Mechanics NAME OF LECTURER: Dr Annie Bekker

199 Pages·2015·3.54 MB·English

by  Stoffberg, Beryl

DIVISION: Mechanics

NAME OF LECTURER: Dr Annie Bekker

Reference: ABEK1

PROJECT TITLE: The reconstruction and assessment of human vibration on the
Dynamic Seat Testing Facility
CAN PROJECT BE COMPLETED IN THE 1st SEMESTER? (Yes/No) No
DIRECTION: Mechanical (Yes) Mechatronic (Yes)
STUDENT:
DESCRIPTION:
A time-signal of a recorded vibration stimulus from a harsh environment will be
reconstructed on the platform of the Dynamic
Seat Testing Facility in the Structural
Laboratory. This stimulus will be recorded on
the chassis of a vehicle while driving over a
rough road. The necessary user interface and
analysis tools are to be developed in LabView
and MATLAB to enable vibration reconstruction
on the platform of the dynamic seat testing
facility from a computer interface. The
reconstructed signal in the laboratory should
match the test signal in both the time and
frequency domain on a test seat for different seated subjects. The algorithm will be
validated through physical tests on the platform with seated subjects. This will
involve the measurement of the seat transmissibility function and will require real-
time vibration signal analysis for human comfort according to ISO 2631-1.
Elective module required (only for Mechanical): Finite Element Methods
Reference: ABEK2

PROJECT TITLE: The manipulation of vehicle interior sound by the use of image
processing to identify sound phenomena from spectrograms.
CAN PROJECT BE COMPLETED IN THE 1st SEMESTER? (Yes/No) No
DIRECTION: Mechanical (Yes) Mechatronic (Yes)
STUDENT:
DESCRIPTION:
The exhilaration of driving a vehicle is closely
related to the sound quality and noise
experienced by the occupants in the
passenger cabin. Current advances in sound
trouble shooting include the use of image
recognition in sound spectrograms. These
spectrograms involve the presentation of data
such that a colour plot of sound the sound
magnitude at each frequency is presented as a function of time. Various sounds
(such as rattles and squeaks, pure tones, vehicle accelerations) will be recorded.
Artificial sound manipulation concepts will be generated, such as frequency and
amplitude modulation functions. The stimuli will be presented as spectrograms and
exposed to image processing techniques to attempt to identify the prevailing
patterns that characterize different sounds. These techniques will be implemented
to manipulate and enhance vehicle drive-train sounds in the passenger cabin.
Elective module required (only for Mechanical): None
Reference: ABEK3

PROJECT TITLE: DEVELOPMENT OF PAIRED COMPARISON PROCEDURES FOR
SOUND QUALITY METRICS
CAN PROJECT BE COMPLETED IN THE 1st SEMESTER? (Yes/No) Yes
DIRECTION: Mechanical (Yes) Mechatronic (Yes)
STUDENT:
DESCRIPTION:

The development of sound quality metrics entails paired comparison testing (similar
to eye tests performed by an optometrist) in a laboratory environment through
binaural headphones. The paired comparison test is a simple procedure that can be
used with untrained jurors (e.g. customers). A jury is asked to listen to pairs of
sounds and then choose one based
upon a question, for example;
“Which sound do you think is the
more powerful?” or “Which sound do
you think is louder?” Paired
comparison testing is a very time
consuming process. The purpose of
this project is to develop some paired comparison test procedures with an interface
in MATLAB. This entails a thorough literature survey and the engineering design of a
sound quality test. These procedures will be evaluated in terms of efficiency and
accuracy through jury testing of recorded sound stimuli.
Elective module required (only for Mechanical): None
Reference: ABEK4

PROJECT TITLE: The design and verification of a human vibration exposure
calculator
CAN PROJECT BE COMPLETED IN THE 1st SEMESTER? (yes / no) No
DIRECTION: Mechanical (Yes) Mechatronic (No)
STUDENT:
DESCRIPTION:
The mining industry has
to ensure that the work
environment adheres to
measures to encourage
the improvements in
the health and safety of
its work force. Workers
are routinely exposed to
hand-arm and whole-
body vibration in mining
environments, some
with potentially
hazardous effects on a
person’s health.. Occupational vibration will be assessed in a variety of working
conditions on-site. A human vibration calculator will be designed and implemented
to process measured data and calculate human vibration exposures. This entails the
use of the appropriate filters in the time-domain as specified in ISO 2631-1 (Whole-
body Vibration) and ISO 5349 (Hand-arm Vibration) and the calculation of the
appropriate metrics. The calculator will operate through a simple user interface
such that complex calculations can be routinely be performed by technicians in the
field and displayed in an intuitive manner.
Elective module required (only for Mechanical): None
Reference: ABEK5

PROJECT TITLE: The use of digital image correlation to determine the dynamic
deflection of beams in bending
CAN PROJECT BE COMPLETED IN THE 1st SEMESTER? (Yes/No) No
DIRECTION: Mechanical (Yes) Yes Mechatronic (No)
STUDENT:
DESCRIPTION:
A beam demonstration model will be
designed and built to allow the filming of
static and dynamic deflections with digital
equipment. The goal is to commission the
combined use of a high speed camera and
digital image correlation software in the
Structural Laboratory. Theoretical
calculation, finite elements and digital
image correlation techniques will be used to determine material properties and
boundary conditions of the demonstration rig. Static and dynamic beam deflections
will be determined analytically and through finite elements. These results will be
compared to those determined through digital image correlation to validate the
feasibility of the technique using a high-speed camera. Further conditions could
include an investigation of structural response in water to evaluate the effects of
hydrodynamic damping.
Elective module required (only for Mechanical): Finite element modelling
Reference: ABEK6

PROJECT TITLE: The design and construction of a musical instrument for the
illustration of the natural frequencies of systems
CAN PROJECT BE COMPLETED IN THE 1st SEMESTER? (Yes/No) Yes
DIRECTION: Mechanical (Yes/No) Yes Mechatronic (Yes/No) No
STUDENT:
DESCRIPTION:
A musical instrument will be designed and built with the express goal
to offer an audio-visual or audio-sensory demonstration of the
modes of continuous systems with the use of existing laboratory
equipment. The natural frequencies of this instrument will be
determined by experimental modal analysis and could be confirmed
by finite element modelling of the design. Engineering judgement is
required to determine the factors that cause the deviation between
the mathematical boundary conditions and the real life structure. This work can be
complimented by the possible use of material testing, optimization or image
processing techniques. Other innovative means, such as the design of an
instrument to provide sensory feedback of the sound experience could additionally
be investigated.
Elective module required (only for Mechanical): Finite element modelling
Reference: ABEK7
PROJECT TITLE: The development of a low-cost human vibration sensor for
operators of heavy mobile equipment
CAN PROJECT BE COMPLETED IN THE 1st SEMESTER? (Yes/No) No
DIRECTION: Mechanical (Yes/No) Yes Mechatronic (Yes/No) Yes
STUDENT:
DESCRIPTION:
The mining industry is under increased
pressure to ensure a healthy and safe
working environment for the operators of
Heavy Mobile Equipment (HME). Cost-
effective accelerometers will be sourced
and benchmarked against calibrated
instruments to enable more cost-effective
vibration measurements according to ISO
2631-1. Measurements will be conducted in
the laboratory and in the operational field.
The sensing equipment will be complimented by the required post-processing
capability such as the human weighting filters and injury risk assessment through
the calculation of Vibration Dose Values and other vibration exposure metrics.
Elective module required (only for Mechanical): Finite element modelling
NAME OF LECTURER: Albert Groenwold

Reference: AG1

PROJECT TITLE: Optical mirror scanner
CAN PROJECT BE COMPLETED IN THE 1st SEMESTER? (No)
DIRECTION: Mechanical (Yes) Mechatronic (Yes)
STUDENT:
DESCRIPTION:
Optical scanning has many applications. Scanners are for example used in image
projectors and displays, printers, and components in various sensor applications.
Currently, two concepts have been designed and manufactured, but the scanning
frequency of both is rather low. The project will involve the conceptualization,
manufacture and testing of a higher speed mirror scanner. The testing phase should
include a demonstration to describe prescribed patterns (e.g. a circle) from a single
unidirectional laser beam.
Elective module required (only for Mechanical): Finite Element methods
Reference: AG2

PROJECT TITLE: Wax-actuated switch
CAN PROJECT BE COMPLETED IN THE 1st SEMESTER? (No)
DIRECTION: Mechanical (Yes) Mechatronic (No)
STUDENT:
DESCRIPTION: With the advent of smart grid technologies, more and more
emphasis is being placed on the need to have better control over household
electricity usage without the need for more human input. A very important aspect
of this is the ability to interrupt the power supply to some dumb appliance.
Currently this can be done by charging a large capacitor, which unloads a pulse of
power to an electromagnetic coil. The magnetic field then causes a mechanical
switch to change state. However, this solution is expensive due to the required
hardware, and also due to the cost of the supporting circuitry which needs to
handle a high voltage and large current.
This aim of this project is to design an alternative switching solution, which makes
use of the concept of wax actuation. This involves the melting of wax and using the
resulting change in density to do work. The main requirement is that the switch has
to be operated with a low power input, but it is acceptable if the switch takes
several minutes to achieve full actuation.
The project will involve the conceptualization, manufacture and demonstration of a
wax-actuated switch; dramatic improvement of an existing design is envisioned.
Elective module required (only for Mechanical): CFD
Reference: AG3

PROJECT TITLE: A study of composite materials testing and failure
CAN PROJECT BE COMPLETED IN THE 1st SEMESTER? (No)
DIRECTION: Mechanical (Yes) Mechatronic (No)
STUDENT:
DESCRIPTION: The candidate will be involved in manufacturing and testing
samples to specified standards to capture tensile, compression and shear data. The
effect of resin content on the material properties will also be investigated. What is
more: the failure of composite materials is fairly well understood, but there are
huge anomalies in some of the analytical models. Indeed, some models very
popular in industry predict strangth ratios larger than one for specific loads. Further
to caracterizing the popular models, it is hoped that an alternative, physically
sensible model can be proposed.
Elective module required (only for Mechanical): Finite Element Methods

Reference: AG4

PROJECT TITLE: Fracture mechanics testing
CAN PROJECT BE COMPLETED IN THE 1st SEMESTER? (No)
DIRECTION: Mechanical (Yes) Mechatronic (No)
STUDENT:
DESCRIPTION: The candidate will be involved in manufacturing and testing
samples to specified standards to capture fracture mechanics characteristics using
standard fracture mechanics specimens. Previous studies in the Department have
suggested that digital image correlation (DIC) may not be an effective method for
measuring fracture toughness, although some reasonable results have been
reported in the literature. The efficiency of DIC on measuring fracture toughness is
to be determined, and experimental results are to be compared with numerical and
analytical results.
Elective module required (only for Mechanical): Finite Element Methods