Abstract:Impact fatigue problems of materials widely exist in aviation engineering. Launching and landing of carrier-based aircrafts are typical impact fatigue problems. This paper reviews the early development of the concept of impact fatigue, summarizes the main research progress in the field of impact fatigue since 2000, including the main factors affecting the impact fatigue performance of materials, test methods, damage characterization and life prediction of impact fatigue and numerical calculation methods of impact fatigue problems. The results show that the microstructure, boundary condition, service environment and impact load type of the material have significant influence on the impact fatigue performance. This paper summarizes the main challenges of the impact fatigue problems in the aviation engineering, and prospects the future development of the impact fatigue technology in the aviation field based on the requirements of the future engineering structure design.

Abstract:In order to explore the effect of the synthetic jet through a spanwise slot on the friction drag reduction of the turbulent boundary layer of a flat plate, the streamwise velocity were measured by a constant temperature hot-wire anemometer with and without synthetic jet. According to the measured experiment data, the mean velocity profiles, fluctuating velocity profiles, skewness and flatness were obtained respectively. Typical combinations of different frequencies and intensities of synthetic jet were selected to study the variation of the forcing effect in the streamwise direction. The experimental results showed that the skin friction drag reduction in the turbulent boundary layer was related to the characteristics of the imposed synthetic jet and the distance between the local station and the slot. The synthetic jet led to an increase of the skin friction drag in the station close to the slot, and as the flow moved downstream away from the slot, a reduction in the skin friction occurred with the tendency of firstly increasing and then decreasing. The reduction of skin friction caused by the synthetic jet of a higher frequency was more than that of a lower frequency. The power spectral density and autocorrelation of the fluctuating velocities indicated that the effect of the synthetic jet on the turbulent boundary layer decayed in the streamwise direction.

Abstract:In this paper, the dynamic equation of rigid-elastic coupling elastic aircraft is established based on Lagrange method. The landing characteristic of the Global Hawk UAV with large aspect ratio are simulated and analyzed under the parameters of modal mass, generalized installation displacement, frequency and structural damping coefficient. The results show that the elastic modal mass and the generalized displacement of the mounting point can affect the load, stroke, speed of the aircraft buffer and tire support reaction. The smaller the modal mass, the larger the generalized displacement of the mounting point and the smaller the load of the buffer. Generalized displacement of installation point, structural damping coefficient and elastic vibration frequency of body can affect the energy dissipation efficiency of landing impact. The larger the generalized displacement of installation point, the larger the structural damping coefficient, the smaller the elastic vibration frequency and the faster the impact dissipation rate of landing.

Abstract:In order to study the influence of icing on aerodynamic characteristics of compressor inlet guide vane, the commercial software FENSAP-ICE was used to calculate the two-dimensional icing of the 50% blade height profile of compressor inlet guide vane. Using the Navier Stokes (N-S) equation, Euler method and Shallow-Water icing model to calculate the flow field, the droplet impact characteristics and the icing shape respectively. The results of NACA0012 airfoil icing calculation and test are compared to verify the reliability of the algorithm. Finally, the two-dimensional glaze ice and rime ice shapes of the blade-profile are obtained, and the flow field changes of the icing-blade-profile are analyzed. The results show that the commercial software FENSAP-ICE can effectively and accurately predict the two typical icing, the glaze ice and rime ice, of the blade-profile; glaze ice will lead to the area of the separation zone at the tail of the blade-profile increased to about 2 times, the separation point on the suction surface of the blade-profile advanced to 1% of the chord length, the speed nonuniformity at the outlet of the blade-profile increased, and the maximum increase of total pressure loss coefficient of blade-profile is 22%. However, the influence of the rime ice on the aerodynamic characteristics of the blade-profile is very small; the decline of the aerodynamic characteristics of the blade-profile is mainly affected by the upper separation vortex in the separation zone, and the lower separation vortex is formed by the mixing of the upper separation vortex and the main stream, which has little influence on the aerodynamic characteristics of the blade-profile.

Abstract:A backstepping nonlinear robust control method is proposed to overcome the shortcomings of unmanned control ability, nonlinearity and strong coupling of flying wing UAV. This improved Backstepping method, which not only eliminates the influence of nonlinearity, but also guarantees the stability and robustness of the system. This method breaks through the limitation of many robust design methods that the upper bound of uncertainty norm is known, makes full use of the known uncertainty information of the system to improve the performance of the system, and solves the singular value calculation and conservation problems of the traditional Backstepping method. The simulation results show that the control method is reasonable and effective.

Abstract:As a positioning reference part for wing assembly, how to effectively reduce the deformation of wing parts and improve the machining accuracy has always been an important task. According to the accumulated data analysis of the part, its deformation is mainly reflected in the saber bend, length extension and flatness warpage. This paper proposes a control method for the flatness warping deformation of wing beam parts during processing. It is mainly based on the technological characteristics of aircraft wing beam parts to analyze the actual deformation data of parts on the production site, determine the deformation trend, deformation amount and main influencing factors of beam parts. Then by improving the processing plan and controlling the processing deformation, the deformation of beam parts can be reduced to achieve the purpose of improving accuracy. The results show that the flatness value of the parts in the process of machining can be effectively improved and the deformation of beam parts can be significantly improved by the method proposed in this paper.

Abstract:With the best comprehensive performance, Li-ion batteries are going to be widely applied to civil aviation. As the research of its technical characteristics and security risks was defective, and the applicable airworthiness regulations were short of safety standards, foreign administrator issued special conditions, which containing the additional safety standards. Nevertheless, the investigation report of li-ion batteries fire in aircraft showed that the validation and certification of li-ion batteries were defective, and the update of standards fell behind the development of lithium-ion batteries. This paper analyzed the risk of li-ion batteries as s aviation power, interpreted existing regulations and special conditions, and provided suggestions for airworthiness means of compliance. Combined with experiences of service and verification, these suggestions will supplement airworthiness means of compliance, improve the verification standard system, and explore the autonomous foundation of standards.

Abstract:To investigate the mechanism of the propeller slipstream influence on the aerodynamic performance of the submerged inlet, a systematical numerical method is developed to simulating the slipstream and inner flow of oil radiator for a certain turboprop aircraft. The aerodynamic characteristic of the submerged inlet of the oil radiator within the propeller slipstream is deeply analyzed. Moreover, several vortex generators are designed to control the flow around inlet of the oil radiator to increase the flow rate affected by the inhaled low energy flow of the boundary layer in the inlet. The results indicate that, the calculating data agree well with those of test by using the numerical method, and the reasonable vortex generator can effectively improve the flow of the submerged inlet by increasing the flow rate with 12%.

Abstract:In order to make the medium-altitude, long-endurance (MALE)UAV have good dynamic and economic performance in all flight stages, combining the speed characteristic curve, fuel consumption characteristic curve of piston engine and propulsion characteristic curve of propeller, the method of matching constant speed propeller for aero-piston engine is proposed. According to the speed characteristic curve fuel consumption characteristic curve of piston engine, the economic working points of the engine are selected and then efficiencies of each propeller on the economic working points above are compared and analyzed. Wind tunnel tests of full-scale engine and propeller showed that the proposed method could be used to select optimal constant propeller for piston engine which had been preliminarily selected.

Abstract:Taking the composite-to-titanium hybrid structure as the research object, the load distribution characteristics and influence of different assembly forms on bolt load of co-cured, bonded and separated under the joint of two kinds of fasteners, such as the protruding and the countersunk, were analyzed. The stress distribution of the bolt hole in the joint area was measured by strain electric measurement. The numerical simulation model was established by ABAQUS software to analyze the bolt load distribu-tion of joints in composite laminate with metal. The results showed that the load distribution of the co-cured composite laminate with countersunk bolt joint is stepped from the loading end to the opposite end of the branch, while the load distribution of the other joints is high on both sides and low in the middle. The only difference is the proportions of bolt load in each row. The gaps of the separated composite laminate are the largest, the bonded are the second, and the co-cured is the smallest.

Abstract:This article introduces a method for selecting the internal load envelops of high-aspect-ratio aircrafts. By combining with the structure finite element analysis technology and extending the application of engineering beam internal force load, this method could quickly get the critical structure local stress, which is used to identify、select the critical parts of the structure, and then determine the critical condition of load design for aircraft structure more accurately and comprehensively.

Abstract:In order to carry out aircraft structural load safety monitoring and accumulate relevant structural load data for aircraft fatigue life assessment, it is necessary to establish aircraft structural load model related to flight parameters. For the nonlinear relationship between aircraft structural loads and flight parameters,the SMO algorithm with improved stopping criterion and the particle swarm optimization algorithm were used to improve the support vector machine regression method,and the flight parameters involved in the modeling were selected by the method of flight dynamics analysis combined with the Pearson correlation coefficient. The aircraft"s transonic pitch maneuver was taken as an example , and a shear force model of a certain load-bearing section structure of the wing was established. The results show that the accuracy of improved support vector machine regression method is better than the original method. It is concluded that the improved support vector machine regression method can improve the accuracy and generalization ability of the established model.

Abstract:To explore the influence of the lower edge plate hole of the turbine blade on the flow and heat transfer of the internal cooling passage on the upstream trailing edge side, the numerical analysis of the turbine blade from the trailing edge and the lower edge plate was carried out. The effects of hole size, hole shape and hole position of the lower edge plate on the distribution of the flow coefficient of the overflow hole in the trailing edge, the outflow distribution from the trailing edge and the lower edge plate and the heat transfer of the internal cooling passage wall were analyzed. The results showed that: (1) The distribution of the hole flow coefficient of the lower edge of the plate had a significant effect. The hole diameter increased, the flow coefficient of the overflow hole of the trailing edge decreased. (2) The hole diameter increased, the tailing edge outflow ratio decreased, the pressure loss in the cold passage in the trailing edge decreased, and the average heat transfer coefficient of the internal cooling passage increased. (3) The shape of the hole had small effect on the flow and heat transfer in the upstream inner cold passage. (4) The change of the hole position had small effect on the heat transfer coefficient of the inner wall of the inner cold passage, and had a great effect on the local.

Abstract:The cabin cover heating loading test-bed is one of the most effective ways to verify whether the aerodynamic heating and the aerodynamic loading will cause fatigue damage of the cabin cover. In the process of designing and building the test-bed, it is inevitable to encounter some problems such as lagging and overshoot of the temperature field on the surface of the cabin cover. In this paper, under the background of heating the canopy by AC heat exchange, through the way of data acquisition, controller design, simulation and re experiment, the cascade PID control scheme is applied to solve the above heating system problems, and compared with the conventional control scheme, the advantages of the cascade PID control in solving the temperature field control lag phenomenon are obtained.

Abstract:For the development needs of the Chinese navy, a flight control simulation training platform for the carrier aircraft which can service the principle teaching and simulation operation training for flight control was designed to solve the problem of the lack of carrier-based aircraft pilots and related technical support personnel. The core purpose and basic function of the training platform were presented, and the structure of the platform and the principles and functions of each component device were introduced. This simulation training platform can meet the requirements of teaching and training, promoting scientific research and guaranteeing combat troops.

Abstract:The research on the damage degree of the key parts of civil aircraft impacted by UAV is a new hot issue in the field of Civil Aviation .Rocket sled test can provide a new method for the safety assessment of UVA collision civil aircraft.In this paper,based on rocket sled test,the collision simulation,UVA attitude and parameter measurement and so on are studied.The collision technology scheme is designed,the rocket sled design, trajectory contral design,strength check and test scheme are systematically discussed,and the experimental verfications is completed. This paper makes an exploratory research on the test technology of UAV colliding with civil aircraft rocket sled, providing necessary technical reference for subsequent similar collision tests. The multiple impact tests provide effective test data for the safety assessment of UAV impacting civil aircraft.

Abstract:Vibration is an important load for the destruction of airborne electronic equipment, and circuit board components are the core components of electronic equipment. In the design stage of distribution products, it is necessary to carry out dynamic analysis and anti-vibration optimization design of circuit board. Based on the design of an airborne power distribution product, this paper used MSC software to conduct modal analysis and vibration analysis of the product structure, and obtains the natural frequency and vibration response curves of the product. Based on modal analysis, different optimization schemes are put forward. Finally, the optimization model is determined and the re-modeling analysis is carried out, which greatly reduces the vibration value and effectively improves the vibration resistance of the product.

Abstract:Aviation hydraulic actuator is widely used in many parts such as aircraft wing, landing gear, hatch door, etc. The typical seal form is reciprocating seal, and the failure of seal will seriously affect the execution of flight mission and even flight safety. Therefore, simulation of seal has important theoretical and practical significance. This paper establishes a deterministic mixed lubrication numerical model for reciprocating combined seal, the fluid-solid coupling analysis is realized by combing finite element method (FEM) with fluid dynamics analysis. The effects of surface roughness and operating conditions on lubrication and sealing performance are investigated. The results show that increase of roughness and wavelength of three-dimensional sinusoidal rough surface can contributes to the increase of fluctuation amplitude of film thickness and pressure, and the reduction of friction. Increasing of amplitude of the sinusoidal rough surface is beneficial to the reduction of the minimum film thickness and leakage. However, the wavelength change has little effect on the minimum film thickness.

Abstract:In order to solve veracious measurement about the variety of extinguishing agent concentration along with time in the ground simulation test of helicopter/aeroplane powerplant compartment, the special extinguishing agent concentration measurement has been developed. The project includes the principle, the system composition, the rapid air heating, the differential pressure generation and the multichannel synchronous control. The measurement has been successfully used in the ground simulation test of several helicopters, the datum show the response of measurement is real-time about the variety of extinguishing agent concentration along with time, because of response sensitivity. it can be satisfied with the requirement of ground simulation test in the fire extinguisher system of helicopter/aeroplane powerplant compartment.

Abstract:Airline has different demand for market choose, brand construction, flight course and equipment selection, leads a lot of diversity configuration for different aircraft or different block of aircraft, so flexibility and high efficiency customization management is the first key factor for effectively configures customer's aircraft, and provides basement for contract to sign. Based on an specific aircraft type, this paper brings out an product structure management solution for requirements, which constructs the three data layers and variable forms to control customer's requirements through the whole process, and exports the documents generated by the product structure as required. it serves the customized definition for different airlines and ensures the customer's requirements effectively transmitted and exactly implemented, and in accord with the trend of product full life management.