Abstract:To understand the mechanical behavior of a new single-crystal nickel-base superalloy DD407 at high temperature and strain rate,using a CSS4410 quasi-static test machine and Hopkinson pressure bar with high temperature and strain rate coupling function,the plastic flow characteristics are studied in a range of strain rates from 0.001/s to 4000/s,and initial temperature range from 293K to 1273K． Then, the miscrostructure analysises of undeformed and deformed samples are carried out with the aid of the SEM technique． The results demonstrate that,the working temperature of this superalloy is not beyond 1073K,the failure temperature doesn’t change with the increase of strain rate,and the samples are sheared to failure．When the temperature approachs a critical value ,the plastic flow stress shows strong sensitive to temperature and strain rate．Unlike common metallic materials,this material doesn’s show obvious aging phenomenon．

Abstract:The tank of Reusable launch vehicle (RLV) is installed inside the body, forming a double layer structure. The stress characteristics of connection between inner tank and outer vehicle airframe is very important to reducing the structural weight、 improving reliability. In this paper，three kinds of connection scheme were put forward which are statically determinate structure and statically indeterminate structure， the finite element analysis method was used for the static analysis；and explore the effect of thickness on force transmission ratio. We draw a conclusion that the statically indeterminate structure joint scheme is more reasonable; it can adjust the axial load in the inner and outer layer by changing the thickness of structure. In this way, we can achieve the expected purpose.

Abstract:As a new nondestructive detection method, Laser ultrasonic, which gradually goes into our sight, is non-contact , point detection and have the significant advantage in high efficiency of complex shape sample test . The article summarized the principle and advantages of Laser Ultrasonic technique, penetration and pulse reflection method were used to test the sample, which was composite laminated containing a preseted damage . The results showed that Ф2mm preset defects could be tested, which can reach the same detection-rate as a ultrasonic test system with a conventional piezoelectric probe.

Abstract:Based on the three-dimensional progressive damage analysis and cohesive zone model method, a new progressive damage model capable of numerically simulating the behavior of bolted composite joints comprehensively considering composite in-plane and delamination failure is developed. Through the strength analysis of two typical composite single fastener joints, it demonstrate better agreement with the experiments than the traditional 3-D progressive damage model. By this model, a study of the delamination propagation of the composite joints is performed in this paper, and it is found that the direction of delamination propagation is same with the orientation of fracture. The effect of tightening torque on the strength of composite joints and the suppressing delamination propagation of hole is studied.

Abstract:Fault tree, faulty petri net and Bayesian network are three powerful models used to assess a system’s reliability and safety. Fault tree is the most widely used while each of the latter two has its own irreplaceable merits, which can make up fault tree’s deficiency in practice. Based on the basic knowledge about these three models, both method for mapping fault trees into faulty petri nets and method for mapping fault trees into Bayesian networks are discussed. Combing with these two methods stated above, a table that shows these three models’ equivalent classic logic topology is presented, which reveals the inner connection among these three models. On the basis of the table, a method for mapping a faulty petri net into Bayesian network is raised. Meanwhile, a failure event of unexpected ignition of an engine is studied and compared using these three models separately and the results show that faulty petri net describes the process of fault propagation clear and using the equivalent Bayesian network that mapped from a petri net or fault tree, more quantitative information can be calculated.

Abstract:Due to the complexity of motor pattern of mixed-fragments warhead field, it was difficult to get power field related characteristics. We used the ANSYS / LS-DYNA to establish a mixed-fragments warhead power field model, and screened speed, scattering angles and other information with post-processing software LSPREPOST. A computer program was coded to calculate the vulnerability of a particular model of aircraft, taking into account four kinds of damage, such as overpressure, penetration, ignition and detonation, as well as four kinds of warhead. Finally, in condition of the same size of warhead, the double-layer-mixed-fragments warhead obtained the highest kill probability, which provids a theoretical support for the missile warhead design.

Abstract:The paper takes bladed disks with geometric mistuning as the object of the research, the expression of reduced order model was derived from the dynamic equation, based on the modeling method with sectors. The modal analysis and force response analysis of bladed disks with geometric mistuning were finished by using the reduced order method. In this paper validated the method using an academic bladed disks finite element model by comparing the natural frequencies and the force response. The result shows that the data of the two methods was fully meet, which proves the correctness of the reduced order method.

Abstract:The unsteady Navier-Stokes equation and rigid body dynamic equations are solved to simulate the flight trajectory of a spinning projectile. The unsteady aerodynamic computations uses an in-house hybrid unstructured Navier-Stokes flow solver (HUNS3D). The rigid body of 6-DOF motion equations are solved using an advanced Adams prediction-correction method. The Coupled Computation Method is applied to simulate and analyze the flight trajectory of U.S. Army Research Laboratory spinning projectile test model. Computed results are found to be generally in good agreement when compared with experiment data and reference numerical results.

Abstract:The box-wing layout with canard could significantly improve the whole vehicle’s longitudinal pitching moment properties. This thesis focuses on the box-wing layout which is proposed in the literature [5]. The canard’s influence on the aerodynamic performance of box-wing layout, and the influence of the canard installation angle, canard longitudinal position along the body axis, and canard area on the aerodynamic performance of box-wing layout under cruising flight were studied through numerical simulation. Results are showed as below: 1. Canard could increase the box-wing layout’s maximum lift coefficient and the stall angle of attack, and could effectively regulate the longitudinal pitching moment, but would slightly reduce the maximum lift-to-drag ratio; 2. Under cruising angle of attack 3° and cruising speed of 50m/s, the installation angle and area of canard would have a great influence on ??the aerodynamic performance of box-wing layout while the canard longitudinal position would affect less on the box-wing layout. Above all, we could get that the canard could significantly improve aerodynamic performance of the box-wing layout with the comprehensive consideration of these parameters of canard.

Abstract:An aerodynamic optimization chain based on CFD is built for conceptual and preliminary design of unconventional aircraft layout. In this paper, the combination of NURBS parameterization method and CPACS (Common parametric aircraft configuration schema) data format developed by DLR can successfully describe the parameterized configuration of the entire aircraft. The grids for calculating the Euler equations are automatically generated and the aerodynamic characteristics of parameterized aerodynamic shape are evaluated. Then the response surface model (RSM) is built. Based on RSM the SQP gradient algorithm is sought under satisfying constraints. An OneraM6 wing is chosen to validate the optimization chain. The optimization results indicate that under conditions of constraint, he drag coefficient of the optimized wing is reduced severely .

Abstract:This paper briefly presents a parametric flight loads identification method which combines genetic algorithm and extreme learning machine (ELM). The model is based on ELM method, and genetic algorithm is used to develop bias weight and weight matrix between input and hidden layer in ELM network. At the end of the paper, GA-ELM model is used to identify flying load based on real flying data. The identify result is compared with that of BP network and original ELM method, and GA-ELM model is proved to be validated, accuracy and feasible.

Abstract:Abstract：Based on the modern structural design requirement and the overpowering need of reducing structural weight，the major research work in this thesis includes building up the structural geometrical model by CATIA CPD mould of composite RTM Waved-beams with large size and complex thickness area,optimizing the ply stacking sequence of composite laminates by coding Fortran program，implementing the Waved-beams test,the Waved-beams has been successfully applied and meets the need of reducing structural weight 。

Abstract:Dynamics and mathematical Analysis is carried on landing gear according to the actual Physical components, shock strut system, Nose wheel steering system and brake system. Using Matlab/Simulink software to establish a mathematical model of the landing gear system which is applied to aircraft six degree of freedom model and been simulated, including acceleration taxiing characteristics, high/low--speed turns characteristics, take-off characteristics, landing characteristics and brake characteristics. Moreover, the model is used to flight test in the moving base simulator. The simulation result indicates this model appropriately reflects the change of force and moment in the process of plane’s taking off and landing . The model is established use the method of ‘independent modeling of main components of landing gear , Linearly superposition of Kinematics characteristics’,which can easily and quickly applied to the design of the control law and can be applied to different types of landing gear systems, with a strong engineering practicability.

Abstract:As the aircraft flight control system becoming more and more complicate ,flight test has present a mumerical tendency.Before real flight ,simulate the flight handling quality through numerical calqulation can supply a prediction and enhance work efficiency。In this article we analysed the wind tunnel data of certain type aircraft and built its aerodynamic model.On the basis of the model we developed the real time flight simulation platform by using the Flightgear software and accomplished major flight handling quality through numerical experiment.Then we choose typical real flight test data to verify our model.The comparision between the calculation result and experiment result have got a good agreement,and can supply the prediction and reference evident for the flight test.

Abstract:Water System is an important system in civil aircraft. During the design of water system, the design of pipe is a key part. And the numerical simulation of pipe flow can help the design and optimization of pipe. So in this paper, the study on numerical simulation of supply pipe flow in civil aircraft water system is presented, for better use of the numerical simulation in the design of water system pipe. Under different conditions of pressure drops and wall roughness, the water supply pipe flow is simulated with FLOWMASTER Pipe Network System and CFD, and the results of the two methods are analysed . Comparing the simulation of the two methods shows that FLOWMASTER Pipe Network System can obtain the main performance of pipe rapidly, accurately and reliably, such as flow rate; and CFD can get detail information of pipe flow field. In the design of water system pipe, the two methods should be used in conjunction, playing their respective advantages, to finish the work better with the help of complementary advantages of the two methods.

Abstract:The control law is the important part of the windshield heating system design. In this paper, the control law is simulated by finite volume method. The influence of the climate on the system is analyzed by simulating the control rules under the whole flight envelop. The work rules of system in the actual situation are obtained. The final results demonstrate that system would not operate at the full power because of the thermal inertia. The environment has great influence on system. There are great differences in temperature and power of glass in different weather. The control law can be optimized to increase the system heating efficiency. It can be provided as a reference to the design for the windshield heating system.

Abstract:For the purpose of analyzing and predicting spin characteristics of aircraft, the rotary balance testing in wind tunnel is mainly used to measure aerodynamic forces acting on aircraft model rotating around the longitudinal axis of wind axes system. In order to meet the demands of project tests and aerodynamic research, the rotary balance system was developed in FD09 low speed wind tunnel. This paper introduces design feature, performance index, and the verification tests using SDM (standard dynamic model) and fighter plane model of the system. The results indicate that the rotary balance system of FD09 wind tunnel is stable and reliable, the repetition of test curves of FD09 wind tunnel and reference curves are good, the test curves of FD09 wind tunnel are more smoothly than reference curves, and the aerodynamic coefficients yielded by the rotary balance system of FD09 wind tunnel have high accuracy. The rotary balance system of FD09 wind tunnel can be put into the project tests and aerodynamic research.

Abstract:Effect of laminar flow extent on drag reduction characteristic based on engineering practice is developed for some civil plane, which can be the important means to improve the economy. It is simulated for the wing-body model at Reynolds numbers 10 million and 18 million, with the laminar flow extent be kept respectively 7%, 15%, 20%, 30%, 40% of the local chord of wing. The frictional drag coefficient is effectively decreased as the laminar flow extent is increased. Compared with the full turbulence state, the drag can be reduced by about 11 percent and the lift-drag ratio can be increased by 12.3 percent when the laminar flow extent is kept with 40 percent, and drag reduction benefit can be obtained more at lower Reynolds number.

Abstract:During tethered balloon preliminary design, the residual buoyancy choosing directly affect the parameter design of envelop and ballonet such as volume. Inappropriate residual choosing will leading to project cost increasing or cannot achieve equilibrium characteristic. This paper analyzed and calculated the equilibrium characteristic of the same tethered balloon with different buoyancy, and two tethered balloon with different volume at the equal residual buoyancy. The result shows residual buoyancy has significant impact on tethered balloon static equilibrium characteristic, especially for small volume tethered balloon. The residual buoyancy should be serious considered during preliminary design. While considering helium input magnitude, the appropriate residual buoyancy choosing will increase economic characteristic for big volume tethered balloon.

Abstract:Individual aircraft life monitoring is of important significance for tapping the potential of each aircraft's life, to ensure safe use of the aircraft structure and extend aircraft service period. At present, individual aircraft life monitoring can be divided into four categories according to the technology way: regular inspection and maintenance; monitoring based on flight parameter; combination of the monitoring based on strain of dangerous parts and the monitoring based on flight parameter; monitoring based on smart materials and structures. This paper first reviews the aircraft life monitoring of development, technology advantages and disadvantages of each stage were compared, showed the way with the progress of the monitoring hardware technology is constantly progress, increasing accuracy, and then summed up in monitoring technology and its advantages and disadvantages of the four stand-alone way life used to monitor the development process, through the analysis of several technical methods that aircraft health monitoring system that rely on the monitoring of smart materials will be the future direction of development of the single life monitoring.

Abstract:Propeller is the most important aerodynamic part in the UAV system, but the effect of checkout method of UAV’s propeller by measuring rotate speed using piston motor in ground condition is not good in fact. The test rotate speeds are not centralized into the standard range of rotate speed as anticipant, but distributed symmetrically. The check plan of propeller is usually delayed by this reason in actual. The aerodynamic characteristics of propeller are decided by the shape, and the disturbances of slipstream are ignored in this test method using piston motor in ground condition. Accordingly, in basic of results of rotate speed measured by piston motor in ground, wind-tunnel test is used to measure the aerodynamic characteristics of propeller in different velocities and rotate speeds, and flight emulate method is used to compute flight capabilities of the same UAV after using these propellers. Finally, improvements on checkout method of propeller are provided, by analysing wind-tunnel test data and flight emulate results.

Abstract:The common analytical sensitivity method of the large-scale structure takes a lot of time for solving the large-scale equations, the Domain Decomposition Method (DDM) of the FEM stiffness matrix is proposed in the paper. It can make use of the high accuracy of analytical method, and improve the computational efficiency by compressing the large-scale matrix into the smaller. In the large structure, the pseud load of the numerical sensitivity has a lot of zeros, and the displacement components with relevant to design variables have non-zeros. The displacement components are reordered behind others through reordering nodes, by which the stiffness matrix is assembled. Then the stiffness matrix is decompressed to smaller matrixes using the Domain Decomposition Method (DDM). The computational cost can be reduced a lot by using these matrixes to calculate the sensitivities of displacement. These data can be used repeatedly in the optimization process, thus the efficiency is improved greatly.