As an advanced intelligent manufacturing technology, additive manufacturing (AM) can directly produce metallic components with complex macroscopic structure in short lead time and has attracted lots of attention in recent years. It has been widely used in many advanced manufacture fields such as aerospace, medical device, and so on. However, there exhibit limited number of alloy systems suitable for AM printing, and the complex printing process makes it easy to introduce defects. Consequently, the large-scale application of AM is hindered. Machine learning has been widely used in various daily life and industrial production fields due to its excellent data processing and analysis capabilities. In this paper, the application of machine learning in the AM process including processing window establishing, printing quality control, printed metallic microstructure identification, and mechanical properties exploration are reviewed. In the end, the opportunities and challenges of machine learning in AM are discussed, and the further research directions are proposed.

As a “green and lightweight metallic structure material”, magnesium alloy has become a necessary choice to realize lightweight, complex and personalized structure manufacturing. In order to meet the requirements of high-end equipment on the high-performance components and break the barriers of traditional manufacturing technology, laser manufacturing technology of high flexibility, high cleanliness and high precision is gradually adopted to achieve complex and personalized structures. Thereinto, laser cutting, laser welding, laser surface modification and laser additive manufacturing of magnesium alloy are the currently main developing directions of laser manufacturing technology. Therefore, the basic principles, research focus and related research progress of different laser manufacturing technologies are introduced respectively. The development of laser manufacturing technology of magnesium alloy is summarized. Furthermore, multi-scale tools such as real-time monitoring are proposed with the goal of “reducing shape and increasing property”.

The application of ultrafast laser in the field of ceramic surface processing has been initially confirmed. This paper introduces the mechanism of ultrafast laser ceramic surface processing, reviews the research progress of ultrafast laser in the field of ceramic surface polishing and texturing processing, and discusses the processing technology of ultrafast laser on complex freeform surfaces. Also, the development direction of laser polishing and texturing technology is foreseen, and the use of the ultrafast laser to enhance the comprehensive performance of ceramic surfaces provides a reference to further broaden the application of ultrafast laser technology in the field of surface processing.

Mechanical metamaterials (MMMs) have become a research hotspot in the application of aerospace, energy automobile, manufacturing, and military due to their light weight, high strength, and high energy absorption. Selective laser melting (SLM) additive manufacturing can produce complex microstructure with high precision and resolution, thus being suitable to fabricate complex MMMs. In this study, a design scheme of three-dimensional (3D) MMMs models based on a“ double V” configuration honeycomb topology was proposed, which were subsequently printed by SLM. Through the combination of theoretical calculation, simulation, and experiments, the influences of various structural parameters on the compression mechanical response of the “double V” configuration honeycomb MMMs were investigated. The findings provide an approach to manually tailor the negative Poisson's ratio of MMMs.

The unique hydrophobic and pressure-resistant concave angle microstructure of the springtail cuticle provides a new research idea for aircraft anti-icing and drag reduction with super hydrophobic air film of underwater vehicles. In this paper, a flexible hydrophobic microstructure was prepared by taking the springtail cuticle as the biomimetic object. The preparation method of“ duplicating transfer” was put forward. In order to solve the structural deformation and structural rupture problems in the process of duplicating and transferring, the technology of “soft knife and hard mold” and “interface adhesion control” were respectively improved. Based on the idea of “combination of soft and hard”, the scraping method of“ soft knife and hard mold” was adopted to avoid the structural deformation caused by residual PDMS  layer. The PDMS transfer layer was replaced by PET film and surface modification was carried out to avoid excessive adhesion between the structure layer and the homogeneous material of the transfer layer. The surface contact angle of PET film was reduced from 70° to 15° by oxygen plasma modification. The arithmetic mean deviation R_a of surface contour increased from 112.15 nm to 199.74 nm, which increased by 78.1%. Oxygen/carbon (O/C) ratio increased from 0.35 to 0.45. The contact angle of the microstructure surface is 125.2°, and the droplet retraction is obvious in the bouncing behavior. The method of“ duplicating transfer” successfully realized the fabrication of flexible microstructure, and the method of“ soft knife and hard mold” significantly reduced the microstructure deformation, and the structure was successfully duplicating and the deformation was effectively controlled. After surface modification, the surface activity of PET film is increased, the structure is successfully transferred and the rupture is reduced. The results show that the flexible microstructures have good hydrophobic properties.

The Ag–Cr film on the LiNbO3 substrate was etched by an ultrafast pulsed laser with a wavelength of 1064 nm, a pulse width of 10 ps, and a repeat frequency of 100 kHz. The effects of laser energy density and scanning speed on the quality of etched grooves on Ag–Cr films were studied to improve the groove quality. The results show that the laser energy density of 5.38 J/cm² and the scanning speed of 500 mm/s are the optimal laser parameters for etching grooves. In this case, the substrate at the bottom of the trench is intact, and there is no obvious crack at the edge of the trench, which ensures that the final etched interdigital electrode has excellent performance. At the same time, the corresponding groove width is about 14 μm, which makes it possible to process high-quality interdigital electrodes with a line width of 14 μm and above, which can meet the needs of interdigital electrodes for surface acoustic wave devices in the biomedical field. A pair of interdigital electrodes for surface acoustic wave devices in the biomedical field were designed and fabricated with optimized parameters. They have high machining accuracy, good surface morphology and no defects such as adhesion between electrodes.

In order to exploring the influence of process parameters on the forming quality of H13 die steel, the binder jetting additive manufacturing experiment was carried out with different layer thickness and the binder saturation, The influence of layer thickness and binder saturation on forming quality was analyzed, with testing the relative density and dimensional accuracy of green parts as well as the microhardness, surface roughness and density of sintered parts. The results indicate that the layer thickness and the binder saturation can significantly affect the forming quality of the parts. The relative density of the green part decreases with the increase of layer thickness. Due to the binder saturation increasing, the dimensional accuracy and the relative density of the green part decrease, and the surface roughness of the sintered part increase. When the layer thickness and binder saturation are 75 μm and 80% respectively, the relative density of the green part reaches the maximum value of 55.8%, but the sintering density is merely 79.5%. Once the layer thickness and the binder saturation increased to 150 μm and 125% respectively, the sintered sample obtained the highest density of 95.7%, with the microhardness of 785.7HV₁. It makes up for the vacancy of forming and sintering process parameters of H13 die steel in binder jetting additive manufacturing filed.

As an advanced manufacturing technology, laser processing has been widely used in many industries such as instrument and apparatus, aerospace, medical and health community, and automobile manufacturing due to its powerful processing ability. However, there are still some shortcomings in laser processing, such as unclear processing mechanism, difficult real-time monitoring and unable to feedback on the processing state in time, and lack of classification and characterization of the processing structures or defects. The research shows that it is a reasonable technical solution to combine the detection technology with laser processing to regulate the process. As a dynamic nondestructive detection technology, acoustic emission technology has been proved to be an efficient and flexible detection method among various technologies. Combining acoustic emission technology with laser processing to realize online detection of laser processing has become a research hotspot at home and abroad. In this paper, the research status of introducing acoustic emission technology into laser processing by domestic and foreign scholars is reviewed. The characteristics of acoustic emission technology are briefly described. And the acoustic emission technology principle of laser processing, the laser processing research based on acoustic emission analysis method and the application of acoustic emission technology in laser processing are emphatically analyzed. Furthermore, the future development direction of acoustic emission technology in laser processing is prospected based on the current shortcomings.

Using good inter-laminar property of three-dimensional braided composite to meet the requirement of the integral T-joints structure, a T-joints structure has been designed and manufactured with using resin transfer liquid composite molding and 3D six-directional braided composites. The pull-off damage property of the T-joints structure has been studied by tests for different braiding angles (20°, 30°, 40°) and yarns (6k, 9k, 12k). It has been shown by the tests that the damage type of T-joints structure with 3D six-directional braided composites is the web pulling away from the flange; The T-joints structure pull-off strength increased by 53% when braiding angle changing from 20° to 40° for the same braiding yarns and by 8% when braiding yarns changing from 6k to 12k for the same braiding angle. The research results can be an important experimental guidance for the design and development of integrated composite structure.

The detail fatigue property of aluminum alloy curved panel formed by unilateral shot peen forming was studied. As the shot peen formed panel with curved shape, the detail fatigue performance of curved surface sample was evaluated based on SWT model. The local load-bearing stress and strain characteristics on surface of sample during fatigue process were analyzed by means of point cloud mapping modeling, finite element simulation and resistance strain gauge monitoring. The results show that: under the same condition of axial loading 180 MPa nominal stress, the peak stress of flat plate is 263 MPa, and the local peak stress of curved plate is close to 400 MPa. The DFR cut-off value (DFRcutoff) of original flat plate is 184.6 MPa; The DFRcutoff of curved sheet formed by unilateral shot peening is 182.4 MPa by direct measurement, and is 221.6 MPa by SWT model evaluation. The DFRcutoff value of shot peening flat plate (bilateral shot peening) is 241.4 MPa, which is slightly higher than the SWT model evaluation value (error less than 10%), because the work hardening effect is not considered in the SWT evaluation. Therefore, SWT model is an effective method to evaluate the detail fatigue performance of shot peened panel.

Reliability analysis is a key means to quantitatively evaluate the effectiveness of nondestructive test technology. In order to solve the problem that EDM grooves can not effectively characterize fatigue cracks in real components, a transfer function method based on response signal is proposed. Firstly, this paper adopts eddy current detection method to quantitatively obtain the signals of manual grooving defects and fatigue crack defects of the flat plate test block and the signals of manual grooving defects of the target turbine disk test block. Then, according to the curve signals, the transfer function between the eddy current detection data of manual grooving defects and fatigue crack defects of the aero-engine wheel plate sample is established. The probability of detection (POD) curve of aero-engine wheel fatigue crack is obtained. The results show that: Under the condition that the real sample could not be obtained, this paper established the transfer function between grooving and fatigue crack by empirical method, and calculated that the fatigue crack defect of aero-engine wheel that can be effectively detected by eddy current testing is 1.88 mm×0.94 mm, which provides a basis for the design of aero-engine wheel damage tolerance and maintenance planning. It has important guiding significance to the application reliability research of nondestructive testing methods.

Aluminum alloy material is light and widely used to reduce the weight of the construction element, especially in fields such as aerospace. More and more parts choose grinding as the final processing method, and the demand for efficient grinding is increasing. However, due to the good plasticity of aluminum alloy, its grinding performance is poor. The grindability of different kinds of aluminum alloys is quite different, but there are some common problems, such as the deformation of workpiece caused by the grinding force, the plastic deformation in the grinding process and the poor surface quality of the workpiece caused by the blockage of the grinding wheel by the debris. Especially for surface grinding and polishing, both of surface shape accuracy and surface roughness are necessary to control, which bring new challenges to processing technology. Scholars improve the surface quality of workpiece by selecting reasonable grinding tools, optimizing grinding parameters or using grinding fluid. Ultrasonic vibration assisted grinding and other methods are also used to improve the surface grinding quality of aluminum alloy. However, how to control the plastic deformation in aluminum alloy grinding, solve the problem of tool blockage, and achieve efficient and precise grinding of free surface remains to be further studied.