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.

Abstract:As a kind of aeronautical material, aluminum-lithium alloys are favored for their high specific strength and high specific stiffness. In the engineering application like anti-fatigue design, the accurate understanding of the material performance is the foundation for the application of material. Compared with conventional aluminum alloys, aluminum-lithium alloys exhibit unique characteristics towards various aspects of performance, fatigue and fracture properties included. Significant differences can also be found in the performance of aluminum-lithium alloys developed at different times. This paper aims to review different properties of aluminum-lithium alloys by comparing the performance difference between aluminum-lithium alloys and conventional aluminum alloys, and comparing the performance difference among different aluminum-lithium alloys. Based on the analyses of development history, mechanical properties, fatigue limit and fatigue resistance, and fatigue crack growth resistance, some suggestions for material selection in structural design are given.

Abstract:The electrical generation, hydraulic power and pneumatic power of an aircraft is supplied by the secondary power system or the power extracted from engines by the secondary power system. After the mode transition of TBCC, there is no energy from engines for extracting. Therefore, it is needed to solve the problem of long time and high energy output of the secondary power system for airspace hypersonic aircraft. The technical features, application and development of the secondary power system is concluded in this paper, as well as the development of hypersonic aircraft. The combination of ATS & RAT and superconducting generator of more electric engine technology & large energy storage devices are available technical routes for integrated energy of airspace hypersonic aircraft .

Abstract:Blended wing body (BWB) configuration will be the inevitable trend of the aircraft using in the future civil aviation for its excellent performance. Aerodynamic and flow mechanism investigations of the BWB configuration will provide important support for its design. Wind tunnel tests include force measurements and tuft visualization, in addition to computation fluid dynamics (CFD) simulation，are used to investigate the low speed aerodynamic characteristics and flow mechanism and effects of flow-through nacelles for a 300-passenger BWB configuration(BWB-1). Test results show that longitudinal aerodynamic characteristics of BWB-1 are better than those of the Early BWB or N2A. BWB-1 possesses lateral static stability and directional static instability, however, low value of the directional instability degrades the difficulty in directional stability augmentation and control. Investigation also reveals flow development and physical mechanism of a mild stall characteristic of the configuration. Flow-through nacelles are beneficial to both maximum lift and directional stability, and have minimal effects on lateral stability; however, drag and pitch-down moment are increased. Results from CFD simulation show good agreement with tunnel data，which demonstrate the validation of the CFD method. The research results will provide useful reference for the development of next generation civil transport in China.

Abstract:Theredundantmanipulationsondifferentcontrolsurfacesoftilt-rotorcraftareofgreatimportancefor itscontrolreconfiguration.Thenonlinearmodeltrimandsmallperturbationlinearizationprocessingresultare presentedbasedonthesmallunmannedtilt-rotorcraftflightdynamicsmodel.Thepitch,rollandyaw moment changingresultsareobtained,andmanipulationefficiencyisanalyzedindetailunderindependentcontrolofthe differentcontrolsurface,whichconfirmedthatredundantcontrolsurfaceoftilt-rotorcraftisofthereconfiguring capacity.Manipulationstylesunderdifferentflightmodearedetermined,andweightcoefficientmatrixofallo- cationstrategyofcontrolsurfaceisobtained.Basedontheresultsofanalysis,thethreedifferentfullmode flightconversionpathsarepresented,andtherelationsamongtheflightspeedandturnforwardangle,attitude angle,manipulationquantityarecalculated.Theresultsshowthatmanipulationefficiencycanbeachieved throughthethreeconversionpaths,andindicatethatredundantcontrolsurfacereconfiguringabilityoftilt-rotor- craftcanberealized.

Abstract:3D braided composites have been widely used in aerospace engineering and thermal conductivity is one of its important physical properties. Based on the mesoscopic unit cell of 3D 4-directional braided composites, the macro- and micro- multi-scale models for predicting thermal properties of 3D braided composites are established, including the homogenization model for the equivalent properties and multi-scale model for the temperature distribution. And the equivalent properties are calculated by the multiscale finite element algorithm, and agree well with the experimental results. The influences of the braiding angle and fiber volume fraction on the thermal conductivity coefficient are also studied. In addition, the distributions of temperature field inside composites are determined, providing a basis for the analysis of the thermo-mechanical coupling

Abstract:In this paper, a mosaic finite element model of C/C woven composite open-hole is established, and the progressive damage analysis under tensile and compressive loads is performed. In the finite element modeling, a mesoscopic finite element model was established based on the mesostructure of the material in the perforated area of the open-hole plate, and the rest was equivalent to a uniform model. The failure criterion based on meso-mechanics was used to predict the ultimate load and strength of open-hole plates under tensile and compressive loads, and the damage process was studied. Based on the simulation, the damage initiation occurred in many areas of the warp yarn due to the stress concentration in the contact area between the binder and the warp yarn. And the damage area of the open-hole plate exhibits an ‘X’ shape expansion both under tensile and compressive loads.

Abstract:In recent years, composite materials have been widely used in aerospace and other engineering fields. In actual use, the mechanical properties of composites will change significantly in different hydrothermal environments. There have been a large number of experimental studies at home and abroad in response to this problem, while less research has been conducted on the constitutive model theory of composites in different hydrothermal environments. The study of the thermal properties of composite materials is adopted to introduce the concept of hygroscopic expansion coefficient and thermal expansion coefficient on the basis of classical laminated plate theory. We have established the functional relationship between the elastic constants and the thermal parameters of the materials through the definition of a dimensionless temperature, deriving the constitutive equations of the single layer of composite material under the coupling of moisture and heat. Meanwhile, the 3D Hashin failure criteria has been used to simulate the damage evolution and failure mode of the composite laminates. The results show that the model can predict the elastic response of composite laminates in different moist and thermal environments, which provides an important reference to analyze the mechanical behavior of composite material structure in hydrothermal environments.

Abstract:This paper investigates a finite-time adaptive attitude tracking fault-tolerant control problem for non-rigid spacecraft with actuator fault, time-varying inertia and external disturbances, and proposes an adaptive finite-time attitude tracking fault-tolerant control algorithm. Based on the finite-time theory and adaptive approach, a controller is designed to guarantee that the actuator fault attitude tracking system is finite-time stable. Furthermore, for overcoming the inertia uncertainties and rejecting the external disturbances, an adaptive system uncertainty estimation and disturbance estimation were designed to compensate the system respectively. The practical finite-time stability of the system is proved via Lyapunov stability theory. Numerical simulation results demonstrate the effectiveness of the proposed finite-time control strategy.

Abstract:Flapping-wing micro air vehicles (FWMAVS) are subject to lift, drag and inertial loads of violent changes while fluttering at high frequencies, which seriously affect the flight performance and flight life. This paper establishes a mathematical model of wing lift, drag and inertial forces during the FWMAVs fluttering based on the analysis of movement and force conditions of the wing. A multi-objective optimization model targeting at improving the distribution of loads in the time domain is then proposed and solved by using NSGA-II algorithm in Matlab environment. After all the work, the Pareto optimal solution set of the hovering state is obtained. Comparison and analysis of the data show that after the optimization, the peaks of lift and inertial forces decline significantly and the load distribution is obviously improved, which shows that results of this optimization method meet the design requirements.

Abstract:The boundary layer control method by blowing is applied to the tail of amphibious plane to improve the steering ability of rudder. Using the CFD numerical simulation method, a two-dimensional scheme for the boundary layer control of the tail of a large amphibious aircraft was studied, design a seam baffle between the vertical stabilizer and the rudder, so as to prevent the high-pressure air flow on the windward side from hitting the leeward surface, Obstructing the air-blowing adhesion; The combined blowing scheme of the front edge of the tail stabilizer surface was studied to prevent the rudder from stall earlier. The results show that the steering ability of rudder is increased by about one times after the vertical tail is controlled by a blowing and combined with a seam baffle and a combination of blowing.

Abstract:Abstract: Benefit from the refined design of the hull layout, the seaplane can efficiently take off and land on the water surface. In-depth understanding characteristics of the water take-off and taxiing is crucial for the development of aircraft. Two research methods, towing test and numerical simulation method, are used to explore the flow mechanism, and the hydrodynamic characteristics of the large-scale amphibious seaplane during taxiing are analyzed. In order to ensure that the hydrodynamic and aerodynamic forces in the towing test are similar at the same time, the force and moment are unloaded, meantime the rigid external force module is added to the calculation platform to simulate the test unloading. The results show that CFD technology can be used for the two-phase flow coupling six-degree-of-freedom motion of complex shape without any detrimental loss of accuracy, and the flow field and model dynamics in the test are reproduced by simulation, yielding that the resistance error is within 10% during the whole take-off process. Furthermore, for large amphibious seaplanes with landing gear, the strong splash from the fore-body hull is the root cause of the hump drag.

Abstract:According to the some problems existed in the unmanned vehicle, a new amphibious hydrofoil vehicle with variable shape was proposed based on the characteristics of the torpedo and hydrofoil in this paper. The hydrodynamic characteristics of the amphibious hydrofoil vehicle is numerical simulated based on the LBM-LES. Lift curves and drag curves of the amphibious hydrofoil vehicle under water and surface of the water are got. The comparison results shows that the vehicle retracts its hydrofoil to make the drag smaller in a small angle of attack under water, it suitable for high speed navigation. The vehicle unfolds the hydrofoil to increase lift and reduce drag on the surface of the water. Meanwhile, the amphibious hydrofoil vehicle can meet its requirements of navigation under water and on the surface of the water by changing its shape. Shape design and amphibious navigation performance of vehicle still have much room for optimization.

Abstract:To investigate the blast resistance of sandwich structures with cellular metallic core, the dynamic response of sandwich structures with MHS(metal hollow sphere)and aluminum foams were studied both experimentally and numerically by employing ANSYS/LS-DYNA. Experimental results prove that sandwich structure with MHS can be used to resist blast. According to the parametric studies, the sandwich structures with thin inner face sheet and thick outer face sheet have stronger blast resistance than others. Comparison between sandwich structures with metal hollow spheres and those with aluminum foams was studied experimentally and numerically and the results demonstrate that structures with aluminum foam have advantage over the other in most cases. Also the results show that sandwich structures with interlaced hollow spheres have a better performance than those with paratactic hollow spheres. Moreover, it's inferred that the density graded core with the biggest density as the first impact layer and the least density as the last layer has more benefits in energy absorption. The conclusions are referable in the optimization of sandwich structures.

Abstract:Taking variable-section rotating cracked beam as an example, the damage identification based on auxiliary mass method combined with fractal dimension theory. Firstly, the mass-crack beam model is established, and the natural frequency curve is calculated with the mass position changing. Then the fractal dimension curve of natural frequency curve is obtained by using fractal dimension method, and the location and depth of the crack can be detected. Futhermore, the effects of crack position, crack depth, auxiliary mass and rotating speed are investigated in detail. The simulation results demonstrate the efficiency and accuracy of the proposed method.

Abstract:The titanium alloy bulkhead frame is one kind of the important components in the aircraft structure. It could be fabricated by using the new method of Electron Beam Welding (EBW) for parts assembly. An introduction is taken on the disadvantages of mechanical joints and Submerged Arc Welding for titanium bulkhead frame parts assembly, the advantage of EBW is distinct compared to the other two methods above. The Building Block Approach was adopted in the research of series tests. Firstly, the heat treat procedure of TC4-DT after welding was based on the welding specimen tension results according to specific parameter comparison. Secondly, the data base was built by doing series of experiments of standard specimen in tension, also for fracture toughness and crack growth rate. Finally, the EBW of TC4-DT titanium alloy bulkhead frame was successfully applied on the specific aircraft after doing short beam experiments and component experiments. Good mechanical properties of the welding joints was verified, and the weight reduction was distinct compared to the mechanical joints.

Abstract:Low altitude Airspace resources has always been the development bottleneck of the general aviation industry, and is also one of the key factors in restricting the development of general aviation in China. Based on theoretical research and field research, the article constructs the evaluation index system for the availability of the low-altitude airspace resources, using the multivariate linear regression method to analyze the impact factors of the military and civil aviation which affect low altitude aviation resource, then determines the index weight at all levels. Taking Jiangsu province for example, the article analyzes the current situation of the available low altitude airspace resources in Jiangsu province. By summarizing the regional actual situations and the collected large amounts of data, through multiple linear regression, the results show the influence value of various different factors on the region, and finally draw a conclusion related to low-altitude airspace resource availability. The research results demonstrate that the method is scientific and effective, and provide a reference for rational use of China"s low altitude airspace resources and the declaration of general aviation airspace.

Abstract:In view of the characteristics of the damage to the shallow layer of the airport and the requirements of the repair technology, the high early strength and rapid repair mortar prepared by the self-made special cementitious material has reached 32.5MPa and 4.2MPa of the compressive strength and flexural strength of 2h respectively. Then, the bonding property and durability of the mortar were studied. The results showed that the bonding strength of 2h and 28d of high early strength rapid repair mortar reached 62% and 79% of flexural strength respectively. Compared with C40 concrete, the mending mortar has a micro expansibility in the early stage, the compensation interface shrinkage, the decrease of 120d shrinkage by 60.5%, and the wear resistance of 3d can reach the wear resistance of C40 concrete 28d, and it has excellent permeability resistance and impact resistance.