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Yogendra Joshi - Friction Modelling for Advanced Binder Systems

Supervisors:
Professor Richard Dashwood – WMG Academic Director
Dr Iain Masters – Senior Research Fellow, WMG

The following is an interview conducted with Yogendra and his supervisors for JLR's in-house magazine:


Can you tell us a little about your background and your area of research?


Yogendra:
My background is as a manufacturing engineer and I worked professionally for four years with companies like Tata Motors and the Defence Ministry of India before coming to WMG for my Master’s in 2012. During my time here I realised that I was more inclined towards research and I wanted to undertake a course where I could apply my research to a real world problem, which is how I came to apply to the EngD programme.

My project is all about tribology in the blank holding systems. Tribology is a branch of materials and engineering science looking at interacting surfaces and relative motion. Blank holders are where you grip a sheet of metal for forming a shape. There is interaction between the sheet, the holder, and the lubricant between the metal sheets. Friction in forming is not very well understood yet and since it’s not understood it’s not represented very well in literature or simulations. Because the models aren’t developed to any sort of finished level we have to look at a lot of physical prototypes in the manufacturing process which means time and money.

What’s interesting to me is not just where the material has split when put under stress, but also where the material has been gripped at the edges. That affects the flow of the material and can cause problems or variations.

Dr Masters:
The current trend with computer modelling packages is to use a fixed value for friction which is determined by doing some physical tests, then adjusting the value until your simulation matches what’s happening in the physical test. The assumption is that is your friction value. The reality is that the friction value is going to vary. Simulations are reasonably accurate at the moment but in probably 20% of cases you’ll do the simulation, cut the part, then have issues when trying to prove the tool. We’re trying to make a notable improvement in the simulation by being able to represent friction more precisely. That means more tools will be correct first time. With new parts being pressed all the time, the simulation might say it’s fine but when they come to pressing the part, engineers will find they have problems.

The major variables are pressure to grip the material, lubricant which is affected by temperature, and obviously the temperature of the material itself because as it’s pressed it generates heat. We’re trying to get a clearer picture of the variables in the simulation.

Yogendra:
Until now, there hasn’t been a way of measuring new metals and how they react to friction. We are helping the simulation engineers to get a better model for friction. It was steels before and now it’s alloys. I’m also working on designing a test rig to measure friction, which very few universities have.


How is the project going and what benefits are you seeing in parties working together?


Yogendra:
As well as my supervisors at WMG, I have two industrial supervisors at JLR; Richard Aylmore and Matt Stanton. I go to the site at Gaydon every Thursday and talk with their lubrication engineer. It’s great to meet and to understand their problems and what they’re doing about it.

Tribology is such a massive subject area so I had a problem initially to try and concentrate my study, however what the EngD does is help target the problem, especially for JLR. They’ve helped me to narrow down the project area and also assist with expert industry opinions. They also give practical input.

In terms of obtaining test materials, getting test parameters and using the correct software, JLR provide all of this. I hadn’t realised before I came to WMG and started this project just how serious about research JLR are.

The scheme has been very rewarding and exciting at the same time. It’s not like a traditional PhD where you bury yourself in books and papers and no one really guides you and it can be very hypothetical. This is always anchored to a real-world issue.

I think what JLR is doing is fantastic as they’re not just coming to WMG for an answer to their problem; they’re funding research to work through the issue and then potentially gaining a specialist engineer at the end of it who can directly help the company.

Yogendra Joshi




Yogendra Joshi and Supervisors