A. Raza “Investigation of dynamic characteristics and vibration control of additively manufactured composite structures using piezoelectric actuators” doctoral dissertation defence

Author, Institution: Ali Raza, Kaunas University of Technology

Science area, field of science: Technological Sciences, Mechanical Engineering, T009

Research supervisor: Assoc. Prof. Dr. Rūta Rimašauskienė (Kaunas University of Technology, Technological Sciences, Mechanical Engineering, T009)

Dissertation Defence Board of Mechanical Engineering Science Field:
Prof. Dr. Regita Bendikienė (Kaunas University of Technology, Technological Sciences, Mechanical Engineering, T009) – chairperson
Prof. Dr. Saulius Baskutis (Kaunas University of Technology, Technological Sciences, Mechanical Engineering, T009)
Assoc. Prof. Dr. Michal Kazimierz Budzik (Aarhus University, Denmark, Technological Sciences, Mechanical Engineering, T009)
Prof. Dr. Giedrius Janušas (Kaunas University of Technology, Technological Sciences, Mechanical Engineering, T009)
Assoc. Prof. Dr. Pawel Kudela (The Polish Academy of Sciences, Poland, 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 (Gedimino 50, Kaunas) and on the internet: A. Raza el. dissertation.pdf

© A. Raza, 2025 “The text of the thesis may not be copied, distributed, published, made public, including by making it publicly available on computer networks (Internet), reproduced in any form or by any means, including, but not limited to, electronic, mechanical or other means. Pursuant to Article 25(1) of the Law on Copyright and Related Rights of the Republic of Lithuania, a person with a disability who has difficulties in reading a document of a thesis published on the Internet, and insofar as this is justified by a particular disability, shall request that the document be made available in an alternative form by e-mail to doktorantura@ktu.lt.”

Annotation: This dissertation investigates the dynamic characteristics of additively manufactured (AM) structures and develops an effective vibration control methodology by integrating macro fiber composite (MFC) actuators to suppress their vibration amplitudes. To achieve this, polylactic acid (PLA) and PLA-based composite structures including PLA reinforced with short carbon fibers (PLA-SCF), continuous carbon fibers (PLA-CCF), and continuous glass fibers (PLA-CGF) were fabricated with both unidirectional (0°–0°) and cross-ply (0°–90°) layer orientations. The influence of layer orientations on the dynamic characteristics (natural bending mode frequencies, bending mode shapes, amplitude spectrum, and damping) of each AM structure was investigated. Vibration amplitude suppression was then performed on these structures by applying a vibration control methodology using MFC actuators, identifying the orientation and structure exhibiting the maximum vibration suppression. Additionally, the effect of the signal phase (ranging from 0° to 360°) applied to the MFC actuators on the vibration amplitude was examined, and the phase that provides the maximum vibration suppression for each AM structure was determined. Non-destructive C-scanning was conducted to identify internal defects in the AM structures using the THz spectrometer (TPSTM Spectra 300 THz Pulsed Imaging and Spectroscopy from TeraView). Finally, a finite element based numerical simulation approach has been developed to study dynamic characteristics and vibration suppression behaviour of the AM structures using MFC actuators. The trends of the simulation results were thoroughly compared and validated with experimental results.