Advanced Search

2007 Vol. 33, No. 10

  Previous Issue | Next Issue 
Display Method:
Comparison of two-equation turbulent models for hypersonic flow simulations
Liu Jingyuan, Lee Chunhian
2007, 33(10): 1131-1135.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1134
Abstract:
A two-equation turbulent model based on the mixed Reynolds and Favré (density weighted) average was modified for hypersonic compressible turbulence. In order to suppress the influences of the numerical viscosity toward the boundary layer, and yet to maintain simultaneously the high resolution on capturing the disco ntinuities in the hypersonic flow field, a new entropy correction function was proposed for the total variation diminishing (TVD) scheme. A test case on hypersonic flows over a ramp was then computed using the modified mixed averaged model, as well as the incompressible models proposed by the others together with their respective compressibility correction models. The comparative study shows that the compressibility corrections to the two-equation turbulence models are necessary for hypersonic ramp-type flows, and the numerical results by the modified mixed averaged model are closest to the experiments simultaneously.
Computation of shock wave/boundary-layer interactions with GAO-YONG turbulence equations
Xu Libo, Gao Ge
2007, 33(10): 1136-1140.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1807
Abstract:
Rational GAO-YONG compressible turbulence equations were applied to simulate numerically the flat plate shock wave/turbulent boundary layer interactions. The equations were solved using the semi-implicit method for pressure-linked equations (SIMPLE) algorithm. The discretization of convection and diffusion terms were respectively adopted quadratic upwind interpolation of convective kinematics(QUICK) scheme with third-order precision and center difference (CD) scheme.The calculational results predict well the flow characteristics of turbulent boundary layer separation induced by incident shock wave: a separation shock followed by expansion fan around separation bubble and shock in reattachment point.The computational results of the time-averaged parameters, such as the velocity profiles along the x-coordinate, pressure along the wall surface and skin-friction coefficient along the wall were compared with the experimental results. It is shown that when the GAO-YONG compressible turbulence equations are applied to the shock wave/turbulent boundary layer interacting cases, the basic feature and details of shock flows can be well simulated.
Numerical simulation of damage and fracture on typical interfaces of plasma sprayed thermal barrier coatings
Wei Hongliang, Yang Xiaoguang, Qi Hongyu
2007, 33(10): 1141-1145.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1068
Abstract:
Based on the idea of interface damage mechanics, a new type of interface elements with three nodes was proposed. Compared with traditional interface elements, these elements have the quality of indicating the normal direction of interface with arbitrary shape. The modified model was implemented into ABAQUS by user subroutine UEL. The numerical simulation of the damage and fracture for cosine shape interface were achieved considering the rough interface of the plasma sprayed thermal barrier coatings. The calculating results show that, under thermal cycle loadings, the displacement between nodes of the interface elements is not continuous which represents the opening process of the interface crack, the damage increases with the number of thermal cycle loadings and the max damage is caused during the first cycle, the top of the interface is the critical position and the normal separation dominants, under uni-axial tension loadings, the wavy interfaces have better capability of load bearing than the linear interfaces for PS-TBC. Simulation of damage and fracture for different materials with arbitrary interface using the modified interface elements is available, and the results are reasonable.
Static aeroelastic divergence analysis by introducing correction techniques of aerodynamic data
Yan De, Yang Chao, Wan Zhiqiang
2007, 33(10): 1146-1149.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1195
Abstract:
The correction techniques of aerodynamic forces were introduced in the computation and analysis of static aeroelastic divergence. According to steady pressure distribution data on a three dimensional wing, the correction factors to pressure and downwash were obtained and the steady aerodynamic influence matrix based on planar double lattice method was corrected. The divergence speed of the wing was calculated using the mode method. The results show the divergence speeds of the wing after pressure correction and downwash correction are both lower than that before, due to the aerodynamic center of steady pressure distribution on the three dimensional being closer to the leading edge than that of planar double lattice method.
Large eddy simulation based on non-Favre filtering
Li Bin, Wu Songping
2007, 33(10): 1150-1153.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1019
Abstract:
The equations of motion for large eddy simulation(LES) were obtained by filtering the compressible NS equations. For conventional compressible LES, the Favre filtering was used. This avoids some complexity, but gives rise to difficulties when comparing to experimental data, which is not Favre filtered. A tensor-diffusive model(TDM) for compressible turbulent flow which uses the standard compressible LES filtered variables(non Favre filtering) was proposed. The difficulties mentioned above have been overcome by the TDM approach. The approach is closer to the physics of the problem, because the information of the density is not lost. To validate this approach, the hypersonic flow through an double ellipsoidal sphere was simulated using the non-Favre filtering equations. The results were compared with experiment, as well as the data of BL model and Smagorinsky model.
Payload configuration for multi-mission navigation constellation based on ant colony algorithm
He Quan, Han Chao
2007, 33(10): 1154-1157.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 866
Abstract:
A methodology for multi-mission navigation constellation was presented to optimize the payload configuration via the ant colony algorithm (ACA), which is a heuristic technique based on artificial ant colony searching strategy. An optimization model of payload configuration for multi-mission navigation constellation was built. n+1 coverage ratio was defined and put forward to evaluate constellation coverage performance. Ant colony algorithm which is a novel meta-heuristic inspired on the biological behavior of ants was applied to optimize the payload configuration, and then heuristic value and ant-cycle model were modified to suit the optimization. Then, an optimization framework of payload configuration was given based on ACA. Simulation results show that ACA is quick and effective and the solution of payload configuration can meet the requirements of multi-mission constellation.
Heat transfer and flow resistance in a notched crossed-rib channel
Deng Hongwu, Pan Wenyan, Tao Zhi, Ding Shuiting
2007, 33(10): 1158-1161.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 879
Abstract:
The investigation of heat transfer, flow resistance and the pressure across the channel in turbulator cooling channel with a special crossed-rib channel which has slots was studied experimentally, then got amount of experimental results. All experiments were made in stillness states. The method of vapor concreting heat transfer was adopted for the heat transfer experiments. The experiment was conducted in the range of Reynolds number from 5 000 to 45 000. Compared with the channels which are no slots, the same dimensions ones with slots have more significant effects on the whole heat transfer enhancement. Besides, the experimental comparisons of characteristics were made to the different slots width channels. For the channels of different slots width, the heat transfer effects of 4 mm slot width channel are best, the following are 2 mm, 6 mm and 8 mm in turn.
Optimal design of nozzle for hypersonic vehicle
Cao Deyi, Lee Chunhian
2007, 33(10): 1162-1165.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1121
Abstract:
An optimal design procedure was proposed by utilizing the method of characteristics in conjunction with a multi-island genetic algorithm. The reflection angle of the nozzle upper wall, the length of the lower wall, and the flap length and angle were chosen to be the design variables, and a parametric study with respect to these variables was performed. The numerical results demonstrate that the proposed procedure is highly efficient, and capable of providing sufficiently accurate data for nozzle optimal design. It is also found that all four parameters chosen as the design variables will substantially affects the aerodynamic performances of the nozzle, among them, the reflection angle of the nozzle upper wall and the flap have remarkable influence on lift and thrust respectively. Hence, the trade-off among these variables must be taken into account to achieve the optimum result.
Attitude description and dynamics modeling for Halo-orbit spacecraft
Xu Ming, Jia Yinghong, Xu Shijie
2007, 33(10): 1166-1169.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1412
Abstract:
Halo orbit locates about the libration point in the Sun-Earth system and has no orbital plane focusing the Earth, which makes the attitude description and dynamics modeling for Halo-orbit spacecraft is quite different from that for the usual satellite around the Earth. Two different schemes of attitude description were proposed for the spacecraft in the three axis stabilization, sun-orienting scheme (Scheme I, using the Sun and Earth attitude sensors) and rotating-reference scheme (Scheme II, using the Star attitude sensor). So the attitude dynamics can be modeled from the different orbital coordinates defined by the two schemes. The upper limits of relative errors for the two schemes were estimated theoretically: no more than 5% for Scheme I, and 0.005% for Scheme II. A controller was designed for the attitude stabilization to validate the feasibility of the schemes. The research shows that Scheme II is set as the normal mode with the astronomical ephemeris periodically corrected, while Scheme I is used as the alternate device for the failure mode.
Numerical simulation to effects of trailing edge jet on delta wing vortices
Chen Yu, Yan Chao
2007, 33(10): 1170-1173.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 948
Abstract:
In order to study the influence of trailing edge symmetrical jet on leading edge vortex breakdown location and flow structure over a delta wing, vortex flows over a 60oswept delta wing with trailing symmetrical edge jet and without trailing edge jet were studied using high precise simulation of N-S equations. The results show that the ratio of jet velocity to free flow velocity affects the location of vortex breakdown. Compared with the condition without jet, the variation of the ratio of jet velocity to free flow velocity determines vortex breakdown location advance or delay. The difference from the traditional opinion is that not every case with trailing edge jet could delay the location of vortex breakdown. In addition, the trailing edge symmetrical jet has little influence on the position of the vortex axis. The trailing edge jet does not change the rule of topological structure transformation of the cross section, but it impacts the velocity of limit ring spread.
Fuzzy logic models for unsteady post stall maneuver
Kong Yinan, Wang Lixin, He Kaifeng, Qian Weiqi
2007, 33(10): 1174-1177.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1056
Abstract:
The fuzzy logic models of unsteady aerodynamics were lucubrated. The system′s fuzzy logic models, structures and parameters identification and model establishment were researched. The new modeling method makes the models has more abroad practicability. With using the typical test data, fuzzy logic modeling of nonlinear unsteady aerodynamic was developed. First, two fuzzy logic models of unsteady aerodynamics of oscillating delta wing were developed. One model employs the reduced frequency, the other uses the incidence history to account for the unsteadiness of flow characteristics. It was shown that both model results agree with the experimental values. Second, these two fuzzy logic models were used to simulate the typical post-stall Cobra maneuver, and the applicability of these two fuzzy logic models were demonstrated.
Experimental on canopy payload performance of parachute
Yu Li, Zhang Xinhua, Li Shuisheng
2007, 33(10): 1178-1181.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1536
Abstract:
The opening process of the circle flat parachute with the differential size and the differential vent position of the canopy by the steady flow wind tunnel were dynamic tested. The transient opening loads and the inflation shape of canopy were measured and the dynamic relation of them was gained. The results show that the transient opening loads are influenced not only by the aerodynamic forces of parachute, and the force produced by the change rate of added mass, but also by the instability and wave of canopy (or parachute suspension line). At mean time, the mean payload of canopy is nearly equal to 60% of the opening shock for the steady canopy. Besides, the load fluctuation is mostly produced by the "breath" phenomena. The bigger actual vent area of canopy, the better stability of a parachute, but the parachute inflation performance will worsen. The experiment investigation may be helpful for the further research.
Predictions of collection efficiency and anti-icing surface temperature
Bu Xueqin, Lin Guiping
2007, 33(10): 1182-1185.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1127
Abstract:
Computational fluid dynamics (CFD) software toolkit FLUENT was used to predict the droplet collection efficiency and anti-icing surface equilibrium temperature on two-dimensional airfoils when the ice protection system was in operation. Collection efficiencies were obtained using the Eulerian multiphase model, implemented through user-defined functions in FLUETN. The surface equilibrium temperature distribution in responding to certain flight condition and the hot-air inlet configuration was predicted by an integrated airfoil leading-edge interior-exterior thermodynamic analysis. Some examples and validation studies were presented. The numerical results are acceptable and consistence with the theory analysis. The presented research work indicates a validity of using FLUENT in studying aircraft anti-icing, including prediction of water collection efficiency and temperature distribution on anti-icing surface, which are useful for future study in design of aircraft hot-air anti-icing system.
Lateral-directional control characteristics of high aspect-ratio flying wing configurations
Li Lin, Ma Chao, Wang Lixin
2007, 33(10): 1186-1190.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1360
Abstract:
High aspect-ratio flying wing configurations usually use split-drag-rudder (SDR) and a set of elevons to fulfill the lateral-directional control, without the traditional vertical tail and rudder. The control characteristics of SDR were specially researched, including the generation of the roll and yaw control moments and the control power effects, compared with the conventional side-force-rudder. The ability and characteristics of the yaw and roll control of high aspect-ratio flying wing configurations were presented, including lateral-directional control trimming and maneuver coordination. And the differences between the conventional aircraft configurations and flying wing configurations were emphatically analyzed. Evaluation data show that single-engine-out is the most critical case for directional control and the yaw control effect requirement is beyond what SDR can provide. As a result, the control volume of SDR ought to be properly increased or the current flying wing configuration needs improving.
Optimal Lambert transfer based on adaptive simulated annealing genetic algorithm
Lu Shan, Chen Tong, Xu Shijie
2007, 33(10): 1191-1195.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1005
Abstract:
The optimization of Lambert two-impulse transfer was studied. The traditional optimization methods were inefficient or even ineffective for the Lambert transfer with unfixed initial position, final position and transfer time, because of various variables and the complexity of equations. The adaptive genetic algorithm (AGA) was adopted to find the optimal variables. Meanwhile, the adaptive simulated annealing genetic algorithm (ASAGA) was developed by combining AGA and simulated annealing algorithm. The new algorithm not only provided global search capacity, but also improved local search capacity of AGA. The optimization results of AGA and ASAGA were compared. The results validate the effectiveness of two algorithms, and also the stronger search capacity of ASAGA.
State partition technique in mixed-circuit fault diagnosis
Wan Kai, Ma Qishuang, Wang Peng
2007, 33(10): 1196-1199.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1617
Abstract:
Based on fault dictionary technique and discrete event system (DES) off-line diagnosis model, a new approach called state partition (SP) technique was proposed to model the mixed-circuit in an unified way. Mathematic analysis was made the main part with relationship between system states and state partitions concerned specially. The definition of "cross intersection" was given, and the operation of cross intersection was proved close and to be a conjunction of the partition set. With the idea mentioned in DES off-line diagnosis model, the concept of system diagnosability was built. The existence and reachability of minimal phenomenon set were also proved in SP model. To locate system status, phenomena were used to divide state set into partitions. So fault dictionary technique and DES off-line diagnosis model are unified theoretically from math aspect in relation between state and its partitions. SP model is also proved a universal method in circuit fault diagnosis.
Fault diagnosis of rectifier in aircraft power system
Niu Xingyan, Shen Songhua, Dong Shiliang, Chen Zhuo
2007, 33(10): 1200-1203.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1041
Abstract:
The built-in test equipment in a type of aircraft power system is composed with traditional logic hardware, so the abilities on expansion and reliability are limited hardly. According to the characters of built-in test equipment in the next generation, such as computerization and intelligence, based on the fault pattern analysis of the rectifier in aircraft power system, the key points on frequency to each fault pattern were gained by the frequency analysis on output voltage. By using the multi-resolution analysis in the wavelet theory, the basic wavelet function and scale corresponding to key points was confirmed. And then, the wavelet coefficient was converted to a character vector that is the input of the BP neural network which fulfill the diagnosis by defining frequency energy character vector. The results show that this method can distinguish each fault efficiently.
Performance monitoring and optimization design of database access layer about J2EE management information system
Tang Wenzhong, Xu Xiaoman
2007, 33(10): 1204-1207.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 988
Abstract:
Based on the character of J2EE management system performance, an application data layer and a database access monitoring tool were designed and implemented for the applications performance optimization during the development period. At the data layer, some special data access operation methods were provided to improve the data access efficiency and some convenient measures were adopted for posterior system performance optimization works. System database access steps and the performance parameters can be monitored with aspect-oriented programming(AOP) technology, which will help developer to find the key factor of side-effect during system tuning period. According to the monitoring results, developer can modify the source code of side-effect and then optimize the system performance bottle-neck SQL and replace the originally inefficient SQL sentence for the data layer.Therefore the purpose of optimization system database access performance may be achieved.
Sliding mode control of permanent magnet synchronous motor with great inertia load
Li Yi, Guo Hong, Yu Yongqiang
2007, 33(10): 1208-1211.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1287
Abstract:
When the moment of inertia becomes big, huge inertia torque will be produced when the directly drive permanent magnet synchronous motor(PMSM) system starts, stops or changes speed, thus to bring impact on the system performance. In order to solve this kind of problem, the control method on the sliding mode variable structure was adopted. The mathematic model of the PMSM was established and the factor of friction was considered. And the sliding mode variable structure controller was designed. The Simplorer simulation system of Ansoft Company was used to simulate the whole system. Then a comparison was made between the performance of proportion-integral (PI) control and sliding mode variable structure control. The results show that the sliding mode variable structure controller method can be adapted to the moment of inertia loading control system.
Kind of guidance device for field vehicle based on embedded image processing
Li Chao, Li Yunhua, Wang Guodong, Li Linsheng
2007, 33(10): 1212-1215.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 917
Abstract:
The feature of elevating transporter in bridging construction was analyzed. Aimed at the primary problem of vehicle′s guidance and on-site′s practical requirement, a new kind of auxiliary device for vehicle′s guidance based on embedded image processing using single chip microcomputer was developed. The relevant hardware platform was designed, and such key technologies in single chip microcomputer system as video acquisition, image processing, judgment of vehicle′s off tracking and output of alarm were introduced in detail. The results of experiments revealed that this device meeted the traveling requirement of the elevating transporter on the track-beam. The device was applied in field construction, and the method of design and implementation is well worthy for other large-scale field vehicle′s guidance.
Method for measuring the focal distance of 3D-CT imaging system with high accuracy using image auto-correlation
Yang Min, Sun Cuili, Li Baolei
2007, 33(10): 1216-1219.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1078
Abstract:
In the three dimensional computed tomography imaging system, it is impossible to measure the X-ray focus to object-rotating-axis distance (FOD) by direct means, so how to obtain the value of FOD with simple and feasible method is an involved engineering problem. Through acquiring the digital radiography(DR) images of the double-circled object at two imaging positions, the auto-correlation operation was executed, so as to get distance of the two circles- projection center. Then through solving equations, the value of FOD was finally obtained. Experiment results prove that the accuracy of this method can satisfy the requirements of the practical scanning system. This testing method is also easy to realize and of high anti-noise ability. Furthermore, it can be realized automatically by software.
One novel UAV aerial video compression method
Nie Zhengang, Zhang Xiaolin
2007, 33(10): 1220-1222.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1121
Abstract:
To resolve the video compression bit rate fluctuation due to odd frames generated by the bad weather or electromagnetic (EM) interference in aerial video sequences from unmanned aerial vehicle (UAV), a new video compression method which analyze video sequences in advance and remove the detected odd frames before video compression was proposed. By constructing models of several popular types of odd frames, the characters of odd frame signals were analyzed. With combination of signal statistics and information entropy measurements, the odd frames in video sequence were robustly detected. Finally, the video sequence without odd frames was compressed with the new H.264 standard. Both theoretic analyses and experiments prove that this method greatly improves video compression efficiency of aerial video sequences from UAV and keeps constant compression bit rate, meanwhile does not lose any useful information.
Aeronautical static inverter based on repetitive control
Guan Miao, Shen Songhua, Wang Yong, Ma Qishuang
2007, 33(10): 1223-1227.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1360
Abstract:
Aimed at the voltage wave distortion of ASI (aeronautical static inverter), a scheme based on the repetitive control technique was proposed. The repetitive controller based on the theory of internal model produces correction signal based on the control error of the last cycle to eliminate the error in the latter cycle. The compensator of the ASI was analyzed, and its stability and convergence were proved. The design of control parameters in frequency domain was also presented. Simulation courses with the parameters were obtained from a SPWM (sinusoidal pulse width modulation) ASI. Simulation results show that the control model and design method of parameters are feasible, and also the concept to use the repetitive control approach to improve the wave distortion of ASI with non-linear loads or disturbed by periodic signal can be verified practically.
Novel deterministic directed diffusion routing protocol for WSNs
Zhong Ying, Feng Jinxin, Xiong Qingxu
2007, 33(10): 1228-1232.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1416
Abstract:
A novel deterministic directed diffusion routing protocol was proposed for wireless sensor networks (WSNs) to prolong network lifetime. The sink broadcasted its Interest periodically in flooding fashion. A node set up its gradients towards the neighbor nodes in the arrival order of Interest from them, the earlier arrival the larger gradient. The node toward by the maximum gradient was selected to form a path from the source to the sink. The node energy consumption was balanced by adjusting the energy threshold to preserve lower energy nodes from joining the path. Qualitative analysis and simulation results show that the proposed routing protocol can achieve better performance in terms of energy consumption and reliability than the directed diffusion protocol in the cases of single-sink-single-event and multi-sink-multi-event respectively, and it is easier to practical implement. Analytic discussion also illuminates that the proposed routing protocol has better performance in terms of delay and jitter.
Spacecraft attitude slew maneuver control via backstepping method
Zheng Minjie, Xu Shijie
2007, 33(10): 1233-1236.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 831
Abstract:
The backstepping control method was applied to the slew maneuver of the rigid spacecraft. In order to avoid the complicated calculation of the derivation of the intermediate control law which is required in the conventional backstepping method, the intermediate control law presents in a form of differential equation. On this basis, two methods were applied to reduce the requirement in the max actuator output torque by means of postponing the peak of the control torque. One method is to change the initialization of the intermediate control law. The other is to utilize a worse angular velocity tracking law. The system stability with the second control law depends on the parameters of the controller, however, the max control torque can be accurately restricted. Simulation results illuminate the availability of the derived control laws.
Method for inducing reliability test measured vibration data
Luo Min, Jiang Tongmin, Yuan Hongjie
2007, 33(10): 1237-1240.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1028
Abstract:
To solve the problem of traditional inductive method for measured random vibration data only applying to normal distribution data, the way for selecting the suitable curve in Johnson curves family was introduced, and the method of fitting measured non-normal random vibration data by Johnson curves family was researched. Then, power spectrum density(PSD)upper probability limit of measured non-normal random vibration data was given by using it. Based on these results, a new method for inducing reliability test vibration force was developed. Some product measured random vibration data induction result shows that the method can give a reasonable PSD upper probability limit of measured random vibration data with any distribution successfully. Furthermore, comparing with traditional normal-based data inductive method, the result of the method is more reliable for characterizing vibration environment condition.
Modeling technique of aircraft development based on configuration item
Tao Jian, Fan Yuqing
2007, 33(10): 1241-1245.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1243
Abstract:
Business process of aircraft manufacturing industry is a dynamic and complicated system engineering with that the quantity of data is huge. How to build product development module simply and perfectly is always a difficult problem in business process improvement (BPI). The importance of configuration item (CI) technology was emphasized in the lifecycle of aircraft development and the accurate mathematics definition was confirmed referring to Boeing company ideas about aircraft configuration management and the module of product structure. Then, two technologies of configuration management and Petri net (PN) were used to make the product information module simply and the product process module more perfectly. CI and PN were combined based on the two technologies to ensure the consistency and integrity of aircraft development module in product lifecycle. At last, the CI-PN module was proposed to describe the information module and the process module of the whole aircraft development process. The case to describe, analyze and optimize the module of developing the wing-box was given.
Electrochemical behaviour of LY12CZ under applied stress
Rao Sixian, Zhang Yubo, Zhu Liqun, Zhong Qunpeng
2007, 33(10): 1246-1250.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1041
Abstract:
Potentiodynamic polarization and electrochemical impedance spectroscopy(EIS) techniques were applied to investigate the corrosion behavior of LY12CZ in 3％NaCl aqueous solution.The effects of stress to anodic polarization behavior,free corrosion potential,breakdown potential,polarization resistance and double-layer capacitance of LY12CZ were summarized.Results show that the polarization curve and breakdown potentials show obvious negative removals,and the mechanochemical effects reached maximum during the strain hardening stage. If stressed,under equivalent immersion time, polarization resistance also decreased significantly with the increase of stress.The nagetive removal of breakdown potential and decrease of polarization resistance indicate that stress plays an important role in the localized corrosion of LY12CZ.
Straightening technique for distorted aeronautical monolithic component based on finite element numerical simulation
Zhang Hongwei, Zhang Yidu, Wu Qiong, Zhao Xiaoci
2007, 33(10): 1251-1255.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1085
Abstract:
For aeronautical monolithic component, because of the complication of machining distortion, straightening parameters are difficult to be gained quantitatively in the process of distortion correcting that inevitably leads to the distorted components discarded as useless. The research on straightening technique based on finite element simulation was carried out by integrating machining distortion with straightening process. Correlated key technologies were studied, including finite element modeling for straightening, numerical simulation method for straightening process, determination of straightening parameters, different kinds of straightening load, the law of residual stress redistribution due to straightening load and so on. The straightening process for aeronautical monolithic component was simulated using finite element analysis software with these technologies. The results show that the integration of machining distortion simulation and straightening simulation is an efficient way to research on straightening technology. In the straightening process, the prime distorted model can be extracted from machining distortion simulation. The analysis for loading and unloading was carried out to simulate straightening process and straightening parameters can be obtained quantitatively.

Copyright © Journal of Beijing University of Aeronautics and Astronautics

Address: Editorial Department of Journal of Beijing University of Aeronautics and Astronautics, 37 Xueyuan Road, Haidian District, Beijing Post Code: 100191 Email: jbuaa@buaa.edu.cn

Supported by: Beijing Renhe Information Technology Co., Ltd.