A Predictive Approach to Modelling Frictional Joint Performance (PAMFJP)
Lead Research Organisation:
University of Oxford
Department Name: Engineering Science
Abstract
The proposed research aims to address the problems inherent in predicting the behaviour of frictional joints. Such joints are an important feature of a wide range of engineering products. Joint behaviour can be beneficial (e.g. by introducing frictional damping and controlling vibration amplitude) or detrimental (e.g. by inducing accelerated wear of fatigue failure). Whilst models now exist for some of these phenomena, it is at present difficult to predict the frictional behaviour of an interface in advance without making experimental measurements under representative conditions. Indeed, uncertainties associated with the behaviour of frictional joints are one of the remaining obstacles to reliable prediction of vibration amplitides and resulting component life.The proposed work addresses the difficulteis outlined above through a combined experimental and modelling programme undertaken by two leading groups in the traditionally separate areas of vibration and structural integrity. The work will be undertaken from a common standpoint and will result in a holistic approach which is valuable to both communities. Intitially, measurements will be made of joint performance using two standard geometries and two material pairs. Measurements will then be taken to characterise the surface topography, material properties, and interface behaviour at microstructural and asperity scales. These measurements will provide input for modelling of the contact, initially at the scale of a single asperity, but later generalised using statistical methods to provide predictions of overall contact behaviour. These predictions will be based on recent developments in the understanding of interface behaviour at the micro- and nano- scales.Finally, validation experiments will be carried out. These will be carefully chosen to give validation of the model in circumstances which differ significantly from the initial characterisation experiments. The overall output of the proposed work will be an enhanced understanding and predictive modelling approach for frictional joints in engineering assemblies such as gas turbine engines. The result will be increased confidence in joint (and therefore overall system) performance, and a reduction in the need for characterisation experiments.
Organisations
Publications
Daniele Dini (Author)
(2008)
FRICTIONAL CHARACTERISTICS OF RANDOMLY ROUGH HERTZIAN CONTACTS IN PARTIAL SLIP
Saverio Reina (Author)
(2009)
ON THE EVOLUTION OF FRICTIONAL HYSTERESIS LOOPS IN FRETTING EXPERIMENTS
Kartal M
(2010)
Torsional contact between elastically similar flat-ended cylinders
in International Journal of Solids and Structures
Nowell D
(2010)
Predicting the behaviour of frictional interfaces: a 'grand challenge' in mechanics
in Strain
Kartal M
(2010)
Determination of the Frictional Properties of Titanium and Nickel Alloys Using the Digital Image Correlation Method
in Experimental Mechanics
David Nowell (Author)
(2010)
A simple model for the prediction of tangential contact stiffness in frictional contact
Mulvihill D
(2011)
An elastic-plastic asperity interaction model for sliding friction
in Tribology International
Mulvihill D
(2011)
Investigation of non-Coulomb friction behaviour in reciprocating sliding
in Wear
Kartal M
(2011)
Measurements of pressure and area dependent tangential contact stiffness between rough surfaces using digital image correlation
in Tribology International
Kartal M
(2011)
Measurement of Tangential Contact Stiffness in Frictional Contacts: The Effect of Normal Pressure
in Applied Mechanics and Materials
Mulvihill D
(2011)
Investigation of the Friction Variation with Sliding which is Commonly Observed in Individual Fretting Test Cycles
in Applied Mechanics and Materials
Kartal M
(2011)
Partial slip problem for two semi-infinite strips in contact
in International Journal of Engineering Science
Daniel Mulvihill (Author)
(2011)
AN ASPERITY INTERACTION MODEL FOR FRICTION
Medina S
(2012)
The Influence of Surface Topography on Energy Dissipation and Compliance in Tangentially Loaded Elastic Contacts
in Journal of Tribology
Medina S
(2012)
Analytical and Numerical Models for Tangential Stiffness of Rough Elastic Contacts
in Tribology Letters
Mulvihill D
(2013)
A Comparison of Contact Stiffness Measurements Obtained by the Digital Image Correlation and Ultrasound Techniques
in Experimental Mechanics
Description | The project was established as a collaboration between the University of Oxford and Imperial College, with two industrial partners: Rolls-Royce plc and AWE. The initial phase of the work consisted of measuring hysteresis loops for well-characterised surfaces on different rigs at Oxford and Imperial. This addressed the question of whether it was possible to measure the contact stiffness and friction coefficient as properties of the interface, independently of the apparatus used. Good agreement was found for the friction coefficient. However, the contact stiffness proved more difficult to measure. As part of the work, a new method of measuring the stiffness was developed at Oxford, involving the use of digital image correlation. Once this was implemented, more consistent results were achieved with the two rigs. Alongside the experimental work, modelling of the surface interactions was undertaken. A simple theoretical model of the tangential stiffness for rough contacts was formulated, which produced predictions in-line with more sophisticated numerical modelling. Modelling of asperity interaction was also undertaken using finite element methods and taking account of plasticity and material failure. Results from a single asperity model were generalised using a statistical approach and were able to provide realistic values of predicted friction coefficient. The final phase of the work was some validation experiments, where the predictions of the modelling approach for contact stiffness were investigated using contacts of different area and normal load. The results confirmed the expected behaviour that stiffness increased in proportion to apparent area of contact and with increasing normal load. Aside from the work described above, the project also investigated some non-Colomb features of hysteresis loops, which were attributed to surface registration effects and wear. Ultrasonic measurement of contact stiffness was also carried out in conjunction with the University of Sheffield. |
Exploitation Route | A greater understanding of the behaviour of joints will be of significant benefit in the design of complex systems, where there is frequently load transfer by friciton between adjacent components. This will allow better simulation of system behaviour (e.g resonant frequencies, vibration amplitudes, frictional damping etc) and hence will reduce the dependence on prototype testing. Some of the outputs from the project will be directly exploited by our project partners Rolls-Royce plc and AWE in future designs. Other exploitation will be through the normal routes of journal publications and conference presentations. As a result of their developing experise in the area, Professors Nowell and Hills have been nominated as members of the ASME research committee on jointed structures. The reseach also feeds into short course content for courses given by Professors Nowell and Hills to industrial companies (e.g Rolls-Royce and John Deere). |
Sectors | Aerospace, Defence and Marine,Energy,Transport |
URL | http://www.eng.ox.ac.uk/solidmech/publications/Publications.html |
Description | The findings have been used to further our understanding of frictional contacts. We are continuing work in collaboration with Rolls-Royce plc to investigate and model contact stiffness and to incorporate these models into the next generation of finite element codes. |
First Year Of Impact | 2012 |
Sector | Aerospace, Defence and Marine,Energy,Transport |
Impact Types | Economic |
Description | Rolls-Royce Plc |
Amount | £36,296 (GBP) |
Funding ID | UTC/11/20 |
Organisation | Rolls Royce Group Plc |
Sector | Private |
Country | United Kingdom |
Start | 12/2011 |
End | 12/2012 |
Description | Rolls-Royce Plc |
Amount | £36,296 (GBP) |
Funding ID | UTC/11/20 |
Organisation | Rolls Royce Group Plc |
Sector | Private |
Country | United Kingdom |
Start | 06/2011 |
End | 06/2012 |