The Recent Advances in Magnetorheological Fluids-Based Applications

The magnetorheological fluids (MRF) are a generation of smart fluids with the ability to alter their variable viscosity. Moreover, the state of the MRF can be switched from the semisolid to the fluid phase and vice versa upon applying or removing the magnetic field. The fast response and the controllability are the main features of the MRF-based systems, which make them suitable for applications with high sensitivity and controllability requirements. Nowadays, MRF-based systems are rapidly growing and widely being used in many industries such as civil, aerospace, and automotive. This study presents a comprehensive review to investigate the fundamentals of MRF and manufacturing and applications of MRF-based systems. According to the existing works and current and future demands for MRF-based systems, the trend for future research in this field is recommended

Development of Rotary Variable Damping and Stiffness Magnetorheological Dampers and their Applications on Robotic Arms and Seat Suspensions

This thesis successfully expanded the idea of variable damping and stiffness (VSVD) from linear magnetorheological dampers (MR) to rotary magnetorheological dampers; and explored the applications of rotary MR dampers on the robotic arms and seat suspension. The idea of variable damping and stiffness has been proved to be able to reduce vibration to a large degree. Variable damping can reduce the vibration amplitude and variable stiffness can shift the natural frequency of the system from excitation and prevent resonance. Linear MR dampers with the capacity of variable damping and stiffness have been studied by researchers. However, Linear MR dampers usually require larger installation space than rotary MR dampers, and need more expensive MR fluids to fill in their chambers. Furthermore, rotary MR dampers are inherently more suitable than linear MR dampers in rotary motions like braking devices or robot joints. Hence, rotary MR dampers capable of simultaneously varying the damping and stiffness are very attractive to solve angular vibration problems. Out of this motivation, a rotary VSVD MR damper was designed, prototyped, with its feature of variable damping and stiffness verified by experimental property tests in this thesis. Its mathematical model was also built with the parameters identified. The experimental tests indicated that it has a 141.6% damping variation and 618.1% stiffness variation. This damper’s successful development paved the way for the applications of rotary MR dampers with the similar capability of variable damping and stiffness

Tribological characteristics of smart fluids

Diplomová práca sa zaoberá experimentálnym štúdiom tribologických charakteristík smart kvapalín. Smart kvapaliny sú látky v kvapalnom skupenstve reagujúce na prítomnosť magnetického alebo elektrického poľa zmenou reologických vlastností. Pre možnosť aplikácie v zariadeniach využívajúcich konvenčné mazivá je potrebné zvoliť vhodnú smart kvapalinu a študovať vplyv budenia na utváranie mazacej vrstvy, trenie a opotrebenie. Komplexný popis vplyvu budenia je realizovaný použitím troch experimentálnych zariadení a teoretického modelu pre stanovenie parametrov meraní. Hodnotená je hrúbka mazacej vrstvy, priebeh súčiniteľa trenia a opotrebenie počas aktivácie smart kvapaliny v nekonformnom kontakte. Výsledky ukazujú výrazný pozorovateľný vplyv budenia na všetky hodnotené aspekty. Pochopenie mechanizmov budenia smart kvapalín môže byť kľúčovým krokom pri vývoji inteligentných zariadení s aktívnym externým riadením správania a povahy maziva, ktoré by napomohli k zníženiu nákladov na údržbu a k zlepšeniu efektivity.The master's thesis deals with experimental study of tribological characteristics of smart fluids. Smart fluids are substances in liquid state reacting to the presence of magnetic or electric field by change in rheological properties. For possible application in devices using conventional lubricants is necessary to choose suitable smart fluid and study the influence of excitation on formation of lubricating layer, friction and wear. Comprehensive description of excitation influence is executed using three experimental devices and theoretical model for measurements parameters specification. Assessed are lubricant film thickness, friction coefficient and wear under smart fluid activation in non-conformal contact. Results show significant observable influence of smart fluids excitation on all assessed aspects. Understanding the mechanisms of smart fluids excitation can be a key step in development of intelligent devices with active external control of lubricant behaviour and character, that could lead to maintenance cost reduction and effectivity improvement.

Emerging Trends in Mechatronics

Mechatronics is a multidisciplinary branch of engineering combining mechanical, electrical and electronics, control and automation, and computer engineering fields. The main research task of mechatronics is design, control, and optimization of advanced devices, products, and hybrid systems utilizing the concepts found in all these fields. The purpose of this special issue is to help better understand how mechatronics will impact on the practice and research of developing advanced techniques to model, control, and optimize complex systems. The special issue presents recent advances in mechatronics and related technologies. The selected topics give an overview of the state of the art and present new research results and prospects for the future development of the interdisciplinary field of mechatronic systems