Article Co-authored by: Stuart Cunningham & Josh Leworthy

In September 2017, Dukosi was approached by Heriot Watt University with a proposal for us to become involved in a group project involving senior mechanical engineering students. Dukosi’s ongoing working relationship with Heriot Watt University meant that when the idea was proposed, we did not hesitate before saying yes.

Having two mechanical engineers and an electronics engineer who are graduates from Heriot Watt, Dukosi was keen to get involved with the scheme which aims to provide a live company-driven design project to a group of 4th year students to be completed over two semesters.

In brief, Dukosi would present the students with a problem for them to solve over the course of two semesters. The students would utilise their engineering design skills and best practice to come up with a solution.  Throughout the process Dukosi would provide customer feedback and specific guidance in order to help the students learn about engineering design and manufacture in a commercial setting.  The process is one which both of Dukosi’s mechanical engineers completed during their undergraduate study and strongly believe gave them valuable experience of work in the commercial world prior to graduation.

Testing of lithium Ion cells forms a fundamental part of Dukosi’s ongoing business.  In order for our technology to be accurate and effective we need to first test the specific cell performance and characterise their operation.  To do this we require test jigs which can compress the cells during testing as required.  Compression is important as it controls the natural expansion mechanism of the lithium ion cell structure under charge/discharge conditions and keeps them performing at an optimum rate and prevents premature degradation.  Dukosi performs testing inside a thermal controlled chamber, this means there is a considerable restriction on both the size and overall weight of the compression rig. The rigs need to be able to accept pouch cells of varying sizes and thicknesses and be capable of applying pressures evenly across their surfaces up to 125kPa in a controlled and repeatable manner. With all that in mind, we handed this information to the students to see if they could come up with any innovative solutions.

Dukosi assigned mechanical engineers, Josh Leworthy and Stuart Cunningham for the process. Each engineer would mentor their own team of students and the results would be compared upon completion.  This added a competitive edge to the process with both Josh and Stuart confident they could guide their team to a more successful product.  That said there would naturally be a lot of cross pollination and the work was completed in a good natured, friendly and professional manner!

Team 1

Team 1 was made up of five students and were mentored by Josh throughout the project. From the get go, the students were incredibly enthusiastic about the project, kicking things off with some research into Li-ion cells. It was imperative that the students understood the effects of cell compression and safety requirements for working with Li-ion cells in order to design a successful solution to the problem. The students very quickly produced a number of designs for the rig, meeting the design specification and making rigs that are safe and easy to use. The team met regularly with Josh throughout the project, giving updates on progress and ensuring Dukosi had input at every stage. The team successfully designed, manufactured and tested three compression rigs. The rigs were a substantial improvement of the equipment previously used at Dukosi and have been put to use in our labs already! Josh thoroughly enjoyed working with the student team and was happy to assist them in CAD design and FEA analysis. You can see Team 1’s final rigs below.

Compression Rig CAD Model

Figure 1.  Team 1 – Compression Rig CAD Model

Figure 2 - Team 1 - Final Compression Rig

Figure 2. Team 1 – Final Compression Rig

 

Team 2

Team 2 was also made up of five students and were mentored by Stuart.  The team began immediately, and after some design brainstorming had selected three designs which they would put more detail in to allowing them to further critique before making a final decision and moving on to purchasing materials and building the unit.  The group remained engaged throughout the process and Stuart was impressed by their continued communication and enthusiasm.  The group performed in depth critique of their work including finite element analysis (FEA) and accurate costings, design drawings and mass estimations.  Stuart was happy to provide material selection and design advice and thoroughly enjoyed working with the team. The final rig set up (CAD and as manufactured) can be seen in the image below.

 

Figure 3. Team 2 - Compression rig as designed. Figure 2. Team 2 - Compression rig as manufactured.

Figure 3. Team 2 – Compression Rig as designed

 Figure-2.-Team-2-Compression-rig-as-manufactured

Figure 2. Team 2 – Compression Rig as manufactured

 

Both student groups were successful in delivering the compression rigs to Dukosi within their budgets and time scales. The rigs have enabled Dukosi to conduct further cell testing that was previously unachievable with the existing equipment at our labs. We really enjoyed the experience working with the student groups and intend to submit more projects to the university in the coming years. We also received great feedback from the student groups and are glad they enjoyed the project too!

“It has been a pleasure working with Dukosi for the last 9 months. They offered us support during the design stages and took continuous interest in the project, which allowed us to supply a finished compression rig that was tailored to their liking. Working with Dukosi offered a keen insight into the world of engineering and we appreciate them opening their doors to us to see the work they are conducting with Li-Ion cells and for giving us the chance to contribute. The project presented was clearly set out, with explicit targets to complete and gave an overall well-rounded view of the processes involved in project work. This enabled the group to have defined concept, design, fabrication, testing and re-design stages, whilst also allowing insight to be gained into the complexities and complications of engineering design. All round it was a pleasure working with Josh, Stuart and Dukosi on this project. Thanks for the great time!” – Heriot Watt Student Teams