Dynamics - Projects & Facilities
The group is active in the following areas:
Acoustic & Vibration
We have excellent experimental facilities which include a new purpose-built Acoustics and Vibration Laboratory comprising state-of-the-art Anechoic and Reverberation chambers. Major areas of current research activity include: Generation and propagation of structural vibrations in cars and aircraft, Vehicle and aircraft interior noise, Vibrations and waves in complex structures, Vibrational power transmission techniques, Statistical Energy Analysis (SEA), Noise Path Analysis (NPA), Acoustic evaluation of vehicle integrity, Ground vibrations from rail and road traffic, Acoustics of aperture devices, Duct acoustics, Powertrain acoustics, Vibration transmission in built-up structures
Dynamics of Strongly Nonlinear Systems
Research area includes fundamental studies of synergistic effects of multiple impact interactions in solids, excitation and control of non-linear resonances in contact zones, development of methods for analysis and simulation of vibro-impact systems. These reveal the basic mechanisms of dynamic contact phenomena for mutual applications in machine dynamics, vibration engineering, structural mechanics and material processing.
Nano-scale Physics of Motion
In many engineering applications the trend is toward component miniaturisation. This is evident from rapid growth in the area of nano-technology and micro-engineering, with diverse applications. The physics of motion in nano-scale, however, is not well understood, with kinetic interactions often not being in accord to Newtonian physics, whilst not complying necessarily to other established theories of physics in any form other than by an initial postulate such as quantum mechanics. Of particular interest are lightly loaded tribological conjunctions between molecularly smooth contiguous bodies in contact. Much of modern information storage and retrieval systems' performance depend on the fundamental behaviour of molecular interactions in such vanishing narrow gaps. Other dynamic phenomena of significant importance is the elastic and viscoelastic behaviour of thin layered solids such as coatings, when subjected to cyclic or other form of oscillatory loads.
Machine Dynamics
Research can be undertaken for dynamic analysis and optimisation of machine structure, interaction of machine with drive and load, control of machine motion and vibration activity. The development of high-speed robotic systems and precise electro-mechanical scanners for control of laser beams were resulted from the previous studies. Precision machine tool spindle performance is invariably affected by bearing induced vibration, which are induced by rolling elements' motions and their surface interactions with the raceways, including the effect of waviness of surfaces. Methods of accurate non-contact measurement of these vibrations and cause and effect analysis are developed for prediction of very small amplitude vibration of the order of tens of nanometre to a few micrometers.
Vibration Control and Testing
Research areas include the development of resonant vibro-impact generators, vibro-impact testing of materials and structures, validation of finite element models and dynamic analysis of engineering structures under extreme environmental conditions: shocks, wide-band excitations, g-loads.
Vibration and Impact Protection
Research and development of new approaches to the vibration protection which rely on the use of optimal vibration isolation structures, dynamic vibration absorbers, non-linear shock absorbers, self-detuning and active systems.
Cryogenic and Vacuum Engineering
Design, research and development of "silent" and vibration protected cryogenic and vacuum systems. Current project concerns the reduction in low and high frequency microphony in infrared applications.
Vibration Processing
Excitation and control of vibration with systematic impacts is an effective way for intensification of different technological processes. These are tampering and cultivating of ground, mixing, transportation and separation of multi-component granular media, demolishing of hard and brittle materials. Current projects include separation of drilling mud, impact fatigue of materials, fragmentation of brittle materials.
High Power Ultrasonics
Research areas are ultrasonic cutting and drilling of hard and brittle materials, autoresonant excitation of ultrasonic systems, development of ultrasonic transducers and wave guides. Current projects are development of new methods for machining of aviation materials.
Non Contact Measurements of Dynamic Processes
Noise and vibration measurement and analysis and, in particular, the use of non-contact laser technologies for vibration measurement. Development of laser vibrometry for diverse applications including measurement on ultrasonic machinery and for measurement of radial, axial, torsional and bending vibrations directly from rotors. Non-contact measurements and analysis of impacts in solids, especially for large elastic deformations.
Elastohydrodynamics
Lubricated conjunctions play a crucial role as load bearing surfaces in almost all machines and mechanisms. At moderate to high loads, with relative motion of parts the lubricant film is entrained into the contact conjunction between mating members. Rapid rise in lubricant viscosity, rendering it as an amorphous solid at high contact pressures of the order of hundreds of Pascal to a few Giga-Pascal result in local elastic deformation of adjacent solids. This condition gives rise to the mechanism of elastohydrodynamic action. Such conditions are prevalent in meshing teeth contacts in transmission systems, between piston skirt and cylinder bore surface, in journal/engine bearings, ball and rolling element bearings and cam-follower contact, to name a few. Solutions for all these cases have been achieved including generalised solutions for all forms of conformal and counterformal contact configurations. Transient solutions have also been obtained by a variety of solution methods, and verified against experimental findings. At narrower conjunctions other complex kinetics affect the motion of lubricant molecules, such as Van der Waal forces, solvation effect, electromagnetic and polarisation effects and meniscus force. These are also taken into account (see section on Nano-Scale Physics of Motion).
Powertrain Dynamics
Noise and vibration concerns have become a prominent issue for vehicle customers and legislature. There are plethora of such concerns in power train engineering; from engine noise and vibration such as engine roughness to drivetrain untoward motions from low frequency phenomena such as clutch judder and driveline shuffle to medium and high frequency impact induced vibration such as gear rattle and driveline clonk (an onomatopoeic term). The latter involves elasto-acoustic coupling in hollow driveshaft responses. Research group is involved in root-cause investigation and solution of many of these problems with industry in the UK, Europe and North America.
Vanishing Point
Vanishing Point is an arcade-style race car game, developed by Clockwork Games Ltd in conjunction with the vehicle dynamics team at the Aeronautical and Automotive Engineering department here at Loughborough. The aim was for 'more realistic vehicle behaviour than Gran Turismo' - and we think we've achieved it.
Vehicle Dynamics
Vehicle dynamic simulation is now extensively used in industry for ride and handling analysis as a part of the vehicle development process. Large multi-body dynamic models have been developed by the research group which incorporate essential features of such realistic simulation studies, including tyre-road interaction, elasto-kinetic suspension analysis, aerodynamic interactions and various load cases such as kerb strike, single event shock and impulse studies, and all forms of transient manoeuvres with high g forces.