guxiangying , song chen , Ma Tielin , Zhang Xiao ou
2019, 10(S1):1-5. DOI: 10.16615/j.cnki.1674-8190.2019.S1.001
Abstract:The landing gear is an important part of the aircraft. The strength of its structure directly affects the safety in the take-off and landing process. The landing gear of the aircraft is designed for the strength and rigidity specification. This paper extracts the attitude and motion information during landing process from flight data to analysis ground loads of the landing gear, thus providing reference and input for troubleshooting. The results show three-direction load may be one of the causesfor the damage of landing gear.
2019, 10(S1):6-11. DOI: 10.16615/j.cnki.1674-8190.2019.S1.002
Abstract:As one of the numerical calculation methods, the Finite Element Model(FEM) has been used a lot in the civil aircraft strength design and structure optimization, and also been recognized as the most useful numerical calculation methods in the aviation domain. But still now on, there is no one effective way to validate FEM for certification. This paper solved this problem from regulation by discussing the FEM airworthiness certification requirements and methods to make sure the certification points and established the certification evaluation system finally. The method of verifying the FEM for certification can contribute for the future civil aircraft design.
2019, 10(S1):12-18. DOI: 10.16615/j.cnki.1674-8190.2019.S1.003
Abstract:Accompanying with the improvements in design technology and application of advanced materials, the structure of modern aircraft is much lighter and more flexible, which induced significant aeroelastic effects. Decoupling of the rigid-body motion and the elastic vibration is not always present. As a result, this dissertation works in the interdisciplinary field of flight dynamics and aeroelasticity to search for an integrated flight dynamic modeling methodology for flexible aircraft. The Lagrange equations of motion of the flexible aircraft are derived, which considered the rigid-body degrees of freedom and elastic degrees of freedom. With the assumption of small disturbance on the nonlinear trim equilibrium state, the state-space equations describing the motion with rigid-body degrees of freedom and elastic degrees of freedom are established. The unsteady aerodynamics in the frequency domain is computed by the doublet-lattice method, and then it is transferred into the time domain by the rational function approximation. The state-space equations are applied to analyze the stability of the very flexible aircraft, and the results are compared to the rigid method and linear method, in order to illustrate the effects of geometric nonlinearity and the coupling between rigid-body motion and elastic vibration. The results of nonlinear analysis indicate that the critical stability flight speed is even lower than the result of linear analysis.
Jiao Jun , Wei Fei , Wang Mingzhen , Sun Feng
2019, 10(S1):19-23. DOI: 10.16615/j.cnki.1674-8190.2019.S1.004
Abstract:In order to investigate the effect of crosswind on helicopter ditching performance,designing of a crosswind-fan system and ditching experiment of a helicopter model were conducted , investigated the effect of blade angle and distance between fans on crosswind velocity,then investigated the effect of crosswind velocity on attitude angle,overload and bottom-pressure of the helicopter model。The results show that,the blade angle equal 18 degree is better than 15 degree and 20 degree.The crosswind velocity uniform distribution when L/D equal 1.66.The crosswind has almost no effect on pitch angle but makes the roll angle amplitude larger and more difficult to be stabilized.When the crosswind velocity increases,the overload,the bottom-pressure at the plane of symmetry and near crosswind-fan system increases,but the bottom-pressure far from crosswind-fan decreases.
Xu Mao , Tang Yihao , Hong Shaobo
2019, 10(S1):24-27. DOI: 10.16615/j.cnki.1674-8190.2019.S1.005
Abstract:Sandwich composites are becoming more acceptable as primary components in the structure of helicopter. The design of laminate zone is extremely important, not only need to meet the requirements of the design of part assemble and aerodynamic shape, but also to achieve the goal of the light weight design as possible. An investigation with experiment and analysis on typical laminate test article of SynCore film has been accomplished. The results show that the experiment data of HC 9823.1 K20 aero laminate is steady and reliable, take the extrusion strength of 44.8MPa could be the reference of the helicopter structure design and check analysis of sandwich composites.
wanghongzhen , yuqin , ligang , dengxingmin
2019, 10(S1):28-33. DOI: 10.16615/j.cnki.1674-8190.2019.S1.006
Abstract:For the problem of fatigue failure on of bolt in random vibration test, the random vibration fatigue life is estimated by finite element method. The method is based on the information of the frequency domain of random loading history. In this paper, bolts are simulated by rigid connection. Firstly, the stress transfer function of the structure is analyzed by frequency response simulation, obtained peaks per second of the bolt. Secondly, the force of bolt was picked. Thirdly, the stress of bolt was calculated. Combined with S-N curve of 17-4PH and fatigue damage accumulation theory, random vibration fatigue life of bolt is analyzed by Three-band method.
LI Baozhu , HE Yu , Liu HaiTao
2019, 10(S1):34-37. DOI: 10.16615/j.cnki.1674-8190.2019.S1.007
Abstract:With regard to the fuselage stiffened panel, it is essential to attain the stress intensity factor, and the core work is to calculate the geometrical factor. According to the analysis method of the stiffened panel structure which was put forward by Swift, the corresponding analysis tool was programmed,by which the geometrical factor of the fuselage panel with circumferential was obtained, then the theoretical result was compared with other result which was computed by finite element analysis. In the last, the geometrical factor was input into the Nasgro software which was adopted to carry out the crack growth analysis, the life was almost identical with the test result. This method was pretty efficiency, it can help save a lot of time and money and have a strong engineering application value.
2019, 10(S1):38-43. DOI: 10.16615/j.cnki.1674-8190.2019.S1.008
Abstract:At present,most of the structural crack propagation path judgment in helicopters is based on experience,lack of theoretical numerical simulation and effective analysis methods.The paper based on abaqus finite element software and practical experience seting up initial crack, a typical helicopter structure was selected for crack propagation simulation,investigating corrosion area and strengthening slot on crack propagation. The method and conclusion presented in this paper provide a new idea for the crack propagation path and damage tolerance design of helicopter structure, and provide some references for the improvement of engineering desing..
YuQin , LiuXiaotiao , MaMina , LiJie
2019, 10(S1):44-49. DOI: 10.16615/j.cnki.1674-8190.2019.S1.009
Abstract:In this paper, the finite element model of a torsion tube universal joint assembly and supporting bearing of C919 is established. The modal analysis and sinusoidal analysis are carried out. The fatigue life calculation formula under sinusoidal vibration is deduced and the life of the model is predicted. The correctness of the model is verified by modal test. The correctness of the fatigue life calculation is verified by sinusoidal test. The fatigue life evaluation can be used to predict the sinusoidal vibration fatigue life of related models through sinusoidal test.
SONG Botao , MIAO Zhitao , CHI Fujian
2019, 10(S1):50-54. DOI: 10.16615/j.cnki.1674-8190.2019.S1.010
Abstract:The relative velocity is always very large when the bird impacting on the aircraft windshield, it is an important factor for damage of aircraft structures which could even lead to aircraft crash and death of crew members in the most disastrous cases. Based on the bird strike problem, this paper adopts the method of comparative analysis, Introduces the ground test, engineering calculation and finite element simulation of the current method for bird strike in detail. Then select a certain aircraft windshield laminated glass as the research object, established the bird strike windshield model by FEM, using the arbitrary lagrange euler coupling (ALE) method for the simulation, got the windshield’s displacement, velocity, acceleration and other parameters, which can provide reference for windshield design by comparing the parameters.
2019, 10(S1):55-61. DOI: 10.16615/j.cnki.1674-8190.2019.S1.011
Abstract:Taking a certain type of tilt-wing UAV as the research object, the motion mode of each component during the transition period is analyzed, in order to enable the UAV to fly smoothly and successfully complete the transition phase, a tilting device with a worm and wormwheel mechanism as the main component is designed. The worm and wormwheel device is smooth transporting power and can make the tilting wing part have a self-locking effect, so that it does not get relative motion due to the influence of air force after reaching the predetermined position, and it will also ensure the stability of the forward flying mode of the UAV. The platform is a tool for analyzing the movement conditions of the tilting device and completing the strength and life check analysis of the device. The analysis results show that the designed device can meet the existing strength and life requirements, and the calculation results can provide some reference for subsequent optimization.
2019, 10(S1):62-66. DOI: 10.16615/j.cnki.1674-8190.2019.S1.012
Abstract:In the case of good design ratio of the area,we can obtain higher load of the structure about wall panel design. But for the Integrally panel, establish skin and finning separation surface position is very difficult in the practice design.Aiming at the problem on the related research work,the skin thickness in 2.5mm to 3.5 mm “hit” within the scope of whole wall, in the area under the same conditions for a given separation surface position, get the skin and the optimun design for the bar area ratio. This area ratio design of thick skin,the shape of integral panel under axial compression load capacity of the strongest.
Zhong Xiaohong; Lu Sheng; Huang zhijun;Pei HuaPing , Lusheng , Huangzhijun , Peihuaping
2019, 10(S1):67-71. DOI: 10.16615/j.cnki.1674-8190.2019.S1.013
Abstract:According to the structural characteristics of the pipe nipple which is located in the main landing gear actuating cylinder of an aircraft, combine with structural function and connection strength analysis, this article mainly put forward the measures to improve the pipe nipple, what can meet the requirement of expected goal.
Zhu Liyuan , Chen Lei , Sun Yingchao , Lin Haibin , Wu Huaqing
2019, 10(S1):72-75. DOI: 10.16615/j.cnki.1674-8190.2019.S1.014
Abstract:Based on the flex-rigid coupling dynamics theory, the flex-rigid coupling dynamics model was built using the software LS-DYNA. The problem of transient collisions when folding-wing deploying to expected position was analyzed. The dynamics process of the partial contact impact was numerical simulated by establishing the contact model and joint between the different parts mainly. The model method properly obtains the dynamics response of folding-wing, and the impact characteristic of folding-wing was acquired. The stress distribution could be gained in the process by the method. The result can be used for the design of the folding-wing.
Zhang Mengdi , Zhao Caixia , Li Jiangang
2019, 10(S1):76-81. DOI: 10.16615/j.cnki.1674-8190.2019.S1.015
Abstract:In order to study the influence of the mechanism with clearance, a kind of projection mechanism is analyzed and simplified into a kind of four-bar mechanism, an nonlinear spring-damp model is established. Then the model considering joint clearance is incorporated into ADAMS and the dynamic simulation is carried out. The simulation results show the dynamic model can be built by using ADAMS and analysed the effects of clearance, and give the basis of mechanism and optimization.
zhaocaixia , zhangmengdi , lijiangang
2019, 10(S1):82-86. DOI: 10.16615/j.cnki.1674-8190.2019.S1.016
Abstract:Localized defects in operating planetary gears would cause abnormal gears meshing and impact. Correspondingly, the characteristic frequency would be changed. In this paper, a rigid-flexible coupled model for planetary gear trains was built using ADAMS and ANSYS. The frequency domain curve of meshing force was calculated by FFT. At this point, the characteristic frequencies of the defect-free planetary gear trains and both the planetary gear trains and sun gears with localized defects were analyzed. The simulation result is consistent with the theoretical results which indicated that the proposed model of virtual prototype machines is reliable: Respectively, the characteristic frequencies of the defects-free planetary gear trains, the planetary gear trains and sun gears with localized defects are 265.34Hz, 17.67Hz and 36.13Hz. this conclusion could be applied in identification of localized defects in planetary gears and sun gears in gear trains. Furthermore, it provides guidance for research on reliability and vibration performance of planetary gear trains.