Composite materials have been widely used in many fields. Composite structures are becoming more and more complex, their sizes are becoming larger and larger, the quality requirement is becoming higher and higher, thus resulting a higher requirement on accuracy and reliability of non-destructive testing. Through advanced ultrasonic visual detection technique, the internal defects and structural details of composites can be visualized with high precision, which is very conducive to improving the accuracy and reliability of composite detection, and realizing digital evaluation of internal quality of composites. In this paper, an accurate digital evaluation method for defects in composites based on our developed mono-pulse ultrasonic (MU) visualization technique is proposed. The research and application results show that the MU detection and digital defect evaluation methods can significantly improve detectability and detection resolution of composites. It is more helpful to accurately reveal internal defect behavior of composites, achieve accurate visual inspection and digital evaluation of internal quality of composites. Ultrasonic detection dead-zone and lateral resolution reach to a single ply thickness (approximately 0.125 mm). The similarity between the detected and the design value of defects is close to 1.0. It can realize accurate defect detection and digital evaluation of composites. It has been applied in practice.

Industrial robots have received high attention in the aviation manufacturing industry due to their intelligent advantages, and the rapid development of the global aviation manufacturing industry has given them a huge market demand. Industrial robots have been widely used in fields such as automobiles and 3Cs, but due to the wide variety of components, small batches, complex production processes, and higher accuracy in the aviation manufacturing field, higher performance requirements are put forward for industrial robots. Firstly, based on the characteristics of the aviation manufacturing industry, analyze the key technical requirements of industrial robots for high-precision, multifunctional, human-machine collaboration, rapid programming, and multi-machine collaboration; Secondly, the current application status of industrial robots in the field of aviation manufacturing at home and abroad is analyzed and summarized from the aspects of composite material component production, structural component processing, flexible assembly, surface spraying, intelligent detection, etc. Finally, it is predicted that industrial robots for aviation manufacturing should develop towards digitization, modularization and intelligence

The skin–rib joint is a very important form in carbon fiber composite panels. Because of the complex in geometric structure, internal layer, defect behavior and orientation of fibers therein, defect characterisation, detection and evaluation have been the technical difficulties and focus in their applications. In this paper, a new method for defect characterization and evaluation is proposed using mono-pulse ultrasonic (MU) wave. The experimental results show that the echo signals resulted from the skin–rib joints have very good time-domain resolution under MU reflection condition. When echo signal is close to one pulse cycle, the ultrasonic surface detection dead zone can reach a single layer thickness (about 0.125 mm). Delamination, disbanding, adhesive layer, resin layer and internal layer variation in the skin–rib joints can be characterized, detected and evaluated. The minimum deviation of detected defect is close to 0.0 mm, and the maximum deviation is about 1.0 mm compared with their designed sizes. The depth positioning deviation of detected defect is less than 0.5 prepreg ply thickness. It provides a very effective ultrasonic characterisation and evaluation method for the composite panels. Good practical application has been obtained.

Titanium alloy has the characteristics of high strength, good corrosion resistance and high heat resistance,V and is widely used in aerospace and other fields. Aiming at the problems such as low signal-to-noise ratio, easy omission during ultrasonic phased array detection of internal micro defects, a deep learning based ultrasonic phased array detection image noise reduction method for micro defects was proposed. Firstly, the original images with defects and noise are obtained through the phased array detection experiments of titanium alloy test block, and the Mask RCNN model is trained to construct high–low noise data sets. Then, the noise reduction model of micro defects detection images is designed based on the variational autoencoder. By comparing with the traditional noise reduction algorithms, it is proved that the proposed algorithm can retain the defect details of the original image. Compared with the original image with noise, the peak signalto-noise ratio is optimized by 11.35% and the structural similarity is improved by 154.17%. Finally, the ultrasonic phased array testing experiment of a titanium alloy aviation casing ring was carried out. The proposed method was used to reduce the noise of the image with a φ 0.2 mm flat bottom hole inside the ring, effectively reducing the influence of scattered noise on the detection of small defects, it’s also proved that the proposed noise reduction algorithm has good generalization performance.

Laminated composite materials are formed by laminating two or more layers of the same or different materials. Due to the excellent mechanical properties, laminate composite materials are widely used in aerospace and navigation fields. However, during the production and service stage, defects such as disbond and delamination between, layers have greatly affected the stability of component. Currently, the commonly used contact ultrasonic testing has limitations such as large blind area, small field of view, many artifacts and water coupling. Combining the advantages of laser ultrasound and air-coupled ultrasound, a non-contact laser ultrasonic testing system consisting of eight elements 250 kHz air-coupled transducer is developed to detect thin laminated composite materials with thickness of 0.8 mm metal–carbon fiber and 0.3 mm metal–metal, respectively. The system can not only clearly display multiple disbond defects inside the sample, but also successfully identify micro cavity defects formed by bonding layer indentation and bubbles. The imaging field and SNR are up to 220 mm and 35 dB, respectively. Besides, compared to high-frequency phased array and X-ray testing, the system exhibits excellent imaging contrast, resolution, and sensitivity. The experimental results show that the developed large-field air-coupled laser ultrasonic testing system has broad application prospects in the large laminated composite materials.

The conventional ultrasonic method for the R-zone of composite has a series of problems, such as reducing detection sensitivity caused by the incident sound beam not be perpendicular to the surface of the R-zone, difficulty in full coverage detection of the R-zone, and inability to evaluate the size of defects along the curvature direction of the R-zone. To solve the above issues, the ultrasonic phased array method was used to detect the R-zone of composite material, and the sound field distribution law in the R-zone was studied. The influence of the number of virtual probe on the detection sound field was analyzed. Through research, it has been found that the number of array element chips affects the sound field distribution. The more chips there are, the greater the difference in sound field distribution strength, the stronger the maximum sound field intensity, and the closer the position is to the surface, the larger the 6 dB sound beam width; Under the focusing detection method, the maximum sound field intensity is generally higher than that of the non focusing detection , and the 6 dB sound beam width is generally smaller than that of the non focusing sound field; The distribution of sound field generated by virtual probes with different angles of arc array probes is basically consistent, and the maximum sound field intensity of the central group chip is the highest. Through experimental verification, the use of ultrasonic phased array method and the use of arc array probes with reasonable detection parameters can effectively detect artificial defects in flat bottomed holes with different angles, burial depths, and aperture of about 3 mm in the R-zone.

As the main dimensional component of the aircraft, the aircraft skin has the function of bearing loads and maintaining its aerodynamic performance. Compared with traditional skin defect detection methods only relying on visual inspection, the use of automated ultrasonic detection of internal defects and machine vision-based external defect detection methods have significant advantages such as high detection efficiency, high automation and strong consistency of detection results. According to the research progress of automatic detection of aircraft skin defects, the typical defect types of aircraft skin are introduced, and the application of automatic ultrasonic non-destructive testing technology and machine vision image processing technology in skin defect inspection is summarized respectively. The current problems and technical difficulties in the field of skin defect inspection are summarized, and the future development trend of aircraft skin automatic inspection is prospected.

To ensure the simultaneous matching and coordination of multiple assembly holes and module axis in the automatic docking of spacecraft segments, cabin docking attitude recognition method based on the feature constraint of holes is proposed. Firstly, the assembly hole images on the docking end face of the cabin section are collected using a binocular vision measurement system. After a series of image processing such as denoising, edge detection, arc matching, fitting ellipses, and deduplication, the assembly hole is evaluated based on Topsis ellipses to obtain two-dimensional information. Then, a binocular elliptical cone model is established to solve the attitude direction of holes. Afterwards taking the optimal attitude matching of holes as the goal, the optimal mathematical model of the overall attitude estimation of the cabin was established to maximize projection vector modulus-length sum, which was made of the common projection vector in the attitude direction of these holes. The model was solved by genetic algorithm (GA) method, and the optimal attitude direction of large cabin was obtained. The simulation case showed that the effectiveness of the proposed method was verified by comparing with the ideal attitude and the accuracy of the method was tested on the experimental bench. The relative error of the actual deflection attitude angle of the module and the calculated attitude angle is 1.92%, which meets the requirements of the attitude estimation of large cabin.

Based on the traditional laminated structure composite materials and titanium alloy bonding, the composite/titanium alloy bondline internal quality and bonding strength under different factors were studied from the aspects of titanium alloy surface treatment methods, adhesive layer thickness and other aspects. The results show that: the bondline internal quality of composite/titanium alloy adhesive test pieces are all intact while the bonding strength between the laminated structure composite and the titanium alloy is higher than that of the woven structure composite under different processes; the pickling and grit blasting on the surface of the titanium alloy is more conducive to the composite structure/titanium alloy than the polishing treatment, and the bonding strength can be significantly improved by using surface pretreatment agent to treat the bonding surface of titanium alloy; the thickness of the adhesive layer has a great influence on the bonding strength of the composite structure/titanium alloy.

The adhesive thickness is very important to the bonding strength of the stiffened panel. Taking fourbar T-shaped stringer stiffened panel as the object, measure the springback of T-shaped stringer by tri-ordinate measuring machine, observe the bonding section and measure the adhesive thickness of the panel by sectioning, to explore several influencing factors, including springback deformation, flange width and edge chamfer of the T-shaped stringer on adhesive thickness. Meantime, simulate the springback and the flange deformation of T-shape stringer by finite element software ABAQUS. The result shows that the springback is 0.4°–0.5°, which has a significant effect on the adhesive thickness. The thickness of adhesive layer from the stringer edge to web changes from thick to thin when flange width is 22 mm. The thickness of adhesive layer from the stringer edge to web changes from thin to thick and then to thin when flange width is 73 mm. The adhesive thickness can be improved by edge chamfer, avoiding sudden change of adhesive thickness because of skin wrinkle, and then improve bonding quality. During part manufacturing, the adhesive thickness can be significantly improved by controlling the above factors to ensure the bonding strength of the parts.

In order to improve the preload control effect of rotor bolted connection of aero-engine, a torque method for loading target torque based on test data is proposed. In this paper, combined with the characteristics of multiple assembly and adjustment process of aero-engine bolts, the assembly process difference conditions are set, and three torque modification strategies are designed, and experimental research is carried out based on the flange connection disc simulation parts built. The dispersion of the bolt preload obtained under various loading strategies and the deviation from the target preload were analyzed and evaluated, and the improvement effect of various torque modification strategies on the rotor bolt preload control ability under different process conditions was given. It is recommended that for the bolt tightening requirements of aero-engine rotor, the difference in lubrication conditions and tightening times should be considered to improve the target preload, and the target torque correction strategy related to the change of self-locking torque and the number of tightening times should be adopted to regularly calibrate the target torque and avoid no lubrication as much as possible.