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University of Michigan

Af Jeppe Jørgensen, Fulbright 2015-16

The primary outcome of the study abroad semester:
The main outcome of the study abroad at the University of Michigan is a paper that is accepted for the 37th Risø International Symposium on Materials Science – Understanding performance of composite materials – mechanisms controlling properties. The paper is subsequently published in the journal: IOP conference series – Materials science and engineering.

The paper presents some of the experimental results conducted through the research stay at University of Michigan. Test of specimens shown on Figure 1 were used to study crack deflection at interfaces. Crack deflection at interfaces is one of the main strength controlling mechanisms for adhesive joints used in wind turbine blade joints. Results and images conducted using digital image correlation, as shown on Figure 2, showed that a secondary crack formed at the interface before the main crack grow and reached the interface. This finding is important in order to understand the strength controlling mechanisms in adhesive joints.

In the end I conducted more than 200 tests during the research stay and currently I am using these tests to write up another journal paper that also includes the models I developed through the research stay.

Other outcomes from the study abroad semester:
Collaborating with some of the leading researchers in the field gave a significant impact on the results obtained in this PhD project. Personally, I learned how to conduct reliable experiments and subsequently develop models accordingly. This parallelization of experimental work and numerical modeling was found very successful.

Working under supervision by prof. Michael D. Thouless gave insight to a whole new view point on mechanics and I felt that this collaboration have pushed my professional skills to a new level. Testing materials are very tricky since many things can go wrong in the experimental setup or materials might behave differently than expected. His broad overview in the field of mechanics helped steering the project in the right direction and account for issues that I would never have foreseen. Furthermore, I had skype meetings with my supervisors in Denmark every week to keep all stakeholders aligned in the project direction.

Working in the academic environment at University of Michigan was very inspiring. The lab facilities were great and the other researchers were very helpful giving introductions to the very advanced equipment e.g. digital image correlation equipment. The research groups were rather large and specialized hence it was always possible to find help when I was stuck in some modeling or experimental work. Finally, I got some strong relations among the other researchers and I still keep in touch with them to share knowledge and experiences.

All in all it has been a very successful research stay, both academic and personal, and I wish I can go back some day in the future.