New doctoral dissertation

December 20, 2023
VILNIUS TECH Library invites you to follow the published new dissertations. The dissertation „Investigation of the inkjet printing process, evaluating the dynamics of the ink and the properties of specific printing surfaces“ („Rašalinio spausdinimo proceso tyrimas, įvertinant rašalo dinamiką ir specifinių spausdinimo paviršių savybes“) prepared by VILNIUS TECH, Tim Tofan. The doctoral dissertation was prepared at Vilnius Gediminas Technical University in 2019–2023., Supervisor – Assoc. Prof. Dr Raimondas Jasevičius.

The dissertation was defended at the public meeting of the Dissertation Defence Council of the Scientific Field of Mechanical Engineering in the SRA-I Meeting Hall of Vilnius Gediminas Technical University at 10 a.m. on 20 December 2023.

The most well-known and commonly used printing techniques made the inkjet printing technology more popular among manufacturers for its simplicity and flexibility. Demand for printing products is increasing in such areas as textile printing, microchip production and personalised production, raising quality requirements. Thus, inkjet printing is continuously enhancing its capabilities. With the printing market expected to grow, there are many propositions to improve the productivity of inkjet process. The dissertation aims to study the dynamics of an inkjet droplet at different stages of its formation, considering its interaction with the surface to improve the quality and speed of high-class inkjet printing and improve inkjet printhead testing applications. The present dissertation reviews theoretical and numerical techniques of inkjet printing process modelling by applying the Computational Fluid Dynamics (CFD) module using the finite elements method. Inkjet printing inks are calculated as Newtonian fluid. The ink flow is modelled by the incompressible Navier–Stokes equations. The presented simulation model is solved using a level set method to determine the ink and air interface. Experimental investigation results are reported on the inkjet printing process colour reproduction on different linen fabrics, and modelling results are given for droplet ejecting, printing and interaction processes with the flat surface and the interaction with the inkjet droplet with physically treated polymer surfaces. Based on systematic and analysed numerical simulations of research on the operation of inkjet printing heads, Article 1 describes the inkjet print-head models, which analyse how different inks impact droplet formation and movement at different time steps. Article 2 presents an experimental realisation of colour reproduction by inkjet printing possibilities on different materials in different printing settings. Article 3 presents the physical and numerical experiments on the impact characteristics of inkjet printhead droplets with flat surfaces. Different surface treatment methods were investigated to increase droplet adhesion with flat surfaces. Article 4 investigates the numerical model of the print head modelled in three-dimensional space. Various parameters of drop formation and fall were experimentally determined with a change in the time of the excitation impulse. A numerical analysis was carried out regarding the influence of the excitation time on the droplet formation and further movement. The supplemented articles were published in four peer-reviewed scientific journals listed in the Clarivate Analytics Web of Science database with an impact factor. The study results were presented at three international conferences.

Doctoral dissertation readers can search via VILNIUS TECH Virtual Library.

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