Abstract:Thestabilityofhybridfiniteelementmethodoftransientthermalstressproblemishardtobeguaran-teedbecauseofthedifficultyofsatisfyingtheladyshenskaya-babuska-brezzi(LBB)conditions,accordingly,the combinedhybridfiniteelementmethodoftransientthermalstressproblemisproposed.Combinativevariation principleandthecorrespondingfiniteelementdiscretizationoftransientthermalstressproblemisconstructedon thebasisofdomaindecompositiontechnique.Thenumericalperformanceofcombinedhybridelementforsol-vingtransientthermalstressproblemisverifiedbynumericalexperiments.Thenumericalresultsindicatethat combinedhybridelementwith8nodes(CHH(0-1))cangivealmostthesamecomputingaccuracyofdisplace-mentandbettercomputingaccuracyofstresscomparedwithcuboidelementwith20nodes(B20). Keywords:transient;thermalstressproblem;combinativevariationprinciple;stability;combinedhybridele-ment;bigwidth-to-thicknessratio;stressaccuracy

Abstract:Three-dimensional tactical training Airspace planning is a complex combinatorial optimization problem. it is very important to construct the corresponding model and design the efficient and fast algorithm to improve the efficiency of airspace utilization and training. Aiming at the characteristics of airspace, this paper divides the whole airspace into cubical units. Based on this, the training airspace planning model is constructed, and an improved genetic algorithm is used to find the optimal solution, which excludes a large number of infeasible solutions and improves the convergence rate. The experimental results show that the method is feasible and stable, and has a strong practical value, which can effectively solve the planning problem of 3D tactical training airspace.

Abstract:Given that human factors are the key factors that affect flight safety, and the decision-making factors are difficult to measure, so the SHELL model and the matter element theory were combined to carry out the study of flight safety comprehensive assessment. Based on the SHELL model, the flight safety assessment index system is established by the human factors of the aircrew as the main object. The weights of each index in the evaluation index system are calculated by using the analytic hierarchy process (AHP). The evaluation model was established by the matter element theory to calculate the correlation degree of evaluation index for each security level, and then the comprehensive evaluation result of flight safety assessment is calculated. Through further analysis of the results, the key factors influencing flight safety can be found in order that airlines can take precautions in advance accordingly, safety management can be strengthened and the occurrence of flight accidents can be avoided. At the end of the article, an example verifies that the method is feasible and valid, and the uncertainty of the assessment process can be solved to the maximum extent. It provides a feasible method for flight safety management of airlines.

Abstract:Electric load simulator, which can simulate aerodynamic loads acting on aircraft rudder, is an important equipment in hardware-in-loop simulation. A kind of double-loop motor driven load simulator with rapid response is introduced in this paper. The mathematical model of the load simulator is established and is verified by the comparison of simulation curve and experimental curve. It is indicated that the double-loop load simulator restrains the disturbance torque effectively, and can reach the frequency band at 40Hz with steering gear perturbation under simulation circumstances. The research provides an implementation with higher frequency and better compatibility for electric load simulator.

Abstract:With the openning of low-altitude and development of general aviation, low-altitude airspace flow will increase dramatically, this is bound to cause more flight conflics.To solve the problem of low-altitude conflict, this paper gives a conflict avoidance algorithm based on ADS-B information, in order to offer the pilot with reasonable avoidance strategies if needed. Firstly, the algorithm excluded the safe aircrafts after analyzing situation around plane by using relative motion.And then researched collision resolution strategies for the potential conflict aircrafts,including course change and speed change.Finally, validity of the algorithm is verified through the computer simulation. Simulation results show that this algorithm is correct and effective, which can quickly find the flight conflics and give collision resolution strategies, and the validity of course change is better than speed change.

Abstract:This paper illustrated by the case of some army helicopter, conducting a research of capabilities-based army helicopter flying quality flight test designing and evaluation. Based on the operational mission requirement of army helicopter and operational capabilities evaluation, carrying on the flight test design, flight test result anylsis and flyling quality level evaluation research and so on. Present a thought of capabilities-based army helicopter flying quality demonstrate flight test designing, and valid evaluation method.

Abstract:The reliability of Aviation four stations gas support equipment is improving constantly, but gas support process of the accident is still happening. STAMP regards safety as a matter of control, believing that the accident is caused by unreasonable control and inaccurate information feedback. This paper first introduces the working mechanism of STAMP / STPA, and then constructs the STAMP model for Aviation Four Stations Gas Support Process. The STPA safety analysis method is used to analyze the safety of the Aviation Four Stations Gas Support Process and identify the unsafe control action, the scene analysis of the generated unsafe control behavior is performed, and finally the comparison with Accidents Tree Analysis (ATA) is carried out to confirm the superiority of the method.

Abstract:The purpose of this paper is to find a simple and effective method to evaluate the damage tolerance of complex structure. Aiming at the problem of evaluating fatigue life of complex structure repaired in aviation engineering, a simple and effective method was put forward to obtain the stress intensity factor. Combined with damage tolerance analysis method, the fatigue life and the residual strength of the repaired structure with cracks in the flange of a frame floor of a frame are analyzed. A simplified analysis model is built according to the loading characteristics of fuselage floor beam structure, the stress intensity factor of crack tip under different crack length was calculated, and then the dimensionless stress intensity factor is determined by the relationship between structural boundary load and stress intensity factor. According to the damage tolerance analysis method program, the lifetime of the structure from the initial crack to the critical length and the residual strength of the structure under the length of each crack are calculated. The analysis shows that the fatigue life and residual strength of repaired structures meet the design requirements of damage tolerance. The damage tolerance analysis procedure and method presented in this paper can be applied to evaluate the damage tolerance of similar structures in engineering.

Abstract:Numerical studies were performed to analyze the thrust-vectoring performances of a bypass dual throat nozzle (BDTN) under different conditions. The main results show that：The BDTN has the same flow-filed structure with the conventional dual throat nozzle (DTN), but can generate a better thrust vectoring performance with producing more steady and ef?cient vectoring de?ection. A thrust vector angle of 24.6° is obtained with little thrust penalty. The thrust vector angle and the thrust ratio are decreasing with NPR increasing. The high temperature and high pressure can lead to the thrust vectoring ef?ciency loss tremendously with the thrust vector angle can decrease to 12.75°and the thrust ratio can decrease to 0.882.

Abstract:In this paper, we presented a new way that used bending moment as piezoelectric exciter force to simulate the force of new novel piezoelectric exciter Macro Fiber Composites. The simulation results and the experimental results were fitted to simulate the force of the piezoelectric exciter. It is the basis of the experimental research on the actuator as the exciter or the control actuator. Firstly, A dynamic simulation model of wing structure with piezoelectric exciter was established by means of the finite element model. Then by modifying the magnitude of the piezoelectric moment of the simulation model based on the results of the ground test of the piezoelectric exciter in order to fit the simulation results with the ground test results, and finally the nonlinear piezoelectric actuator was obtained. The magnitude of the force was verified by other ground test data. The force simulation technique is applied in different experiments. The force simulation of MFC was realized through the above research, and the force value was obtained.

Abstract:Supercharger is widely used in vehicle engines because of its good response characteristics while the application in aircraft piston engines is still very rare. The working process of the supercharger was analyzed, and the linear relationship between the opening and closing pressure of the bypass valve and the turbocharger pressure ratio is modeled on the basis of the reed valve model. The GTPOWER numerical simulation model of a certain type of aero piston engine was established and confirmed. Based on the whole model, the mass flow rate of the bypass valve and the flow area of the bypass valve at different heights were studied. The results show that under the cruise condition, the valve is closed at 2680m above sea level, and the valve is closed at 3000m above sea level under taking off condition which confirm the accuracy of the model provides the theoretical basis for the actual high altitude flight of the engine

Abstract:Distributed sound localization system for low altitude targets based on the platform of TMS320C6713 is constructed. In the system, DSP is the core processor and signals received by the microphone are sampled via AD chips. The direction of the sound source is calculated through TDOA and the angles of each node are fused by direction finding cross localization method to calculate the position of the sound source. The simulation and experimental results show that the system has high precision and stability and can meet the needs of the practical applications for low altitude targets.

Abstract:This paper studies that a twin-engines light general aircraft completed modification, which changed the aerodynamic characteristics, so it also impacted the flight performance and control-stability. As an example in this paper, the aerodynamic characteristics of an aircraft with external pods were calculated using CFD，then the influence of the fight performance after modification was calculated and the control-stability was analyzed. The result show that, the modification has some influence to the flight performance, and less effect to the control-stability，also it can guide the aircraft mounting pods, meanwhile it has a certain reference value of airworthiness certification and flight test.

Abstract:There are unable to make full use of available exit problems in emergency situations of civil aircraft. In order to reduce evacuation time of occupant in emergency and improve personnel safety, a dynamic estimating method for aircraft emergency evacuation process was proposed. The method based on the cellular automata theory, considering the exits availability impacting on the process of evac-uation. An emergency evacuation guidance model was built, in which five kinds of a total of 20 rules was formulated. For a passen-ger cabin layout scheme of 149 seats as case, the total evacuation time guided by the proposed method is reduced by more than 6% compared with the typical evacuation process, and OPS decreased by 30%. The results show that camera monitoring equipment and voice prompt device installed in the aircraft cabin can improve the efficiency of the overall evacuation combined with a dynamic esti-mating method.

Abstract:The flexible beam is two bidirectional flexure hinge beam，is widely used as main component of wind tunnel cassette strain gauge balance，its stiffness performance directly affects the accuracy of wind tunnel cassette strain gauge balance，and it is an important guarantee for accuracy of test data of engine test bench，whereas flexure hinge design is the key of flexible beam design. Firstly，four kinds of typical flexure hinges are analyzed by finite element method，a flexure hinge which has good integrated stiffness is selected. Secondly，for selected hinge style， the influence of three key structural parameters on hinge stiffness performance is researched. Finally，basis on above research，five kinds of min-thickness flexible beams are designed and analyzed by finite element method，and their stiffness performance are validated by loading test. The result shows the hinge that has b=40mm，R=50mm and t=40mm can get best stiffness performance，in addition，there is a good agreement between calculation and test (the maximum error is less than 5%)，this indicate it is feasible and reliable that finite element method is used to design and optimization of flexible beam.

Abstract:Based on the establishment of system mathematic models for civil aircraft cabin pressurization system, simulate and analyze system performance under flight envelope, as well as its performance under abnormal conditions, such as single failure of air conditioning pack, emergency depressurization and burst depressurization. The result shows that single failure of air conditioning pack has little influence on system performance, and emergency depressurization can meet the requirement of airworthiness standards. For burst depressurization, cabin depressurizes fastly using near the same pressure dump time with different leak area.

Abstract:Process noises and measure noises exist in flight test data, which lead to incompatibility of flight data. To solve the problem that output error method the popular method used in flight test data compatibility checking is not fit for helicopter model and fixed plane lateral model data compatibility checking with serious coupling. Firstly, extended Kalman filter is applied for states estimation. Next, compatibility analysis for results of extended Kalman filter is carried on by way of output error method. By this technology, problems of wave filtering errors which are caused by externed Kalman filter primary convergence are solved, and problems of time delay modification by hand in output error method is conquered and inconvergence of output error method when errors in measuring data are big are solved , respectively. Verification effect and computational efficiency are greatly improved.

Abstract:The high cycle fatigue properties of single crystal IC10 superalloy were investigated at room temperature and 750℃ in ambient atmosphere. The high cycle fatigue strengths of single crystal IC10 was 288Mpa at room temperature and 416Mpa at 750℃ with ratio of stress R=-1 and loading frequency 83.3Hz. The fatigue facture surface morphology was observed by SEM, and the fatigue cracks were found mainly originate from defects on surface or subsurface of specimen. The fatigue fractures were composed of fatigue source, fatigue district and final stage. The internal mechanism of the high cycle fatigue properties of IC10 single crystal superalloy at room temperature and 750 ℃ was discussed based on the observation.