Modelling Frictional Interfaces in Structural Dynamics Simulation

Models of natural frequencies and mode shapes of vibration of a single component can be very accurate thanks to advances in FE modelling over the last few decades. However, the majority of structures consist of an ensemble of components joined together (bolted joints, dovetail joints and many more). When frictional interfaces are present (as is the case with assemblies of components) additional damping and compliance are introduced by the interfaces. The major challenge in structural dynamics at present is contact interfaces. The complexity of frictional interfaces is simply not accounted for in dynamics models. These features make it difficult to predict the vibration characteristics of assemblies with the same degree of accuracy as can be achieved for single components.

Frictional interfaces are complex and highly non-linear. Friction dissipates energy and introduces vibration damping. In addition, contact interfaces also have inherent stiffness – called ‘contact stiffness’, that arises from the inherent roughness of real surfaces. The problem is not as simple as just ascribing values for normal and tangential contact stiffness. This is because contact stiffness varies with parameters including contact pressure and contact area. It is also affected by wear as contacts in a vibrating structure will be subject to reciprocating sliding or partial slip.

This project will develop an FE modelling tool to accurately describe the interface with the aim of enabling a step change in the accuracy of structural vibration models. One level of success is to achieve an FE interface capably of mimicking experimentally measured mechanical interface responses (i.e. contact stiffness versus pressure curves etc.). A higher level of success would be for the user to be able to enter a core material and surface properties and for the tool to be able to calculate the required responses. Validation tests would be carried out to check the performance of the new interface model in making predictions in specially chosen ‘test case’ assembled dynamic structures.

A bespoke FE tool that could accurately describe the required complexity of interface response would revolutionise structural dynamics modelling and mean that accurate predictions could be made about the vibration of complex multi-component structures (thereby solving a problem that has existed to today). This is critical in the energy sphere. Firstly, there are several renewable energy structures where vibration modelling is paramount such as wind turbines, and tidal and wave energy generating structures. There is also the important point that a huge amount of energy is wasted due to suboptimal interface design and modelling - friction is one of the major energy dissipators in global energy consumption. With accurate interface modelling, structures and machines can be optimised and made substantially more energy efficient.

Selection will be made on the basis of academic merit. The successful candidate should have, or expect to obtain, a UK Honours degree at 2.1 or above (or equivalent) in Mechanical/Materials/Aerospace/Marine Engineering, Materials Science or Mathematics.

APPLICATION PROCEDURE:

Formal applications can be completed online: https://www.abdn.ac.uk/pgap/login.php

• Apply for Degree of Doctor of Philosophy in Engineering

• State name of the lead supervisor as the Name of Proposed Supervisor

• State ‘Self-funded’ as Intended Source of Funding

• State the exact project title on the application form

When applying please ensure all required documents are attached:

• All degree certificates and transcripts (Undergraduate AND Postgraduate MSc-officially translated into English where necessary)

• Detailed CV, Personal Statement/Motivation Letter and Intended source of funding