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In recent years, the emergence of the Metaverse has created a significant impact worldwide. It represents the ultimate application of the latest information and communication technologies, introducing a brand new digital world to our society. With the industry sector being the core engine of our society, it holds the key to unlocking the potential of Metaverse application, particularly in the form of an Industrial Metaverse. The success of the Industrial Metaverse will greatly contribute to the overall development of the Metaverse. Therefore, this paper conducts a survey on the Metaverse to gather evidence of the growing trend towards an Industrial Metaverse. Furthermore, the key technologies required for implementing an Industrial Metaverse are analyzed. Lastly, the opportunities and challenges associated with the Industrial Metaverse are discussed.
In recent years, the emergence of the Metaverse has created a significant impact worldwide. It represents the ultimate application of the latest information and communication technologies, introducing a brand new digital world to our society. With the industry sector being the core engine of our society, it holds the key to unlocking the potential of Metaverse application, particularly in the form of an Industrial Metaverse. The success of the Industrial Metaverse will greatly contribute to the overall development of the Metaverse. Therefore, this paper conducts a survey on the Metaverse to gather evidence of the growing trend towards an Industrial Metaverse. Furthermore, the key technologies required for implementing an Industrial Metaverse are analyzed. Lastly, the opportunities and challenges associated with the Industrial Metaverse are discussed.
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Point set registration (PSR) is a key component of computer vision and pattern recognition tasks, with the goal of assigning correspondence and recovering the transformation that maps one point set to another, to achieve optimal alignment. The geometric quality inspection of aviation complex parts is mainly based on the digitization of the object, and realizes the effective evaluation of geometric quality by analyzing the digital information that characterizes the shape of object, which is of great significance for the high performance and reliability service of aircraft. However, PSR is the mathematical foundation for solving the point cloud alignment problems in the geometric quality inspection of aviation complex parts, the association between the two has not been systematically discussed, which leads to unfavorable research results. Therefore, this paper first gives a mathematical description of PSR. Secondly, the representative fundamental algorithms for PSR are introduced, mainly include: distance-based PSR algorithms, Kernel correlation-based PSR algorithm, mixture model-based PSR algorithms, global-local structure preservation-based PSR algorithms, feature-based PSR algorithms and learning-based PSR algorithms. Besides, the ideas, basic steps, and limitations of these are revealed. Thirdly, the works on point cloud alignment problems in geometric quality inspection of aviation complex parts and the PSR algorithms used are reviewed, i.e. the application of PSR. Finally, the development direction of PSR and the challenges faced in the geometric quality inspection of aviation complex parts are discussed.
Point set registration (PSR) is a key component of computer vision and pattern recognition tasks, with the goal of assigning correspondence and recovering the transformation that maps one point set to another, to achieve optimal alignment. The geometric quality inspection of aviation complex parts is mainly based on the digitization of the object, and realizes the effective evaluation of geometric quality by analyzing the digital information that characterizes the shape of object, which is of great significance for the high performance and reliability service of aircraft. However, PSR is the mathematical foundation for solving the point cloud alignment problems in the geometric quality inspection of aviation complex parts, the association between the two has not been systematically discussed, which leads to unfavorable research results. Therefore, this paper first gives a mathematical description of PSR. Secondly, the representative fundamental algorithms for PSR are introduced, mainly include: distance-based PSR algorithms, Kernel correlation-based PSR algorithm, mixture model-based PSR algorithms, global-local structure preservation-based PSR algorithms, feature-based PSR algorithms and learning-based PSR algorithms. Besides, the ideas, basic steps, and limitations of these are revealed. Thirdly, the works on point cloud alignment problems in geometric quality inspection of aviation complex parts and the PSR algorithms used are reviewed, i.e. the application of PSR. Finally, the development direction of PSR and the challenges faced in the geometric quality inspection of aviation complex parts are discussed.
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One of the disadvantages of the permeability-based fluidic topology optimization method is that seepage inside the solid region makes the optimized results highly sensitive to the selection of the impermeable parameter in the standard Darcy model. In this paper, fluid seepage in the solid region is greatly reduced by imposing zero-velocity constraints along the normal direction of the fluid-solid interface. In each optimization iteration, the fluid-solid interface can be traced by setting a predefined threshold of design variables, and a body-fitted mesh is constructed explicitly by cutting the original square element into quadrilateral and triangular elements. Several representative fluidic optimization examples, for which problems associated with the seepage effect arise when using the standard Darcy model, illustrate the effectiveness of the proposed method.
One of the disadvantages of the permeability-based fluidic topology optimization method is that seepage inside the solid region makes the optimized results highly sensitive to the selection of the impermeable parameter in the standard Darcy model. In this paper, fluid seepage in the solid region is greatly reduced by imposing zero-velocity constraints along the normal direction of the fluid-solid interface. In each optimization iteration, the fluid-solid interface can be traced by setting a predefined threshold of design variables, and a body-fitted mesh is constructed explicitly by cutting the original square element into quadrilateral and triangular elements. Several representative fluidic optimization examples, for which problems associated with the seepage effect arise when using the standard Darcy model, illustrate the effectiveness of the proposed method.
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As one of the hydraulic control systems of an aircraft, the hydraulic drive system of the aircraft cabin door can cause severe impact on the safe operation of the plane once failed. In order to enhance the safety and reliability of the hydraulic drive system of the aircraft cabin door, this paper takes the rotary hydraulic drive system of the aircraft cabin door as the research object, and analyzes its working principle. Additionally, five types of potential failures are summarized, including gain reduction fault in angular displacement sensors, blockage fault in flow control valves, air pollution fault, leakage fault in motor plungers, and motor plunger failure fault. Using the AEMSim software to establish a fault simulation model, the fault characteristics of the system under various fault conditions can be studied, which can effectively reduce the cost of physical simulation and testing, improve design efficiency and provide simulation data for other research.
As one of the hydraulic control systems of an aircraft, the hydraulic drive system of the aircraft cabin door can cause severe impact on the safe operation of the plane once failed. In order to enhance the safety and reliability of the hydraulic drive system of the aircraft cabin door, this paper takes the rotary hydraulic drive system of the aircraft cabin door as the research object, and analyzes its working principle. Additionally, five types of potential failures are summarized, including gain reduction fault in angular displacement sensors, blockage fault in flow control valves, air pollution fault, leakage fault in motor plungers, and motor plunger failure fault. Using the AEMSim software to establish a fault simulation model, the fault characteristics of the system under various fault conditions can be studied, which can effectively reduce the cost of physical simulation and testing, improve design efficiency and provide simulation data for other research.
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The relationship between the crystallographic features and the anisotropic mechanical properties of a Laser Powder Bed Fusion (LPBF) fabricated GH5188 alloy were investigated. For this purpose, the LPBF-ed GH5188 alloy was subjected to a tensile test in two different tensile axis orientations, perpendicular and parallel to the building direction, which we call “horizonal” and “vertical” orientations correspondingly. The techniques of EBSD and TEM were employed to characterize the different strained samples. The results show that the LPBF-ed GH5188 alloy exhibits a<001>fiber texture with elongated grains along the building direction. Compared to the vertical samples, the horizonal samples acquire a higher Taylor factor and a higher KAM (kernel average misorientation) value during deformation, which lead to a better yield strength and a higher strain hardening rate. Furthermore, the texture of the deformed samples revealed that the horizonal samples have a better coordinated deformability, which leads to higher ductility compared to the vertical samples.
The relationship between the crystallographic features and the anisotropic mechanical properties of a Laser Powder Bed Fusion (LPBF) fabricated GH5188 alloy were investigated. For this purpose, the LPBF-ed GH5188 alloy was subjected to a tensile test in two different tensile axis orientations, perpendicular and parallel to the building direction, which we call “horizonal” and “vertical” orientations correspondingly. The techniques of EBSD and TEM were employed to characterize the different strained samples. The results show that the LPBF-ed GH5188 alloy exhibits a<001>fiber texture with elongated grains along the building direction. Compared to the vertical samples, the horizonal samples acquire a higher Taylor factor and a higher KAM (kernel average misorientation) value during deformation, which lead to a better yield strength and a higher strain hardening rate. Furthermore, the texture of the deformed samples revealed that the horizonal samples have a better coordinated deformability, which leads to higher ductility compared to the vertical samples.
Corner smoothing for CNC machining of linear tool path: A review
Advanced virtual manufacturing systems: A review
A short review on milling dynamics in low-stiffness cutting conditions: Modeling and analysis
Machining process monitoring and application: a review
On-line tool wear monitoring based on machine learning
Electrochemical discharge machining for fabricating holes in conductive materials: A review
Prediction and suppression of chatter in milling of structures with low-rigidity: A review
Intelligent forming technology: State-of-the-art review and perspectives
Titanium alloy material has excellent properties such as low density, high strength, good oxidation resistance, creep resistance, etc. It has a broad application prospect in various fields. However, these characteristics also make it dif-ficult to process. Grinding is an essential method for high efficiency and precision machining of titanium alloy, ob-taining good machining precision and surface quality. The removal mechanism of titanium alloy is helpful to im-prove the surface quality of titanium alloy grinding. The recent research results in this field are reviewed. Firstly, the grinding technology types of titanium alloy were summarized, and the machining characteristics were systematically analyzed from two aspects of abrasive wear and material removal behavior of titanium alloy. Finally, the development trend of titanium alloy grinding technology in the prospect.
Machining data have been increasingly crucial with the development of modern manufacturing strategies, and the explosive growth of data amount revolutionizes how to collect and analyze data. In machining process, anomalies such as machining chatter and tool wear occur frequently, which strongly affect the process by reducing accuracy and quality as well as increasing the time and cost. As a typical type of machining data, signals acquired in real time by advanced sensor techniques are widely embraced to detect those anomalies. This paper reviews the recent development and applications of process monitoring technologies in machining processes, and typical application scenarios in machining processes are discussed with the latest literatures and current research issues. Potential future trends of process data monitoring and analysis for intelligent machining are put forward at the end of the paper.
The dynamic responses of milling system change the ideal trajectories of cutting teeth and therefore plays a critical role in determining the machining accuracy. The amplitude of cutting vibrations could reach tens of or even hundreds of micrometers in low-stiffness cutting conditions, for example, when milling thin-walled parts and/or using slender tools. Usually, moderate cutting parameters are utilized to avoid excessive cutting loads, strong milling chatter or large dynamic deflections, which however, significantly lowers the productivity. In spite of decades of study, it is still a challenge to accurately model, efficiently analyze, reliably monitor and precisely control the dynamic milling process in low-stiffness cutting conditions. In this paper, the recent advances and research challenges on dynamics modeling and response analysis are briefly reviewed.
The rapid development of artificial intelligence (AI) technology makes it possible for achieving intelligent forming. It will bring great breakthrough of material forming technology, realizing the unmanned watching, intelligent processing design and intelligent control during forming process. Moreover, it can greatly improve the forming accuracy, mechanical properties, forming efficiency and economic benefits, and promote the continuous emergence of new forming technology. Thus, the intelligent forming technology, integrating AI technology and advanced forming technology, has become an international research focus. This paper reviews the recent developments of intelligent forming technology from four kinds of common forming technology, i.e., intelligent casting, intelligent plastic forming, intelligent welding, and intelligent additive manufacturing. Moreover, the current research issues and future trends of intelligent forming technology are put forward at the end of the paper.
The processed surface integrity of the propeller has a vital impact on the performance, efficiency, and noise of the entire power energy conversion device, and the bionic micro-structured surface is conducive to improving the noise reduction performance of the working parts. In this paper, the microstructure of the propeller blade surface is machined by precision abrasive belt grinding. Based on the surface roughness detection and 3D morphology analysis results, a univariate model of propeller surface groove with V-shaped section is established. The flow field analysis, numerical analysis of cavitation, and noise performance analysis of general marine propellers and bionic marine propellers are also carried out. The results show that the maximum noise of the propeller with the bionic grooved surface is 94.7 decibels, and the maximum noise of the general propeller is 146 decibels. The noise reduction effect is increased by 35%, which provides a new method of precision abrasive belt grinding for the noise reduction of the propeller.
Milling is widely used to machine the structures with low-rigidity in astronautic and aeronautic industries, while chatter vibration, which is a great limitation and a serious problem, is easy to occur in this kind of process due to the weak stiffness of the structures. To solve the machining problems caused by chatter, prediction and suppression are two important methods that are commonly used by researchers and industry engineers. This article reviews the study progresses on the prediction and suppression of the chatter occurring in milling process of the low-rigidity structure. The dynamic model, acquisition of dynamic parameters, and suppression techniques are introduced. Besides, the problems and the outlooks of the future coming research are also given in the conclusions.
Compared with traditional additive manufacturing technology (3D printing), 4D printing technology (four-dimensional printing) increases the time dimension. The structure prepared by 4D printing process can change its shape and configuration with the external environment (i.e. light, heat, magnetism, electricity, etc.), which has a broad application prospect. This paper introduces several typical implementation methods of 4D printing in combination with the typical research results of 4D printing in recent years. The printing materials, design methods, and simulation methods of current 4D printing technology are summarized. Finally, the possible development directions of 4D printing technology and its application prospects in the fields of biomedicine, soft robotics, aerospace, etc. are introduced, and some problems of 4D printing technology are discussed.
Due to the advantages in weather resistance, light transmittance and dimension stability, PMMA has been widely used in various fields such as aerospace and optical engineering. However, fully automatic robot systems are seldom used for polishing complex PMMA parts with high surface integrity. Therefore, a robotic polishing system with a new active end-effector is developed in this paper. In the system, a 6-degree-of-freedom industrial robot is utilized to polish the part profile along the preprogrammed paths, and then the system configuration is introduced in detail. For precisely controlling the normal contact force, both a linear voice coil motor and a force sensor are used in the designed end-effector. Meanwhile, a tilt sensor is also used to compensate the gravity component of the polishing tool along the force-controlled direction. Subsequently, a hybrid force controller, which consists of a PID controller and a Fuzzy controller, is designed to maintain the contact force between the polishing tool and the part within an allowable range. Finally, validation experiments are conducted with the designed robotic polishing system on a complex PMMA part. The experimental results show that the proposed robotic polishing system can strictly control the normal contact force and ensure high surface integrity of the PMMA part.
Structured light method is one of the best methods for automated 3D measurement in industrial production due to its stability and speed. However, when the surface of industrial parts has high dynamic range (HDR) areas, e.g. rust, oil stains, or shiny surfaces, phase calculation errors may happen due to low modulation and pixel over-saturation in the image, making it difficult to obtain accurate 3D data. This paper classifies and summarizes the existing high dynamic range structured light 3D measurement technologies, compares the advantages and analyzes the future development trends. The existing methods are classified into multiple measurement fusion (MMF) and single best measurement (SBM) based on the measurement principle. Then, the advantages of the various methods in the two categories are discussed in detail, and the applicable scenarios are analyzed. Finally, the development trend of high dynamic range 3D measurement based on structed light is proposed.
This article presents a comprehensive review on the machining technology of aero-engine casings. The material removal mechanism of mechanical machining and nontraditional machining is introduced in the first part. Then, several mechanical machining technologies of aero-engine casings (e.g. numerical control machining, turn-milling complex machining, machining vibration suppression) are summarized. Subsequently, the research progress and academic achievements are explored in detail in terms of the electrochemical machining, electric discharging machining and ultrasonic machining in the field of nontraditional machining technology of aero-engine casings. Finally, the existing challenges in mechanical machining technology and nontraditional machining technology of aero-engine casings are analyzed, and the developing tendencies to aero-engine casings machining is proposed.
