Hong Hee Yoo

Bio: Hong Hee Yoo is an academic researcher from Hanyang University. The author has contributed to research in topics: Vibration & Equations of motion. The author has an hindex of 26, co-authored 180 publications receiving 2527 citations.

Vibration analysis of rotating cantilever beams

Abstract: Equations of motion of a rotating cantilever beam are derived based on a new dynamic modelling method in this paper. The derived equations (governing stretching and bending motions), which are coupled through gyroscopic coupling terms, are all linear, so they can be directly used for the vibration analysis including the coupling effect, which could not be considered in the conventional modelling method. With the coupling effect ignored, the analysis results are consistent with the results obtained by the conventional modelling method. With the coupling effect considered, eigenvalue loci veerings and mode shape variations could be observed through numerical study. Generally, when the rotating speed increases up to a certain value, the analysis results including the coupling effect show significant difference compared to the results ignoring the coupling effect. A modal formulation method is also introduced in this study to calculate the tuned angular speed of a rotating beam at which resonance occurs.

Dynamic analysis of a rotating cantilever beam by using the finite element method

Abstract: A finite element analysis for a rotating cantilever beam is presented in this study Based on a dynamic modelling method using the stretch deformation instead of the conventional axial deformation, three linear partial differential equations are derived from Hamilton's principle Two of the linear differential equations are coupled through the stretch and chordwise deformations The other equation is an uncoupled one for the flapwise deformation From these partial differential equations and the associated boundary conditions, are derived two weak forms: one is for the chordwise motion and the other is for the flapwise motion The weak forms are spatially discretized with newly defined two-node beam elements With the discretized equations, the behaviours of the natural frequencies are investigated for the variation of the rotating speed In addition, the time responses and distributions of the deformations and stresses are computed when the rotating speed is prescribed The effects of the rotating speed profile on the vibrations of the beam are also investigated

Dynamics of flexible beams undergoing overall motions

Abstract: A modelling method for straight beams undergoing large overall motions as well as small elastic deformations is presented in this paper. Different from the classical linear Cartesian modelling method which employs three Cartesian deformation variables, the present modelling method uses a non-Cartesian variable along with two Cartesian variables to describe the elastic deformation. A quadratic form of the strain energy expressed with the hybrid set of deformation variables is used to obtain the generalized active forces and a geometric constraint equation relating the non-Cartesian variable and Cartesian variables is used to obtain the generalized inertia forces in the equations of motion. The present modelling method not only provides accurate simulation results but also clarifies the limit of validity of the classical linear Cartesian modelling method.

Dynamic model for free vibration and response analysis of rotating beams

Abstract: A new modeling method for the vibration analysis of a rotating cantilever beam is proposed and compared to the other modeling methods. Applying the Hamilton principle, the equations for the axial, chordwise and flapwise motions are derived. During the derivation of these equations, the nonlinear von Karman strain and the corresponding linear stress are used to consider the stiffening effect due to rotation. The derived equations of motion obtained from the proposed method are analytically and numerically compared to equations from the previous modeling methods. Computations of the natural frequencies and time responses show that the described equations of motion are more reliable than the equations of the other modeling methods.

Modal characteristic of a rotating rectangular cantilever plate

Abstract: Modal characteristics of a rotating cantilever plate are investigated in the present work. A dynamic modelling method for rectangular plates undergoing prescribed overall motion is employed to derive the equations of motion. The general equations are particularized for the modal analysis of a rotating cantilever plate and dimensionless parameters are identified through dimensional analysis. The effects of the dimensionless parameters on the modal characteristics of the rotating plate are investigated. Incidentally, eigenvalue loci veering and crossing phenomena along with the corresponding modeshape variations are exhibited and discussed.

Dynamic analysis of flexible manipulators, a literature review

Abstract: In this paper a survey of the literature related to dynamic analyses of flexible robotic manipulators has been carried out. Both link and joint flexibility are considered in this work and an effort has been made to critically examine the methods used in these analyses, their advantages and shortcomings and possible extension of these methods to be applied to a general class of problems. Papers are classified according to modeling, control and experimental studies. In case of modeling they are subdivided according to the method of analysis and number of links involved in the analysis. An effort has been made to include the works of a huge variety of researchers working in this field and a total of 433 papers created in the years 1974–2005 have been reviewed in this work.

A review of energy harvesting using piezoelectric materials: state-of-the-art a decade later (2008–2018)

Abstract: Energy harvesting technologies have been explored by researchers for more than two decades as an alternative to conventional power sources (e.g. batteries) for small-sized and low-power electronic devices. The limited life-time and necessity for periodic recharging or replacement of batteries has been a consistent issue in portable, remote, and implantable devices. Ambient energy can usually be found in the form of solar energy, thermal energy, and vibration energy. Amongst these energy sources, vibration energy presents a persistent presence in nature and manmade structures. Various materials and transduction mechanisms have the ability to convert vibratory energy to useful electrical energy, such as piezoelectric, electromagnetic, and electrostatic generators. Piezoelectric transducers, with their inherent electromechanical coupling and high power density compared to electromagnetic and electrostatic transducers, have been widely explored to generate power from vibration energy sources. A topical review of piezoelectric energy harvesting methods was carried out and published in this journal by the authors in 2007. Since 2007, countless researchers have introduced novel materials, transduction mechanisms, electrical circuits, and analytical models to improve various aspects of piezoelectric energy harvesting devices. Additionally, many researchers have also reported novel applications of piezoelectric energy harvesting technology in the past decade. While the body of literature in the field of piezoelectric energy harvesting has grown significantly since 2007, this paper presents an update to the authors' previous review paper by summarizing the notable developments in the field of piezoelectric energy harvesting through the past decade.

Computational strategies for flexible multibody systems

Abstract: The status and some recent developments in computational modeling of flexible multibody systems are summarized. Discussion focuses on a number of aspects of flexible multibody dynamics including: modeling of the flexible components, constraint modeling, solution techniques, control strategies, coupled problems, design, and experimental studies. The characteristics of the three types of reference frames used in modeling flexible multibody systems, namely, floating frame, corotational frame, and inertial frame, are compared. Future directions of research are identified. These include new applications such as micro- and nano-mechanical systems; techniques and strategies for increasing the fidelity and computational efficiency of the models; and tools that can improve the design process of flexible multibody systems. This review article cites 877 references. @DOI: 10.1115/1.1590354#

Moving-load dynamic problems: A tutorial (with a brief overview)

Abstract: This tutorial is dedicated to the study of structural dynamics problems caused by moving loads. Through a simple example of a simply supported beam traversed by a moving mass, several fundamental concepts peculiar to moving-load problems are introduced. The necessary mathematics involved is presented. The analytical procedure is also presented for a circular plate excited by a rotating oscillator. Then numerical results of a circular beam spinning about its longitudinal axis excited by an axially moving surface load are provided. A variety of moving-load problems are briefly reviewed with some published papers and books to help readers quickly get into problems of their interests. Readers are expected to get a flavour of what moving-load problems are about, what general methods are available and what research has been done from studying this tutorial. Knowledge of partial differential equations and vibration theory of beams and plates is required in order to understand this tutorial.

Internet of Things (IoT): Opportunities, issues and challenges towards a smart and sustainable future

Abstract: The rapid development and implementation of smart and IoT (Internet of Things) based technologies have allowed for various possibilities in technological advancements for different aspects of life. The main goal of IoT technologies is to simplify processes in different fields, to ensure a better efficiency of systems (technologies or specific processes) and finally to improve life quality. Sustainability has become a key issue for population where the dynamic development of IoT technologies is bringing different useful benefits, but this fast development must be carefully monitored and evaluated from an environmental point of view to limit the presence of harmful impacts and ensure the smart utilization of limited global resources. Significant research efforts are needed in the previous sense to carefully investigate the pros and cons of IoT technologies. This review editorial is partially directed on the research contributions presented at the 4th International Conference on Smart and Sustainable Technologies held in Split and Bol, Croatia, in 2019 (SpliTech 2019) as well as on recent findings from literature. The SpliTech2019 conference was a valuable event that successfully linked different engineering professions, industrial experts and finally researchers from academia. The focus of the conference was directed towards key conference tracks such as Smart City, Energy/Environment, e-Health and Engineering Modelling. The research presented and discussed at the SpliTech2019 conference helped to understand the complex and intertwined effects of IoT technologies on societies and their potential effects on sustainability in general. Various application areas of IoT technologies were discussed as well as the progress made. Four main topical areas were discussed in the herein editorial, i.e. latest advancements in the further fields: (i) IoT technologies in Sustainable Energy and Environment, (ii) IoT enabled Smart City, (iii) E-health - Ambient assisted living systems (iv) IoT technologies in Transportation and Low Carbon Products. The main outcomes of the review introductory article contributed to the better understanding of current technological progress in IoT application areas as well as the environmental implications linked with the increased application of IoT products.