Abstract:The composite bonded-bolted hybrid joint(BBHJ) is widely focused and developed in aerospace and aviation fields for its full consideration of advantages of bolt and bonded joint. In this review, the relative research development of this BBH joint in composite structures at home and abroad is thoroughly summarized. Focusing on enhancing load sharing and structure bearing ability, the research status, research development and related achievements are introduced from the aspects of composite repairing and damage tolerance, forming process and force-transferring route, parametric influence and load sharing, adhesive de-bonding inhibition and multi-bolt load sharing, and the bearing strength prediction. The existing problems, probable solutions and future developing direction of this joint style is further discussed in order to provide useful reference for the further application of BBHJ in composite structure.

Abstract:Flows past a wide-body aircraft operated at cruise, drag divergence and dive Mach numbers are transonic flows. When the aircraft model is tested in a transonic wind tunnel, strong shock wave may be induced due to the tunnel wall, which will incur the complex wall interference as a strong nonlinear coupling phenomenon. In order to investigate the wall interference to the standard model of a wide-body aircraft mounted in the FL-26 wind tunnel, a numerical simulation method based on a porous wall model was developed, and employed to research the interaction between the wall and the model at Mach numbers ranging from 0.8 to 0.92. Compared with the wall pressure information method, results obtained with the porous wall model indicate that the effect of the porous wall on the curve of lift coefficient can be captured better without measured data, but larger effect on the drag coefficient is produced.

Abstract:The traditional rain flow counting method is suitable for conventional fatigue, but it cannot retain the frequency information of vibration fatigue. Frequency is very important for vibration fatigue. Therefore, a frequency rain flow counting method is proposed based on the traditional rain flow counting method, which can effectively retain the frequency information. Spectrum developing process, and developing vibration fatigue load spectrum. Taking a certain type of engine test vibration signal as an example, determine the load classification to 0.5g, the vibration signal power spectrum, conventional load spectrum, and vibration fatigue load spectrum are developed It provides guidance for the subsequent vibration fatigue life assessment and reliability test of the main components of reusable engines. The results show that the prepared load spectrum can reflect the actual working load of the engine and meet the load spectrum requirements of the laboratory fatigue test .This paper presents a method for develop vibration load spectra suitable for the assessment of vibration fatigue life of similar structures in engineering. Keywords: vibration fatigue; load spectrum; engine; rainflow counting method; power spectral density

Abstract:The safety risk situation of the air traffic management system will directly affect the safe operation of air transportation. Comprehensively considering the safety operation characteristics of air traffic management system, the evaluation index system of safety risk is constructed. The combination weights of the evaluation index are obtained by means of the Euclidean distance function. The matter-element analysis method is introduced to establish the matter-element model for safety risk assessment of air traffic management system. The empirical analysis shows that the matter-element analysis method can obtain the overall safety risk status of the air traffic management system, and at the same time can obtain the safety risk status of each evaluation index. This is helpful to take effective measures to improve the safety risk management level of the air traffic management department.

Abstract:In order to improve the safety operation ability of aviation network, a key node identification method based on kernel extreme learning machine is proposed. Firstly, it evaluates the comprehensive importance of nodes based on analytic hierarchy process (AHP). Then, it selects three simple indices and establishes the importance evaluation model based on the mapping relationship between simple indices and comprehensive importance of kernel extreme learning machine. Simulation results show that the proposed method is accurate in evaluation and can overcome the problem of high computation time complexity.

Abstract:Engine failure is like the heart disease, and the in fight shut-down (IFSD) of the aero-engine is seen as a killer of the flight because of its high risk and uncertainty. We must do a good job of prevention and disposal. Aiming at the problem of IFSD, This paper uses the social network analysis method to make a quantitative analysis of the research status of the aero-engine IFSD in China. In the CNKI database, IFSD were used as parallel keywords to search relevant research literature. The SATI 3.2 software was used to preprocess the literature data to obtain high-frequency keywords and construct the confession matrix. Then, the Ucinet 6.0 software was used to conduct social density analysis, centrality analysis, condensate subgroup analysis and core-edge analysis on key words. Through quantitative analysis, the current research hotspot and frequency were extracted, the focus and development trend of subsequent research were predicted.

Abstract:In order to study the aerodynamic interference and movement rules of external store, computational fluid dynamics (CFD) methods were used to simulate the release process of airborne buoy in R/S UAV. A Moving-embedded grid approach is used coupled with an unsteady N-S equations, and a 6-DOF kinetic equations is fully integrated into the CFD solution procedure to capture the time-dependent interference between the stationary and moving boundaries. All major parameters, such as displacement, angular orientations and force, and their change trends were obtained. The results show that free separation of buoy cover could have a significant impact on the safety of UAV during the release process of airborne buoy. Consider the state of the buoy cover attached to the buoy parachute, the closest range of buoy from the propeller is 0.151m when the initial speed is 0.0 m/s, the safety margin is not enough; however, the closest range of buoy from the propeller is 0.671m when the initial speed is 1.8 m/s, the safety margin is enough.

Abstract:Aircraft landing system is the critical system to ensure the safe approach and landing of aircraft, and how to evaluate the landing system to meet the safety design requirements is one of the important parts of the system design. The basic process of the safety assessment for the civil aircraft is described. Taking the microwave landing system (MLS) as an example, for a given MLS block diagram, the failure condition complete loss of both sides MLS information is evaluated by the fault tree analysis (FTA) method. The process and method of tree modeling are described in detail. The results show that FTA plays an important role in the design of the system architecture. The FTA and system architecture design are closely combined and feedback each other. Especially when the probability requirements associated with the failure condition cannot be met, the FTA cutset report can find the weaknesses and key parts of the system architecture, so as to take effective measures to complete the optimization design of the system architecture.

Abstract:For amphibians aircraft, Ground and water handling characteristics should meet the requirements of airworthiness regulations, and an accurate computation analysis method should be established to carry out the evaluation during the optimization design process of the aircraft scheme, so as to ensure the airworthiness compliance of the aircraft scheme and reduce the risk of design change. Based on the planing boats hydrodynamic analyzing methods, landing gear system multibody dynamic modeling technology and Matlab/Simulink simulation environment, a mathematical flight simulation model of flying boat in water was built, as well as another simulation model on the ground. The time history of various motion state variables, undercarriage parameters, hydrodynamic forces of the aircraft are obtained after the simulation. Finally, a contrastive analysis of the taking-off process between the simulation results and expremental data was made. The results showed that the ground and water flight simulation method was consistent with test data of the amphibious aircraft, can achieve the accuracy requirement of aircraft type design. This method has an important theoretical and practical value in evaluating and improving the aircraft designed, as well as in guiding the airworthiness compliance flight test.

Abstract:The fire resistance requirements of wires and cables in airworthiness regulation CCAR25-R5 are investigated in the study. It is found that the mainly related items are CCAR 25.1713, 25.831 and Appendix F. It is shown that requirements to wires and cables’ toxic gas in fire are claimed at system level in terms of consequence in CCAR 25. Therefore, the requirements need to be distributed step by step during aircraft design process. The requirements in domestic and international specifications are also analyzed for the fire resistance. It is shown that only flammability and smoke are mainly demanded, no requirements for toxic or hazardous gas are asked for. Finally the airworthiness roadmap of wires and cables are discussed. It is suggested that the characteristic values of selected wire/cable are to be generated by referring to the advanced standards of foreign enterprises, so as to reduce the content of verification and the risk of airworthiness.

Abstract:在高速旋转状态下,开展对高压涡轮转子叶片的振动特性和缘板阻尼装置减振效果的试验研究,有利于后期的设计迭代,获得真实的叶片振动情况。以高压涡轮转子模拟件为对象,采用雾化油滴非接触式激励方式模拟涡轮叶片周期性气动激励,建立高速旋转状态下高压涡轮转子叶片振动特性试验系统,并进行介于静止状态夹具固定式测试和整机直接测试之间的组件级试验,在高速旋转状态下实现叶片非接触式高频激振,获取叶片的振动特性和缘板阻尼装置对转子叶片的减振效果。结果表明:在常温 10000~19000r / min 运行转速下,缘板阻尼装置对转子叶片减振约 40% ,阻尼质量较大的叶片频率较高。

Abstract:In order to study the fuel temperature during the continuous climbing process of a UAV, the simulation model of the UAV fuel system is built by using the Flowmaster software. Taking the parameters of environment temperature, initial fuel temperature, initial fuel quantity and fuel consumption rate as boundary conditions, the fuel temperature in the fuel tank during the flight is obtained by simulation. The feasibility of the simulation model is verified by comparing with the actual flight test data. Based on the simulation model, the influence of environment temperature, fuel consumption, fuel consumption rate, climbing speed and other factors on the fuel change law is further quantitatively studied. The research results can provide scientific basis for the flight test of the UAV and the design of ventilation and pressurization system.

Abstract:In order to simulate the pressure load of the cabin cover in flight more accurately on the ground test bed, the controller design of the cabin pressurization system of the test bed is carried out by introducing the idea of piecewise control. According to the system structure of the cabin pressurization system of the test bed, the control system model is established, and then the PID closed-loop control of the cabin pressurization system is realized by piecewise control technology in the virtual instrument, so as to improve the applicability and stability of the system. The results show that the PID controller designed in this paper can improve the control accuracy and test efficiency of aircraft cabin pressurization system and meet the technical requirements of test bed pressure control system.

Abstract:Orifice is the main ways of magnetorheological damper to produce damping. According to the actual magnetorheological dampers, the related models are established. Use commercial software Fluent to analyze the flow field of the different size of magnetorheological damper’s throttle aperture, and compared with the experimental results. The results show that the main reasons for determining the initial damping and time delay effect are the flux and jam of magnetorheological fluid. The time-delay effect is the most obvious when the throttling aperture diameter is 0.2mm, and the response speed of the magnetorheological damper to external excitation decreases significantly with the increase of frequency.

Abstract:As an important means of atmospheric threat awareness, airborne weather radar plays an important role in aviation security. This paper analyzes the development process of airborne weather radar and foreign products and technologies, looks forward to the development trend of airborne weather radar, and combs its key technologies and difficulties in order to promote the research and development of related technologies in China.

Abstract:With the development and wide application of automatic dependent surveillance-broadcast (ADS-B) technology, there have been emerging many ADS-B manufacturers who have developed a large number of ADS related products with versatile configurations for different airborne platforms. This paper firstly categorizes the diverse ADS-B products with respect to configuration and intended platform, and then, analyzes the functional and technical characteristics of the ADS-B products designed for airlines, general aviation, and unmanned aircraft system (UAS). Finally, this paper analyzes and discusses the countermeasures to the challenging problems of ADS-B system including information security, enhanced reception in dense jamming environment, as well as 1090MHz channel capacity improvement.

Abstract:The Wireless Avionics Communication Technology in the civil aircraft will be an important technology for the development of the next generation aircraft, which can further reduce the weight of the aircraft, enhance the safety of the aircraft, and improve the operation economy of the civil aircraft. This paper describes the definition of wireless Avionics Intra-Communication (WAIC) network, summarizes the research status of WAIC network at home and abroad, analyses the characteristics of WAIC network, and gives the key technologies, such as network architecture, time synchronization, network management, network security and hardware design in the process of WAIC network design. It also puts forward the realization of 4.2GHz-4.4GHz wireless communication based on software defined radio in WAIC network.

Abstract:The lightning protection design and verification of aircraft is a necessary measure to ensure the safety of pilots and aircraft, especially with the poor lightning protection ability of composite materials. The conductivity of the composite is much weaker than that of the metal, which needs to provide additional pathways for the lightning current conduction. Based on the electromagnetic modeling of aircraft internal structure rarely mentioned in domestic related research, this paper proposes a set of electromagnetic modeling and precision control method for aircraft internal structure, constructs the internal metal structure from left wing to right wing of F22 aircraft as lightning current conduction path, and simulates the indirect effect of aircraft lightning based on general electromagnetic simulation software. The simulation results of electromagnetic field and cable coupling in aircraft interior under three conditions of composite skin, metal mesh skin, metal mesh skin and internal metal structure are compared. After evaluation, reasonable lightning current conduction path design can reduce the current intensity induced by the cable inside the aircraft by half, and play a good lightning protection expected effect.

Abstract:In order to obtain the operating permit in the high-intensity radiation field environment, the civil aircraft must carry out the protection design and airworthiness verification in accordance with the airworthiness provisions related to the protection of high-intensity radiation field (HIRF) issued by airworthiness authorities. Currently, the internal HIRF environment of aircraft is determined mainly through test methods and similarity assessment method. In this paper, for the first time, the data estimation method is used to determine the internal environment level of HIRF for the 23 part aircraft with only class a display system, so as to realize the airworthiness verification of HIRF protection for the whole aircraft. The key technology and feasibility of this method are discussed, which provides reference for the protection verification of civil aircraft HIRF. The method proposed in this paper has been applied to the practical engineering of Y12F aircraft HIRF protection airworthiness verification, which effectively reduces the complexity of the whole machine protection airworthiness verification. The method saves the test cost and improves the test efficiency.

Abstract:To ensure the reliable operation of the bus network for distributed systems, a bus network checking procedure should be made before the operation of the system to eliminate the influence of a faulty node or faulty cables. However, a timing problem may occure during the checking procedure, when the source clock of the bus controller switched. Base on a false alarm during the checking procedure for a distributed integrated navigation system, the author explored the causes and timing sequence of the false alarm by theoretical analysis and simulation. The research shows that the asynchronous clock between the integrated navigation computer and the bus controller causes the software of the integrated navigation computer to read the same cache in DPRAM in two adjacent cycles, which is the root cause of false alarm.