Author, Institution: Alfredas Brunius, Kaunas University of Technology
Science area, field of science: Technological Sciences, Mechanical Engineering, T 009
Scientific Supervisor: Prof. Dr. Egidijus Dragašius (Kaunas University of Technology Technological Sciences, Mechanical Engineering, T 009).
Dissertation Defence Board of Mechanical Engineering Science Field:
Habil. Dr. Algimantas Bubulis (Kaunas University of Technology, Technological Sciences, Mechanical Engineering, T 009) – Chairman;
Assoc. Prof. Dr. Saulius Baskutis (Kaunas University of Technology, Technological Sciences, Mechanical Engineering, T 009);
Prof. Dr. Vytautas Bučinskas (Vilnius Gediminas Technical University, Technological Sciences, Mechanical Engineering, T 009);
Dr. Joanna Mystkowska (Bialystok University of Technology, Poland, Technological Sciences, Mechanical Engineering, T 009).
The doctoral dissertation is available at the libraries of Kaunas University of Technology (K. Donelaičio St. 20, 44239 Kaunas, Lithuania) and Vytautas Magnus University Agriculture Academy (Studentų St. 11, Akademija, 53361 Kauno raj., Lithuania).
The doctoral dissertation consists of an introduction, four chapters, conclusions, bibliography, list of scientific publications and annexes. The first chapter provides an analysis of active magnetoreological fluids, an overview of piezoelectric materials and an overview of other sedimentation measuring methods in MR fluids. The second chapter is a mathematical model. In this chapter the movement of the particle in the MR fluid was mathematically described when they are in the middle of the tube or near the wall. Also a mathematical model is described where an infinite strip is affected by harmonic oscillations. The formula of the degree of resistance to sedimentation is derived. The theoretical and experimental results were compared. The third chapter is dedicated to experimental research. It experimentally validates the created mathematical model. This chapter presents the research of five different liquids using the rheometer, the magnetization curves of these MR fluids, photos of MR fluids using the microscope, and the special created electrical resistivity measurement sensors. Experimental investigations of sedimentation were performed with this sensor by measuring the electrical resistance of the MR fluid under magnetic field. The sedimentation level was also determined by measuring inductance of a coil. The fourth chapter presents the design and development of the device to determine the level of sedimentation in MR fluids and automatically mix the fluid.