The Sound & Vibration Research Group
The Department of Mechanical and Mechatronic Engineering at Stellenbosch University
The Sound and Vibration Research Group (SVRG) is situated in the Department of Mechanical and Mechatronic Engineering at the University of Stellenbosch. The SVRG has established expertise, equipment and laboratory facilities to conduct research and investigations into noise and vibration problems for industry as well as the public sector. Our research is primarily focused on human response to vibration and dynamic structural loading in the marine, automotive and mining industries.
- To establish a centre of expertise in sound and vibration measurement, analysis and assessment with the associated measurement equipment and software tools to contribute to the international research arena.
- To train engineers with the necessary skills and knowledge to work in the field of sound and vibration research and to serve industry as specialists in the field.
- To assist South African companies in solving sound and vibration problems to ensure that their products are more competitive and that their workforce enjoys a safe and healthy working environment.
AREAS OF EXPERTISE
- General noise and vibration measurement, analysis and assessment to reduce overall noise and vibration levels, troubleshoot specific problems and investigate the application of advanced methodologies, such as vibration monitoring, to reduce maintenance and operating cost.
- Modal analysis, both experimental and using finite element models to verify structural response.
- Signature testing and order analysis on rotating machines.
- Measurement and assessment of industrial noise and vibration to ensure healthy and safe working environments.
- Assessment of automotive NVH (noise, vibration and harshness) according to national and international standards.
- Environmental testing of components and structure for vibration endurance.
- In-situ measurements of sound for playback in jury panel evaluations and the calculation of metrics to assess the sound quality of products and vehicles.
DIGITAL TRANSFORMATION OF THE SA AGULHAS II
Industry 4.0 is the digital transformation of global industry. Digital twins pose to disrupt conventional business as they harness real-time data alongside a digitized representation of the state and behaviour of real assets to offer decision support. Sound and vibration research often entails multi-sensor measurements, signal processing and analytics providing an ideal training background to embrace the current innovation climate.
HEALTHPROP pursues life prediction and health monitoring of a marine propulsion system under ice impact. During ice navigation, ship propulsion system failures pose grave implications, as vessels often cannot be repaired outside of port, creating risks to the vessels and their passengers as well as great logistical challenges for supporting rescue operations and infrastructure. Stellenbosch University will partner with the Norwegian University of Science and Technology, the Technical University of Hamburg, RWTH Aachen, Piening propeller and EDRMedeso to develop a digital twin for the remaining useful life of a ship propulsion exposed to ice impact. This 36 month project will kick off in August 2020 and will be commissioned and evaluated on the SA Agulhas II on full-scale.
SOUTHERN OCEAN SEASONAL EXPERIMENT
This interdisciplinary experiment aims to span seasonal and decadal time scales in the south east Atlantic sector of the Southern Ocean, thereby contributing long-term observations towards a greater understanding of the Southern Ocean seasonal cycle. The spring and winter cruises of the SA Agulhas II exposed the vessel to large waves and rough weather for a unique study of wave slamming, and the effects of these vibrations on the ship hull structure and the well-being of passengers. Current investigations focus to determine if vibration from wave slamming will lead to premature fatigue of the structure and what vibration thresholds disturb sleep and work of the people on board.
THE WEDDELL SEA EXPEDITION
In January 2019 the SA Agulhas II embarked on the Weddell Sea Expedition, funded by the Flotilla Foundation. The ship would be the first vessel to sail in this remote environment since the Polarstern in 2004. The ice-going limits of this PC-5 vessel would be challenged by the effort to navigate through multi-year ice to reach the wreck site of Sir Ernest Shackleton’s Endurance. This voyage allowed the unique capture of data, including multiple ice ramming events, during which the SA Agulhas II carved out almost a square kilometre of ice to recover an Automated Underwater Vessel from under a multi-year ice floe. Sensor data confirmed that the hull of the SA Agulhas II is prudently strengthened to DNV ICE-10 and that the limiting factor in her ice-going ability is her propulsion power.
POLARSTERN: FULL-SCALE OPERATIONAL MODAL ANALYSIS
In 2016 two students from the SVRG participated in the PS-100 voyage from Tromso in Norway, via Svalbard to the Arctic onboard the German RV-Polarstern. The ship was equipped with 2 km of cable to allow for a network of 20 accelerometers to be installed throughout her hull structure. Strain gauges were also added to her shaft to allow engineers to determine her propulsion thrust and the twisting torque in the shaft-line when ice impacts the propellers. Stellenbosch University determined the principal modes of bending and twisting of the ship when she voyages in ice in collaboration with the German Space Agency and the Technische Hochschule, Ingolstadt, Germany.
OPERATIONAL WHOLE-BODY VIBRATION ASSESSMENT
The SVRG assessed the occupational whole-body vibration of heavy mobile equipment operators at a South African opencast mine. A fleet of 22 vehicles were measured in 32 different operational measurements accumulating 68 hours of data. The rugged terrain included sandy dunes, gravel roads, forest and plantations in a warm, humid climate. A field data sheet was developed and occupational health and safety teams were trained in rigorous measurement practice. Seated operators in this environment are regularly exposed to shock, much of which can be reduced by simple interventions such as installing ramps at level changes in warehouses.
Weddell Sea ExpeditionPast projects
Electric Motor Model AnalysisGallery
4 Bulldozers move a pumpPast projects
SAA II approaching Cape TownGallery
S.A. Agulhas II at workGallery
S.A. Agulhas II in AntarcticaGallery
S.A. Agulhas II from a distanceGallery
Ice Core TeamGallery
Agulhas II Ice ShelfGallery
Enjoying Antarctic wildlifeGallery
The team @workGallery
- Soal, Y. Govers, J. Bienert, and A. Bekker. (2019) System identification and tracking using a statistical model and a Kalman filter, Mechanical Systems and Signal Processing, 133, p. 106127.
- Vichi, M., Eayrs, C., Alberello, A., Bekker, A., Bennetts, L., Holland, D., et al. (2019). Effects of an explosive polar cyclone crossing the Antarctic marginal ice zone. Geophysical Research Letters, 46, 5948 – 5958.
- Swart, D.J., Bekker, A. (2019) The relationship between consumer satisfaction and psychoacoustics of electric vehicle signature sound. Applied Acoustics, 145, pp.167-175.
- Swart, D.J., Bekker, A., Bienert, J. (2018) Electric vehicle sound stimuli data and enhancement. Data in Brief, 21, pp.1337-1346.
- De Waal, R.J.O., Bekker, A. and Heyns, P.S. (2018) Data for indirect load case estimation of ice-induced moments from shaft line torque measurements, Data in Brief, 19, pp. 1222-1236.
REFEREED CONFERENCE PAPERS
- Bekker, A., Muiyser, J. & Purcell, E. (2019), The effect of measurement duration on daily whole-body vibration exposure metrics, 26th International Congress on Sound and Vibration, Montreal, Canada.
- Bekker, A., Muiyser, J. & Purcell, E. (2019), Whole-body vibration of heavy mobile equipment operators at an opencast mine, 26th International Congress on Sound and Vibration, Montreal, Canada.
- Nickerson, B.M. & Bekker, A. (2019),’Validation of external moment determination for the shaft-line of the S.A. Agulhas II’, International Conference on Ocean, Offshore & Arctic Engineering, Glasgow, Scotland.
- Bekker, A. Lu, L., Van Zijl, C.M., Matthee, J. & Kujala, P. (2019), ‘Correlation between bow ice loads and operational responses during ice navigation in the Weddell Sea’, International Conference on Port and Ocean Engineering under Arctic Conditions, Delft, Netherlands.
- Bekker, A. & Van Zijl, C.M. (2019),’ The use of line detection to identify random impulses in long time histories’, International operational modal analysis conference (IOMAC), Copenhagen, Denmark.
Some Fun Facts
Prof Annie Bekker
Landline: +27 21 808 3914