Author, Institution: Sharath Peethambaran Subadra, Kaunas University of Technology
Science area, field of science: Technological Sciences, Mechanical Engineering, T009
Scientific Supervisor: Prof. dr. Paulius Griškevičius (Kaunas University of Technology, Technological Sciences, Mechanical Engineering, T009)
Dissertation Defence Board of Mechanical Engineering Science Field:
Prof. Dr. Giedrius Janušas (Kaunas University of Technology, Technological Sciences, Mechanical Engineering, T009) – chairperson
Dr. Andrey Aniskevich (University of Latvia, Latvia, Technological Sciences, Materials Engineering, T008)
Prof. Dr. Gintautas Dundulis (Kaunas University of Technology, Technological Sciences, Mechanical Engineering, T009)
Prof. Dr. Valdas Eidukynas (Kaunas University of Technology, Technological Sciences, Mechanical Engineering, T009)
Prof. Dr. Juozas Padgurskas (Vytautas Magnus University, Technological Sciences, Mechanical Engineering, T009)
Dissertation defence meeting will be at Rectorate Hall of Kaunas University of Technology (K. Donelaičio 73-402, Kaunas)
The doctoral dissertation is available at the library of Kaunas University of Technology (K. Donelaičio g. 20, Kaunas) and on the internet: S. Peethambaran Subadra_dissertation.pdf
Annotation: Polymer composites are widely used in applications ranging from the automotive to the aerospace sector. During their service life these materials are subjected to various loading conditions and their failure mechanisms are unique among materials because it’s a combinations of various failure mechanisms like delamination, debonding, fibre rupture that causes the final damage. Low velocity impact damages are characterised by matrix determinant delamination and this PhD dissertation is an attempt to study the causes and ways to improve impact performances of composites. In this regard, nano reinforcements were used initially to improve the impact resistance. Though experiments showed that such methods do improve the impact performance, but the method is limited by its sophistication and costs. Improvement of impact performance was accessed by introducing hybrid architectures into composites, which transformed the brittle nature of composites into more “ductile-like” nature. Termed as the hybrid-effect which makes composite damage more predictable and, in the process, making them tougher by taking in more energy to initiate and propagate damage. To further understand the role of matrix, in-plane and out-of-plane waviness was introduced and subjected to flexure in addition to hybrid architectures. It was observed that the presence of in-plane waviness improved the load bearing capacity of composites under flexure. Numerical simulations showed that two strain parameters affected the numerical outcome to match with that of the experimental observations. Deducing from this outcome, the introduction of in-plane waviness affects the shear properties which is affected greatly by the matrix being used which lend itself to better flexural performance and since flexure dominates while under impact, could lend to better impact resistance.
August 28 d. 10:00
Rectorate Hall at Kaunas University of Technology (K. Donelaičio 73-402, Kaunas)
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