A review on modelling and dynamic analysis of viscoelastic rotor systems

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Krishanu Ganguly ◽  
Saurabh Chandraker ◽  
Haraprasad Roy
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Behaviour ◽  
Basic Part ◽  
Content Type ◽  
Rotor Systems ◽  
Rotor Shaft ◽  
Modelling Techniques ◽  
Collective Information ◽  
Real Time Application ◽  
Critical Literature

Purpose The purpose of this study is to bring down collective information about various issues encountered in modelling of rotor systems. Design/methodology/approach The most important and basic part of “rotor dynamics” is the study related to its different modelling techniques which further involves the analysis of shaft for understanding the system potential, competence and reliability. The issues addressed in this study are classified mainly into two parts: the initial part gives out a vast overview of significant problems as well as different techniques applied to encounter modelling of rotor systems, while the latter part of the study describes the post-processing problem that occurs while performing the dynamic analysis. Findings The review incorporates the most important research works that have already placed a benchmark right from the beginning as well as the recent works that are still being carried out to further produce better outcomes. The review concludes with the modal analysis of rotor shaft to show the importance of mathematical model through its dynamic behaviour. Originality/value A critical literature review on the modelling techniques of rotor shaft systems is provided from earliest to latest along with its real-time application in different research and industrial fields.

FINE-TUNING OF MODELLING STRATEGY TO SIMULATE THERMO-MECHANICAL BEHAVIOUR OF DOUBLE FRICTION PENDULUM SEISMIC ISOLATORS UST ESTIMATOR

2019 ◽  
Vol 3 (Special Issue on First SACEE'19) ◽  
pp. 165-172
Author(s):  
Vincenzo Bianco ◽  
Giorgio Monti ◽  
Nicola Pio Belfiore
Keyword(s):  
Multibody Dynamics ◽  
Mechanical Behaviour ◽  
Mechanical Model ◽  
Dynamic Behaviour ◽  
Experimental Testing ◽  
Fine Tuning ◽  
Proposed Model ◽  
Modelling Techniques ◽  
Friction Pendulum

The use of friction pendulum devices has recently attracted the attention of both academic and professional engineers for the protection of structures in seismic areas. Although the effectiveness of these has been shown by the experimental testing carried out worldwide, many aspects still need to be investigated for further improvement and optimisation. A thermo-mechanical model of a double friction pendulum device (based on the most recent modelling techniques adopted in multibody dynamics) is presented in this paper. The proposed model is based on the observation that sliding may not take place as ideally as is indicated in the literature. On the contrary, the fulfilment of geometrical compatibility between the constitutive bodies (during an earthquake) suggests a very peculiar dynamic behaviour composed of a continuous alternation of sticking and slipping phases. The thermo-mechanical model of a double friction pendulum device (based on the most recent modelling techniques adopted in multibody dynamics) is presented. The process of fine-tuning of the selected modelling strategy (available to date) is also described.

New Arch Footbridges

2021 ◽  
Author(s):  
Jiří Stráský ◽  
Tomas Romportl ◽  
Pavel Kaláb ◽  
Leonard Šopík
Keyword(s):  
Czech Republic ◽  
Dynamic Analysis ◽  
Dynamic Behaviour ◽  
Human Dimensions ◽  
Span Length ◽  
Structural Members ◽  
The Czech Republic ◽  
The Usa ◽  
Structural Solution

<p>Four arch pedestrian and cyclist bridges built in the USA, Slovakia and in the Czech Republic are described in terms of their architectural and structural solution, static and dynamic behaviour, and technology of their construction. The bridges with span length up to 104 m have slender decks which are suspended on arches of a butterfly arrangement. The dynamic analysis proved that all structures are comfortable to users. The footbridges are structurally efficient, they are light and transparent, correspond to the scale of the landscape and all structural members have human dimensions.</p>

Modern pretreatment techniques for phytochemical extraction

2019 ◽  
Vol 49 (3) ◽  
pp. 441-454 ◽  
Author(s):  
Satakshi Aggarwal ◽  
Tanu Jain
Keyword(s):  
Ohmic Heating ◽  
Anthocyanin Content ◽  
Thermal Pretreatment ◽  
Content Type ◽  
Advantages And Disadvantages ◽  
Hybrid Approaches ◽  
Final Yield ◽  
Pre Treatment ◽  
Collective Information ◽  
Phytochemical Extraction

Purpose Modern thermal and non-thermal pretreatment techniques, namely, enzymatic treatment, gas phase plasma treatment and ohmic heating have become more pronounced over conventional techniques for enhanced coloured phytochemicals (pigments) extraction. Presently, numbers of pretreatment techniques are available with some unique feature. It is difficult to choose best pretreatment method to be employed for phytochemicals extraction from different sources. Therefore, this paper aims to discuss different modern pretreatment techniques for extraction with their potential results over conventional techniques. Design/methodology/approach Research and review articles targeting to the thermal and non-thermal pretreatment techniques were collected from Google Scholar. The required information has been tabulated and discussed which included qualities of modern pretreatment techniques over conventional techniques, phytochemical extraction and best pretreatment methods for optimized results. Findings Every pre-treatment has its own advantages and disadvantages for a particular phytochemical and its extraction from various sources. Enzymes can be used in combinations to enhance final yield like extraction of carotenoids (pectinase, cellulase and hemicellulase) from chillies and lycopene (pectinase and cellulase) from tomato. Utilization of each method depends upon many factors such as source of pigment, cost and energy consumption. CO2 pretreatment gives good results for carotenoid extraction from algae sources. Ohmic heating can yield high anthocyanin content. Modifications in conventional blanching has reduced final waste and improvised the properties of pigment. Originality/value This study comprises collective information regarding modern pre-treatment for extraction over conventional pre-treatments. The study also covers future trends and certain new hybrid approaches which are still less flourished.

China in Africa: a critical literature review

2016 ◽  
Vol 12 (1) ◽  
pp. 40-60 ◽  
Author(s):  
Abdoulkadre Ado ◽  
Zhan Su
Keyword(s):  
Literature Review ◽  
Design Methodology ◽  
Empirical Support ◽  
Future Research ◽  
Evidence Based ◽  
Content Type ◽  
Academic Literature ◽  
Current State ◽  
Comprehensive Literature Review ◽  
Critical Literature

Purpose – The purpose of this paper is to critically assesses the major contributions to the academic literature on China’s increased focus on Africa, from 2001 to 2011. It discusses the key trends concerning China’s presence in Africa and draws conclusions on the significance of the studies by emphasizing and contrasting the prevailing positions. Design/methodology/approach – Based on a qualitative approach using an integrative and comprehensive literature review, the authors performed a content analysis of high-impact, peer-reviewed papers. Findings – The paper questions and repositions some of the existing controversies. The results from existing studies remain questionable, requiring further clarification and more theoretical backing. It, moreover, highlights the notion that behind the explicit neutrality views of China’s presence in Africa, implicit assumptions may exist. These are often the differences in narratives conveyed by Western and Southern stakeholders. Research limitations/implications – Most of the conclusions drawn from this paper need to be re-explored and supported by additional research. This could be done by widening the scope of the analysis. Studies need to provide more empirical support for their assertions through quantitative data and evidence-based qualitative analyses – all within a framework that considers more cultural, social and historical dimensions. The paper also suggests that an institutionally based view appears most relevant in better explaining China in Africa. Originality/value – This paper reviews a decade of research on China in Africa and presents a snapshot of the current state of knowledge. It also raises concerns to be analyzed by future research and proposes new avenues for better understanding China’s presence in Africa.

Recent advances in reliability analysis of aeroengine rotor system: a review

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xue-Qin Li ◽  
Lu-Kai Song ◽  
Guang-Chen Bai
Keyword(s):  
Reliability Analysis ◽  
Surrogate Model ◽  
Engineering Application ◽  
Rotor System ◽  
Engineering Structures ◽  
Content Type ◽  
Reliability Design ◽  
Rotor Systems ◽  
Practical Engineering ◽  
Complex Engineering

PurposeTo provide valuable information for scholars to grasp the current situations, hotspots and future development trends of reliability analysis area.Design/methodology/approachIn this paper, recent researches on efficient reliability analysis and applications in complex engineering structures like aeroengine rotor systems are reviewd.FindingsThe recent reliability analysis advances of engineering application in aeroengine rotor system are highlighted, it is worth pointing out that the surrogate model methods hold great efficiency and accuracy advantages in the complex reliability analysis of aeroengine rotor system, since its strong computing power can effectively reduce the analysis time consumption and accelerate the development procedures of aeroengine. Moreover, considering the multi-objective, multi-disciplinary, high-dimensionality and time-varying problems are the common problems in various complex engineering fields, the surrogate model methods and its developed methods also have broad application prospects in the future.Originality/valueFor the strong demand for efficient reliability design technique, this review paper may help to highlights the benefits of reliability analysis methods not only in academia but also in practical engineering application like aeroengine rotor system.

Dynamic analysis of a helical geared rotor-bearing system with composite rotating shafts

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ying-Chung Chen ◽  
Xu Feng Cheng ◽  
Siu-Tong Choi
Keyword(s):  
Composite Material ◽  
Dynamic Analysis ◽  
Dynamic Characteristics ◽  
Mesh Stiffness ◽  
Content Type ◽  
Gear Mesh ◽  
Rotor Bearing ◽  
Rotating Shafts ◽  
Gear Mesh Stiffness ◽  
Bearing System

Purpose This study aims to study the dynamic characteristics of a helical geared rotor-bearing system with composite material rotating shafts. Design/methodology/approach A finite element model of a helical geared rotor-bearing system with composite material rotating shafts is developed, in which the rotating shafts of the system are composed of composite material and modeled as Timoshenko beam; a rigid mass is used to represent the gear and their gyroscopic effect is taken into account; bearings are modeled as linear spring-damper; and the equations of motion are obtained by applying Lagrange’s equation. Natural frequencies, mode description, lateral responses, axial responses, lamination angles, lamination numbers, gear mesh stiffness and bearing damping coefficients are investigated. Findings The desired mechanical properties could be constructed using different lamination numbers and fiber included angles by composite rotating shafts. The frequency of the lateral module decreases as the included angle of the fibers and the principal shaft of the composite material rotating shaft increase. Because of the gear mesh stiffness increase, the resonance frequency of the coupling module of the system decreases, the lateral module is not influenced and the steady-state response decreases. The amplitude of the steady-state lateral and axial responses gradually decreases as the bearing damping coefficient increases. Practical implications The model of a helical geared rotor-bearing system with composite material rotating shafts is established in this paper. The dynamic characteristics of a helical geared rotor-bearing system with composite rotating shafts are investigated. The numerical results of this study can be used as a reference for subsequent personnel research. Originality/value The dynamic characteristics of the geared rotor-bearing system had been reported in some literature. However, the dynamic analysis of a helical geared rotor-bearing system with composite material rotating shafts is still rarely investigated. This paper shows some novel results of lateral and axial response results obtained by different lamination angles and different lamination numbers. In the future, it makes valuable contributions for further development of dynamic analysis of a helical geared rotor-bearing system with composite material rotating shafts.

Volatility dynamics of Malaysian listed property companies within the Asian public property markets by using a switching regime approach

2019 ◽  
Vol 25 (1) ◽  
pp. 5-39
Author(s):  
Mohammad Muzzammil Zekri ◽  
Muhammad Najib Razali
Keyword(s):  
Global Financial Crisis ◽  
Content Type ◽  
Public Property ◽  
Switching Regime ◽  
Property Companies ◽  
Egarch Model ◽  
Modelling Techniques ◽  
The Global Financial Crisis ◽  
Autoregressive Conditional Heteroscedasticity ◽  
Property Markets

Purpose This paper aims to examine the dynamic of volatility of Malaysian listed property companies within pan-Asian public property markets based on different volatility perspective over the past 18 years, especially during the global financial crisis (GFC). Design/methodology/approach This study uses several statistical methods and formulas for analysing the dynamic of volatility of Malaysian listed property companies such as exponential generalised autoregressive conditional heteroscedasticity (EGARCH) and Markov-switching (MS) EGARCH. The MS-EGARCH model provides new insights on the volatility dynamics of Malaysian listed property companies compared to conventional volatility modelling techniques, particularly EGARCH. Additionally, this paper will analyse the volatility movement based on three different sub-periods such as pre-GFC, GFC and post-GFC. Findings The findings reveal that the markets perform differently under different volatility conditions. Moreover, the application of MS-EGARCH provides a different view on the volatility dynamics compared to the conventional EGARCH model, as MS-EGARCH provides more comprehensive findings, especially during extreme market conditions. Originality/value This study contributes to the literature on the dynamics of Malaysian listed property companies within pan-Asian countries, as the approach for assessing the volatility performance based on different volatility conditions is less explored by previous researchers.

Dynamic analysis of swivel construction method under multi-variable coupling effects

2019 ◽  
Vol 10 (4) ◽  
pp. 580-598
Author(s):  
Wang Jiawei ◽  
Sun Quansheng
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Model ◽  
Static Analysis ◽  
Friction Stress ◽  
Construction Method ◽  
Coupling Effects ◽  
Content Type ◽  
Multiple Factors ◽  
Real State ◽  
Variable Coupling

Purpose Swivel construction is a new bridge construction method, which can minimize the impact on railway and highway traffic. Previous studies were based on single factor and static analysis, which cannot reflect the real state of structures. The purpose of this paper is to establish a dynamic model of the structure and to analyze the situation under multi-variable coupling effects to accurately simulate the real state of the structure. Design/methodology/approach Finite element software ANSYS was used to establish dynamic model of turntable structure and then to analyze the effects of multiple factors on total stress, friction stress and slipping distance of the turntable structure. Findings It is concluded that the unbalanced weight and radius of spherical hinges have great influence on the turntable structure, so the design should be strictly considered. Friction stress and angular acceleration have little effect on the turntable structure. Originality/value This paper provides simulation of the whole process of swivel construction method. Whereas previous studies focused on static analysis, this paper focuses on the dynamic analysis of swivel construction method. The mechanics of the swivel structure under multiple factors was analyzed. According to the analysis results, the design parameters of the turntable structure are optimized.

Psy-science and the colonial relationship in the mental health field

2014 ◽  
Vol 19 (3) ◽  
pp. 176-184 ◽  
Author(s):  
W.J. Penson
Keyword(s):  
Mental Health ◽  
Design Methodology ◽  
Postcolonial Theory ◽  
Scaling Up ◽  
Mental Health Field ◽  
Frames Of Reference ◽  
Content Type ◽  
Research Perspectives ◽  
Health Field ◽  
Critical Literature

Purpose – The purpose of this paper is to critically discuss how the psy-sciences have been, and continue to be, typified by some critics, as colonizers and are credited with Imperialistic motivations. However, rarely are these critiques developed beyond a pejorative characterisation. Design/methodology/approach – This paper reviews the criticisms of psychiatry as colonial and outlines the tensions in taking different frames of reference in the mental health field, before going on to suggest theoretical and research perspectives arising from postcolonial theory that might advance these critical positions more coherently and the implications of doing so. Findings – This study suggests an engagement with humanities-based methods and fields such as postcolonial scholarship. Social implications – This argument is timely, especially given recent controversies over the publication of DSM5, the scaling up agenda for mental health in the Global South and increased attention to the agenda of Big Pharma. Originality/value – Postcolonial intersections with psy-science remains a relatively undeveloped area in the critical literature.

Sign in / Sign up

Export Citation Format

Share Document