With the increasingly urgent repair demand brought by the extensive application of composites in industrial field, the advanced non-destructive testing and evaluation (NDT & E) methods and techniques for composite repairs have been highly concerned in the industry. At present, integrated visual NDT & E methods and techniques suitable for different repair scenarios are lacking. A integrated visual NDT & E method based on the principle of multimode ultrasound (MU) is proposed. The NDT & E requirements and features for composite repairs situ, off-location and manufacturing scenarios were analysed. A MU visual NDT & E method for multi-repair scenarios was constructed. Typical composite repair specimens were prepared. The regularity of ultrasonic signals and images from the composite repaired areas and the visualized detection effect of the developed integrated MU method were revealed experimentally. The results  show that the geometrical topologies of the matrix, repaired zone and repaired edges in the composite body can be clearly identified and quantitatively characterized based on the change characteristics of ultrasonic signals from the repaired composites. Different ultrasonic modes have different visualized imaging effects and defect detection capabilities, among which mono-pulse ultrasonic mode (M₃) and asymmetric-frequency ultrasonic mode (M₂) have the best visual imaging quality and defect detection capabilities, while air-coupled ultrasonic mode (M₁) is obviously inferior to M₂ and M₃. M₃ has the most imaging details compared with M₁ and M₂; M₂ and M₃ have the highest accuracy and resolution in detected defects, the smallest surface detection dead-zone, and their sensitivities for detected out delamination and disbonding reach Φ3 mm. The surface resolution of M₂ and M₃ is smaller to a single ply thickness in omposites (about 0.125 mm). The sensitivity of M₁ for detecting delamination and disbonding is close to Φ6 mm. Thus, the integrated MU method and technique provide a powerful and visualized quantitative NDT & E approach for composite repairs in different repair scenarios, and have been applied well in practical inspection.

Manufacturing defects in composite material structures and damage during service are inevitable, therefore, conducting research on composite material repair science and engineering technology is of great significance for ensuring the safe and reliable operation of advanced aviation aircraft throughout their entire life cycle. This article first elaborates on the connotation of composite material repair science and engineering technology; Secondly, the development direction of aviation composite material repair technology at home and abroad was sorted out, with a focus on analyzing the scientific and technical problems of advanced composite material repair theory, process, design, testing, and evaluation. The focus was also on the new cutting-edge repair design and technology of functional load-bearing integrated composite material structures; Finally, the future development trends of composite material repair science and engineering technology were discussed, providing reference for the research and application of intelligent and rapid repair technology for composite materials in China.

In the new situation, composites are widely used in the manufacture of high-performance aircraft tructures, with the continuous improvement of the service range and service time of China’s new generation fighter aircraft, it is increasingly urgent to improve the reliability and service life of the body composite components. With the background of the unique application of automatic drilling and riveting technology in the field of military aviation maintenance, this paper studied the drilling characteristics of the layered damaged component, built and developed the drilling force curve prediction model and the damage interface recognition algorithm, realized the variable parameter drilling of the damaged component, and detailed characterization of the static/dynamic performance of the layered specimen before and after the damage repair. The reinforcement principle and damage repair tolerance of the drilling and riveting repair process are expounded. At the same time, the drilling and riveting process and high-precision robot in-situ drilling and riveting repair equipment for complex layered damage conditions of composite panels are developed, and a complete technical system and intelligent equipment for lamination damage drilling and riveting repair of composite panels are formed.

The effect of the addition method of thermoplastic poly ethylene-co-meth acrylic acid (EMAA) on the interlayer toughness of carbon fiber reinforced polymer (CFRP) composites was studied using a combination of experimental and simulation methods. Firstly, EMAA was made into thin filaments with diameters of 1.2 mm and 50–75 μm, and then added to CFRP composite materials by sewing and layering, respectively. The effects of EMAA addition method and content on the type I interlayer fracture toughness and self-healing efficiency of CFRP composite materials were studied by adjusting the suture spacing and layering density. The results show that the addition of EMAA significantly increased the type I interlayer fracture toughness of CFRP composite materials, with improvements of 110% and 402% achieved through stitching and layering, respectively. In addition, numerical analysis using the cohesive zone model (CZM) further demonstrated that EMAA can enhance the type I interlayer fracture toughness of CFRP composite materials. After thermal healing, double cantilever beam (DCB) tests were conducted again, and it was found that the interlayer toughness of CFRP composite materials toughened by suture and layup was effectively restored, with repair efficiencies reaching 85% and 105%.

Chinese version hot bonder for aviation grade composites is a national composite material repair equipment developed in response to the call of “China’s high-end equipment localization alternative application”. According to the research progress of hot bonders at home and abroad, combined with the development and application requirements of equipment, six key points in the development process of domestic hot bonders, such as maintenance applicability, temperature parameters, vacuum degree, control technology, man-machine interaction and reliability were studied. This paper introduces the development process of a domestic heat repair instrument by selecting the equipment index, designing the operation interface layout, constructing software structure and program running logic. Domestic hot bonder has formed a series of products, including single-zone versions, dual-zone versions and multi-functional versions, and the product performance indicators have met and exceeded similar foreign products. The domestic hot bonder adopts a full Chinese graphical interface, which is easy to operate. The multi-functional version of the product integrates two functions of composite bonding repair design and repair implementation, which supports the efficient calculation and acquisition of composite repair design scheme under the field environment, and provides technical support and equipment support for the frontline technicians to carry out the in-situ repair of aircraft composite structural damage. After the preliminary assessment and application by the air force maintenance factories, troops and colleges, the domestic hot bonder can completely replace the foreign hot bonder products.

As a key technology in modern engineering field, the damage repair of composite materials in service is very important to ensure the long-term reliability and economy of the materials. The repair technology of composite materials is directly concerned with the performance recovery after the damage of materials or structures, and the repairability is the problem of how to reduce the difficulty of repair in the design and manufacturing stage of materials and structures. In this paper, the characteristics, technical development, shortcomings and problems encountered in engineering applications of traditional processes such as patching repair, digging repair, glue injection repair and mechanical connection repair are reviewed. The principle and progress of external and intrinsic self-healing composite materials and the technological development of deadhesive adhesives for replacement repair are also summarized from the perspective of composite materials and their structural repairability. Finally, the main technical difficulties that need to be overcome in the study of repair technology and repairability of composite materials are summarized.

BN/SiC coatings were deposited on the surface of SiC fibers by chemical vapor infiltration (CVI) process, and the physicochemical properties of the surface coatings and the fibers were further investigated by characterization techniques in a high-temperature oxidation environment. The fibers coated with BN/SiC coatings were treated at 1050 – 1200 ℃ for 0.5 – 2 h in air environment. The morphology, structure and composition of the oxidized BN/SiC coatings were characterized by scanning electron microscopy (SEM), X-ray diffractometer (XRD), nano-scanning Auger (AES) and X-ray photoelectron spectroscopy (XPS). The mechanical properties of SiC fibers coated with BN/SiC coatings after oxidation were evaluated by tensile strength of monofilament. The results show that the BN/SiC coatings are not completely oxidized and still have the ability to protect the internal SiC fibers. Through further analysis of the experimental data, it is found that the main failure mechanisms of the fibers attached to the coatings after oxidation at 1200 ℃ and 1350 ℃ are different, with the former being the formation of gaps and pores between the coatings and fibers, and the latter being the production of oxides and their cracks.

The interface construction between high performance carbon fiber and composite matrix is the key to give full play to the excellent mechanical properties of carbon fiber. As an effective method of surface modification of carbon fiber, electrochemical modification has been widely used in the design and manufacture of carbon fiber composites. This paper reviews the recent research progress on the modification of inert carbon fiber surfaces using electrochemical methods, including electrochemical oxidation, electrochemical grafting and electrochemical deposition. Additionally, it explores the future development prospects and directions for the electrochemical modification of carbon fiber.

With the rapid development of aviation and aerospace manufacturing technology, high-performance thermoplastic composites have received more and more attention and applications. Their application parts and scope also expand from non-load bearing to secondary load-bearing and then to the main load-bearing structure, from static to moving parts. The working environment tends to be diverse. For example, friction and wear problems exist in some moving parts, which put forward higher application requirements for high-performance thermoplastic composites. This paper focuses on the study of friction and wear properties of continuous fiber-reinforced high-performance thermoplastic composites, composites based on poly etherether ketone (PEEK), poly aryl ether ketone (PAEK), polyetherimide (PEI), polyphenylene sulfide (PPS), etc., and their latest research progress. Expects to provide a reference for the application research of continuous fiber-reinforced high-performance thermoplastic composites under friction working conditions and to provide an opportunity for their use in aerospace applications. It is expected to deliver a reference for the research on the application of continuous fiber-reinforced high-performance thermoplastic composites under friction conditions and to provide data accumulation and theoretical guidance for their practical application in the aerospace field.

High-performance thermoplastic composites have great potential for structural weight reduction because of their excellent performance in impact resistance and damage tolerance. Due to its weldability in processing, thermoplastic composites are recyclable and reusable, which is an important way to achieve the green development of aviation structure and contribute to the reduction of aviation carbon emissions. This work summarized the key technologies in the application of high performance thermoplastic composites such as prepregs technology, molding technology, welding technology as well as automation equipment and processing. The development status of thermoplastic composite structure researches for civil aircraft were reviewed. The main influencing factors, development trend and application prospective of these key technologies were analyzed. According to the characteristics of manufacturing process of thermoplastic composites, the applicable objects of different manufacturing processes were analyzed, and the suggestions for the process selections of thermoplastic composite main structures of civil aircraft was proposed.

In recent years, thermoplastic composites have been gradually used in aerospace, marine equipment, transportation, and other fields because of their excellent mechanical properties, environmental resistance, and recyclable potential. They can be prepared by various forming processes. Among them, overmolding, which is a unique molding process for thermoplastic composites can combine the prefabricated parts with the injection molding process. Due to the diversity of its structure and material design, process flexibility, it has gradually attracted wide attention from researchers. Based on the whole process of overmolding, this paper will introduce its research progress, including material system, manufacturing and pre-treatment of prefabricated parts, injection molding, post-treatment of structures, as well as the numerical simulation means and combined application methods involved in this process, and analyze the current process difficulties and future development direction.

Continuous fiber reinforced polymer composites (CFRPCs) have been widely used in the aerospace field due to their advantages of lightweight, high specific strength, and high modulus. However, its manufacturing cost has always been high, and the emergence of additive manufacturing technology has opened up new directions for the design and manufacturing of high-performance, low-cost complex composite structures. This study reviews the design changes, material systems, and process progress brought about by the additive manufacturing technology of CFRPCs, and analyzes the performance defects of CFRPCs in extrusion molding additive manufacturing. Further analysis was conducted through relevant literature on the relationship between extrusion molding additive manufacturing process, microstructure, and performance, providing a reference direction for improving the performance of additive manufacturing CFRPCs. Furthermore, this article summarizes the typical applications and future prospects of additive manufacturing of CFRPCs. Composite additive manufacturing will continue to play an important role in the application of composite materials in aerospace field.