Abstract:Recently, with the continuous development and improvement of UAV technology, it not only plays an important role in the military field but also has been widely used in the civil field. However, the continuous reduction in the use of the UAV brings tremendous convenience to people"s life and production. At the same time, the abuse of UAV also pose a huge safety hazard to the country, society and citizens. Therefore, the demand for countermeasure and pro-tection against low-altitude drones is very strong in the military and civilian areas. This article focuses on the ap-plication of UAV in different fields, introduces the safety problems caused by UAVs flying at low altitude, and discusses the types and sources of threats. On this basis, this article focuses on the domestic and foreign anti-UAV technology in-depth analysis of the status quo, systematically on the existing anti-UAV technology and related systems, advantages and disadvantages are introduced. In addition, the future development trend of key technologies of detection and protection in low-altitude anti-aircraft UAV is analyzed and discussed based on the intelligent, integrated and autonomous research and development of low-altitude UAV systems.

Abstract:The development about experiment of vibration and response for rotating blade with dry friction damper was summarized. Device , excitation method and dynamic characteristic method used in vibration test for rotating blade with dry friction damper were discussed emphatically , in order to provide technical support for test program, Improving structural reliability and efficiency, vibration reduction and lifetime extension. Experiment of vibration and response for rotating blade with dry friction damper were divided into two types：dynamic characteristic test based on loading the centrifugal force on the blade and damper, vibration stress measure based on blade and damper actuated by engine.According to present situation of experiment of vibration and response for rotating blade with dry friction damper,new research directions were suggested:establishment of test equipment model library,which according to the different tenon structure and angle of adjacent blade; exploring the coupling loading method for high frequency and measuring method of vibration response; investigation on excitation method more in line with real environment, developing the high idetifying measure method using the strain gauge and sensor.

Abstract:To provide superior cruise thrust for high subsonic intermediate-long range missiles, small turbojet and turbofan engines have become the competitive focus for militarySpowers. The turbine engines for missiles are characteristic of low cost, short life, small size, high speed, low pressure ratio, severe volumetric heat release rate and various starting or ignition methods. They were widely equipped on strategic and tactical weapons, such as cruise, anti-ship and air-to-ground missiles. The development situation of small turbine engines within 100～700daN since 1970s is summarized and analyzed comprehensively in this paper, including well-known products, main technical parameters, basic features, application status and development trend. The study can provide references for the research work on missile propulsion systems. Lower cost, less fuel and fewer parts will be the future goals. The propfan engines have advantages of nice high subsonic performance and low fuel consumption, and the pulse detonation turbine engines possess high thermodynamic cycle efficiency and simple structure. They are both important development directions of advanced turbine engines for missiles.

Abstract:Actuator rate limiting is the primary course of Aircraft Pilot Coupling (APC) for fly-by-wire (FBW) aircrafts. To avoid APC with minimum cost, the rate limiting boundary determining method is proposed based on the Pilot Vehicle System (PVS) closed-loop stability requirements. The actuator rate limiting is modeled by describing function. The relationships between actuator rate limiting, APC onset frequency and PVS closed-loop stability are analyzed. On the basis of this, an actuator rate limiting boundary determining method is proposed. A Relaxed Static Stability (RSS) aircraft is taken as an example, based on the optimized McRuer pilot model, the longitudinal actuator rate limiting boundary that can ensure the closed-loop stability is determined. The OLOP criterion evaluating results shows that the determined actuator rate limiting boundary coincides with the actuator rate corresponds to OLOP criterion boundary, indicating that the proposed rate limiting boundary determining method is reasonable.

Abstract:Bayesian Network(BN) is a mathematical model based on probabilistic reasoning, which have a great advantages in solving the uncertainties between complex systems. Because of the complexity and uncertainty in air-combat, aiming at the problems in effectiveness evaluation, combined with the air-combat theory and reality. The effectiveness evaluation model of air-combat based on BN is build, the effectiveness evaluation method of air-combat based on BN is given, and simulation analysis is carried out. The results show that the model is valid and accurate, and the method has a strong ability to learn and reasoning.

Abstract:The actuator disk model applied in ducted fan based on self-developed "TRI sonic Platform"(TRIP 3.0) is developed, and the aerodynamic characteristics of BWB analog low-speed aerodynamics configuration with and without ducted fan are analyzed. Firstly, the computational results of thrust and torque of a single propeller are in good agreement with the testing data. Secondly, in order to achieve the designed fan thrust, the key parameters of blade number, mounting angle and rotational speed of a isolated ducted fan are calculated. Finally, applied the key parameters in ducted fan of aircraft, a BWB analog low-speed aerodynamics configuration with and without ducted fan are presented. The results show that pressure coefficients distribution at fuselage and tail had obvious effect with ducted fan compared to without fan. By sucking the forward flow with ducted fan, the flow speed above the fuselage was increased and the angle of attack of horizontal tail was decreased. Therefore, the lift and pitching moment coefficients of fuselage and horizontal tail influenced by with and wihout fan were obvious. Otherwise, in the range of little angle of attack, with the effect of ducted fan, the lift and pitching moment of fuselage is increased and horizontal tail is decreased, but for the entire aircraft, the different of lift and pitching moment coefficients with and without ducted fan is comparatively small.

Abstract:Leading slat configurations can affect the flow features of multi-element airfoil, and also have an impact on the distributions of slat noise sources. Based on LES simulations and FW-H integration equation, together with the typical multi-element airfoil 30P-30N model, the flow characteristics and far field noise features are investigated. Through adjustment of slat configurations, the sensitivity of slat noise radiation to slat position parameters is analyzed. The position parameter features are studied by keeping high aerodynamic performances and effectively attenuating slat noise. The study shows, with fixed slat gap and overlap, slightly decreasing slat deflection angle could effectively reduce slat noise without any compromise with aerodynamic performance. On the condition of fixed deflection angle, decreasing gap width, meanwhile increasing overlaps could suppress slat noise to some degree.

Abstract:The coating for cockpit glass is one of the important ways to realize aircraft stealth technology. In order to study the stealth characteristics of Nb-doped ITO (Indium Tin Oxides) coated glass, the definition of RCS (Radar Cross Section) mean gain is proposed, and when the gain increases, the stealth characteristic is reduced. A series of RCS darkroom tests are carried out for Nb-doped ITO coated glasses with different sheet resistance, and the electromagnetic scattering characteristics with different incident frequencies and polarization modes are analyzed. It’s found that, when the sheet resistance increases, the electromagnetic scattering decreases, and the appropriate sheet resistance (less than 40Ω/m2) is beneficial to realize the shape-stealth of cockpit, and its scattering characteristic is also close to the metal’s, the peak of specular scattering is narrow when the frequency is high.

Abstract:A new test method is proposed about fuselage panels under internal pressure load. “D” jig and “Arch” connectors are utilized to simulate the boundary conditions of fuselage panel subjected to internal pressure load. Test fixture and fuselage panel specimen were designed and manufactured. Tests were conducted based on the proposed method. The test results demonstrated that hoop stress and axial stress about transition area were much more lower than it’s about the test area. Hoop stress ,axial stress and displacement about the test area are consistent with theoretic result. The proposed test settle for engineering precision requirements and provides reference for configuration-selection tests of fuselage panel subjected to internal pressure load.

Abstract:Reducing the weight and increasing the torsion stiffness are the two main pursuits in propeller blade structure design. And the application of composite materials has improved the designability of propeller structure. In this paper we present an optimization process on a composite propeller blade, in which the composite layup numbers and angles are optimization parameters, the strength and bending stiffness are optimization constraints and the weight and torsion stiffness are optimization objectives. Non-dominated Sorting Genetic Algorithm is adopted to get a Pareto front of the two objectives. Results show that the optimization method is effective.

Abstract:In the composite material single lap joint structure, due to the eccentricity of the load, the lateral force is generated in the lap joint, which causes the lateral displacement of the joint and deflects the bolt.The stress distribution of bolt and nut under static load is analyzed in this paper. Results show that eccentric moment in the single lap produces a strong stress in the thread position of the bolt, resulting in the fracture failure of the bolt. And a strong circumferential stress raiseing in the nut, causing the nut to break.The lateral constraints on the laminated plates can effectively reduce the stress amplitude in the bolts and nuts.The calculated results agree with the test failure mode.

Abstract:In order to calculate the contact force of the flight lock mechanism, the function and main design basis of flight lock are firstly introduced in this paper. Then the working principle of the flight lock for a specific civil airplane is illustrated, following with the analysis of its force transmission path. Then three calculation methods (engineering method, rigid multi-body model, and flexible multi-body model) are used to compute the contact force between crank and rocker arm. Finally the three calculation methods are compared and analyzed to find out the reasons of the differences between the contact forces for each methods. The results shows that the arm variation caused by mechanism banking leads to the difference between the forces calculated by engineering method and rigid multi-body model. On the other hand, structure deformation is the main factor that causes the difference between the forces calculated by rigid multi-body model and flexible multi-body model. These analysis results can be consulted for the structural design of civil airplane’s flight lock.

Abstract:A heavy-duty quadrotor UAV which has the features of foldable, light weight, high strength is designed according to the performance requirements. The maximum payload of this UAV is 10kg. The finite element model of the quadrotor structure is established. Static and buckling analysis of the UAV arm and central plate are carried out based on the actual loading cases. The layer structures of the arm and central plate are optimized. The strength, stiffness and stability of the UAV are verified. Compared with the initial layer structures, the weight of the arms drops by 43%, and the weight of the central plate drops by 35%. The weight of the UAV structure drops by 560 grams. The lowest weight requirement is achieved. An UAV static test platform is built, and the structure static loading test is completed. The strain relative error between the test value and the analysis value is less than 15%. The reliability of the UAV finite element model and the optimized layer structures is verified.

Abstract:At present, the research on emergency departure is mostly about the departure track or the departure system.The strength analysis of the emergency door actuator is rarely involved.In order to solve this problem, the fire and explosion emergency gate actuator is taken as the research object.A shock intensity analysis method is proposed, which converts the detonation pressure to the initial impact velocity, simulates by the transient dynamic analysis method, and evaluates product impact strength based on fracture strength of materials.Simulation results show the effectiveness of the proposed method.The results show that the method can be used to analyze the impact strength of the explosive and emergency gate actuator, and has a certain versatility and accuracy.

Abstract:Clamping rods layout optimization method was investigated to solve wall thickness monitoring issue of wax pattern of gas turbine blade in this study. First, the resultant force and moment of ceramic core were obtained based on the simulation results of non-uniform pressure exerting on the ceramic core during injection process. Moreover, the ceramic core shifting with incompletely constrained of clamping rods was computed based rigid dynamic principle. Further, a clamping rods layout optimization model was established to control core shifting. An improved genetic algorithm was proposed to optimize the layout scheme for clamping rods. The experimental results indicated that the proposed method can minimize the shifting of ceramic core.

Abstract:Most of the modern turbojet airplanes are mounted with reversing system, which can promote the economy, availability and safety of airplanes. However, failures of reversing system may have significant effect on airplane and people onboard and on the ground. The design and compliance demonstration of reversing system is also one of the key certification issues that the authority usually focuses on. The applicable airworthiness requirements for reversing system are collected and analyzed, and general design considerations and compliance strategies for reversing system are introduced. Additionally, an example of a specific aircraft reversing system compliance demonstration is introduced to offer effective reference for others.

Abstract:In this paper, according to the characteristics of structural parts, CAPP system is constructed based on manufacturing feature of aeronautical structural parts to improve the production efficiency of aviation structural parts. Six manufacturing features are summed up according to the machining process by researching on classification of common aircraft structural parts. In the VC++6.0 environment, a coding system based on manufacturing feature is designed according to OPITZ standard. The step retrieval algorithm is designed for feature recognition about between target parts and entity library parts. The similarity of features is achieved between the target parts and the physical library parts. Taking the frame parts with 44 slots as an example, 40 Manufacturing features are automatically identified by the algorithm program. The automatic recognition rate is 91%. The result showed the feasibility and correctness of the algorithm in CAPP system.