Abstract:The Co-flow Jet technology, as a new type of integrated flow control technology, has shown potential in lift control,drag Control, and stall control. Due to the relatively short development time, the correlated studies are still under the primary stage,but it has already shown its unique advantages . This paper summarizes the research of existing CFJ technology, discusses the mechanism of this technology and its applications on various aircrafts, and analyzes key technologies which affect the performance of this technology，such as fluid analysis technology, component layout strategy, design of flight control system, aircraft integrated design method.

Abstract:Honeycomb sandwich panels have become more and more widely used in the aerospace field, and the fatigue problems that occur during their application have become increasingly prominent. At present, there is little research on the fatigue of honeycomb sandwich panels, and the test methods used in the study are also very different. Under different test methods, the fatigue process of Nomex honeycomb sandwich panels varies greatly. This article mainly reviews the research progress of the fatigue of honeycomb sandwich panels. The purpose is to compare the fatigue damage process of honeycomb sandwich panels under different test methods and summarize the similarities and differences of the fatigue performance of honeycomb sandwich panels. By introducing the fatigue test method, fatigue damage process, fatigue life prediction method and fatigue life curve of honeycomb sandwich panel, the research direction of the fatigue of honeycomb sandwich panel is proposed.

Abstract:With the consideration of damages in composite bolted joint structures under tensile load, a three dimensional nonlinear model is established by combining the Hashin’s criterion, energy dissipation rate method, Puck’s criterion and continuum damage degradation method, including intra-laminar and inter-laminar damage. Comparing the results of quasi-static tensile test on notched laminate with the numerical simulation results, both of the stress-strain response and final failure mode are consistent, hence the constitutive model is validated. After that, the constitutive model is adopted to analysis tensile failure of the double-lap single-bolt composite joint. The displacement-load curves between numerical simulation and test are in good agreement. Meanwhile, the deviation of ultimate tensile load is no more than 5%, it meets the requirement of engineering application. Furthermore, the overall structural stiffness of composite bolted joint decreases due to the hole edge deformation and damage accumulation, and the ultimate failure mode is bearing failure of the mid-plate.

Abstract:Two parameter fracture criterion is a simple method to predict residual strength. However, some assumptions were taken by the initial derivation process. To provide a more rigorous deduction, two parameter fracture criterion was derived strictly based on Neuber equation. Besides, two parameter fracture criterion was simplified by replacing specimens’ critical crack lengths with initial crack sizes. The residual strengths of M(T) and C(T) were predicted by this simplified method, and the estimated errors are less than 7%. In order to verify the capability of this simplified method to predict the residual strength of complex structures, the residual strengths of three-hole crack tension specimens were predicted, and all of these discrepancies are less than 5%.

Abstract:Runway incursions have become an important factor that threaten the safe operation of aviation. Based on the thoughts of system engineering, main factors causing runway incursion incidents and their associated relationships were analyzed and a runway incursion risk assessment index system is established from three aspects of airports, air traffic control, and airlines; The traditional Analytic Network Process is improved by triangular fuzzy numbers, and a research model for runway incursion risk assessment is established based on this; Through verification, the main factors affecting the runway incursion risk are obtained. The results show that the method is feasible and effective, which can reflect the relationship between risk factors and reduce the influence of subjective judgment on the index weight, and help to develop effective measures to prevent runway incursions.

Abstract:Service bulletin (SB), which is a document issued by the civil aircraft manufacturer for releasing improvement, modification and inspection requirements for delivered products, is an important method for continuous improvement of products and maintain aircraft continued airworthiness in the entire service life cycle. Moreover, SB is the most standardized and widely used customer service document in the civil aviation field, the quality and management efficiency of SB directly represent the capability and quality of customer service that the manufacturer provided. This paper analyzes the domestic civil aircraft manufacturer’s SB production and management system from the regulatory and industry practice perspective, and puts forward the optimization proposal by reference to industry leaders'' experience.

Abstract:In order to improve the flexibility and fatigue resistance of helicopter rotor anti-icing system, the metal mesh braided with nickel alloy filaments is used as heating element, and the heating element is arranged in the blade in an extended way. Through the design, the diameter of wire and the size of mesh were determined. Combining with the existing composite material forming process, the electrical heating test pieces were prepared. The electrothermal performance test, mechanical property test and laboratory simulated deicing test of the prepared heating pad were carried out. The results show that the temperature rising speed of the heating pad is 2℃/s, the temperature uniformity in the plane is less than 2℃, and the simulated deicing effect in the laboratory is good.

Abstract:The frame pitch is related to aircraft overall design and structure design. Now most of the references just give a frame pitch of 20in as an empirical value. This article takes the frame pitch as a parameter, the fuselage strength and stability as constraint and the fuselage weight as objective function to make an analysis of the frame pitch, and give a method that how the frame pitch could be designed. And with that method the 20in have been verified for aircraft of 150 seats. Also this article make an impact analysis of the section parameter of the frame to skin stress by FEA and DOE, and give a feasible region for the section parameter of the frame.

Abstract:The trap panel structure is an important part of the aircraft wing body butt structure. It is located in the front end of the landing gear opening, which is connected with the rear beam, and plays the role of spreading the outer wing load to the fuselage. The study of the force transmission characteristics of the trap panel structure is conducive to the design of a reasonable and effective joint structure. The position of trap panel structure in aircraft is introduced, and how to transfer load is analyzed. It is pointed out that the trap panel structure can improve the stress distribution in the rear girder area of the wing. The situation of trap panel structure for civil aircraft is enumerated and analyzed. The trap panel structure of typical model is described, and the trap panel structure with flexible connection and rigid connection is introduced emphatically. Taking the B model as an example, the force and action of the trap panel structure are analyzed. Finally, the main points of the design of the trap panel structure are summarized.

Abstract:It occur that the loading point changes with the test piece in the aircraft structure test. In particularly, the large deformation of the wing will cause the issue that loading point is not perpendicular with the flat of the wing. In this paper, a kind of servo loading systems is applied in composite materials airplane wing. The wing is divided into N characteristic of flying points by using the method of finite element analysis. To keep all levels of loading points are vertical with the flat of wing we keep the fly points move with loading. It implements vertical following loading. This system is used to complete the highSaspectSratio test. The test results show that the system can realize the test of the UAV by using the servo load systems,and the laoding procedure is smooth. The test piece is no jitter, its deformation is uniform, and the strain data meets the test requirements which can offer a reference for the analogous loading systems and has a large practical significance and application value.

Abstract:The weight reduction design method of a micro turbojet engine compressor is studied numerically in this paper. Firstly, the finite element calculation is carried out on the solid compressor, and the stress and deformation data of the compressor structure under the condition of the design speed are grasped, which is used as the design constraint space for the weight reduction optimization. On this basis, the weight loss optimization design of the solid part of centrifugal compressor disc is carried out with the help of the characteristics of high strength and high stiffness of honeycomb structure. The results show that the weight loss of the compressor can reach 22% under the condition that the equivalent stress of Mises is not increased and the radial displacement of the tip of the blade is not significantly increased compared with the load bearing capacity of the compressor before and after optimization.

Abstract:s：Vertical milling is often adopted in manufacturing of complex curved surfaces such as thin-walled blades used in the air navigation industry. In order to improve the machining efficiency and surface quality. The contact between tool and workpiece was always increased. But the cutter structure parameter is very important for milling stability. The influencing factors in the process of vertical milling cutter was analyzed in this paper. The equation of milling force is established. AdvantEdge FEM software was used for finite element simulation of milling. The milling force, machining deformation, stress and strain are analyzed with the consideration of spiral Angle, diameter and the number of milling cutter blade. The analysis provides a theoretical basis for further study on vibration analysis of line contact milling and tool optimization design.

Abstract:In the current civil aviation chart, the instrument flight chart does not contain ground reference objects, and the visual flight chart contains only the basic terrain profile. Therefore, the general aerial vehicle, which mainly operates by visual rules, urgently needs a low altitude VFR system which can contain the information of no-fly zone, dangerous obstructions, urban settlement and other various surface intelligence information. This paper will briefly introduces the basic framework and basic functions of a low altitude VFR system. This low altitude VFR system is based on the exploitation environment of MyEclipse, and the development language is JAVA. The basic geographic information database、subject geographic information database and file database of data center are managed by SQL Server system. The data center collects the relevant information of each database to provide the data service for the client, and each database regularly updates and perfects the relevant data. Finally, the WebGIS client of the low-altitude visual navigation map information system is developed by using OpenLayer, and the basic data, special data and management data layer are superimposed on the user access interface.

Abstract:In this paper, the theoretical models and influencing factors of fatigue short crack propagation at home and abroad in recent decades are reviewed, the shortcomings of the elastic model of short crack propagation are discussed, the elastic-plastic mechanical parameter j-integral is introduced to describe the stress field at the tip of short crack, and the new research methods are discussed, which combining macroscopic mechanics and the concept of micro-mechanics, analyze the propagation rule of short crack. In view of the special non-propagation crack in the short crack stage, the causes of the crack are discussed, and the difference between the fatigue strength reduction coefficient Kf and the theoretical stress concentration coefficient Kt is explained. The influence of the geometry, notch plastic zone, microstructure and test environment on the short crack propagation is introduced. At last, the author further confirmed the unique "V" type propagation law of short crack by studying the propagation law of main crack and secondary crack in the experiment, and tried to explain the non-propagation crack behavior of short crack by observing the whole process of crack propagation and using the change of crack tip stress field.

Abstract:In order to simulate the grain evolution of superalloy at different heat treatment temperatures, the phase field model was improved by introduced the Arrhenius relationship, in order to describe the quantitative relationship between the grain boundary movement and temperature. Based on the improved phase field model and fitted model parameters, the grain average size and morphology evolution of superalloy FGH96 during the longer heat treatment process were simulated, and the simulated results were compared with the experimental results. The results show, the calculated data coincide with the experiment data, the evolution law of grain is consistent with the experimental observation and theoretical analysis. These results prove that the grain boundary mobility M in the Arrhenius relationship is suitable for simulating the heat treatment process at the corresponding temperature. At the same time, the feasibility of the improved method and accuracy of the fitted parameters of the phase-field model are verified.

Abstract:System parameter identification can be divided into two research directions: time-invariant system parameter identification and time-varying system parameter identification. The research on time-invariant system parameter identification has become mature, while the research on time-varying system parameter identification is still in its infancy. For multi-degree-of-freedom time-varying structures, a method for parameter identification based on time frequency slice decomposition is proposed in this paper. The first step of this method is to collect the displacement response of the structure, and then obtains the time-frequency energy distribution of the response in the whole time-frequency band. According to the time-frequency distribution characteristics of the structure, multiple time-frequency window signals are sliced out, and the inverse transform of FSWT is performed to reconstruct the signals in time domain. The reconstructed signal corresponds to each order modal displacement response signal of the structure. The instantaneous frequency of the signal is extracted by Hilbert transform, and the modal frequencies of each order of the structure are identified. According to a simulation experiment of the three-degree-of-freedom mass spring damping system, the method is proved to have good identification accuracy and practical engineering value.

Abstract:In order to study the properties of stiffened composite panels (T300/BA9913) which were intended to use for a type of UAV, it carried out the impact damage. The primary details is : Impact in the middle of the wall plate and the joint of rib and wall plate, the impact energy is 6.67 J/mm, measuring the impact indentation depth and delamination damage area.; This paper applies the commercial software ABAQUS and writes the corresponding VUMAT subroutine to simulate the impact damage. The strain-based 3D Hashin criterion was applied to the damage criterion of composite single-layer panels by using the suitable material model, the type of unit and the contact with different attributes in the software. The comparison of stiffness reduction of materials based on continuous stiffness degradation principle of fracture toughness and impact test data verified the validity and accuracy of the established impact model.

Abstract:with the continuous progress of the vibration test technology, the vibration fatigue test has a good test basis and can carry out the vibration fatigue simulation test under various environment. The current method can not meet the needs of the deep study of the vibration fatigue test. In this paper, the method of synchronous measurement of vibration fatigue of aluminum alloy is put forward. At the same time, the vibration fatigue specimens of aluminum alloy under different accelerations are measured by infrared monitoring technology, acoustic emission technology, microtest technique and strain testing technology. The changes of various measurement parameters with the damage are studied. Some new vibration fatigue of aluminum alloy was found and the conclusions are obtained..

Abstract:To realize the aircraft maneuvering turn during ground operations,the aircraft’ s nosewheel control systemshouldprovidetherateofnosewheeldeflectionashigheraspossible.To prevent the aircraft’ s wheel fromlateralslipthedeflectionrateshouldbelimitedinacertainrange.Take a certain type of aircraft as anex- ample,theeffectoflateralslipunderthelargenosewheeldeflection,thefrictioncoefficientontheground,the aircrafttaxiingspeedandtherateofnosewheeldeflectionareanalyzed.Resultsshowthattheaircraftmakes largenosewheeldeflectionattherateof0.3~0.4rad/s,itcanbasicallymeetthegroundstabilityrequirements, buttoreducetheriskoflateralsliponthelowfrictionpavement,the rate of nose wheel deflection needs to be re- ducedwhenthenosewheeldeflectstoalargeangle.