Structural Dynamics Research in Mechanical Engineering at the University of Sheffield

The Dynamics Research Group (DRG) based in the Department of Mechanical Engineering at the University ofSheffield conducts research into vibrations and the dynamics of structures. The main areas of research are:nonlinear dynamics, structural health monitoring, active and passive vibration control, smart materials andstructures and acoustics.In the field of nonlinear dynamics, the main area of research is concerned with nonlinear system identification,currently centred on Bayesian methods, machine learning and optimisation-based approaches. The group iscurrently part of an EPSRC Programme Grant consortium on 'Engineering Nonlinearity' – a multi-million poundprogramme based on a collaboration between researchers in Bristol, Cambridge, Sheffield, Southampton andSwansea. The group also has considerable expertise in analytical nonlinear dynamics and applications ofcomputer algebra in the field, control of nonlinear systems and in uncertainty analysis for nonlinear systems.Our research into Structural Health Monitoring (SHM) is mostly focused on machine learning and patternrecognition methods an approach pioneered in Sheffield in collaboration with colleagues from Los AlamosNational Laboratory in the US. Both vibration-based and ultrasonic SHM methods are pursued within the groupand the dominant applications are currently to civil infrastructure (mainly bridges) and aerospace structures.Recent work has seen an expansion into the field of renewable energy with projects on the condition and healthmonitoring of wind turbines. Experimental verification and validation is a strong element of the SHM work. Manyof the machine learning algorithms are based on biologically-inspired ideas, such as artificial neural networksand evolutionary algorithmsIn terms of active and passive vibration control, our main efforts have been in the development of novel materialdamping technologies and for many years the group hosted a Rolls-Royce UTC on the subject. Technologiesdeveloped and extended within the group – like particle dampers – have been successfully adopted by aerospaceindustry. The group also has expertise in active control applied to manufacturing processes e.g. in the mitigationof 'chatter', a notoriously destructive problem of excessive vibration that can occur in cutting operations. Recentdevelopments in the area of vibration control have successfully incorporated 'hardware-in-the-loop' concepts.A closely related technology to vibration suppression is that of energy harvesting and a number of recentprojects in this area have been carried out within the DRG; this work has overlapped substantially with the workon nonlinear dynamics.In the area of smart materials, the group has considerable expertise in piezoelectric actuation, shape memoryalloys and Electroand Magneto-Rheological (ER and MR fluids); applications include automotive and railwaydamping systems and biomechanical systems. In recent years the MR fluid technology proved very successful indeveloping mountain bicycle dampers.Finally, in the field of Acoustics, fundamental research is carried out in the numerical analysis of soundtransmission in complex materials and structures and also applied research is carried out in the acoustics ofwater pipelines; the group is associated with the Pennine Water Group and has a strong link with theDepartment of Civil and Structural Engineering in the University of Sheffield. References1. Worden (K.) and Tomlinson (G.R) 2001 Nonlinearity in Structural Dynamics: Detection, Identification and Modelling.Institute of Physics Press.2. Wagg (D.) and Neild (S.) 2010 Nonlinear Vibration and Control: For Flexible and Adaptive Structures. Springer.3. Farrar (C.R.) and Worden (K.) 2012 Structural Health Monitoring: A Machine Learning Perspective. John Wiley and Sons.