Harmony Hewlett

Research

Thesis: Simulation of Acoustic Emission from Heavily Loaded Mixed-Elastohydrodynamic Contacts

In industry, gears often operate such that their surface roughness is of a similar scale to the thickness of lubricant used between them. This means that peaks on these rough surfaces (referred to as 'asperities') intermittently contact each other during operation, leading to wear. This operating condition is referred to as the 'mixed elastohydrodynamic lubrication' regime, and is common in aerospace and renewable energy applications (e.g. wind turbine gearboxes).

Over time, gears operating under this lubrication regime can fail. In order to spot this failure in advance, before it becomes catastrophic, gears need to be inspected. However, this can be costly and inconvenient due to the need for shutdown and potential difficulty accessing the gears.

Fortunately, elastic stress waves pass through gears and can be measured with sensors to give information about lubrication conditions and any damage. This phenomenon is known as 'Acoustic Emission' (AE).

During the course of my PhD, I aim to create computer simulations of the AE signals occurring in gears under mixed elastohydrodynamic lubrication, and to validate the results using real experimental data. This will help improve our understanding of what AE can tell us about damage, and eventually allow gears to be remotely inspected using sensors, without the need for shutdown.

Supervisors:  Dr Alastair Clarke and Dr Simon Hutt 

Funding: The Jost Foundation's '2023 Jost Studentship'

Teaching

Graduate Demonstrator:

• Solidworks tutorials
• Gearbox design tutorials

Biography

Honours and awards

• Evan Llewellyn Davies Prize in Mechanical Engineering - 2024
• • Highest average mark in Mechanical Engineering degree examinations at Cardiff University.

• Dr Michael Riese Best Heat Transfer Project Prize - 2024
  
  • Best 3rd-year Mechanical/Integrated Engineering project in the area of heat transfer at Cardiff University.

• IMechE First Year Undergraduate Scholarship - 2022
  
  • IMechE scholarship to study Engineering at Cardiff University.