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Article
Publication date: 27 November 2018

Mubing Yu, Xiaodong Yu, Xuhang Zheng, Hang Qu, Tengfei Yuan and Daige Li

This paper aims to describe a theoretical and experimental research concerning influence of recess shape on comprehensive lubrication performance of high speed and heavy…

Abstract

Purpose

This paper aims to describe a theoretical and experimental research concerning influence of recess shape on comprehensive lubrication performance of high speed and heavy load hydrostatic thrust bearing with a constant flow.

Design/methodology/approach

The lubrication performance of a hydrostatic thrust bearing with different recess shape under the working conditions of high speed and heavy load has been simulated by using computational fluid dynamics and finite volume method.

Findings

It is found that the comprehensive lubrication performance of a hydrostatic thrust bearing with circular recess is optimal. The results demonstrate that recess shape has a great influence on the lubrication performance of the hydrostatic thrust bearing.

Originality/value

The simulation results indicate that to get an improved performance from a hydrostatic thrust bearing with constant flow, a proper selection of the recess shape is essential.

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Article
Publication date: 30 November 2018

Mubing Yu, Xiaodong Yu, Xuhang Zheng and Hui Jiang

The purpose of this paper is to study thermal-fluid-solid coupling deformation and friction failure mechanism of bearing friction pairs under the working conditions of…

Abstract

Purpose

The purpose of this paper is to study thermal-fluid-solid coupling deformation and friction failure mechanism of bearing friction pairs under the working conditions of high speed and heavy load.

Design/methodology/approach

The deformation is simulated based on thermal-fluid-solid coupling method, its deformation distribution law is revealed and the relationships of deformation of friction pairs, rotational speed and bearing weight are obtained.

Findings

The results prove that the oil film temperature rises sharply, the lubricating oil viscosity decreases rapidly, the film thickness becomes thinner, the deformation increases, the whole deformation is uneven and the boundary lubrication or dry friction are caused with the increase in rotational speed and bearing load.

Originality/value

The conclusions provide theoretical method for deformation solution and friction failure mechanism of hydrostatic thrust bearing.

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Article
Publication date: 31 October 2018

Jun-peng Shao, Guang-dong Liu and Xiaodong Yu

This paper aims to improve the bearing capacity of hydrostatic thrust bearing under working conditions of high speed and heavy load; a new wedge-shaped structure opened on…

Abstract

Purpose

This paper aims to improve the bearing capacity of hydrostatic thrust bearing under working conditions of high speed and heavy load; a new wedge-shaped structure opened on an edge of oil seal is put forward, the loss and insufficiency for hydrostatic bearing capacity are made up by using dynamic pressure, and then, hydrostatic hydrodynamic lubrication is realized.

Design/methodology/approach

Oil film three-dimensional models of unidirectional and bi-directional hydrostatic hydrodynamic oil pad are established by using UG. The oil film pressure fields of two kinds of oil pad are simulated by using ANSYS ICEM CFD and ANSYS CFX; the pressure fields distribution characteristics are obtained, and the effects of workbench rotary speed and bearing weight on pressure field are analyzed. Also, the experimental verification is made.

Findings

The results demonstrate that with an increase in workbench rotary speed, the oil film pressure of two kinds of hybrid oil pad increases gradually, and the maximum pressure of the bi-directional one accounts for 95 per cent of the unidirectional one when the load is constant. With an increase in load, the oil film pressure of two kinds of hybrid oil pad increases gradually, the difference between them is 9.4 per cent under the condition of load of 25 t when the rotary speed is constant.

Originality/value

The paper can provide theoretical basis for a structure design of hybrid thrust bearing under different rotary speed and load conditions, and compensate the shortage of static pressure-bearing capacity by using dynamic pressure, improve the stability of vertical CNC machining equipment.

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Article
Publication date: 10 August 2018

Xiaodong Yu, Xu Zuo, Chao Liu, Xuhang Zheng, Hang Qu and Tengfei Yuan

Hydrostatic thrust bearing is a key component of the vertical CNC machining equipment, and often results in friction failure under the working condition of high speed and…

Abstract

Purpose

Hydrostatic thrust bearing is a key component of the vertical CNC machining equipment, and often results in friction failure under the working condition of high speed and heavy load. The lubricating oil film becomes thin or breaks because of high speed and heavy load and it affects the high precision and stable operation of the vertical CNC machining equipment; hence, it is an effective way of avoiding friction failure for achieving the oil film shape prediction

Design/methodology/approach

For the hydrostatic thrust bearing with double rectangular cavities, researchers solve the deformation of the friction pairs in hydrostatic bearing by using the computation of hydrodynamics, elasticity theory, finite element method and fluid-thermal-mechanical coupled method. The deformation includes heat deformation and elasticity deformation, the shape of gap oil film is got according to the deformation of the friction pairs in hydrostatic bearing, and gets the shape of gap oil film, and determines the influencing factors and laws of the oil film shape, and achieves the prediction of oil film shape, and ascertains the mechanism of friction failure. An experimental verification is carried out.

Findings

Results show that the deformation of the rotational workbench is upturned along its radial direction under the working condition of high speed and heavy load. However, the deformation of the base is downturned along its radial direction and the deformation law of the gap oil film along the radius direction is estimated; the outer diameter is close but the inner diameter is divergent wedge.

Originality/value

The conclusion can provide a theoretical basis for the oil film control of hydrostatic thrust bearing and improve the stability of vertical CNC machining equipment.

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Article
Publication date: 19 July 2019

Yanqin Zhang, Jichang Sun, Pengrui Kong, Xiangbin Kong and Xiaodong Yu

The purpose of the paper is to analyze the bearing capacity of hydrostatic bearing during the change of film thickness under different working conditions and to improve…

Abstract

Purpose

The purpose of the paper is to analyze the bearing capacity of hydrostatic bearing during the change of film thickness under different working conditions and to improve the processing efficiency and precision of equipment.

Design/methodology/approach

In this study, Q1-205 double rectangular cavity hydrostatic thrust bearing is selected as the research object. The dynamic mesh method and ANSYS/FLUENT software are used to simulate the curves of oil film thickness and oil pressure under different operating conditions. Finally, the change of pressure in the oil cavity at different operating speeds under a certain inlet flow rate was tested through design experiments.

Findings

When the film thickness was thick, the maximum pressure in the oil cavity at different inlet velocities showed little difference. With a larger inlet flow, the maximum pressure in the oil cavity was higher. The pressure at the edge of the oil seal was linearly distributed. The oil pressure in the downstream side was greater than that in the counter flow side. When the working pressure was low, the pressure in the oil cavity slightly decreased with the increase of working speed. Moreover, the pressure loss at high speed was considerable.

Originality/value

Based on the lubrication theory, the mathematical model of the bearing oil film was set up. The bearing capacity equation of the hydrostatic cavity was derived. The double-rectangular-annular hydrostatic guides studied in this paper have not been reported in previous research literature and the method of dynamic mesh dynamic simulation of variable viscosity is seldom studied before. The bearing characteristics and the change of oil film thickness under different working conditions have been studied systematically and comprehensively. The theoretical analysis results are basically consistent with the experimental results.

Details

Industrial Lubrication and Tribology, vol. 71 no. 9
Type: Research Article
ISSN: 0036-8792

Keywords

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Article
Publication date: 8 January 2018

Xiao-dong Yu, Lei Geng, Xiao-jun Zheng, Zi-xuan Wang and Xiao-gang Wu

Rotational speed and load-carrying capacity are two mutual coupling factors which affect high precision and stable operation of a hydrostatic thrust bearing. The purpose…

Abstract

Purpose

Rotational speed and load-carrying capacity are two mutual coupling factors which affect high precision and stable operation of a hydrostatic thrust bearing. The purpose of this paper is to study reasonable matching relationship between the rotational speed and the load-carrying capacity.

Design/methodology/approach

A mathematical model of relationship between the rotational speed and the load-carrying capacity of the hydrostatic bearing with double-rectangle recess is set up on the basis of the tribology theory and the lubrication theory, and the load and rotational speed characteristics of an oil film temperature field and a pressure field in the hydrostatic bearing are analyzed, reasonable matching relationship between the rotational speed and the load-carrying capacity is deduced and a verification experiment is conducted.

Findings

By increasing the rotational speed, the oil film temperature increases, the average pressure decreases and the load-carrying capacity decreases. By increasing the load-carrying capacity, the oil film temperature and the average pressure increases and the rotational speed decreases; corresponding certain reasonable matching values are available.

Originality/value

The load-carrying capacity can be increased and the rotational speed improved by means of reducing the friction area of the oil recess by using low-viscosity lubricating oil and adding more oil film clearance; but, the stiffness of the hydrostatic bearing decreases.

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Article
Publication date: 25 July 2019

Hui Zhang, David Bourell, Yanling Guo, Xiaodong Zhang, Yu Zhuang, Yueqiang Yu, Kaiyi Jiang and Wasim M.K. Helal

A pine/co-PES composite (PCPES composite) was proposed as the feedstock for powder bed fusion (laser sintering, LS). This paper aims to provide some necessary experimental…

Abstract

Purpose

A pine/co-PES composite (PCPES composite) was proposed as the feedstock for powder bed fusion (laser sintering, LS). This paper aims to provide some necessary experimental data and the theoretical foundation for LS of pine/co-PES, especially for the application of using the laser-sintered pine/co-PES parts as complex structural patterns in investment casting.

Design/methodology/approach

The PCPES composites with different pine loadings were mixed mechanically. The composite’s preheating temperature and processing temperature during LS were determined experimentally based on the material’s thermal behavior. The effects of pine powder on the binding mechanism of PCPES composites were discussed through analyzing the microstructure of the laser-sintered parts’. Mechanical properties and dimensional precision of laser-sintered PCPES parts in different pine loadings were tested, and the parts’ mechanical properties were strengthened by wax-infiltration post-processing. The influence extents of process parameters on the mechanical properties of laser-sintered 20 Wt.% pine/co-PES parts were investigated using a 1/2 fractional factorials experiment.

Findings

20 Wt.% pine/co-PES is considered to be a promising wood-plastic composite for laser sintering. The relationship between mechanical strength of its laser-sintered parts and process parameters was built up using mathematical formulas. Experimental results show density, tensile strength, flexural strength and surface roughness of laser-sintered 20 Wt.% pine/co-PES parts are improved by 72.7-75.0%, 21.9-111.3%, 26.8-86.2%, 27.0-29.1% after post-process infiltration with a wax. A promising application of the wax-infiltrated laser-sintered parts is for investment casting cores and patterns.

Research limitations/implications

The proper process parameters and forming properties of laser-sintered parts are limited to the results of laser sintering experiments carried on using AFS 360 rapid prototyping device.

Originality/value

This investigation not only provides a new feedstock for laser sintering with the advantages of low cost and fabricability but also uses an advanced technique to produce personalized wood-plastic parts efficiently. Mathematical models between mechanical properties of laser-sintered PCPES parts and LS process parameters will guide the further LS experiments using the 20 Wt.% pine/co-PES composite. Besides, the laser-sintered PCPES parts after wax-infiltration post-processing are promising as complex structural patterns for use in investment casting.

Details

Rapid Prototyping Journal, vol. 25 no. 8
Type: Research Article
ISSN: 1355-2546

Keywords

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Article
Publication date: 12 March 2019

Liang Li, Ziyu Chen, Yaobing Wang, Xiaodong Zhang and Ningfei Wang

The purpose of this paper is to solve the tracking problem for free-floating space manipulators (FFSMs) in task space with parameter uncertainties and external disturbance.

Abstract

Purpose

The purpose of this paper is to solve the tracking problem for free-floating space manipulators (FFSMs) in task space with parameter uncertainties and external disturbance.

Design/methodology/approach

In this paper, the novel cerebellar model articulation controller (CMAC) is designed with the feedback controller. More precisely, the parameter uncertainties in the FFSM are considered for achieving the robustness.

Findings

By using the dynamically equivalent model, the CMAC can be designed and trained with the desired performance, such that the prescribed trajectory can be followed accordingly. The simulation results are presented for illustrating the validity of the derived results.

Originality/value

Based on the designed CMAC, the tracking error would be approaching zero by choosing appropriate quantization level in CMAC and the corresponding learning rules can be tuned online.

Details

Assembly Automation, vol. 39 no. 1
Type: Research Article
ISSN: 0144-5154

Keywords

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Article
Publication date: 7 October 2020

Yanping Zhang, Xiaodong Li and Juho Hamari

This study aims to investigate how aspects of mobility affect social media advertising effectiveness (i.e. consumer purchase intention) on mobile platforms from the…

Abstract

Purpose

This study aims to investigate how aspects of mobility affect social media advertising effectiveness (i.e. consumer purchase intention) on mobile platforms from the perspective of the fit-viability model.

Design/methodology/approach

Data were collected through an online questionnaire survey of 378 WeChat users and used to test hypotheses with structural equation modeling.

Findings

Consumer purchase intention is significantly positively influenced by time flexibility, spatial flexibility, mobile lifestyle and ad relevance. Meanwhile, ambivalence toward ads mediates the relationships of time flexibility and spatial flexibility with purchase intention and moderates the relationships of mobile lifestyle and ad relevance with purchase intention.

Research limitations/implications

The findings offer researchers and practitioners a new angle to understand advertising effectiveness on mobile social media and extend the application of the fit-viability model.

Originality/value

This paper fills the research gap on the role of mobility in social media advertising.

Details

Industrial Management & Data Systems, vol. 120 no. 11
Type: Research Article
ISSN: 0263-5577

Keywords

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Book part
Publication date: 10 December 2015

Chun Kit Lok

Smart card-based E-payment systems are receiving increasing attention as the number of implementations is witnessed on the rise globally. Understanding of user adoption…

Abstract

Smart card-based E-payment systems are receiving increasing attention as the number of implementations is witnessed on the rise globally. Understanding of user adoption behavior of E-payment systems that employ smart card technology becomes a research area that is of particular value and interest to both IS researchers and professionals. However, research interest focuses mostly on why a smart card-based E-payment system results in a failure or how the system could have grown into a success. This signals the fact that researchers have not had much opportunity to critically review a smart card-based E-payment system that has gained wide support and overcome the hurdle of critical mass adoption. The Octopus in Hong Kong has provided a rare opportunity for investigating smart card-based E-payment system because of its unprecedented success. This research seeks to thoroughly analyze the Octopus from technology adoption behavior perspectives.

Cultural impacts on adoption behavior are one of the key areas that this research posits to investigate. Since the present research is conducted in Hong Kong where a majority of population is Chinese ethnicity and yet is westernized in a number of aspects, assuming that users in Hong Kong are characterized by eastern or western culture is less useful. Explicit cultural characteristics at individual level are tapped into here instead of applying generalization of cultural beliefs to users to more accurately reflect cultural bias. In this vein, the technology acceptance model (TAM) is adapted, extended, and tested for its applicability cross-culturally in Hong Kong on the Octopus. Four cultural dimensions developed by Hofstede are included in this study, namely uncertainty avoidance, masculinity, individualism, and Confucian Dynamism (long-term orientation), to explore their influence on usage behavior through the mediation of perceived usefulness.

TAM is also integrated with the innovation diffusion theory (IDT) to borrow two constructs in relation to innovative characteristics, namely relative advantage and compatibility, in order to enhance the explanatory power of the proposed research model. Besides, the normative accountability of the research model is strengthened by embracing two social influences, namely subjective norm and image. As the last antecedent to perceived usefulness, prior experience serves to bring in the time variation factor to allow level of prior experience to exert both direct and moderating effects on perceived usefulness.

The resulting research model is analyzed by partial least squares (PLS)-based Structural Equation Modeling (SEM) approach. The research findings reveal that all cultural dimensions demonstrate direct effect on perceived usefulness though the influence of uncertainty avoidance is found marginally significant. Other constructs on innovative characteristics and social influences are validated to be significant as hypothesized. Prior experience does indeed significantly moderate the two influences that perceived usefulness receives from relative advantage and compatibility, respectively. The research model has demonstrated convincing explanatory power and so may be employed for further studies in other contexts. In particular, cultural effects play a key role in contributing to the uniqueness of the model, enabling it to be an effective tool to help critically understand increasingly internationalized IS system development and implementation efforts. This research also suggests several practical implications in view of the findings that could better inform managerial decisions for designing, implementing, or promoting smart card-based E-payment system.

Details

E-services Adoption: Processes by Firms in Developing Nations
Type: Book
ISBN: 978-1-78560-709-7

Keywords

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