The interaction between fibres and the surrounding matrix material is key to the mechanical performance of fibre-reinforced composites, widely used in industries like aerospace, energy, and automotive. However, traditional methods of characterizing these interfaces often suffer from significant inaccuracies.
Royson Dsouza’s doctoral research at Tampere University introduces enhanced microbond (MB) test setups integrated with finite element (FE) modelling, addressing these long-standing challenges. His study reveals that simplified assumptions in conventional MB tests can lead to up to 80 % error when estimating interfacial properties. To overcome this, Dsouza introduced the use of laser-interrogated Fibre Bragg Grating (FBG) sensors in MB tests, allowing the capture of local fibre strains and significantly improving the calibration of cohesive zone model (CZM) parameters.
"By embedding sensing capabilities directly in the MB test, we were able to simulate detailed interfacial behaviour that traditional methods missed," says Dsouza.
His research further developed a novel sample holder structure enabling cyclic micro-fatigue testing of the interface, shedding light on how fatigue mechanisms influence fibre-matrix interactions over time. Additionally, he examined how the formation of a thin polymer film during sample preparation — due to Rayleigh-Plateau Instability — alters the mechanical response without significantly affecting properly calibrated CZM parameters.
Overall, Dsouza’s dissertation provides both experimental and numerical innovations that pave the way for more reliable design and analysis of composite materials in demanding applications. His findings are expected to have significant societal impact by contributing to the development of safer, more durable composite structures.
Royson Donate Dsouza conducted his doctoral research at the Faculty of Engineering and Natural Sciences, Tampere University, supported by funding from the European Union’s Horizon 2020 programme and Finnish foundations.
Public defence on Friday 30 May
The doctoral dissertation of MSc (Research) Royson Donate Dsouza in the field of Materials Science and Engineering, titled Numerical analysis of fibre-matrix interface for accurate debonding in microbond tests, will be publicly examined at the Faculty of Engineering and Natural Sciences at Tampere University at 13:00 noon on Friday 30 May 2025 at Hervanta campus, Tietotalo building, auditorium TB104 (Korkeakoulunkatu 1, Tampere).
The Opponents will be Professor Malin Åkermo from KTH Royal Institute of Technology, Sweden and Doctor Fulvio Romano from Italian Aerospace Research Centre, Italy. The Custos will be Professor Mikko Kanerva from Tampere University.
The doctoral dissertation will be available online.
The public defence can be followed via remote connection.