Abstract:In this paper, several concepts of structural health monitoring and their applications are introduced. The requirements of structural health monitoring are discussed, and the typical engineering cases of aircraft structural health monitoring technology are analyzed with the examples of F-35 and A400M. Then, the individual aircraft tracking and life control of typical aircraft, the load spectrum survey and life prediction of an aging aircraft are given, and the research on damage monitoring method and the main limitation of its application are discussed. The main idea of aircraft structural health monitoring system design and basic flow of life prediction are put forward, and main tasks of structural health monitoring including selection of control points and flight parameters, construction of load/ strain equation, calculation of damage and fatigue life, results output and verification of the equation are also introduced . Finally, the future research of aircraft structural health monitoring is prospected.

Abstract:With the acceleration of propeller engine installation system’s localization, relevant technical research must be carried out and dynamic design is an important part of which. This paper firstly compares and analyzes the dynamic performance characteristics of installation systems with different structures. Summarized the technical requirements of the installation system dynamic designing proceeding from the military and civilian standards and engineering practics experience.The development history and current situation at home and abroad of the installationsystem dynamics design technology are reviewed.It is pointed that the gap is mainly reflected in the design concept ,key technology and practical experience of application etc.On this basis,the development trend of the dynamic design of the propeller engine mounting system is prospected. This paper provided a reference for current and future research on the design technology of propeller engine installation system.

Abstract:This paper proposes a novel application of topology optimization method for designing replacement of the damaged part for emergency support and rush-repair based on additive manufacturing. The cooling fan of an airplane is investigated as an example. Based on the analysis of the service environment and rush-repair requirement, the replacement part of the damaged cooling fan should be designed for additive manufacturing using alternative to the materials of the original part. Meanwhile, the weight and the moment of inertia of the replacement part should be kept as equal as possible to those of the original part. Accordingly， the topology optimization formulation is established to minimize the overall structural compliance under the interval constraints of the weight and the moment of inertia of the whole structure. Sensitivity analysis is carried out consider the design-dependent effects of the centrifugal forces. According to the topology optimization result and the analysis data of the re-modelled structure, the obtained replacement part meets the requirements of performances and additive manufacturing process. Finally, the replacement part is successfully printed using Selective Laser Melting, demonstrating the proposed method is effective for additive manufacturing.

Abstract:Flying wing is a preferred configuration for unmanned combat air vehicle (UCAV), in which its airframe is highly integrated with intake and exhaust of propulsion system. To implement rapid geometric model of flying wing UCAV concept, this paper proposes a parametric geometry modeling method for flying wing UCAV configuration integrated with the intake and exhaust. Firstly, parametric models for configuration of the flying wing airframe and the intake and exhaust are established using class function/shape function. Then, the related geometry parameters between the flying wing airframe and the intake and exhaust are identified, and the correlative control rules are set to match airframe-propulsion interactions. 3D geometric models of the flying wing UCAV configuration are automatically generated by use of the parametric geometry model and CATIA API. Application examples indicate that flying wing UCAV configurations can automatically adjust its shape to match the different intake and exhaust concepts by use of the proposed method. The method can effectively improve efficiency for flying wing UCAV conceptual design.

Abstract:The abatement of sonic boom noise level is a decisive issue for supersonic transport of next generation. The low sonic boom optimization always make the configuration to a trend of higher swept and longer distribution of the wing along the fuselage, which is unfavorable to the trim and low speed characteristics. A civil supersonic transport was researched in this paper. A parametric geometry representation method based on class function/shape function transformation(CST) was developed to describe the wing body configuration. The effects of geometry parameters on sonic boom was analyzed by supersonic linearized theory. Based on the above work, the low sonic boom and pitch moment characteristics optimization were taken for the fuselage, wing planform and twists separately and the optimal result was validated by CFD. The numerical simulation results show that compared with the basic configuration, the drag decrease 19 cts (unit of drag coefficient) and the over pressure at near-field is abated obviously without the distinct increase of pitch moment, which bring 5.1 PLdB reduction of loudness on the ground.

Abstract:Complex engineering systems such as aircraft are usually affected by uncertain factors, such as material performance degradation and time-varying loads during operation. When solving complex time-variant reliability analysis (TRA) problems, the developed methods usually cost a lot. In order to improve the efficiency of solving complex TRA problems, based on the approximating most-probable-points trajectory (AMPPT) method, the efficient approximating the most-probable-point trajectory (EAMPPT) method for TRA is proposed. According to the characteristics that the reliability of weakest part of the system determines the reliability of the system, EAMPPT takes full account of prediction values and their errors in the process of approximating the most-probable-point trajectory. A mathematical example demonstrates the effectiveness of the adaptive sampling method. EAMPPT is applied to solve TRA problems involving hydrokinetic turbine blades and the wing of the reusable aerospace during reenter. The results show that the calculation accuracy of the proposed EAMPPT and time-discretization based TRA (TDTRA) method is similar, but the number of performance function evaluations of EAMPPT is less than 3% of TDTRA.

Abstract:The QAR(Quick Access Recorder) data can reflect the aircraft status and most of the flight operation process, so it can be used to analyze the risk of runway excursion events. Therefore, based on the QAR data, the risk analysis for runway excursion is performed. The QAR data is divided into three categories: flight status, operation instructions and information, so as to analyze the status of the aircraft in the three stages of take-off run, landing and landing run. Through the operating characteristics reflected by the QAR data, combined with the SOP (standard operating procedures), the operations that exceed the normal data and do not conform to the standard operations can be deduced, and the risk factors affecting the normal flight are obtained. Based on the 2-4 model of behavior safety, the risk assessment index system of runway excursion can be established. Based on the causative mechanism of an accident, focusing on the analysis of operational characteristics and human factors, the risk prevention and control measures for overshoot runway excursion are proposed. The results show that, through the analysis of flight data and flight operation characteristics, the countermeasures and suggestions are put forward for runway excursion, which can effectively improve the safety of operation for flight. And theoretical basis for improving the safe operation of runway excursion is provided.

Abstract:Rotating nozzle profile enables the supersonic variable Mach number wind tunnel to continuously adjust the Mach number of the experimental area during a single operation, which is important for studying the aerodynamic problems in the maneuvering process of the aircraft and the starting process of the inlet. In the process of controlling the nozzle profile rotation, whether the flow field parameters can change linearly is an important criterion to measure the performance of supersonic variable Mach number wind tunnel. Therefore, this paper analyzes the linear variation law of flow field parameters in the experimental area of variable Mach number wind tunnel, and a numerical simulation model is established using the spring smoothing dynamic grid technique to verify whether the flow field parameters in the experimental area meet the linear variation law when the nozzle is located at the corresponding position of Mach number 3.041~3.215. The results show that the linear change of the flow field parameters in the wind tunnel experimental area is achieved by controlling the rotation of the nozzle profile, and the dynamic calculation results are in good agreement with the expected linear change law of the flow field parameters in the experimental area. In the linear change process of flow field parameters with different accelerations, the deviation between the average parameters of the experimental area and the expected parameters at each time is less than 0.13%.

Abstract:Aero-engine turbine rear casing is an important load-bearing component of aero-engine. Due to its complex working conditions, multiple uncertain factors, it is a key component for aero-engine safety. In order to explore the influence of the uncertainty of input random variables on the failure probability of a turbine rear casing structure, a parametric finite element model was established for the deterministic analysis of the aero-engine intermediate casing. Considering the uncertainty of material properties, geometric parameters and external loads of the aero-engine intermediate casing, limit state functions are constructed for the two most typical failure modes: static strength and stiffness failures. By constructing an adaptive Kriging surrogate model for two failure modes and combining importance sampling method, the failure probability of the intermediate casing structure was predicted. And the uncertainty source of the reliability of the turbine rear casing structure was analyzed by a global sensitivity analysis method based on failure probability. And the importance order of all input random variables was identified, which provides guidance for the reliability design of the turbine rear casing structure.

Abstract:The safety of civil aircraft design is mainly guaranteed by the combination of finite element (FEM) analysis and experiment, the FEM analysis is an supplement to the experiment, while the experiment is a demonstration to the FEM analysis. Based on the principle of equivalent stiffness, the FEM modeling of beam structures in civil aircraft design are usually simplified to the combination of rod elements and shear plane elements, which ensures the stiffness of the FEM cross-section almost equal to the designed section, however the area of the two sections are not equivalent, thus the FEM results can not accurately reflect the stress in critical positions. To address the deficiencies in the existing method, a new method in which the height of the FEM cross-section is modified to realize stiffness equivalence is proposed in this article, the computation results of the traditional method and the proposed method are compared to analytical results, which demonstrates the accuracy of the proposed method.

Abstract:Aiming at the problems of inaccurate crack segmentation and difficult detection under complex background in the process of aircraft structure X-ray image evaluation, an intelligent evaluation model ELAN-Seg for X-ray crack images of aircraft structures is proposed based on efficient layer aggregation network. The backbone network of the model is stacked by the efficient layer aggregation network. The low-level and high-level features extracted from the backbone network are enhanced by using SPPCSPC spatial pyramid and ASPP spatial pyramid respectively, so as to realize multi-level and multi-scale feature extraction of input features. The attention mechanism is embedded after the enhanced feature extraction, and the low-level and high-level features after the enhanced feature extraction are fused, so as to realize the intelligent segmentation of the crack area of the X-ray image. The model was verified by X-ray images obtained from aircraft strength test and field operation process, and the crack leakage rate was less than 3.8%, indicating that the method has engineering applicability.

Abstract:Abstract: The takeoff and landing control algorithm of rocket assisted UAV is studied in order to innovate a short takeoff and landing method for large high subsonic UAV. In the research process, the control strategy of rocket assisted UAV during takeoff and landing is designed; The mathematical models of UAV aerodynamic force, booster rocket force, engine thrust and control law are established; The dynamic equation of UAV takeoff and landing process is constructed; A control algorithm based on PID control is designed to control the take-off and landing process of the target UAV safely and stably under various interference environments. MATLAB software is used for programming and simulation. The simulation results show that the designed control algorithm and control rate meet the control requirements of the takeoff and landing process of the target UAV.

Abstract:When designing the retractable landing gear of aircraft oil-gas mixed type, the medium flow characteristics between the inner cavities should be fully considered, and the damping aperture and fuel filling amount of a certain UAV landing gear buffer should be taken as the research object, and the single factor experimental method was used to analyze the changes of gas-liquid flow inside the buffer caused by each factor, and the gas-liquid characteristics of the buffer under different damping apertures and oil filling amounts in the lowering stage were simulated and calculated by Fluent software, and the results showed that the damping hole oil flow during the landing gear lowering process is only related to the size of the pore size, not affected by the oil filling amount of the buffer, the damping hole flow rate in the buffer is not related to the liquid level height of the upper cavity of the buffer during the buffer is lowered, the smaller the damping pore diameter, the smaller the flow rate, but the oil filling time is affected by the oil filling amount and pore size, the more oil filling, the less oil required for the lower cavity of the buffer, the shorter the gas-liquid filling time. Under the 637ml oil filling required by this type of UAV, the buffer oil filling time under the 6mm aperture has reached 131s, which exceeded the 2 minutes required for the completion of gas-liquid filling of the buffer cavity of the landing gear of this model, which affects the landing gear buffer performance of the aircraft landing stage, so for the landing gear of this model, the buffer damping aperture should be greater than 6mm. For other types of landing gear buffers, when the oil filling amount is determined, the gas-liquid filling of the buffer that meets the drop stage should be used as one of the buffer damping hole design criteria.

Abstract:Ram air turbine (RAT) system is the emergency power generation system of the aircraft. It supplies power to the aircraft after the aircraft loses the main AC power. RAT is stowed in the RAT bay in the non air tight area normally and deployed into the air flow under emergency conditions. The temperature of the RAT bay determines the deploy time of the RAT, thus affecting the safety of the aircraft under emergency conditions. The temperature prediction of the RAT bay is of significant for the safety under emergency condition. In this paper, the RAT bay temperature, altitude, atmospheric static temperature, flight speed, and cabin temperatures around the RAT bay are analyzed as a whole through the Proper Orthogonal Decomposition (POD), and the RAT bay temperature is predicted under specific working conditions through RAT bay temperature model and the mapping relationship between the simplified model and the complete model. This paper selects the test data as the sample data, and uses POD method to predict the temperature of the RAT bay. According to the prediction results, the energy distribution of the first order mode exceeds 99% of energy of all modes. After data normalization, the absolute average error of the prediction results could reach 0.063 as the minimum, and the variance could reach 0.07 as the minimum; furthermore, the resuls show that the better the prediction effect could be achieved with more samples.

Abstract:As aircraft systems become increasingly highly integrated and automated, pilots are often ill-prepared to cope with an actual emergency or failure, and their corrective actions may be erroneous, delayed or incomplete. Therefore, there is an urgent need to consider flight crew human factors in system safety assessment. By analyzing the requirements of CCAR25.1309(b)(c) and failure processing process of flight crew, based on the failure conditions in functional hazard assessment, the method of requirements capture and analysis of flight crew human factors is proposed. By applying these methods in the aircraft development, top down design for safety which from failure condition to alert and procedures is achieved, and a complete chain of compliance evidence for human factor of safety is established, to demonstrate compliance with CCAR25.1309(b)(c).

Abstract:In order to enhance the human appliance interaction and improve the overall operation of the aircraft, the development process of the aircraft cockpit is summarized. It is clear that the smart development of the aircraft cockpit is inevitable, explores the differences between intelligent and wisdom, and puts forward the concept and design of the smart cockpit. Depth perception and immersion of the interaction, the category of cognitive, openness and personalized customization services of the smart cockpit design elements are put forward. And put forward the development of smart cockpit urgently need to solve the four key technologies: multidimensional depth information acoustic perfume and fusion technology,advanced information display technology, immigration natural interaction technology, intelligent situation cognitive technology and multi-integral independent adaptability technology. The study has a new thinking about the design of the smart cockpit.

Abstract:With the development of civil aviation transportation, the whole transportation network needs to improve operational efficiency, especially the airport, which plays an important role in the civil aviation transportation network. The re-search results and engineering applications have shown that airport collaborative decision making can effectively improve the operational efficiency of airports. This paper compiles the development history of collaborative decision making in airports and the current situation of research and application of collaborative decision making in academ-ia and industry, both in China and worldwide; analyzes and discusses the future development trend of collaborative decision making in airports and the challenges faced by collaborative decision making in the current period; at the same time, gives some suggestions for the development of collaborative decision making in airports based on the actual situation in China, and provides theoretical support and basis for improving the operational efficiency and economic benefits of airports and the whole air transportation network. Theoretical support and basis are given to improve airports" operational and economic efficiency and the whole air traffic network.

Abstract:As a common deicing system for turboprop aircraft, it is of great significance to evaluate the influence of deicing airbag on the aerodynamic characteristics of the aircraft. Based on the aerodynamic deicing system installed on one aircraft, simulating the aerodynamic characteristics when the deicing airbag working by using the CFD method, and analyzing the influence of the simplified deicing airbag model on the calculation results. The results suggest that: with the height of the deicing airbag increases, the effect on the aerodynamic characteristics of the aircraft becomes more obviously, the stalling angle advanced by about 10 degrees, the maximum lift coefficient lost nearly 60%, and the maximum lift-to-drag ratio decreased by about 2.9. Influenced by the expansion of the deicing airbag, a flow along the wingspan appears in the leading edge, and the length of separation zone is the same as the deicing airbag. The pressure distribution at leading edge is oscillating because of the expanded deicing airbag, so the whole airfoil’s pressure distribution is further affected. Besides, with the height of the simplified deicing airbag increases, the stalling angle advanced by about 1 degree, the maximum lift coefficient lost nearly 21%, and the maximum lift-to-drag ratio decreased by about 2.2. All results above show that the aerodynamic performance of the aircraft in flying tests is decreased due to the different working conditions of the deicing air bag.

Abstract:The process from test starting to supersonic flow state established in an outlet-opening wind tunnel, i.e. the starting problem of supersonic flow, has become a recognized challenge. The aim is to establish feasible flow field starting method, laying the foundation for the use of outlet-opening wind tunnel. Three-dimensional numerical research on starting problem of supersonic compressor cascade was carried out in the supersonic wind tunnel at Shenyang Engine Research Institute. The failure reason of supersonic flow field starting on experimental condition was analyzed, three flow field starting schemes were established. The results show that: The starting failure reason is the formation of a strong normal shock wave at the leading edge of the cascade. Increasing the inlet total pressure alone cannot establish the supersonic flow; The supersonic cascade flow field can be started by increasing the overflow gap width on lower wall side, but the number of effective cascade passages decreases and the boundary layer thickness increases; Maintaining the width of overflow gap on the upper and lower walls at more than 1.0 pitch, setting upper and lower supersonic walls in front of cascade and conducting suction can effectively start the supersonic flow field. The maximum fluctuation of outlet Mach number is 0.01, the maximum fluctuation of outlet flow angle is 0.09°. The periodicity can meet the experimental requirements.

Abstract:With the gradual maturity and application of digital assembly technology, the interchangeability design, which adapts to digital quantity transfer, has significant practical significance for improving the efficiency of large aircraft control surface design, stabilizing assembly quality and reducing maintenance cost. Taking the interchangeability design of a certain type of aircraft control surface as the research object, according to the requirements of the con-trol surface interchangeability, the paper analyses the design points, and establish the interchangeability design process coordinated with digital assembly. The structural elements of the interchangeability design are analyzed from the configuration characteristics of the control surface. The technical approach to realize the interchangeabil-ity of the control surface is proposed, and the corresponding reference indexes are given. Combined with the test method of aircraft interchangeability, the aileron of a certain type of aircraft is taken as an example to analyze and design the interchangeability of the control surface, which is verified by the actual assembly inspection.

Abstract:In order to improve the efficiency and reliability of the graphite heating element, this paper investigates the failure process of graphite heating device, and determines the reliability quantitative index of heating element, temperature uniformity; four circuit parameters to quantify the output performance was advanced, the thickness, the width of the strip, the gap between the strips, and the radius of the gap rounding. The mechanism of influence of cir-cuit parameters on heating capability and reliability was investigated through coupled thermal electric finite element method analysis. The results show that the thickness determine the heat output capability, while the remaining three circuit parameters determine the reliability. The advancements in this paper play an important role in the development of high performance graphite heating device.

Abstract:Target tracking is the basic function of airborne ADS-B surveillance applications. Improving the target tracking performance of weak maneuvering airliner around the aircraft is of great significance for mastering the traffic situation and improving flight safety. Therefore, a target tracking method for ADS-B surveillance application based on interactive multiple model Kalman filter (IMMKF) algorithm is proposed. Firstly, aiming at the flight characteristics of airliner under the background of weak maneuver, a set of motion models including constant velocity model and standard coordinated turning model is established, and the models are linearized and approximated; Then, the model prediction and ADS-B state vector measurement data are used as the input of multiple parallel Kalman filters in IMMKF algorithm for parallel filtering; Finally, the estimation of the target state vector and the model approximation probability are calculated and used as input for the next iteration. The simulation results show that compared with the Kalman filter target tracking method based on the constant velocity model, the position tracking error of IMMKF method is reduced by 59%, and the velocity tracking error is reduced by 77%, which significantly improves the state estimation performance, and has high tracking accuracy, robustness and computational efficiency. It has practical application value and reference significance in ADS-B surveillance applications.