Yangfan Li, Yingjie Zhang, Lin Zhang and Bochao Dai
The purpose of this paper is to analyze the changes in its importance due to the maintenance and repair of components.
Abstract
Purpose
The purpose of this paper is to analyze the changes in its importance due to the maintenance and repair of components.
Design/methodology/approach
In this paper, a concept of time-varying importance measure is proposed to solve the problem of component importance change caused by maintenance. When the system is broken-down, the probability difference between the component works well after repairing and the component break down before repairing is solved, this difference is measured as an index of time-varying importance method. Then, the approach has been verified by the CNC machine tool.
Findings
The paper provides a method to analyze the importance of changes of components in the system due to maintenance. The time-varying importance measure can evaluate the component importance anytime during its whole life span, and it has the ability to find out the most responsible component for a system failure in the actual production process. What is more, it provides guidance for the next maintenance work.
Originality/value
The proposed method can guide the next maintenance time according to the change of component performance caused by each maintenance activity of the manufacturing system, and avoid the waste of resources caused by repeated maintenance.
Details
Keywords
Yangfan Li, Yingjie Zhang, Ning Zhang and Bingchao Xu
This paper aims to improve the meshing effect of the gear teeth. It is recommended to analyze the deformation difference between the inner and outer surfaces of the flexspline…
Abstract
Purpose
This paper aims to improve the meshing effect of the gear teeth. It is recommended to analyze the deformation difference between the inner and outer surfaces of the flexspline. The purpose of this paper is to modify the profile of the flexspline based on the deformation difference to improve the transmission accuracy and operating life of the harmonic drive.
Design/methodology/approach
In this paper, ring theory is used to calculate the deformation difference of the inner and outer surfaces of the flexspline, and the actual tooth profile of the flexspline is corrected based on the deformation difference. Then, the flexspline is divided into multiple sections along the axial direction, so that the three-dimensional tooth profile of the flexspline is modified to improve the gear tooth meshing effect.
Findings
This paper proves the effect of the deformation difference between the inner and outer surfaces of the flexspline on the tooth backlash, which affects the transmission accuracy and life of the harmonic drive. It is recommended to modify the tooth profile of the flexspline based on the deformation difference, so as to ensure the tooth meshing effect.
Originality/value
This paper provides a new way for the optimization of the three-dimensional tooth profile design of the harmonic drive.
Details
Keywords
Lin Zhang, Yingjie Zhang, Manni Zeng and Yangfan Li
The purpose of this paper is to put forward a path planning method in complex environments containing dynamic obstacles, which improves the performance of the traditional A…
Abstract
Purpose
The purpose of this paper is to put forward a path planning method in complex environments containing dynamic obstacles, which improves the performance of the traditional A* algorithm, this method can plan the optimal path in a short running time.
Design/methodology/approach
To plan an optimal path in a complex environment with dynamic and static obstacles, a novel improved A* algorithm is proposed. First, obstacles are identified by GoogLeNet and classified into static obstacles and dynamic obstacles. Second, the ray tracing algorithm is used for static obstacle avoidance, and a dynamic obstacle avoidance waiting rule based on dilate principle is proposed. Third, the proposed improved A* algorithm includes adaptive step size adjustment, evaluation function improvement and path planning with quadratic B-spline smoothing. Finally, the proposed improved A* algorithm is simulated and validated in real-world environments, and it was compared with traditional A* and improved A* algorithms.
Findings
The experimental results show that the proposed improved A* algorithm is optimal and takes less execution time compared with traditional A* and improved A* algorithms in a complex dynamic environment.
Originality/value
This paper presents a waiting rule for dynamic obstacle avoidance based on dilate principle. In addition, the proposed improved A* algorithm includes adaptive step adjustment, evaluation function improvement and path smoothing operation with quadratic B-spline. The experimental results show that the proposed improved A* algorithm can get a shorter path length and less running time.
Details
Keywords
Han Shen, Xinge Li and Yangfan Zhang
With the development of tourism industry, online travel agencies (OTA) have gradually become an important channel for tourism product supplies and sales. Some OTAs provide…
Abstract
With the development of tourism industry, online travel agencies (OTA) have gradually become an important channel for tourism product supplies and sales. Some OTAs provide consumers with a platform for tourism guidance and online travel sharing. They not only satisfy some tourists’ desire to share their experiences but also provide reference for more consumers to choose travel products. This process is the process of value co-creation by customers and online travel companies. This study is conducted under DART theory, a theoretical framework of value co-creation composed of four dimensions, namely dialog, access, risk-assessment, and transparency. Brand equity is divided into four aspects: brand loyalty, brand awareness, customer perceived value, and brand image. This study uses the structural equation model to investigate the impact of customer value co-creation behavior on brand equity of online travel enterprises and interprets the process and mechanism of customer value co-creation behaviors for online travel business brand equity, which provides more efficient strategies and methods for platform interaction and value co-creation.
Details
Keywords
Tao Wei, Sijin Zhao, Zongzhan Gao, Ke Zhang, Wenxuan Gou and Yangfan Dang
Fatigue and creep are the key factors for the failure of polymethyl methacrylate (PMMA) in the engineering structure, so a great of quantity attention is focused on the life…
Abstract
Purpose
Fatigue and creep are the key factors for the failure of polymethyl methacrylate (PMMA) in the engineering structure, so a great of quantity attention is focused on the life prediction under the creep and fatigue conditions. This paper aims to mainly summarize the traditional life assessment method (S–N curve), life assessment method based on crazing density and life assessment method based on transmittance. S–N curve and classical creep curve are introduced on the traditional life assessment method; the variation of the craze density with the logarithm of cyclic numbers is given in different fatigue load. A linear relationship is obtained, and a higher stress leads to a higher slope, suggesting a faster growth of craze. Furthermore, a craze density model is purposed to describe this relationship; the variation of craze density with the time at different creep load is given. The craze density has two obvious stages. At the first stage, craze density ranged from approximately 0.02 to 0.17, and a linear relationship is obtained. In the following stage, a nonlinear relationship appears till specimen rupture, a new creep life model is proposed to depict two stages. The relationship between transmission and time under creep load is shown. With increasing of time, the transmittance shows a nonlinear decrease. Through polynomial nonlinear fitting, a relationship between the transmittance and residual life can be obtained. To provide reference for the life assessment of transparent materials, the paper compares three life assessment methods of PMMA.
Design/methodology/approach
This paper uses the traditional life assessment method (S–N curve), life assessment method based on crazing density, life assessment method based on transmittance.
Findings
The variation of the craze density with the logarithm of cyclic numbers is given in different fatigue loads. A linear relationship is obtained, and a higher stress leads to a higher slope, suggesting a faster growth of craze. Furthermore, a craze density model is proposed to describe this relationship, and the variation of craze density with the time at different creep loads is given. The craze density has two obvious stages. The relationship between transmission and time under creep load is shown. With increasing of time, the transmittance shows a nonlinear decrease. Through polynomial nonlinear fitting, a relationship between the transmittance and residual life can be obtained.
Originality/value
Fatigue and creep are the key factors for the failure of PMMA in the engineering structure, so a great of quantity attention is focused on the life prediction under the conditions of creep and fatigue. This paper mainly summarizes traditional life assessment method (S–N curve), life assessment method based on crazing density and life assessment method based on transmittance.
Details
Keywords
Chong Xu, Pengbo Wang, Fan Yang, Shaohua Wang, Junping Cao and Xin Wang
This paper aims at building a discharge model for the power cable bellows based on plasma energy deposition and analyzing the discharge ablation problem.
Abstract
Purpose
This paper aims at building a discharge model for the power cable bellows based on plasma energy deposition and analyzing the discharge ablation problem.
Design/methodology/approach
Aiming at the multiphysical mechanism of the discharge ablation process, a multiphysical field model based on plasma energy deposition is established to analyze the discharge characteristics of the power cable bellows. The electrostatic field, plasma characteristics, energy deposition and temperature field are analyzed. The discharge experiment is also carried out for result validation.
Findings
The physical mechanism of the bellows ablative effect caused by partial discharge is studied. The results show that the electric field intensity between the aluminum sheath and the buffer layer easily exceeds the pressure resistance value of air breakdown. On the plasma surface of the buffer layer, the electron density is about 4 × 1,019/m3, and the average temperature of electrons is about 3.5 eV. The energy deposition analysis using the Monte Carlo method shows that the electron range in the plasma is very short. The release will complete within 10 nm, and it only takes 0.1 s to increase the maximum temperature of the buffer layer to more than 1,000 K, thus causing various thermal effects.
Originality/value
Its physical process involves the distortion of electric field, formation of plasma, energy deposition of electrons, and abrupt change of temperature field.
Details
Keywords
Chuyu Tang, Genliang Chen, Hao Wang and Yangfan Yu
Hull block assembly is a vital task in ship construction. It is necessary to obtain the actual poses of the assembly features to guide further block alignment. Traditional methods…
Abstract
Purpose
Hull block assembly is a vital task in ship construction. It is necessary to obtain the actual poses of the assembly features to guide further block alignment. Traditional methods use single-point measurement, which is time-consuming and may lead to loss of key information. Thus, large-scale scanning is introduced for data acquisition, and this paper aims to provide a precise and robust method for retrieving poses based on point set registration.
Design/methodology/approach
The main problem of point registration is to find the correct transformation between the model and the scene. In this paper, a vote framework based on a new point pair feature is used to calculate the transformation. First, a special edge indicator for multiplate objects is proposed to determine the edges. Subsequently, pair features with an edge description are noted for every point. Finally, a voting scheme based on agglomerative clustering is implemented to determine the optimal transformation.
Findings
The proposed method not only improves registration efficiency but also maintains high accuracy compared to several commonly used approaches. In particular, for objects composed of plates, the results of pose estimation are more promising because of the compact pair feature. The multiple ship longitudinal localization experiment validates the effectiveness in real scan applications.
Originality/value
The proposed edge description performs a better detection for the edges of multiplate objects. The pair feature incorporating the edge indicator is more discriminative than the original template, resulting in better robustness to outliers, noise and occlusions.
Details
Keywords
Suvranshu Pattanayak, Susanta Kumar Sahoo, Ananda Kumar Sahoo, Raviteja Vinjamuri and Pushpendra Kumar Dwivedi
This study aims to demonstrate a modified wire arc additive manufacturing (AM) named non-transferring arc and wire AM (NTA-WAM). Here, the build plate has no electrical arc…
Abstract
Purpose
This study aims to demonstrate a modified wire arc additive manufacturing (AM) named non-transferring arc and wire AM (NTA-WAM). Here, the build plate has no electrical arc attachment, and the system’s arc is ignited between tungsten electrode and filler wire.
Design/methodology/approach
The effect of various deposition conditions (welding voltage, travel speed and wire feed speed [WFS]) on bead characteristics is studied through response surface methodology (RSM). Under optimum deposition condition, a single-bead and thin-layered part is fabricated and subjected to microstructural, tensile testing and X-ray diffraction study. Moreover, bulk texture analysis has been carried out to illustrate the effect of thermal cycles and tensile-induced deformations on fibre texture evolutions.
Findings
RSM illustrates WFS as a crucial deposition parameter that suitably monitors bead width, height, penetration depth, dilution, contact angle and microhardness. The ferritic (acicular and polygonal) and lath bainitic microstructure is transformed into ferrite and pearlitic micrographs with increasing deposition layers. It is attributed to a reduced cooling rate with increased depositions. Mechanical testing exhibits high tensile strength and ductility, which is primarily due to compressive residual stress and lattice strain development. In deposits, ϒ-fibre evolution is more resilient due to the continuous recrystallisation process after each successive deposition. Tensile-induced deformation mostly favours ζ and ε-fibre development due to high strain accumulations.
Originality/value
This modified electrode arrangement in NTA-WAM suitably reduces spatter and bead height deviation. Low penetration depth and dilution denote a reduction in heat input that enhances the cooling rate.
Details
Keywords
Mohanraj R., Abdul Basith S. N., Chandru S, Gowtham D and Pradeep Kumar M
Wire arc additive manufacturing (WAAM) is one of the most researched and fastest-growing AM technique because of its capability to produce larger components with medium…
Abstract
Purpose
Wire arc additive manufacturing (WAAM) is one of the most researched and fastest-growing AM technique because of its capability to produce larger components with medium complexity. In recent times, the use of WAAM process has been increased because of its ability to produce complex components economically when compared with other AM techniques. The purpose of this study is to investigate the capabilities of wire arc additive manufacturing (WAAM), which has emerged as a recognized method for fabricating larger components with complex geometries.
Design/methodology/approach
This paper provides a review of process parameters for optimizing and analyzing mechanical properties, hardness, microstructure and corrosion behavior achieved through various WAAM-based techniques.
Findings
Limited analysis exists regarding the mechanical properties of various orientations of Inconel 625 alloy. Moreover, there is a lack of studies concerning the corrosion behavior of Inconel 625 alloy fabricated using WAAM.
Originality/value
The review identifies that the formation of intermetallic phases reduces the desirability of mechanical properties and corrosion resistance of WAAM-fabricated Inconel 625 alloy. Additionally, the study reported notable results obtained by various research studies and the improvements to be achieved in the future.