Governed by: Ministry of Industry and Information Technology of the People's Republic of China
Sponsored by: Northwestern Polytechnical University  Chinese Society Aeronautics and Astronautics
Address: Aviation Building,Youyi Campus, Northwestern Polytechnical University
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    2024,15(3):1-12,26. DOI: 10.16615/j.cnki.1674-8190.2024.03.01
    Abstract:
    Morphing aircraft can change its aerodynamic configurations to obtain optimized aerodynamic performance. Smart material actuator and flexible skin are the key technologies of morphing aircraft. The research of actuators made of shape memory alloys, piezoelectric materials and magnetostrictive materials is introduced. The development of flexible skin based on material elasticity and structure design is analyzed. The related research issue and interests are summarized and prospected.
    2024,15(3):13-26. DOI: 10.16615/j.cnki.1674-8190.2024.03.02
    Abstract:
    With the widespread application of ceramic matrix composites in hot end components of advanced aero-engines, it becomes particularly important to conduct efficient and accurate nondestructive characterization of defects/damages formed during the whole life cycle. Due to the complex preparation and forming process of ceramic matrix composites and the high heterogeneity and anisotropy caused by multiphase composite, the traditional nondestructive testing technology based on the assumption of global homogenization faces many challenges. Based on the application of ceramic matrix composites in aero-engine field, the typical defect/damage types and characteristics in the whole life cycle of ceramic matrix composites were analyzed. The research progress and application of nondestructive characterization techniques of ceramic matrix composites in recent years were reviewed, the main challenges faced by existing nondestructive characterization techniques were summarized, and the future development trend was prospected.
    2024,15(3):27-44. DOI: 10.16615/j.cnki.1674-8190.2024.03.03
    Abstract:
    The aircraft power supply system is the power source of all electrical equipment on board, thus its safety and reliability are pretty important. Against the backdrop of environmental protection and high-efficiency development needs, research and application of more/all electric aircraft technology with electric power as the core is advanced. The widespread use of electric drive devices and power electronic devices has led to the complexity of aircraft power supply system structure, which puts forward higher requirements for aircraft reliability, safety, testability and maintainability, so that researches on fault diagnosis technology for aircraft power supply systems are of great significance. This paper firstly introduced the composition structure and respective functions of aircraft power supply system. Secondly, the development process of aircraft power supply system was outlined. Thirdly, the characteristics of typical domestic and foreign power supply systems were compared. Fourthly, the main failure modes, fault characteristics and failure causes of aircraft power supply system were summarized, and a design architecture of aircraft power health management system was proposed. Fifthly, the research progress of fault diagnosis methods based on model and data were reviewed, then, the characteristics of various diagnostic methods were evaluated from aspects such as accuracy, data demand, applicability and implementation difficulty. Finally, this paper gave the challenges and development trends of fault diagnosis technology for aircraft power supply system.
    2024,15(3):45-51,70. DOI: 10.16615/j.cnki.1674-8190.2024.03.04
    Abstract:
    The classic sled-type landing gear makes it challenging to take off and land in challenging terrain, with the widespread usage of rotorcraft UAVs in both civil and military domains. This research develops a two-stage buffered adaptive landing gear that is similar to a human leg in order to increase the landing area and application range of rotorcraft UAVs. An adaptive landing gear attitude adjustment strategy was proposed after researching the positive and negative kinematics of the bionic leg. A bionic quadruped hexacopter UAV landing dynamics model was established, landing dynamics simulation was carried out using the multi-body dynamics software simcenter 3D, and a comparison of landing performance with the conventional sled landing gear was carried out. The research demonstrates that the two-stage cushioned adaptive landing gear in the landing leg style and its attitude adjustment strategy can reduce roll angle by 95.69% and overload coefficient by 34.06%, proving that the two-stage cushion adaptive landing gear has excellent shock absorption and cushioning capability in the face of complex terrain.
    2024,15(3):52-61. DOI: 10.16615/j.cnki.1674-8190.2024.03.05
    Abstract:
    In aerospace engineering, it is important to study the influence of wet and thermal environment on the interlayer fracture toughness of resin matrix composites. In this paper, the microstructure of type I and type II interlayer fracture toughness experiments under different wet and thermal conditions were analyzed, and the effect of wet and thermal environment on the interlayer fracture toughness of resin matrix composites was obtained. The research results indicate that the humid and hot environment has a completely opposite effect on the interlayer fracture toughness of type I and type II resin composite materials. As the temperature increases, the interlayer fracture toughness of type I resin composite laminates shows an upward trend, while the interlayer fracture toughness of type II resin composite laminates shows a downward trend. During Type I delamination, a large number of fiber bridging phenomena occur. In humid and hot environments, the resin softens and fiber bridging phenomena increase, leading to an increase in Type I interlayer fracture toughness with increasing temperature; In a humid and hot environment, as the temperature increases, the shear strength of the resin gradually decreases, and the interfacial shear strength between the resin and fibers also gradually decreases, resulting in a decrease in type II interlayer fracture toughness with increasing temperature.
    2024,15(3):62-70. DOI: 10.16615/j.cnki.1674-8190.2024.03.06
    Abstract:
    Fault prediction technology has important application value in ensuring the reliable operation of instrument landing system and improving ATC effectiveness. Combining the operation characteristics of instrument landing system and actual operation and maintenance work, a fault prediction method of instrument landing system based on GRU is proposed. Taking heading beacons as the research object, the monitoring parameters are used as fault characteristic parameters after analyzing the relationship between their monitoring parameters and equipment operation status. Then, the GRU algorithm is used to predict the future change trend of the monitoring parameters according to their time step and significant time-varying characteristics. Finally, the probability of "failure" is calculated according to the subordinate function of the monitoring parameters, and the prediction of heading beacon failure is realized. The relative prediction accuracy of the GRU prediction model is over 95% after two years of training with the monitoring parameter data. By comparing the prediction of heading beacon failure data and normal operation data, the validity of the monitoring parameters as failure characteristics to characterize the operation of the heading beacon and the effectiveness of the GRU-based failure prediction method are verified.
    2024,15(3):71-80. DOI: 10.16615/j.cnki.1674-8190.2024.03.07
    Abstract:
    Practice has shown that big data technology can empower the management process. As an important project in the complex high-end program of commercial aircraft development, the commercial aircraft MOC9 test project will generate a large amount of project management data during development. Therefore, it is necessary to study how to use big data technology to promote such projects to achieve project objectives. Based on the characteristics of the MOC9 test project under the commercial aircraft development program and its demand for big data management, this article conducts study on the MOC9 test project from multiple aspects such as architecture planning, data acquisition and storage, data cleaning and processing, analysis mining, and visual display, combined with big data technology processing processes and methods. The study results show that establishing a quantitative visual model for MOC9 projects through big data technology is very helpful for project managers to master the overall situation of the project, locate the root causes of problems, and identify potential risks of the project.
    2024,15(3):81-89. DOI: 10.16615/j.cnki.1674-8190.2024.03.08
    Abstract:
    The long landing distance from 50 ft to touchdown is an over-limit event frequently occurring during the landing phase and also significantly increase the risk of landing accidents. The study on the impacts of geographical environmental factors of the over-limit event can provide references for airport site selection and flight quality evaluation. Based on the flight QAR (Quick Access Record) data, topographic data and climate data of the airports, global and local correlation analysis were adopted to identify the main factors influencing the over-limit event. The regression model between the event frequency and elevation, fluctuation, air temperature was established, based on the geographical weighted regression model. According to the regression coefficients, the impact modes of these factors were divided into five categories using K-means method, so as to explore the spatial pattern and mechanism of geographical environmental factors on the over-limit event. The results show that elevation, fluctuation, air pressure and air temperature have a significant impact on the frequency of the "long landing distance" over-limit event. There is an obvious spatial differentiation of the impact of geographical environment factors. The spatial distribution of airports under the same impact mode shows clustering.
    2024,15(3):90-100. DOI: 10.16615/j.cnki.1674-8190.2024.03.09
    Abstract:
    A quality risk identification and assessment method for aircraft manufacturing and maintenance based on FMEA is applied to analyze the potential failure modes and their causes of aircraft in manufacturing and maintenance, evaluate these failure modes, and formulate recommended measures for important failure modes to reduce or avoid the occurrence of failures. This paper presents a set of mapping rules for the application of DFMEA analysis results in risk identification and assessment of manufacturing and maintenance quality. The analysis scope is extended from the design end to the use and maintenance of aircraft. Through the combination of the above methods and measures, the technology realizes the analysis and evaluation of the potential failure mode, failure cause, Severity, recommended measure effect, measure coverage and repeatability in the manufacturing and maintenance process starting from the design stage, which can more scientifically and comprehensively analyze, evaluate and deal with the quality risk of aircraft manufacturing and maintenance.
    2024,15(3):101-109,142. DOI: 10.16615/j.cnki.1674-8190.2024.03.10
    Abstract:
    The configuration management of civil aircraft brake control system plays a key role in the process of system design and development and airworthiness compliance verification. In order to improve the configuration management capability of civil aircraft brake system, the software designed and developed can meet the airworthiness requirements, this paper introduces the concept and method of brake system control software configuration management, and illustrates how to combine configuration management with software design by means of system thinking and information flow to carry out whole-life-cycle configuration management. By combining with the requirements of DO-178C, configuration data digital management mechanism based on product configuration is established, unique data source of brake control system development is created. The result shows that a unified configuration database is established with configuration baseline management combination in which the information and status are accurately recorded strictly to ensure the real-time, traceability, integrity and effectiveness of status information, and achieve the final configuration control goal to meet the airworthiness requirements.
    2024,15(3):110-119. DOI: 10.16615/j.cnki.1674-8190.2024.03.11
    Abstract:
    The landing-gear retracting and releasing system and braking system of UAV plays a crucial role in the process of takeoff, landing, and braking of UAVs. Electrostatic hydraulic systems not only retain the advantages of traditional hydraulic systems, but also have the advantages of electric actuation. According to the working principle of the electro-hydrostatic actuator, an electro-hydrostatic system integrating the landing-gear retracting and releasing and braking functions of unmanned aerial vehicles is designed. The improved PID control method is applied to the landing-gear retracting and releasing function, and two fuzzy PID control methods are designed to apply to the anti-skid braking function. On this basis, a co-simulation based on AMESim and MATLAB/Simulink is conducted to verify the system performance, Finally, the simulation results are compared and analyzed. The results show that the designed control method can normally complete the landing-gear retracting and releasing and braking of unmanned aerial vehicles, and the control effect is good.
    2024,15(3):120-134. DOI: 10.16615/j.cnki.1674-8190.2024.03.12
    Abstract:
    The integral inertial particle separator is a helicopter air inlet protection device. It has excellent performance and wide application compared with other protection devices, which is of great significance to ensure the regular operation and improve the service life of helicopter engines. This paper summarizes the research progress of integral inertial particle separators, including the following aspects: 1) The classification and aerodynamic parameters of the integral inertial particle separators are introduced. 2)The research methods and their results of the integral inertial particle separators are sorted out. 3)The factors affecting the performance of the integral inertial particle separators are summarized and analyzed. 4)The future development of integral inertial particle separators is predicted. This paper can be the reference for future study and the guide to integral inertial particle separators’ optimization design.
    2024,15(3):135-142. DOI: 10.16615/j.cnki.1674-8190.2024.03.13
    Abstract:
    With the increase of service time, the maintenance quality of old helicopters has brought more challenges. This article introduces the application of aviation non-destructive testing in the field of aviation maintenance and the characteristics and maintenance status of old helicopters, We explores and determines the key parts and key components of non-destructive testing for old helicopters based on the structural characteristics and usage of helicopters, elaborates on the specific application methods for testing key parts of helicopters based on the characteristics of different non-destructive testing technologies, and studies the timing of using non-destructive testing technology in the maintenance practice of old helicopters. Finally, we have made prospects for the application of non-destructive testing technology in the maintenance of old helicopters.
    2024,15(3):143-150. DOI: 10.16615/j.cnki.1674-8190.2024.03.14
    Abstract:
    To reduce the probability of helicopters being discovered during mission execution, based on the geometric optics method and consistent diffraction theory, the effects of different tail rotor airfoil thickness, curvature, and scissor angle of tail rotor on RCS were studied for the helicopter tail rotor. Using radar to irradiate the tail rotor from the ground and radar to irradiate the tail rotor from the rear of the helicopter, the RCS of the tail rotor is analyzed using two different irradiation radar orientations. By comparing the RCS peak and mean values of different parameters of the tail rotor, the more favorable conditions for the stealth of the helicopter tail rotor are determined. When illuminating the tail rotor from the ground, the RCS with small thickness and curvature of the tail rotor will be smaller, and changes in the angle of the scissors will cause changes in the peak phase of the RCS. When the radar illuminates the tail rotor from the rear, the RCS of the tail rotor with smaller thickness is smaller, while the RCS peak of the tail rotor with larger curvature is smaller. Based on comprehensive analysis, the smaller the thickness and curvature of the tail rotor, the more favorable it is to reduce the RCS of the helicopter tail rotor.
    2024,15(3):151-156,190. DOI: 10.16615/j.cnki.1674-8190.2024.03.15
    Abstract:
    The widespread application of composite materials in blades also makes the force and stiffness characteristics of blades more complex than traditional blades. In order to reduce the dynamic stress and vibration level of rotor blades, it is necessary to analyze the dynamic characteristics of rotor blades. This article first designs the overall parameters of the rotor and the aerodynamic parameters of the blade. Secondly, the CFD method is used to analyze the aerodynamic characteristics of the rotor in hover. Finally, the three-dimensional nonlinear elastic model of the blade is decomposed into a two-dimensional linear profile model and a one-dimensional nonlinear beam model for dynamic characteristics analysis. The results show that the rotor can successfully pull up the 230kg unmanned helicopter, the hover efficiency is greater than 0.65, the natural frequency of the blade under the working speed keeps a certain range with the frequency of the aerodynamic excitation force below the 8th order, avoid the speed resonance region and meet the requirements of the blade dynamics design.
    2024,15(3):157-166. DOI: 10.16615/j.cnki.1674-8190.2024.03.16
    Abstract:
    Multipurpose, intelligent, and strong terrain adaptability are important trends in the development of helicopters in the future. The landing gear is a key component to ensure the safety of helicopter takeoff and landing. Due to the poor terrain adapt-ability of the traditional landing gear, a leg landing gear system is designed using the bionics design concept to solve the problem of the helicopter"s smooth land observation in complex terrain environment. Starting from the design require-ments of leg landing gear, the landing architecture was analyzed and the leg structure design was completed. Then, based on the designed leg mechanism, the kinematics analysis and dynamics analysis are completed, and the relevant models are established as the basis for the motion control of the leg landing gear. Finally, motion testing of the leg landing gear was completed in the laboratory, proving the rationality of the structural design and the accuracy of the control algorithm.
    2024,15(3):167-173. DOI: 10.16615/j.cnki.1674-8190.2024.03.17
    Abstract:
    The structural characteristics, manufacturing requirements and interface accuracy requirements of helicopter composite duct are analyzed. According to the structural characteristics and requirements, a new manufacturing technology of helicopter composite duct is proposed, which includes precision manufacturing technology of parts, adhesive assembly technology of duct structure and finishing technology. The technology is discussed and its application is reported. Compared with the traditional dolphin helicopter duct manufacturing technology in many aspects, the new helicopter composite duct manufacturing technology has achieved the effects of reducing cost, shortening manufacturing cycle, simplifying tooling, improving quality and ensuring interface accuracy, which has important reference value for the precision manufacturing of other helicopter parts.
    2024,15(3):174-181. DOI: 10.16615/j.cnki.1674-8190.2024.03.18
    Abstract:
    In order to ensure the high surface quality and high dimension precision of the helicopter landing gear wheel shaft after spraying tungsten carbide coating. In this paper, the research on tungsten carbide coating grinding technology for wheel shat is carried out from three aspects of grinding strategy, clamping tool and grinding strategy. First, we used the orthogonal experimental method to find out the grinding parameters that could make the surface roughness of the parts reach Ra0.4; Then, the problems of ellipse and taper in the process of outer circle grinding are eliminated by improving the fixture, adjusting the way of grinding wheel feed and improving the grinding strategy; Finally, the outer circle dimensions of 15axles were collected and calculated, and the process capability index was not less than 1.33. The feasibility and stability of the whole grinding process are proved.
    2024,15(3):182-190. DOI: 10.16615/j.cnki.1674-8190.2024.03.19
    Abstract:
    In order to effectively evaluate the maritime emergency rescue capability of helicopters and improve their emergency rescue efficiency, it is proposed that the safety issues in the three stages of "pre-prevention--in-event response--post-event recovery" in the rescue process be taken into account in the helicopter maritime emergency rescue system.Based on the "5W1H" analysis method, the research framework was designed, and the evaluation indicators of helicopter maritime emergency rescue capability were screened through literature analysis, questionnaire survey, expert consultation and other methods, and 21 evaluation indicators were determined to build the evaluation index system of helicopter maritime emergency rescue capability. The analytic hierarchy method based on D-S evidence theory was used to determine the index weight, and the fuzzy comprehensive evaluation method was used to construct a comprehensive evaluation model of helicopter maritime emergency rescue capability. The evaluation model was applied to the rescue exercise taking the injury of offshore wind turbine maintenance personnel as an example, and the score was 86.89, and the rescue ability was judged to be "strong".The results show that the evaluation index system and evaluation model have certain practicality, and can effectively evaluate the ability of helicopter emergency rescue at sea.
    2024,15(3):191-202. DOI: 10.16615/j.cnki.1674-8190.2024.03.20
    Abstract:
    Helicopter maritime search and rescue (MSAR) is one of important component in aviation emergency rescue sys-tem. However, the MSAR unit usually analyzes distress information and makes response plans according to previous experience. As a result, it needs theoretical guidance and software support. This paper focuses on the process from receiving the distress message to performing the MSAR mission, and puts forward a kind of decision-making support technology architecture for helicopter MSAR mission facing the operation support issues. Then the re-sponse plan is carried out around which plays a key role in the implementation of this mission. What is more, the MSAR decision-making support system for people in distress has been designed and developed, which can pro-vide effective support for decision maker. Finally, the reasonablility and practicability of prototype system has been verified from the 2020 MSAR comprehensive practice of Xiamen City.
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    Available online:June 12, 2024, DOI:
    Abstract:
    Compared to conventional powered aircraft, the solar-powered aircraft have characteristics of high-altitude and long-endurance. They can modularly change the task loads and carry out related special tasks. Based on the working principle of long endurance solar-powered aircraft, the coupling relationship between the all-day cruising altitude and wing load of solar-powered aircraft under the energy balance design system was analyzed. The coupling parameters, including aerodynamic parameters, solar panels efficiency and paving rate, propulsion system efficiency and load power factor, flight season and flight latitude, were systematically analyzed for sensitivity, The results indicate that the design or optimization of appropriate lift and drag coefficients should be the first consideration for long endurance solar-powered aircraft to achieve best aerodynamic efficiency; When the efficiency of solar panels reaches 0.35 or above, increasing the installation rate of solar panels has a weaker impact on the all-day cruising altitude, but it helps to increase the upper limit of wing load. The research results can serve as a reference for the overall design and improvement optimization of solar-powered aircraft.
    Available online:June 12, 2024, DOI:
    Abstract:
    Fuel cell UAVs have become a research hotspot in green aviation because of their high efficiency, pollution-free emissions and high energy density. Parameter matching of fuel cell hybrid system has an important impact on the economy, environmental protection and efficiency of UAVs. In this study, a vertical take-off and landing fixed-wing UAV was used as a hybrid system of fuel cell + lithium-ion battery. According to the technical indicators, the components of the UAV power system are selected. Firstly, the topology of fuel cell hybrid system is designed, and the parameters of fuel cell (PEMFC), lithium battery, brushless DC motor, propeller and unidirectional DC/DC converter in the hybrid system are matched. Then, the load power is created according to the task profile, and finally the MATLAB/Simulink simulation analysis of the hybrid system is carried out using the finite state machine energy management control strategy. The results show that the designed fuel cell hybrid system can meet the flight load requirements, meet the changes of working conditions during flight, and achieve zero-emission flight.
    Available online:June 12, 2024, DOI:
    Abstract:
    Both drone swarm intensive flight and drone aerial recovery involve the stability problem of drone/carrier-aircraft flight in close range interference flow field. This paper proposes an aerodynamic derivative model for drone/carrier-aircraft interference based on the above application background, simplifies the longitudinal dynamic equations, and derives the simplified stability criteria for the drone. Numerical simulation and analysis indicate that this simplified criterion reflects the relationship between the drone’s motion stability, aerodynamic characteristics, and interference flow field characteristics, and can be used for preliminary analysis and design of flight stability in interference flow fields. Numerical simulation also indicate that the downwash flow can cause the drone to have short-period motion with slower convergence of amplitude, which increases the difficulty of achieving stable and controllable flight in the interference flow field.
    Available online:June 12, 2024, DOI:
    Abstract:
    A UAV flight control system based on STM32F4 and FreeRTOS operating system is designed. Aiming at the problem of large size and high cost of processor ,a set of flight control hardware system consisting of dual micro controllers, various sensors and actuators is designed based on STM32F4 ,achieving the control of attitude and rudder position, serial communication capability for data acquisition and ground communication., and aiming at the problem that the operating system is expensive and the source code is not accessible, the flight control software system is designed based on FreeRTOS, reducing the burden of RAM while ensuring real-time performance. For improving the reliability of the system, dual residual design of the controller and the watchdog module are introduced. The system has been validated by flight trail, which confirms that the system has high stability, high control accuracy and fast response.
    Available online:June 12, 2024, DOI:
    Abstract:
    With the large-scale constellation, the importance of a single satellite is reduced. When formulating a replacement strategy for faulty satellites, multiple replacement methods and the retention of faulty satellites should be considered. In response to this demand, a method for formulating constellation orbit satellite replacement strategy based on Markov decision process is proposed. The orbital state is divided according to the number of satellites working in orbit, in-orbit backup and ground backup. On this basis, combined with the different replacement strategies of faulty satellites and the corresponding ordering, storage and penalty costs, a return function model representing the expected maintenance cost is constructed. In order to minimize the expected maintenance cost of each decision cycle, a sequential replacement strategy is developed and applied to a constellation orbit. The results show that when the ground backup is used to replace the fault satellite, it tends to supplement the consumed backup satellite. The longer the mean time between failure, the lower the expected total maintenance cost, but the effect is gradually weakened. The increase of penalty cost will lead to the solidification of replacement strategy, and the upward trend of total maintenance cost is expected to be greatly slowed down. This method can make a sequential decision on the replacement mode of the faulty satellite according to the state of the constellation orbit, which makes the analysis more comprehensive and has certain value for the formulation of the constellation spare strategy.
    Available online:May 08, 2024, DOI:
    Abstract:
    The supersonic variable Mach number wind tunnel can operate at multiple Mach numbers during a single operation, which has unique advantages for studying supersonic maneuvering process and scramjet Ramjet starting. The supersonic variable Mach number nozzle is the core component for adjusting Mach number during wind tunnel operation, and its design quality directly determines the flow field quality of the experimental section. This article reviews the research progress of nozzle design in supersonic variable Mach number wind tunnels both domestically and internationally in recent years, and introduces four typical variable Mach number wind tunnel nozzle schemes (flexible wall, semi-flexible wall, profile rotation, asymmetric), as well as their numerical simulation and experimental calibration results; Summarized the key considerations in the design of different variable Mach number nozzle schemes, and provided prospects for the next research direction.
    Available online:May 08, 2024, DOI:
    Abstract:
    To clarify the effect of breakaway groove on the breakaway load of emergency fuse-pin for civil main landing gear, a series of FEM simulations were conducted to study the influence of structural changes of breakaway groove on the breakaway load for outer-groove, long outer-groove, inner-groove and short inner-groove emergency fuse-pin. The breakaway load and failure mode were comparison?analyzed between inner-groove and inner-groove emergency fuse-pin by experimental tests. The results reveal that the breakaway failure of fuse-pin is extended from inside to outside. The breakaway loads increase with increasing the sectional area and exhibit a linear relationship. The breakaway load variation with the sectional area(shear strength coefficient) of through-hole pin is the maximum, followed by outer-groove pin, and the inner-groove pin is the minimum. Compared with other pins, the breakaway load of inner-groove pin is easy to control and less affected by sectional area and overall size. The fracture morphology is changed from ductile fracture of outer-groove pin to brittle fracture of inner -groove pin. Accordingly, the design of inner-groove pin meets the aviation regulations requirement for civil main landing gear.
    Available online:May 08, 2024, DOI:
    Abstract:
    The cargo compartments of most current aircraft types are equipped with ventilation function. It is of great significance for flight safety to explore the influence of ventilation effect on smoke diffusion in the cargo compartment and determine the layout of smoke detectors in the cargo compartment under ventilation conditions. A numerical model of fire smoke in DC-10 aircraft cargo compartment is established by using computational fluid dynamics method, and the flow field characteristics of fire smoke are analyzed by simulation. POD flow field orthogonal decomposition theory was used to reveal the influence mechanism of ventilation on fire smoke flow field, the layout of smoke detector in smoke cargo compartment under ventilation condition is studied by simulation and experiment. The results show that ventilation can inhibit the upward diffusion of fire smoke and delay the time for smoke to reach the cargo compartment ceiling. With the increase of ventilation volume, the energy proportion of small and medium-sized disordered flow modes in flow field increased, while the energy proportion of large-scale flow modes of smoke moving close to the cargo ceiling decreased, which resulted in a longer time for smoke to reach the ceiling. By comparing the response performance of the three different detector layouts experimentally, it is concluded that the optimal detector layout is to install the detector near the corner of the cargo hold and away from the vent.
    Available online:May 08, 2024, DOI:
    Abstract:
    The compatibility of aircraft landing gear and pavement is of great significance to the ground motion ability of aircraft. This paper calculates the landing gear load and tire load distribution under different working conditions for a large aircraft. The Portland Cement Association method based on Westgard laminate theory and the United States Army Corps of Engineers method based on California bearing ratio are used to calculate. The influence of the landing conditions, ground mobility, tire number, tire deflation and track widths on the aircraft classification number(ACN) is analyzed. The aircraft floatability under rigid and flexible pavement is analyzed. The increased tire load and uneven load distribution caused by vertical overload and tire deflation can weaken the floatability of aircraft to varying degrees, especially during turning and landing conditions with tail sinking. Therefore, they need to be limited. Increasing the number of tires and the distance between them can improve the floatability, but the structural design, strength margin and other factors should also be taken into consideration to optimize the design of trolley type landing gear.
    Available online:May 08, 2024, DOI:
    Abstract:
    Flight control system is typical safety critical system, and the reliability of flight control system plays an important role in ensuring the safe operation of aircraft. Traditional reliability analysis methods have a heavy reliance on the experience of analysts, which makes it easy for inconsistencies between reliability models and design models. The fault propagation behavior of the system is thoroughly described by the Architecture Analysis Design Language (AADL) and stochastic Petri nets (SPN), and a method for model-based reliability analysis is proposed. The nominal model and error model of a lateral fly-by-wire flight control system were constructed using AADL. A method for extracting error propagation information from the AADL model was proposed, and the SPN model described the fault propagation behavior of the system was automatically generated by extracting the information of AADL model. Based on the SPN model, Monte Carlo simulation was used to evaluate the reliability of the lateral fly-by-wire flight control system, compared with the fault tree analysis method, the error is less than 0.018%, which can be neglected in practice. Through the method of this study, the reliability model is automatically generated by the AADL model, which ensures the consistency between the reliability model and the design model and avoids reliance on the experience of designers.
    Available online:May 02, 2024, DOI:
    Abstract:
    Sensor aircraft and integrated wings embody the integrated design concept of integrating functional components and structures. However, there are problems with discontinuous skin force transmission and difficult connection in the wing structure, making the connection strength of functional skin a control factor in the design process. Therefore, this article combines the functional requirements and structural characteristics of the integrated wing, adopts a simplified connection calculation method, conducts force transfer analysis and connection characteristics analysis on the key sections at the separation surface of the functional skin design, obtains the ideal connection load and connection parameters at the separation surface, completes the connection design and size design, and verifies it through finite element analysis and optimization analysis. The results show that the estimated bending moment distribution of the box section using this force transfer analysis method is consistent with the finite element analysis results; The calculated size distribution of each section of the box section structure is similar to the optimization results, which can meet the requirements of connection strength and stability; The larger the effective height of the wing beam in the box section structure, the greater the load it bears, and the more consistent the optimization results with the force transfer analysis results.
    Available online:May 02, 2024, DOI:
    Abstract:
    The high-performance attitude controller can effectively suppress comprehensive effects caused by uncertainties and external dynamic disturbances, and ensure that the quadrotor can safely and reliably fly to complete the designated mission. Therefore, nonlinear uncertainties of quadrotor flight systems are approximated by a radial function neural network (RBFNN) quadrotor, and an extended state observer is designed to estimate lumped disturbances caused by RBFNN approximation errors and external disturbances in this paper. The black box problem of RBFNN is solved by using a model identification error and a tracking error as decision variables. Then, an adaptive robust anti-disturbance attitude tracking controller is designed for quadrotor flight systems based on dynamic surface control and Lyapunov stability theory, and an auxiliary system is constructed to suppress the effect of filtering error on the closed-loop system performance. Finally, Simulation results show that the quadrotor can precisely track the desired attitude angles, and the proposed controller has strong robustness and stability in the presence of uncertainties and disturbances.
    Available online:May 02, 2024, DOI:
    Abstract:
    In recent years, scholars have conducted extensive research on air precoolers, which are used for pre-cooled combined cycle engines for hypersonic aircraft. These precoolers are generally composed of multiple sets of micro-tube bundles, but they have problems such as large flow-induced vibration and high processing requirements. Therefore, it is necessary to redesign the heat exchange core of the precooler and carry out further research on flow heat exchange. This article analyzes the demand for modification based on biomimetic fractals, sorts out the application of honeycomb-like fractals, tree-like fractals, and mixed structures on biological surfaces, which enhance heat exchange in new pre-cooling cores. Additionally, biomimetic concave-convex surface structures and hydrophobic structures are applied to reduce surface flow resistance and suppress frosting. At the same time, three design examples of “cylindrical” biomimetic pre-cooling heat exchange cores are given, which can be applied to the aerospace field. Finally, the article looks forward to the development prospects of combining biomimetic microchannel heat exchange structures with precooler heat exchange core design.
    Available online:May 02, 2024, DOI:
    Abstract:
    In order to evaluate the propulsive efficiency of turbofan, turboprop and prop-fan engines, a mathematical model for propulsive efficiency analysis was established by using energy-momentum method based on the model of separate exhaust turbofan engines, and a unified propulsive efficiency analysis method was formed for turbofan, turbofan and propeller fan engines. Different external fan pressure ratio, equivalent bypass ratios and different flight Mach number are selected for calculation. The calculation results show that the propulsion efficiency of turboprop engine is higher at medium to low flight Mach number, the propulsion efficiency of prop-fan engine is higher at medium to high flight Mach number, and the propulsion efficiency of turbofan engine is higher at high subsonic flight Mach number. The results confirm the existing flight Mach number interval distribution law of the superior propulsion efficiency of turboprop, prop-fan and turbofan engines, and provide a method for the research and analysis of the propulsion efficiency of turbofan, turboprop and prop-fan engines.
    Available online:May 02, 2024, DOI:
    Abstract:
    The stability of compressor operation has an inducing and amplifying effect on the stability and performance of the entire engine. Therefore, it is required that the wider the flow margin of the compressor, the better, to adapt to the working stability of the engine under variable operating conditions. This paper attempts to propose a new blade structure with micro pits distributed on the suction surface of the mainstream blade by referring to the "golf ball effect". The flow of a certain type of centrifugal compressor impeller is numerically simulated by using the CFX fluid dynamics software to study the effect of adding micro pits on the performance of flow separation structure and flow margin at different parts of the suction surface of the blade. Study the effect of adding micro pit structures with radii of 0.25-0.3mm at different parts of the blade suction surface on structural performance and flow margin. The research results indicate that adding micro pits at the leading and trailing edges of the mainstream blade suction surface can improve the flow margin. When the radius of the micro pits is 0.3mm, the flow margin effect is the best, increasing by 3.01% and 3.15%, respectively. The use of new structural blades reduces smaller peak efficiency and increases compressor flow margin, providing a reference for the design of centrifugal compressor impellers.
    Available online:April 01, 2024, DOI:
    Abstract:
    This paper uses the theory of failure physics and reliability simulation analysis method to analyze the reliability of electronic controller. By establishing a digital prototype model of electronic controller, the corresponding stress analysis and fault prediction are conducted to evaluate the average time to first failure (MTTFF) reliability index of the electronic controller, and optimize the design based on the weak links found in simulation results. It is indicated that the difference between the reliability results and the theoretical calculation results are not significant, and can be used as a basis for evaluating the reliability indicators of models, reducing the cycle and cost of using physical prototypes for reliability testing; At the same time, the optimization and improvement have significantly improved the reliability design of the electronic controller, laying a theoretical foundation for subsequent model reliability evaluation and design.
    Available online:February 15, 2024, DOI:
    Abstract:
    The methods of waypoint setting and point curve fitting which are not complex was usually adopted in the path planning of UAV, and the expected heading angle is given in segments. The expected heading does not automatically modified with changes in the route. The ability to automatically and quickly generate the expected heading and position is lacking. In order to solve the ability, a vector field algorithm suitable for complex flight mission path planning is studied, and a simulation verification system to verify the effectiveness of its algorithm is developed in this paper. The concept of vector field is introduced in order to design a heading angle guidance law. An aircraft at any position can smoothly fly to the desired target path along the desired heading angle, and then complete the flight task along the desired target path. The implicit function equation is used to establish the desired path vector field, and the principle and method of path planning based on vector field are geometrically analyzed. According to the Lyapunov stability theory, the boundedness of the planned path error is proved. The distance error and the heading angle error can be stably converged to 0 with the help of the heading guidance law. Taking the path planning of the altitude hold mission for a quad tiltrotor UAV as an example, the desired path of smooth flight is planned using the vector field method and the piecewise transition strategy. The verification is conducted and some simulation results are given, which show that the vector field path planning algorithm is feasible and effective for the mission flight planning of an aircraft.
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    2023,14(6):153-159. DOI: 10.16615/j.cnki.1674-8190.2023.06.17
    [Abstract] (253) [HTML] (36) [PDF 2.60 M] (10855)
    Abstract:
    The thermal field distribution of generator has a great influence on the failure phenomenon of the overheat protection component, which is the key parameter to be considered in the design. Based on the steady-state pressure solver and turbulence model in ANSYS software, the internal thermal field distribution of the motor under fault mode was simulated. The thermal field distribution of the stator, rotor and shell circulating oil circuit were obtained. The results show that the simulated thermal field is consistent with the actual temperature field distribution. The temperature gradient of low-melting alloy in the thermal trip mechanism is accordance with the internal thermal field distribution of the generator. It is helpful to protect the motor from overheating by changing the melting points of some key parts and the special softening temperature points of materials.
    [Abstract] (3333) [HTML] (0) [PDF 1.89 M] (6840)
    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.
    2021,12(3):161-170. DOI: 10.16615/j.cnki.1674-8190.2021.03.20
    [Abstract] (659) [HTML] (0) [PDF 8.07 M] (5266)
    Abstract:
    The process of folding and inflating the cylindrical airbag is complicated, and there are many inconveniences in using experimental methods to study its expansion process. Two different folding methods are proposed for the cylindrical airbag and the corresponding numerical analysis models are established respectively. The nonlinear dynamics software is used to study the dynamic application characteristics of the cylindrical airbag after being folded, which will affect the skin stress during the airbag expansion process. The factors of volume and internal pressure curve change are analyzed, and the influence of different folding methods and external environmental parameters on the dynamic characteristics of the cylindrical airbag is discussed. The results show that the two folding methods have their own advantages in storage space and material strength. In addition, in the environmental parameters, the external pressure has a greater impact on the stable state of the airbag after expansion, while the temperature has no obvious effect.
    2019,10(3):309-318. DOI: 10.16615/j.cnki.1674-8190.2019.03.003
    [Abstract] (1325) [HTML] (0) [PDF 1.21 M] (4260)
    Abstract:
    The Additive Manufacturing(3D Print) was widely studied and used in recent years, but there wasn"t a systematic, distinct and accurate classification about the Additive Manufacturing. The Additive Manufacturing was divided into 3 sorts and 13 sub sorts according to the category and state of the added materials and heat source of the manufacturing in this paper, as well as the principle, characteristics and trend of the each sorts of the Additive Manufacturing method were analyzed.
    [Abstract] (2546) [HTML] (0) [PDF 1.88 M] (4187)
    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.
    2018,9(1):99-106. DOI: 10.16615/j.cnki.1674-8190.2018.01.013
    [Abstract] (2280) [HTML] (0) [PDF 1.77 M] (3656)
    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.
    2014,5(1):109-115. DOI:
    [Abstract] (3952) [HTML] (0) [PDF 2.89 M] (3626)
    Abstract:
    For free turbine turboshaft engine with high thermodynamic parameters and high-bleed, a new turboshaft performance calculation model which considers bleed position and cooling air expansion work. The model of air bleeding in the middle of the compressor corrects the flow balance and power balance at the same time. The turbine cooling model considers the cooling air expansion work. The calculation results obtained by the new model are analyzed and compared with that of simple turbine bleed and cooling model, which proves that the new model can obtain the influence of the amount of bleeding and bleeding position to the performance of turboshaft engine. The new model are close to the true physical process of turboshaft engine, and can offer input to the air system.
    [Abstract] (1920) [HTML] (0) [PDF 562.11 K] (3411)
    Abstract:
    There are a great deal of influence on many fields of society as a result of the new round of technological revolution and industrial revolution centered on artificial intelligence. All the aerospace powers have conducted many useful experiments and explorations in the combination of artificial intelligence and aerodynamics. The development history and status quo of artificial intelligence technology are reviewed in this paper, the applications of artificial intelligence in wind tunnel test, numerical calculation and flight test are discussed in the background of big data era, the role of artificial intelligence in assisting mass aerodynamic data analysis and knowledge discovery is analyzed in detail, the application values of artificial intelligence in aerodynamic modeling and advanced aircraft design are investigated, the future development direction and challenges of combination of artificial intelligence and aerodynamics are prospected.
    2013,4(2):158-163. DOI:
    [Abstract] (3669) [HTML] (0) [PDF 4.91 M] (3133)
    Abstract:
    Weight is one of the most important performances for the aviation productions. The most effective approach to weight saving is developing the lower density material. Introduce advanced Al-Li (Aluminum-Lithium) alloy with lower density, higher tensile strength, better damage tolerance etc. Compare to conventional aluminum alloys and trade-off study with advanced composites. Analysis the properties of 3rd-generation Al-Li alloy and the applications on advanced aircraft. Provide the proposals of applications in civil program. The research can be the reference of materials selection and weight saving for commercial aircraft, and benefit extending applications of Al-Li alloy.
    2020,11(2):147-158. DOI: 10.16615/j.cnki.1674-8190.2020.02.001
    [Abstract] (1592) [HTML] (0) [PDF 3.27 M] (2976)
    Abstract:
    To reasonably and efficiently guide the safe, reliable and economical operation of civil aircraft, we investigate the main contents and explore the application in operational reliability analysis and feedback of S5000F, i.e., international specification for in-service data feedback, which is organized by AeroSpace and Defence Industries Association of Europe (ASD). The compilation background and purpose of S5000F specification are first elaborated, and the main contents and the relevant business processes in the S5000F specification were then introduced. We finally discussed the application of S5000F specification in the operational reliability analysis and feedback of civil aircraft. In this paper, the S5000F specification is comprehensively interpreted, and its application in the operational reliability of civil aircraft is studied. In this case, we further extend this specification to the design phase and service phase of civil aircraft. The efforts of this study provide effective guidance for the life cycle management of civil aircraft.
    2013,4(2):241-246. DOI:
    [Abstract] (2415) [HTML] (0) [PDF 2.31 M] (2774)
    Abstract:
    In this paper, an approximation method is presented for calculating the wing load envelope and using to size the wing box in wing strength primary design phase. It is found that the triangle weight load distribution is better than other distributions in simulating the wing weight. Furthermore, this paper investigates the characters of critical over loading and centralized loads for large civil aircrafts. An approximation method for calculating the wing load envelope of bending moment and shear force in flight is proposed by combining the Schrenk lift distribution and triangle weight distribution. Then, the proposed method is validated by wind tunnel data of wing shear forces and bending moments.
    [Abstract] (1727) [HTML] (0) [PDF 2.40 M] (2722)
    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.
    2020,11(2):159-166. DOI: 10.16615/j.cnki.1674-8190.2020.02.002
    [Abstract] (1359) [HTML] (0) [PDF 1.20 M] (2603)
    Abstract:
    High Altitude Long Endurance (HALE in short ) UAV has made great development since its birth and participation in war. With the expansion of combat mission to high-risk confrontation battlefield, HALE fly-wing UAV has become a hotspot in the world today. In this paper,the requirements of HALE fly-wing UAV for turbofan engine are described, effect of key design parameters on the performance of turban engine is analyzed based on the basic principle of aero engine, the key problems and research progress of HALE fly-wing UAV are summarized. This paper has important reference value of the selection of turbofan engine for HALE fly-wing UAV and the improvement of its adaptability design.
    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.
    2021,12(4):80-89. DOI: 10.16615/j.cnki.1674-8190.2021.04.09
    [Abstract] (507) [HTML] (0) [PDF 4.02 M] (2542)
    Abstract:
    The effect of thermal load in the creep feed grinding have important effect on the surface quality for ma? chining the tenon teeth of turbine blade. In this paper,the effects of grinding parameters on grinding forces and temperature in grinding DD5 single crystal alloy are investigated by experiments. The influences and formation mechanism of DD5 creep-feed grinding forces and temperatures are analyzed,and a mapping model between thermodynamic effect and grinding parameters is established and verified. The experimental results show that the grinding depth has the greatest influence on the DD5 creep-feed grinding force and temperature,following by the grinding wheel speed,and the feed velocity of work-piece has less influence on the grinding forces and temperature. With the increase of the grinding wheel speed,the grinding force is decreasing,and the grinding temperature has an in?creasing trend. With the increase of feed velocity and grinding depth,both the grinding force and temperature are of increasing trends. Increasing the feed velocity and reducing the grinding depth on the premise of satisfying the material removal rate can avoid the larger grinding thermodynamic coupling layer on the DD5 grinding surface.
    2014,5(1):1-6. DOI:
    [Abstract] (3067) [HTML] (0) [PDF 6.43 M] (2485)
    Abstract:
    Fuel tank damage caused by hydrodynamic ram has became increasingly widespread. Summary and analysis of the research of hydrodynamic ram in recent decades provide a reference for future research work. Hydrodynamic ram research has an early start, early experiment and theoretical analysis formed the theoretical basis. With the progress of the test apparatus and the introduction of finite element method, test results has became more and more accuracy, hydrodynamic ram effect research entered a new phase. But for the hydrodynamic ram effect, there are so many problems, they will be the focus of future work.
    2020,11(4):517-523. DOI: 10.16615/j.cnki.1674-8190.2020.04.009
    [Abstract] (1131) [HTML] (0) [PDF 833.51 K] (2440)
    Abstract:
    The tactical performance and advantages of unmanned aerial vehicle (UAV) system will play an increasingly important role in future high-tech warfare and civil aviation. However, due to the different characteristics of manned and unmanned aerial vehicle flight accidents, the safety analysis and management measures of manned aerial vehicle are not suitable for UAV system. Therefore, the safety and hazard analysis of UAV system is carried out to construct the UAV security management framework. Firstly, according to the statistical analysis of UAV system flight accidents, the characteristics of UAV system accidents are concluded. And then the safety of UAV system is defined, the classification of severity and its corresponding acceptability for UAV system are presented. Finally, hazard analysis is carried out from design, crew training and operation fields.
    2021,12(4):44-51. DOI: 10.16615/j.cnki.1674-8190.2021.04.05
    [Abstract] (1045) [HTML] (0) [PDF 5.62 M] (2423)
    Abstract:
    Rotor airfoil design involves multi-point and multi-objective complex constraints. How to significantly improve the maximum lift coefficient and maximum lift-to-drag ratio of rotor airfoil is a fundamental problem to be solved urgently in the development of high-performance helicopter rotor blades in the future. Novel flow control technology is the most potential method to achieve the high lift enhancement and drag reduction of rotor airfoil. Based on the classic OA312 rotor airfoil, this paper conducts the low-speed wind tunnel test of high lift enhancement and drag reduction of rotor airfoil using Co-flow Jet concept (CFJ) with zero mass and high negative pressure at the leading edge. The rotor airfoil CFJ dynamometric model driven by the micro ducted fan group is designed. The influence of basic parameters such as the injection size, suction size and suction surface translation on lift enhancement and drag reduction is studied. The ratio of jet velocity to mainflow velocity is qualitatively discussed. The optimal value range of key parameters of CFJ rotor airfoil is given. Results show that compared with the OA312 baseline airfoil, the CFJ rotor airfoil can significantly reduce drag coefficients at low angle of attack, and even achieve while the zero-lift pitch moment is basically unchanged. The CFJ rotor airfoil can significantly increase the maximum lift coefficient and the stall angle of attack at high angle of attack. The maximum lift coefficient can be increased by about 67.5%, and the stall angle of attack is significantly delayed by nearly 14.8°. Research results verify the technical feasibility of applying CFJ technology to significantly improve the key performance of rotor airfoil and provide a new feasible solution and idea for the design of high-performance rotor blades in the future.
    2018,9(3):297-308. DOI: 10.16615/j.cnki.1674-8190.2018.03.001
    [Abstract] (1373) [HTML] (0) [PDF 3.91 M] (2394)
    Abstract:
    This paper focuses on the research on the status of adaptive wing and summarizes from the adaptive compliant leading edge, the adaptive compliant trailing edge and the variable thickness wing, respectively. And the key technology that adaptive wing needs to be solved urgently is put forward, which can provide some technical reference for the design and implementation of adaptive wing structure.
    [Abstract] (1361) [HTML] (0) [PDF 1.78 M] (2348)
    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.

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