online prior to the deadline.
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Marking scheme
Task No
T1
T2
T3
T3.2 T3.3 T3.4
T4
Task Description Marks
T1.1 T1.1.1
T1.1.2
T1.1.3 T1.2
T1.2.1 T1.2.2 T1.2.3
Signal Analysis 24 Time domain analysis including
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Program with comments to read, extract and plot ultrasonic signals
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Waveforms produced with correct scale
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Comments on the waveforms observed
Frequency domain analysis including
• Program with comments to plot magnitude frequency spectrum • Spectrum produced with correct scale• Comments on the spectrum observed for echo signal and noise
Noise Reduction 36
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Program with comments to yield filter coefficients and filtered
signal
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Filter frequency response produced with correct scale
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Filtered signal produced with correct scale
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Magnitude frequency spectrum of filtered signal
T2.1
T2.2
T2.3
T2.4
T2.5 •
T2.6 •
Comments on output with respect to input in time and frequency
domains
Effects of cut-off frequency and filter order on filtered signal
Attenuation Estimation 20 • Program with comments to filter all signals and generate
attenuation image
• Illustration of echo peaks extracted and attenuation estimated
• Attenuation images of two different composite plates
• Comments on attenuation images observed
Part Sentencing 20 • Program with comments for statistical analysis of ultrasonic
attenuation
• Ultrasonic attenuation histograms
• Statistics derived from ultrasonic attenuation histograms
• Mechanically stronger composite plate identified with
justification
Total 100
Disclaimer: The information provided in this assessment brief is correct at time of publication. In the unlikely Version:
event that any changes are deemed necessary, they will be communicated clearly via e-mail and a new version 2.0 of this assessment brief will be circulated.
