Dynamics

Research Summary

The group conducts research into vibrations, dynamics of structures and acoustics. The main areas of research are: nonlinear dynamics, structural health monitoring, active and passive noise and vibration control, smart materials and structures and acoustic instrumentation.

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 is currently part of an EPSRC Programme Grant consortium on 'Engineering Nonlinearity' – a multi-million pound programme based on a collaboration between researchers in Bristol, Cambridge, Sheffield, Southampton and Swansea. The group also has considerable expertise in analytical nonlinear dynamics and applications of computer algebra in the field and in uncertainty analysis for nonlinear systems.

Our research into Structural Health Monitoring (SHM) is mostly focused on machine learning and pattern recognition methods - an approach pioneered in Sheffield in collaboration with colleagues from Los Alamos National Laboratory in the US. Both vibration-based and ultrasonic SHM methods are pursued within the group and the dominant applications are currently to civil infrastructure (mainly bridges) and aerospace structures. Experimental verification and validation is a strong element of the SHM work. Many of the machine learning algorithms are based on biologically-inspired ideas, such as artificial neural networks and evolutionary algorithms. The group develops new solutions for the inspection of underground pipes which include novel methods of robotic sensing.
In terms of active and passive vibration control, our main efforts have been in the development of novel material damping technologies and for many years the group hosted a Rolls-Royce UTC on the subject. Technologies developed and extended within the group – like particle dampers – have been successfully adopted by aerospace industry. The results of our research on acoustics of poroelastic materials are used by manufacturers of noise and vibration control solutions. The group also has expertise in active control applied to manufacturing processes e.g. in the mitigation of 'chatter', a notoriously destructive problem of excessive vibration that can occur in cutting operations. Recent developments in the area of vibration control have successfully incorporated 'hardware-in-the-loop' concepts.

In the area of smart materials, the group has considerable expertise in piezoelectric actuation, shape memory alloys, Electro- and Magneto-Rheological (ER and MR fluids) and acoustic metamaterials. Applications include automotive and railway damping systems, biomechanical systems and industrial noise control. In recent years the MR fluid technology proved very successful in developing mountain bicycle dampers.

More specific areas of expertise which the group covers can be found here.


Facilities

The Dynamics Research Group in Sheffield currently numbers 65 members including 14 permanent academic staff, 10 postdoctoral researchers and around 30 PhD students. The group manages three separate laboratories: the Materials Damping Laboratory, the Materials Characterisation Laboratory, JONAS Laboratory and Acoustics Laboratory. These are fully equipped with state-of-the-art dynamic and material testing, acoustic emission, acoustic material characterisation, anechoic chamber with microphone arrays and ultrasonic wave equipment for conducting research and providing consultancy services to industrial customers.

Our industrial partners include, or have included: BAE Systems, EDF, FIAT, HBM-nCode, Johnson Controls, Messier-Bugatti-Dowty, Rolls-Royce, and Volkswagen. Strong collaboration has developed with the University's Advanced Manufacturing Research Centre (AMRC). The Group is developing a bespoke Laboratory for Validation and Verification (LVV) which will enable the team to study the dynamic and acoustic behaviour of full-scale systems in various climatic conditions.