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1 – 10 of 644Di Yang, Weiwei Qu and Yinglin Ke
The riveting process is a metal forming process involving complex elastic-plastic deformation, which will induce a compressive residual stress field and cause local distortions in…
Abstract
Purpose
The riveting process is a metal forming process involving complex elastic-plastic deformation, which will induce a compressive residual stress field and cause local distortions in the connecting areas. Regarding to the aircraft panel assemblies with plenty of rivets, the global deformation is inevitable and undesired, leading difficulties to downstream assembly processes. This paper aims to present a new method for the local distortion calculation and the global deformation prediction of sheet panel assemblies during the automated riveting process.
Design/methodology/approach
In this paper, a simplified algebraic study is presented to analyze the local distortion of single countersunk rivet joint with the consideration of the barrel-like shape of the driven head and the through-thickness variations along the rivet shank. Then, an equivalent rivet unit is proposed based on the result of the algebraic study and embedded into the global-level model for the prediction of the overall distortions of riveted panels.
Findings
The algebraic study is able to reach a more precise contour of the deformed rivet than the traditional assumption of cylindrical deformations and rapidly determine the equivalent coefficients of the riveting unit. The result also shows an industrial acceptable accuracy of the prediction for the global deformations of the double-layered panel assemblies widely used in the aircraft panel structures.
Originality/value
A new local-global method for predicting the deformations of the riveted panel assembly based on the algebraic study of the local distortions is proposed to help the engineers in the early design stages or in the assembly process planning stage.
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Gives a bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the…
Abstract
Gives a bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the theoretical as well as practical points of view. The range of applications of FEMs in this area is wide and cannot be presented in a single paper; therefore aims to give the reader an encyclopaedic view on the subject. The bibliography at the end of the paper contains 2,025 references to papers, conference proceedings and theses/dissertations dealing with the analysis of beams, columns, rods, bars, cables, discs, blades, shafts, membranes, plates and shells that were published in 1992‐1995.
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Cultural heritage, specifically built heritage – including monuments, urban ensembles, religious and palatial complexes – has emerged as a central focus of tensions and…
Abstract
Purpose
Cultural heritage, specifically built heritage – including monuments, urban ensembles, religious and palatial complexes – has emerged as a central focus of tensions and negotiations within the post-disaster recovery landscape in Nepal following the 2015 Gorkha Earthquake. This not only reflects a growing recognition of heritage within international disaster risk management frameworks, but also responds to the critical role played by heritage at national, regional and local levels. The paper aims to examine the entangled realities of “local” and “global” operating in ongoing reconstruction of built heritage in Bhaktapur, Nepal.
Design/methodology/approach
The paper is an account of reconstruction practices observed in Bhaktapur between 2018 and 2020. It is based on data collected by layering ethnographic methods with textual and historical analysis. In seeking to analyse manifestations of global and local, the author presents reflections from fieldwork carried over seven months in Bhaktapur and describes the micro-politics enacted out between researcher, heritage custodians, translators, intermediaries and participants.
Findings
Reconstruction of built heritage in Bhaktapur negotiates between developmentalist-paradigms of post-disaster recovery, heritage conservation discourses as well as religious and quotidian practices of care. It is simultaneously informed by global institutions and policy and local politics and aspirations that operate in constant tension and negotiation.
Originality/value
The current study responds to the call for reframing research agendas and practices set out in the Disaster Studies Manifesto by critically engaging with ideas of local and global. The study builds on the growing body of research linking heritage with disaster risk management.
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Yih‐Chih Chiou, Jian‐Zong Liu and Yu‐Teng Liang
The detection of invisible micro cracks (μ‐cracks) in multi‐crystalline silicon (mc‐si) solar wafers is difficult because of the wafers' heterogeneously textured backgrounds. The…
Abstract
Purpose
The detection of invisible micro cracks (μ‐cracks) in multi‐crystalline silicon (mc‐si) solar wafers is difficult because of the wafers' heterogeneously textured backgrounds. The difficulty is twofold. First, invisible μ‐cracks must be visualized to imaging devices. Second, an image processing sequence capable of extracting μ‐cracks from the captured images must be developed. The purpose of this paper is to reveal invisible μ‐cracks that lie beneath the surface of mc‐si solar wafers.
Design/methodology/approach
To solve the problems, the authors first set up a near infrared (NIR) imaging system to capture images of interior μ‐cracks. After being able to see the invisible μ‐cracks, a region‐growing flaw detection algorithm was then developed to extract μ‐cracks from the captured images.
Findings
The experimental results showed that the proposed μ‐cracks inspection system is effective in detecting μ‐cracks. In addition, the system can also be used for the inspection of silicon solar wafers for stain, pinhole, inclusion and macro cracks. The overall accuracy of the defect detection system is 99.85 percent.
Research limitations/implications
At present, the developed prototype system can detect μ‐crack down to 13.4 μm. The inspection resolution is high but the speed is low. However, the limitation on inspection speed can easily be lifted by choosing a higher resolution NIR camera.
Practical implications
Generally, this paper is a great reference for researchers who are interested in developing automatic optical inspection systems for inspecting solar wafer for invisible μ‐cracks.
Originality/value
The research described in this paper makes a step toward developing an effective while low‐cost approach for revealing invisible μ‐crack of mc‐si solar wafers. The advantages provided by the proposed system include excellent crack detection sensitivity, capability of detecting hidden subsurface μ‐cracks, and low cost.
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Zhengping Chang, Zhongqi Wang, Bo Jiang, Jinming Zhang, Feiyan Guo and Yonggang Kang
Riveting deformation is inevitable because of local relatively large material flows and typical compliant parts assembly, which affect the final product dimensional quality and…
Abstract
Purpose
Riveting deformation is inevitable because of local relatively large material flows and typical compliant parts assembly, which affect the final product dimensional quality and fatigue durability. However, traditional approaches are concentrated on elastic assembly variation simulation and do not consider the impact of local plastic deformation. This paper aims to present a successive calculation model to study the riveting deformation where local deformation is taken into consideration.
Design/methodology/approach
Based on the material constitutive model and friction coefficient obtained by experiments, an accurate three-dimensional finite element model was built primarily using ABAQUS and was verified by experiments. A successive calculation model of predicting riveting deformation was implemented by the Python and Matlab and was solved by the ABAQUS. Finally, three configuration experiments were conducted to evaluate the effectiveness of the model.
Findings
The model predicting results, obtained from two simple coupons and a wing panel, showed that it was a good compliant with the experimental results, and the riveting sequences had a significant effect on the distribution and magnitude of deformation.
Practical implications
The proposed model of predicting the deformation from riveting process was available in the early design stages, and some efficient suggestions for controlling deformation could be obtained.
Originality/value
A new predicting model of thin-walled sheet metal parts riveting deformation was presented to help the engineers to predict and control the assembly deformation more exactly.
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Mustafa Soylak and Veysel Erturun
The purpose of this paper is to examine the effect of changing some riveting parameters on the riveting quality of a riveted aircraft structure. In this study, riveting was…
Abstract
Purpose
The purpose of this paper is to examine the effect of changing some riveting parameters on the riveting quality of a riveted aircraft structure. In this study, riveting was performed by applying friction under pressure.
Design/methodology/approach
During this friction riveting process, a feed of 3 mm/min was applied in the axial direction. Rotation speed values of 2,000, 2,200 and 2,400 rpm were selected. A 3-axis die milling machine was used to achieve the required positioning, pressing force and friction effect. 1.27 mm-thick Al 7075-T6 sheets and 2117-T3 forged rivets were used. The feed rate was applied at 1 mm/min in both tensile shear and cross-tensile tests.
Findings
The feasibility of friction riveting in 2117-T3 rivets was examined, it was shown that it could be done, and the most suitable rotation value for this process was determined.
Originality/value
Clamping force is one of the most important parameters for riveting quality. This study will contribute to a better understanding of the friction-forging riveting process along with the effects of riveting parameters. At the same time, it will lead to more research and expand the application of friction forging riveting to more structural connections.
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Mustafa Soylak and Veysel Erturun
The purpose of this study is to examine the effect of the rivet heads formed on the rivet strength by an experimental study if the bucking bar used in the forged rivet application…
Abstract
Purpose
The purpose of this study is to examine the effect of the rivet heads formed on the rivet strength by an experimental study if the bucking bar used in the forged rivet application includes gaps with different angles.
Design/methodology/approach
0.81 (0.032”) mm thick 2024 T3 sheets were used for the rivet joints. AD 2117 T4 forged rivets with a diameter of 3.2 mm (0.125″, 1/8″) are used for the joints. The special bucking bars (sidewall intersection angles of flat, 40°, 60° and 80°) were manufactured for the riveting process. To determine the mechanical properties of the prepared samples, cross-tension and tensile-shear tests were performed on a universal tensile testing machine.
Findings
As a result of the tensile-shear tests and cross-tensile, use of an 80 degrees bucking bar instead of rivets with a flat bucking bar increases the strength of the joint by approximately 20%. There is no systematic change in elongation. The results of tensile-shear and cross-tensile tests showed that forging rivets by special bucking bars have a significant effect on joint strength.
Originality/value
Increase in strength will require the use of thinner sheet metal and smaller rivets to achieve the same strength. This will reduce the weight of the aircraft. Weight reduction also means less fuel consumption and more economical flight. This increase in strength is a very important scientific achievement.
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Jie Zhao, Shuchun Yu and Hegao Cai
In order to solve the problem that dynamic programming (DP) stereo algorithm is slow, a local‐global stereo matching algorithm is presented. In this method, local and global…
Abstract
Purpose
In order to solve the problem that dynamic programming (DP) stereo algorithm is slow, a local‐global stereo matching algorithm is presented. In this method, local and global stereo algorithms are united to apply to the stereo vision field.
Design/methodology/approach
Local and DP stereo algorithms are used. Multi‐resolution images are obtained by pyramid algorithm and matching costs are gained by using eight‐stripe correlation window.
Findings
The time of disparity space image creation is greatly reduced because matching costs are computed by eight‐stripe window. Candidate ground control points (GCPs) are gained in the low‐resolution image. The total time of gaining GCPs is decreased in the extreme. Whole algorithm has a high matching‐rate and a fast speed.
Research limitations/implications
The time of the whole algorithm is still a little bigger than local algorithm.
Practical implications
The findings can be used in the stereo vision system equipped with planet vehicle.
Originality/value
Local and global stereo algorithms are united to apply to the stereo vision field. Matching costs are gained by using eight‐stripe correlation window.
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Maryam Vaziri, Joan Llonch-Andreu and Pilar López-Belbeze
This paper aims to analyze different brand clarity levels (BCLs) of local, global and glocal types of brands in fast-moving consumer goods from the consumer's perspective. The…
Abstract
Purpose
This paper aims to analyze different brand clarity levels (BCLs) of local, global and glocal types of brands in fast-moving consumer goods from the consumer's perspective. The study also intends to identify whether the consumer's previous experience with such brands may impact BCL.
Design/methodology/approach
Twenty-eight global and local brands were used to test the hypotheses by conducting a survey with 400 consumers in the emerging economy of Iran. The authors applied a quantitative technique of brand classification, previously proposed in the literature. After categorizing the brands as local, global or glocal, one-way ANOVA, Tukey post hoc and t-test analyses were performed to identify whether the different types of brands had different BCLs.
Findings
The results showed that brand clarity was significantly higher for local bands than for global or glocal brands and that it was higher for glocal bands than for global brands. Furthermore, the consumer's prior experience with a brand had no impact on BCL for different types of brands.
Social implications
For global brand managers, it is essential to know that local brands in Middle Eastern emerging markets may have more brand clarity than global brands. Therefore, if global brands intend to enter these markets, adopting a glocal positioning appears to be a helpful strategy. Besides, the results suggest that managers should analyze brand categorization from the consumer's perspective, i.e. from a subjective instead of an objective perspective.
Originality/value
This was the first study analyzing the BCL of local, global and glocal brands and identifying significant differences in their BCL.
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Yuanyuan Guo, Yilang Chen, Antonio Usai, Liang Wu and Wu Qin
Multinational small-to-medium-sized enterprises (SMEs) are increasingly participating in cross-border digital platforms – especially amid the COVID-19 pandemic. Accordingly…
Abstract
Purpose
Multinational small-to-medium-sized enterprises (SMEs) are increasingly participating in cross-border digital platforms – especially amid the COVID-19 pandemic. Accordingly, knowledge integration (KI) has become more and more important. In fact, it has been deemed by many as the key to organizational resilience. Given this burgeoning phenomenon, this study aims to explore a path for improving the resilience of multinational SMEs. Through this process, this study also finds a relationship between the KI processes associated with adopting global digital platforms and the resiliency of local–global businesses. Hence, in part, this paper also explores the effectiveness of all these mechanisms.
Design/methodology/approach
This study used the stepwise regression method in Stata 16.0 to analyze the direct effects of both horizontal and vertical KI processes on the resilience of local–global businesses. Additionally, t-tests were also used to compare the differences in coefficients between the mechanisms. The sample analyzed comprised data on multinational manufacturing SMEs in the Yangtze River Delta region of China who are using global digital platforms.
Findings
The KI processes of these firms, both horizontal and vertical, positively correlate to resilience. Horizontal KI processes more efficiently increase the resilience of global businesses, whereas vertical processes more efficiently increase the resilience of local businesses.
Originality/value
First, this study provides insights into how multinational SMEs can improve their resilience in a crisis. In addition to adding to the knowledge of KI processes, this expands the KM literature on pandemics. Second, by creating two KI processes based on global digital platforms and discussing their influence on resilience, this research deepens the understanding of affordance in the KM literature. Third, focusing on the KI research stream, the results shed light on how KI processes might occur and how firms develop their KI processes.
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