Manufacturing and testing technology of composite

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Large aircraft composite structure manufacturing and testing technology

the amount and application position of composite materials in aircraft has become one of the important indicators to measure the progressiveness of aircraft structure, and the application of composite materials in large aircraft is increasing day by day. Among them, the performance of A380, Boeing 787 and A350 is particularly remarkable. Take 787 as an example, the amount of composite materials has accounted for 50%. At present, composite manufacturing technology has become a hot spot in the research and development of various countries, among which co curing integral molding technology, liquid molding technology, automatic manufacturing technology and testing technology are the basic technical guarantee for the development of advanced composite materials

the data sources of this analysis are three patent databases of the United States (), Europe (), and China (), and the search was conducted from January 9 to 11, 2008 (Note: patents obtained in 2006 and 2007 may not have entered the database). In order to ensure the comprehensive and accurate data, the key technologies for the manufacturing and testing of large aircraft composite structures are first determined. This analysis divides the key technologies into eight parts: bonding/CO curing integral molding technology, stitching integral molding technology, liquid molding technology, automatic placement technology, composite molding mold technology, composite component nondestructive testing technology Superhybrid composite technology and thermoplastic composite component manufacturing technology. Then, according to the key technology, the search term is determined for search, and finally 266 relevant patents are screened. The following analysis will be based on these patents

overview of the development of composite manufacturing technology for large aircraft

1 analysis of the current situation and development trend of manufacturing technology patents

the technical patent documents related to the structural manufacturing and testing of composite materials for large aircraft had little change before the 1990s, and the number of applications was also small, but in the late 1990s, the number increased rapidly, which shows that with the increase of the amount of composite materials used on large aircraft, the technical requirements are also higher and higher, Countries are also increasingly aware of the protection of technology

at present, among the patents related to the manufacturing and testing technology of composite structures for large aircraft, the United States accounts for 59%, Europe for 19%, China for 2%, and partners of other large aircraft manufacturers such as Japan, Canada, Australia account for 18%

the number of patent documents of composite material manufacturing technology for large aircraft in the United States has always been in the leading position, and the growth rate is even faster after the 1990s. At the same time, patents in Japan and European countries have also shown an increasing trend in recent years, while the development of large aircraft in China has just begun, and many technologies are in the exploratory stage, and the patent system has not yet been formed

in addition, the category of patents is analyzed by IPC international patent classification number. The patents with IPC classification number B29C are the most, followed by b32b, b64c and g01n, and the others are less. According to the classification description of IPC number, the technologies of bonding/CO curing integral molding, stitching integral molding, liquid molding and automatic placement of composite materials belong to B29C; Super Hybrid Composites and honeycomb sandwich joint structures belong to b32b; Nondestructive testing technology belongs to g01n

in addition, according to the relevant patents analyzed, there are 1125 patents of the same family, of which 47 are applied in China, and most of the others are patents of the same family from Europe, America, Japan and other countries. It shows that before the inquiry, the intellectual property competition of foreign large aircraft manufacturers was mainly between Europe, America, Japan and other countries

2 life cycle analysis of patented technology

life cycle analysis of patented technology includes the relationship between the applicant and inventor and the time and amount of patent application. After 2000, the number of applicants, inventors and applications for composite material manufacturing technology for large aircraft has increased significantly, which shows that talents in the field of composite material manufacturing are increasing rapidly, patent technology is becoming more and more new, and composite material manufacturing technology has entered a period of rapid growth

3 analysis of the R & D strength and overall patent deployment of major competitors

the major competitors of China's large aircraft manufacturers are Boeing and Airbus, as well as their partners around the world, such as voght and Hexcel in the United States, aviation companies in European countries, Mitsubishi Heavy Industries and Fuji Heavy Industries in Japan, also master many advanced technologies in composite material manufacturing. In addition, many professional technology companies also have advanced technology and equipment. Boeing, Airbus and Lockheed Martin have many patents, among which Boeing's patents account for almost 40% of the patents of the whole large aircraft composite structure manufacturing and testing technology

it can be seen from the distribution of patent applications of major patentees over the years that Boeing had patents on composite material manufacturing technology for large aircraft in the 1970s and 1980s. Since the late 1990s, it has increased more rapidly and has more patents than other companies. Airbus, EADS and Lockheed Martin also have relevant patents after 2000, indicating that composite material manufacturing technology has been valued by various companies, This is inseparable from the advanced properties of composites and the enhancement of the awareness of intellectual property protection in various countries

analysis of relevant technologies for the manufacturing and testing of composite structures for large aircraft

from the development trend of various related technologies in the manufacturing and testing technology of composite structures for large aircraft, it can be seen that the bonding/CO curing integral molding technology, automatic placement technology and stitching technology have had relevant patents in the 1970s and 1980s, and have increased rapidly in recent years. Patents for other technologies appeared in the late 1980s and early 1990s, and increased year by year in a wave trend, The growth rate after 2000 is relatively fast. The patented technology of thermoplastic composites has appeared only in recent years, and there are few relevant patent documents. The following will analyze the level of patent technology, development overview and China's technical status in this field, and preliminarily put forward relevant suggestions

1 bonding/CO curing integral molding technology

bonding/CO curing technology can be used to connect different materials, different thicknesses, two-layer or multi-layer structures. Its structure has light weight, good sealing performance, outstanding anti vibration and flutter performance, and can greatly reduce the number of parts and fasteners, so as to realize the integrated molding of composite structures from design to manufacturing. It has a wide application prospect in large aircraft, It is one of the key technologies of integrated manufacturing. Foreign composite bonding/CO curing integral molding technology has had relevant patents since the 1970s. In recent years, more patents have been applied for, and the technology has become more and more advanced. Among them, the United States is the largest, mainly Boeing, Europe is mainly Airbus, and Japan's Fuji Heavy Industry also has relevant patent documents, which are mainly used in CO curing integral molding stiffened wallboards and fuselage structures, As a well-known domestic testing instrument and testing service supplier, Jinan Sida Testing Technology Co., Ltd. fairing, honeycomb sandwich structure, etc. Some patented technologies also describe many advanced manufacturing technologies currently being used, such as automatic stringer generation technology, mold technology, packaging method, combined positioning, shape and position control, etc, These technologies have high reference value for the development of composite technology for large aircraft in China. There are also some patented technologies that basically cover our current technology, which are high-risk patents and should be avoided in the design and manufacture of large aircraft. In addition, many patents are only structural concepts in terms of technology. For example, some patents on stiffened panel structure can be improved and replaced in terms of design and structure. The improvement, application and formation of their own patents of these patents need to be further studied according to the actual situation. From the analysis results of the whole patent, there is no patent on the aircraft component bonding/CO curing integral molding technology with independent intellectual property rights in China, although some technologies have been applied in some domestic models, and the technical level is equivalent to that of some foreign patents, such as the reinforced wall panel co curing molding technology of Beijing Aviation Manufacturing Engineering Research Institute and the honeycomb sandwich structure co bonding integral molding technology, Compared with the technical level of some foreign patents, we should form our own patents as soon as possible and protect them

2 liquid molding technology

liquidcomposite molding (LCM) refers to a kind of preparation technology that injects liquid polymer into the closed mold cavity paved with fiber preform, or heats and melts the resin film pre placed in the mold cavity, and the liquid polymer completes the infiltration of resin/fiber while flowing and filling the mold, and then solidifies and forms products, Resin transfer molding (RTM) and resin film infiltration (RFI) are the most common LCM technologies. Liquid forming technology is one of the main development directions of low-cost preparation technology of advanced composites. At present, beams and stringers are widely used in large aircraft. In addition, RFI technology is also used to manufacture the wing trailing edge and rear pressure spacer frame of A380. The patents of liquid molding technology are still dominated by Europe and the United States, while Boeing and United technologies have many patents, mainly involving injection equipment and mold technology. Valuable patents are generally in the last decade or so. Through the interpretation of some patented technologies, it is found that the mold technology of Beijing Institute of Aeronautical Manufacturing Engineering, especially the design of resin runner, has surpassed some patented technologies, providing a guarantee for the flow of resin in the process of liquid forming and transfer. There are few patents for liquid molding technology used in large aircraft manufacturing in China, but some institutes are trying to catch up with foreign advanced technology. At present, China has purchased high-temperature RTM injection molding machines, and the runner technology can form new patents by improving its method of forming temporary resin channels, The vacuum assisted reinfusion (vari) technology of Beijing Institute of Aeronautical Manufacturing Engineering has surpassed some foreign similar patented technologies, and is applying for national defense patents. The Institute also has various epoxy resin systems for liquid molding, and will be applied on ARJ21 aircraft in combination with vari technology

3 stitching integral molding technology

stitching technology is to use stitching to strengthen fabric laminated blocks (prefabricated parts) with fibers along the thickness direction. It can greatly improve the interlaminar strength of components and increase the impact damage resistance, so as to further improve the efficiency of composite structures and reduce the weight of structures. Judging from the current patents, there are certain researches at home and abroad, but they mainly involve concepts and influencing factors, and are widely used in military aircraft and aerospace. Relevant patents have appeared in foreign countries since the 1980s, but only in recent years in China. There are some technologies with control software that can automatically obtain experimental data such as elastic modulus, static bending strength, internal bonding strength, surface bonding strength and bonding strength, which are novel and valuable for reference. For example, patents have proposed a suture lattice composite sandwich plate structure, as well as patents on suture type, direction, suture density, suture tension, etc, In addition, there are some patents on the integral suture sandwich structure. In addition to stitching, there is also Z-pin reinforcement technology. The query found that only Boeing applied for a series of patents, including pin reinforced sandwich structure and pin reinforced laminate. At present, Beijing Institute of Aeronautical Manufacturing Engineering has completed the research of lock suture, tufting suture and OSS suture test pieces. On this basis, typical suture test pieces of various structures have been formed through RTM, RFI and vari processes, and the mechanical property test has been completed. It is completely possible to produce new invention Patents according to the combination of suture and other forming methods. Z-pin technology is in the experimental stage in China and has not been applied to typical structural members

4 automatic placement technology

automatic placement technology is nearly 30 years old

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