Mingxuan Xu, Tao Jin, Weihong Kong, Yazhi Li, Xing Shen, Cheng Liu and Tianyang Zhu
This study aims to assess the vibrational behavior of a large transport airship based on finite element (FE) simulation and modal testing of its scaled model.
Abstract
Purpose
This study aims to assess the vibrational behavior of a large transport airship based on finite element (FE) simulation and modal testing of its scaled model.
Design/methodology/approach
A full-size parametric FE model of the airframe was established according to the structural layout of the composite beam-cable airframe of the airship, and vibrational analysis of the airframe was conducted. The influence of cable pre-tension load on the inherent properties of the airframe was investigated. Based on the simplification of the full-size FE model, scaled numerical and test models of the airframe, with a geometric scale factor of 1:50, were established and built.
Findings
The simulation and test results of the scaled models indicated that the mode shapes of the full-size and scaled models were similar. The natural frequencies of both the full-size and scaled models complied with the theoretical similarity relation of the frequency response.
Originality/value
This study demonstrated that the vibrational test results of the scaled model with very large scaling can be used to characterize the modal properties of the beam-cable airframe of a large transport airship.
Details
Keywords
Tianyang Lou, Yuning Zu and Ling Zhu
The purpose of this paper is to investigate impact of playing motivation on team member selection (TMS) in online games specifically related to Massively Multiplayer Online…
Abstract
Purpose
The purpose of this paper is to investigate impact of playing motivation on team member selection (TMS) in online games specifically related to Massively Multiplayer Online Role-playing Game environment.
Design/methodology/approach
A self-administered questionnaire was developed and administered to an online sample of 9,335 CR3 players.
Findings
The findings of this research indicated that social and immersion motivations have a significant effect on TMS. Additionally, it was discovered that achievement motivation has a positive relationship with dispositional TMS, a negative relationship to bond-based TMS. The moderation effect of frequency and gender is also demonstrated.
Research limitations/implications
The study verified the relationships of the theoretical model of the game motivation and TMS.
Originality/value
This study provides advice to operators of online games when motivating players to work in groups.
Details
Keywords
Shiqing Cao, Dandan Yu, Weilan Xue, Zuoxiang Zeng and Wanyu Zhu
The purpose of this paper is to prepare a new modified polybutylene terephalate (MPBT) for fused deposition modeling (FDM) to increase the variety of materials compatible with…
Abstract
Purpose
The purpose of this paper is to prepare a new modified polybutylene terephalate (MPBT) for fused deposition modeling (FDM) to increase the variety of materials compatible with printing. And the printing materials can be used to print components with a complex structure and functional mechanical parts.
Design/methodology/approach
The MPBT, poly(butylene terephalate-co-isophthalate-co-sebacate) (PBTIS), was prepared for FDM by direct esterification and subsequent polycondensation using terephthalic acid (PTA), isophthalic acid (PIA), sebacic acid (SA) and 1,4-butanediol (BDO). The effects of the content of PIA (20-40 mol%) on the mechanical properties of PBTIS were investigated when the mole per cent of SA (αSA) is zero. The effects of αSA (0-7mol%) on the thermal, rheological and mechanical properties of PBTIS were investigated at nPTA/nPIA = 7/3. A desktop wire drawing and extruding machine was used to fabricate the filaments, whose printability and anisotropy were tested by three-dimensional (3D) printing experiments.
Findings
A candidate content of PIA introducing into PBT was obtained to be about 30 per cent, and the Izod notched impact strength of PBTIS increased with the increase of αSA. The results showed that the PBTIS (nPTA/nPIA = 7/3, αSA = 3-5mol%) is suitable for FDM.
Originality/value
New printing materials with good Izod notched impact strength were obtained by introducing PIA and SA (nPTA/nPIA = 7/3, αSA = 3-5 mol%) into PBT and their anisotropy are better than that of ABS.
Details
Keywords
Xiping Yang, Yonghong Fu, Jinghu Ji, Tianyang Chen and Caiyun Pan
The purpose of this paper is to describe the tribological characteristics with different area density of concave-convex micro-texture on the mold surface. It is a new technology…
Abstract
Purpose
The purpose of this paper is to describe the tribological characteristics with different area density of concave-convex micro-texture on the mold surface. It is a new technology to improve the quality of the workpiece to control the tribological properties through the application of concave-convex micro-texture on the mold surface.
Design/methodology/approach
Five groups of laser micro-texture with different area density (ratio of the concave-convex micro-texture area to the all-area) were processed on the surface of the mold steel, and the tribological properties were compared with the smooth surface of the reference sample.
Findings
The time of the running-in stage in different experimental groups was about 300 s. The fluctuation amplitude of concave-convex micro-texture friction coefficient is much larger than that of smooth plane specimen in the running-in stage. After the running-in stage, the friction coefficients were lower than that in the smooth condition and decreased with the increase of the concave-convex micro-texture area density. When the area density reached 25%, the friction coefficients no longer decreased significantly. In addition, the wear of concave-convex micro-texture surface is much lower than that of smooth surface and decreases with the increase of concave-convex micro-texture area density.
Originality/value
Domestic and foreign scholars have done a lot of research on the relationship between concave micro-texture and tribological properties. However, the object of this paper is a new concave-convex micro-texture, which is rarely studied in the field of tribology.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2020-0081/
Details
Keywords
Junchao Zhu, GuangCheng Wei, Chen Zong and DaKuan Xin
This paper aim to take the ship shaft stern bearing as the research object, and studies the influence of journal axial vibration on bearing dynamic characteristics under different…
Abstract
Purpose
This paper aim to take the ship shaft stern bearing as the research object, and studies the influence of journal axial vibration on bearing dynamic characteristics under different misaligned angles and rotation speeds.
Design/methodology/approach
Computational fluid dynamics (CFD) and harmonic excitation method were used to build bearing unstable lubrication model, and the dynamic mesh technology was used in calculation.
Findings
The results indicate that journal axial vibration has a significant effect on bearing dynamic characteristics, like maximum oil film pressure, bearing stiffness and damping coefficients, and the effect is positively correlated with journal misaligned angle. The effect of shaft rotation speed and journal axial vibration on bearing dynamics characteristics are independent; they have no coupling. Bearing axial stiffness is mainly affected by the journal axial displacement, bearing axial damping is mainly affected by journal axial velocity and they are positively correlated with the misaligned angle. The influence of rotational speed on bearing axial stiffness and axial damping is not obvious.
Originality/value
This paper establishes the bearing dynamic model by CFD and harmonic excitation method with consideration of cavitation effect and analyzing the influence of journal axial vibration on the dynamic characteristics. The results are benefit to the design of ship propulsion shaft and the selection of stern bearing. Also, they are of great significance to improve the operation stability of the shaft bearing system and the vitality of the ship.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2022-0337/
Details
Keywords
Shuliang Zhao and Qi Fan
It has been ten years since the policy was implemented, but the effect of the policy needs to be tested empirically. This paper aims to explore the mechanism of policy influence…
Abstract
Purpose
It has been ten years since the policy was implemented, but the effect of the policy needs to be tested empirically. This paper aims to explore the mechanism of policy influence on regional innovation ability by measuring the effectiveness of policy by innovation ability indicators. Further, it reflects the problems in the process of the transformation and development of resource-based cities in recent years and points out the direction for the development of the cities in the future. In addition, this paper discusses the differences between regions and cities in China and seeks the path to narrow the gap.
Design/methodology/approach
This paper mainly uses the difference-in-difference method for the research. This study divided China’s resource-based cities and non-resource-based cities into experimental groups and control groups, and explored the effect of the transformation and development of resource-based cities and the changes of their innovation ability under the influence of the National Sustainable Development Plan for Resource-based Cities (NSDPRC). More carefully, this paper uses the fixed effects regression model, propensity score matching method, bootstrap method and other methods to improve the empirical results.
Findings
This paper finds that NSDPRC significantly improves the innovation ability of resource-based cities, although there is some lag in this effect. Research on the influence mechanism of policies shows that NSDPRC improves the marketization degree of resource-based cities and reduces the proportion of the secondary industry in such cities. Finally, the results of the heterogeneity analysis confirm that policies are more popular in western China and that resource-based cities in growth, maturity and decline are more vulnerable to policy influence. The development of policy effectiveness also requires the size of a city, and maintaining a healthy and reasonable scale is necessary for urban development.
Originality/value
First, the existing research on the development of resource-based cities is mainly from the perspective of economy and environment, but rarely from the perspective of innovation ability, and the index to measure urban development is relatively single. This paper will compensate for this deficiency. Second, different from the European and American countries that have basically completed the industrial transformation, the research on Chinese cities will provide a reference for the transformation of developing countries. Finally, from the perspective of resource endowment theory and innovation theory, this paper discusses the influence of SDPNRBC mechanism on the innovation ability improvement of resource-based cities, and further improves and enriches the theory.