The use of polymer composites based on natural fibres is rapidly advancing in line with the increasing demand for environmentally friendly and sustainable materials across various industrial sectors. Ardy Lefran Lololau presented his research in his dissertation titled “Engineering and Mechanical Characterization of Multiaxial Prepreg Composite of Polylactic Acid Reinforced with Ramie Fibers.” This dissertation was defended during the open doctoral promotion session in Mechanical Engineering, held in the Meeting Room on November 6.
Ardy proposed an innovative solution to optimize ramie fibre-based materials reinforced with polylactic acid (PLA) matrices. His research aimed to refine the fabrication process of composite materials and characterize their multiaxial mechanical behaviour, which is highly relevant for applications in automotive, aeronautics, infrastructure, and naval industries.
Through collaboration between the Mechanical Design and Applied Mechanics Laboratory at FTUI and the Laboratoire Energétique Mécanique Electromagnétisme at Université Paris Nanterre, this research successfully developed natural fibre-based composite materials through three stages of engineering: Alpha, Beta, and Gamma.
“This process involved innovation in the pre-impregnation of ramie fibres using PLA matrices, resulting in optimal resin distribution and improved bonding strength between the fibres and the matrix. Mechanical testing was conducted using a modified Arcan device to simulate multiaxial loading, enabling deeper analysis of material performance under complex conditions,” Ardy explained during his presentation.
The results demonstrated that the material possesses significant fatigue strength, with fatigue strength reaching 36-40% of the ultimate strength for lamina and 42-55% for laminates, obtained at approximately 10⁶ cycles, as the S-N curve stabilized for each load under biaxial ratios. This material also shows great potential for various engineering applications due to its combination of mechanical excellence and eco-friendly properties. Additionally, the research identified that failure criteria such as Tsai-Hill and Hashin provide more accurate predictions in analyzing the material’s mechanical behaviour.
Ardy emphasized the significance of his research in advancing adaptive and sustainable material solutions. “This study proves that natural fibres like ramie when combined with polylactic acid-based matrices, can become reliable and eco-friendly engineering materials. By understanding their mechanical behaviour through multiaxial testing, we pave the way for more sustainable engineering applications,” he stated.
FTUI Dean, Prof. Dr. Ir. Heri Hermansyah, S.T., M.Eng., IPU, praised this research, highlighting the importance of innovation in natural fiber-based materials to support global sustainability. “This research not only addresses technical challenges but also opens new opportunities for developing eco-friendly composite materials with superior performance. It reflects FTUI’s commitment to contributing impactful innovations for society and the environment,” he remarked.
With this dissertation, Ardy Lefran Lololau earned his doctorate in Mechanical Engineering with a cum laude distinction, achieving a GPA of 3.94. He is the 111th doctoral graduate of the Department of Mechanical Engineering and the 571st doctoral graduate of the Faculty of Engineering, Universitas Indonesia. The promotion session was chaired by Prof. Dr. Ir. Yanuar, M.Eng., M.Sc., with Prof. Dr. Ir. Tresna P. Soemardi, S.E., M.Si., IPU ASEAN-Eng as the supervisor, and co-supervisors Prof. Olivier Polit and Prof. Dr. Yudan Whulanza, S.T., M.Sc. The examination committee included Prof. Dr. Ir. Danardono A. Sumarsono, DEA, PE., Dr. Ir. Gatot Prayogo, M.Eng., Prof. Dr. Ir. Hendri D.S. Budiono, M.Eng., Jos Istiyanto, S.T., M.T., Ph.D., and Prof. Dr. Jefri S. Bale, S.T., M.Eng.
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