A Predictive Approach to Modelling Frictional Joint Performance (PAMFJP)
Lead Research Organisation:
Imperial College London
Department Name: Mechanical Engineering
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.
Publications
Dini D
(2009)
Frictional Energy Dissipation in a Rough Hertzian Contact
in Journal of Tribology
Daniele Dini
(2010)
Recent progress in continuum contact mechanics at the nanoscale
Mulvihill D
(2011)
Investigation of non-Coulomb friction behaviour in reciprocating sliding
in Wear
Medina S
(2012)
A Fast Deterministic Model to Study Adhesion in Rough Contacts
Medina S
(2012)
Analytical and Numerical Models for Tangential Stiffness of Rough Elastic Contacts
in Tribology Letters
Medina S
(2012)
The Influence of Surface Topography on Energy Dissipation and Compliance in Tangentially Loaded Elastic Contacts
in Journal of Tribology
Medina S
(2014)
A numerical model for the deterministic analysis of adhesive rough contacts down to the nano-scale
in International Journal of Solids and Structures
Hills D
(2016)
Partial slip incomplete contacts under constant normal load and subject to periodic loading
in International Journal of Mechanical Sciences
Müser M
(2017)
Meeting the Contact-Mechanics Challenge
in Tribology Letters
Description | (i) We performed a comprehensive set of experimental measurements of macroscopic load-displacement (hysteresis) response for two material pairs subjected to relative motion and a range of well-characterised surface topographies and developed a thorough understanding of teh frictional response of these pairs. (ii) We compared and correlated existing approaches to the characterisation of frictional interfaces, which unifies the understanding currently held by the dynamics, tribology and structural integrity communities. A single coherent framework which can describe the interface appropriately in each of these areas was developed, highlighting the importance of surface oxides and material transformation during wear. (iii) Development of an asperity-scale model of frictional contact which incorporates understanding of interface mechanics at the micro and nano-scale together with appropriate material behaviour. (iv) We have conducted detailed studies of single asperieties and failure mechanisms and wear fundamentals, which have helped undertsanding the role of plasticity in contact problems. (v) Development of a statistical model for real surfaces which have been generalised from the asperity-scale model to engineering surfaces and predict the effects of surface topography and material properties on interfacial frictional damping. |
Exploitation Route | The methodologies developed during this project have been used by industrial partners (Rolls-Royce and AWE) to improve the design of frictional interfaces in teh presence of vibratory loads. Research on fretting fatigue and damage has immensely benefited from our findings. Both the new experimental techniques and modelling methodologies we have developed can be used to study a range of systems and materials. |
Sectors | Aerospace Defence and Marine Energy Manufacturing including Industrial Biotechology Transport |
Description | Both the numerical and experimental methodologies developed during this project have been used by Rolls-Royce to develop their next generation of underplatform dampers for turbine blades. Some of the techniques developed have also been used by AWE to optimise teh design of bolted connections in critical components. The investigator have also developed methods nos used to study teh energy dissipation in a variety of contacts involving rough dry surfaces in a number of industrial applications (with Element Six, Ford, Rolls-Royce and Bosch). This has strenghtened the links between the Vibration University Technology Centre at Imperial College and has also enable to establish a strong research stream in triboogy within Rolls-Royce. |
First Year Of Impact | 2009 |
Sector | Aerospace, Defence and Marine,Energy,Manufacturing, including Industrial Biotechology,Transport |
Impact Types | Economic |
Description | EPSRC |
Amount | £1,021,359 (GBP) |
Funding ID | EP/G026114/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start |
Description | Element Six studentship |
Amount | £90,000 (GBP) |
Organisation | De Beers Group |
Department | Element Six |
Sector | Private |
Country | Luxembourg |
Start | 09/2012 |
End | 09/2016 |
Description | Engine Efficiency Benefits from Surface Texturing |
Amount | £130,000 (GBP) |
Organisation | Ford Motor Company |
Sector | Private |
Country | United States |
Start | 01/2016 |
End | 01/2017 |
Description | Platform Grant |
Amount | £1,024,467 (GBP) |
Funding ID | EP/G026114/1 |
Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
Sector | Public |
Country | United Kingdom |
Start | 01/2009 |
End | 12/2013 |
Title | Fast Solver for Contact Models with Roughness and Adhesion |
Description | A new methodology and algorithms to study contact mechanics of rough surfaces |
Type Of Material | Improvements to research infrastructure |
Year Produced | 2009 |
Provided To Others? | Yes |
Impact | Now incorporated in a Research Software TriboSIM and made available to Ford, Rolls-Royce and BP for other projects |
Description | AWE |
Organisation | Atomic Weapons Establishment |
Country | United Kingdom |
Sector | Private |
PI Contribution | We made contributions to look at the fretting damage induced in bolted connections under vibratory load. Important studies emerged from looking at the effect of surface roughness. |
Collaborator Contribution | Contributed to materials and data to study bolted assemblies |
Impact | Maim outcomes: - New design tools for bolted assemblies and PhD research in this area |
Start Year | 2007 |
Description | Rolls-Royce |
Organisation | Rolls Royce Group Plc |
Country | United Kingdom |
Sector | Private |
PI Contribution | We helped developing methodologies to design underplaftorm dampers in turbine and fan blades |
Collaborator Contribution | They provided fudning to carry out specific work and now to design their next generation engines |
Impact | Main outcomes: - New design tools and methods for design of surfaces and dynamic resonse of systems - Strenghten teh links between the Imperial College Rolls-Royce Vibration Univesity Technology Centre, the Tribology Group at Imperial College and teh University of Oxford |
Start Year | 2007 |
Title | TriboSIM |
Description | A suite of tools put together by teh investigators to solve Tribological problems in teh presence of rough contacts |
Type Of Technology | Software |
Year Produced | 2011 |
Impact | Now a research tool used in teh Tribology Group at Imperila College with much potential for commercialisation and exploitation |
Company Name | Floxtrot Limited |
Description | |
Year Established | 2018 |
Impact | So far engaged 3 oil and gas and automotive companies for licences and consultancy projects |
Website | http://www.tribosim.com/ |
Description | Workshop on Frictional Joints |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Industry/Business |
Results and Impact | The aims of the workshop were as follows: 1. To communicate the results we have obtained so far on our current PAMFJP project and to understand how these can be applied in practical engineering situations. 2. To gain a fuller understanding of the range of contact issues experienced in industrial applications 3. To identify areas where the resources remaining on the current project could be applied to address more effectively these application-driven problems 4. To identify priorities for future research in this area (e.g. a new application for research council funding) The workshop was attended by: University of Oxford: D.A. Hills; D. Nowell; M.E. Kartal; D. Mulvihill Imperial College: D.J. Ewins; D. Dini; A. Olver; S. Medina; C. Schwingshackl; D. Proprentner Rolls-Royce plc: J. Schofield; J. Green; N. Banerjee Jaguar/Land-Rover: A Harrison; L. Harper Wärtsilä: C. Lönnqvist Alsthom: S. Osgerby Ferrari: M. Spuria Vestas: C. Nielsen MoD: A. Davis Skoda/Doosan Babcock: D Mitchell; J. Kellner GKN: S. Cragg; B. Mason Three breakout groups addressed the following questions: 1. In what areas is our current understanding of frictional joint behaviour deficient? 2. What are the consequences of this lack of understanding? 3. What physical phenomena do we need to understand in order to make progress in this area? 4. Which of these are the most important? 5. In which of these areas are we most likely to make progress? 6. What are the priorities for research into frictional joint behaviour over the next 5 years or so? 7. To what extent do joints influence the dynamic behaviour of your structures 8. How much of a problem is it that joints vary from build to build and day to day 9. How can we quantify the consequences of better joint modelling capabilities (including economic aspects)? The following is a brief summary of the discussions in each of the groups: Group A (i) Bolted joints were a significant area of uncertainty (ii) There was appreciable variation between nominally similar joints due to manufacturing tolerances etc (iii) Degradation of joints in service was a major issue (through wear etc). This needed more understanding, and better surface treatments (iv) There was a need for a multi-scale modelling approach, bridging a detailed scientific understanding with higher level assessment tools Group B (i) There was a need to understand stiffness, damping, and friction coefficient, but these may not be the only relevant parameters (ii) Wear has a big impact on performance (iii) There would be benefit in moving towards more standardised tests for joints (how do we choose test parameters) (iv) Joint variability was an issue (v) Better understanding of coatings would be helpful Group C (i) Life prediction requires understanding of evolution over time - this is a fundamental feature of joints (ii) Better understanding of wear is important (iii) There was a need for guidelines on how to run tests (and how to choose representative parameters) (iv) Joint evolution and variability represent significant uncertainties at present. |
Year(s) Of Engagement Activity | 2010 |