2014, 12(3):193-200. DOI: 10.6052/1672-6553-2014-046
Abstract:The spacecraft's ability to adapt to the harsh dynamics environment is critical for the whole space mission. Vibration test control technology is the key part of the dynamic environment test. The current progress, fundamental principles and key techniques development level of the spacecraft and vibration control algorithms overseas were analyzed. The basic ideas, effective ways and suggestions were given to domestic following research.
2014, 12(3):201-204. DOI: 10.6052/1672-6553-2014-048
Abstract:Non-linear factors cannot be avoided in the design of aircraft structures. In this paper, a two-degree-of-freedom airfoil and cubic stiffness nonlinearities in pitching degree-of-freedom operating in supersonic flight speed regimes has been analyzed. The averaging method and the theory of flutter were used to analyze the nonlinear dynamic system of the dualistic airfoil in the supersonic flow. Then the correctness of the theoretical calculation was verified by numerical calculation, and the analysis result was given.
2014, 12(3):205-209. DOI: 10.6052/1672-6553-2014-059
Abstract:This paper investigated the passive nonlinear vibration control method used for energy absorbing in structures of spacecrafts. The structure and the dynamic model of the nonlinear energy sink which could adapt to the space environment were proposed. As nonlinear spring could not be acquired easily in reality, we proposed a new design for the NES based on employing an asymmetric NES force which was generated by two pairs of aligned permanent magnets. Then, the dynamic model for a cantilever beam structure coupled with nonlinear energy sink had been built theoretically. In addition, the passive vibration suppression effect of the nonlinear energy sink on the cantilever beam structure under transient excitation had been analyzed through Galerkin method and numerical analysis method. The results showed that the NES acquired up to 92% dissipation of the system energy imposed by shock excitation, hence the NES could adapt to the space environment and improve the reliability of space system.
2014, 12(3):210-214. DOI: 10.6052/1672-6553-2013-104
Abstract:The paper presents a detailed analysis on the dynamics and delayed state feedback control of an oscillator with generalized visco elastic item. The trivial equilibrium of the model is first investigated and shows that uncontrolled model exhibits complicated unbounded behavior. Then a velocity feedback control is introduced to stabilize this unstable system. It shows that the velocity feesback control can stabilize the system. And with properly chosen delay and gain in the delayed feedback path, the velocity controlled model may have stable equilibrium, or periodic solutions resulted from the Hopf bifurcation, codimension 2 bifurcation or complex stranger attractor. Some numerical experiments verify the theoretical analysis.
2014, 12(3):215-219. DOI: 10.6052/1672-6553-2014-049
Abstract:A parametric vibration system was transferred into a linear time invariant system by applying the Liapunov-Floquet transform. After resetting the pole-zeroes position in the system, an active control for parametric vibration system was obtained with the stable response. A coupling vibration example of aero plane wing and rotor in a turbine engine was given, and active control structure for parametric torsional vibration and the simulation result of stable system were illustrated.
2014, 12(3):220-224. DOI: 10.6052/1672-6553-2014-050
Abstract:The automatic transfer task of the sample container is a key link and a kind of necessary technique means of deep space exploration. This paper studied the dynamic process of the parallel multi connecting rod mechanic capturing the sample container and displacing it to the appointed position. The dynamic equation was established, the calculating model was set up by adams, and the whole dynamic process was discussed, which can help the following work of researching and designing.
2014, 12(3):225-229. DOI: 10.6052/1672-6553-2014-051
Abstract:Based on the staggered solution procedure of ANSYS and CFX software, the fluid structure coupling response of projectile during tail slapping has been researched. Structural response was simulated by using FEM and flow field was simulated by using inhomogeneous model and SST turbulence model. Finally, the influences of fluid structure coupling effect have been analyzed and the change law of body stress has been given.
2014, 12(3):230-234. DOI: 10.6052/1672-6553-2014-052
Abstract:In order to ensure the huge energy for normal working of China Space Station and less weight costs in launching, China Space Station adopted the large area flexible solar array (LAFSA) design scheme. The LAFSA has complex structures and extremely low frequency, and bearing loads produced by multiple large maneuver procedure in orbit running, so the strength check and parameter design for each load carrying component become very important segments for the mission's success or failure of China Space Station. This paper established a simplified linear modal for the flexible solar array of China Space Station from the perspective of engineering applications, and computed the loads of every important component of the flexible solar array in on orbit large maneuver procedures, which can be used as the instruction for strength check and lightweight design of the LAFSA.
2014, 12(3):235-238. DOI: 10.6052/1672-6553-2014-053
Abstract:Payload supported bay (PSB) is an important structure between launch vehicle and spacecraft(SC), the vibration characteristics of PSB is a factor which must be considered in mechanical environment design. In this paper, the dynamical performance of PSB was studied for vibration environment control. A method to improve the mechanical environment of SC based on the research of PSB vibration characteristics was presented. A test for mechanical properties of structural material was introduced to build finite element(FE) model. The vibration environment of SC assembled on different PSBs which are made of different material was computed and compared. The influence of structural connection form between PSB and SC was also investigated. Further research was provided on the basis of the analysis results.
2014, 12(3):239-242. DOI: 10.6052/1672-6553-2014-044
Abstract:For the linear coupling of the elastic tank and incompressible and invisid liquid, there are reduced and symmetric finite element equations of coupling system. The system matrix could be obtained by the analogy method, and then the analysis of coupling system will turn to be a problem that could be solved by the general finite element software. For example, the modal characteristics of the rocket with tanks were studied. Coupling modes caused by liquid sloshing were founded, and the result shows the modes of this kind are relevant to the gravity acceleration. In addition, the greater the gravity, the higher the frequency.
2014, 12(3):243-247. DOI: 10.6052/1672-6553-2014-054
Abstract:Random vibration test is very important to the aerospace equipment. The windage of ASD outside the frequency bandwidth was analyzed. The reason, premonition, affection and effective way were given. And the commonly used random vibration test and vibration test metrology standard for the ASD outside the frequency bandwidth were analyzed.
2014, 12(3):248-252. DOI: 10.6052/1672-6553-2014-055
Abstract:The measuring method used to measure kinematic vector parameters was researched. The generalized kinematics model of vector measuring device and a mathematical model with compensation were established, consequently, the simplified model of the separated sensor movement was obtained. Afterwards, based on the sensor movement described by the balance of electromagnetic and electrostatic support and compensation, the kinematics equations of generalized electromagnetic force system for the sensor were derived. Analysis results show that the use of the compensation model can establish a new modular vector measuring device, thus, the influence owing to the analysis of lateral connections is solved.
2014, 12(3):253-258. DOI: 10.6052/1672-6553-2014-056
Abstract:Taking account of the structural stiffness and the low order vibration frequencies, two schemes of multi-objective topology optimization were proposed to obtain the best aircraft lifting-surface structural design. Based on penalized density theory, the scheme one (named as constrain method) is to convert the multi-objective optimization to single-objective optimization by considering the minimum structural mass as the objective with constraints of reference points displacements and the low order vibration frequencies. The scheme two (named as the combination of constrain method and criterion function method) settles the multi-objective optimization by defining combined compliance index (CCI) as the objective, with the constraints of volume fraction and the low order vibration frequencies. The CCI is the function of structural compliance and low order vibration frequencies. Numerical results demonstrate the proposed schemes not only realize reducing the structural mass but also raise the first and second order frequencies.
2014, 12(3):259-263. DOI: 10.6052/1672-6553-2014-057
Abstract:A new hybrid method was presented to predict vibration responses of structures in medium frequency. Finite element method was used to model subsystems with low modal density while wave method was for subsystems with high modal density. A coupled beam system was exemplified to demonstrate the details. Compared with the analytical method, simulation results validate the hybrid method. Energy density response was obtained for the subsystem with high modal density. It is found that the hybrid method produces a more precise prediction in the vicinity of boundaries.
2014, 12(3):264-268. DOI: 10.6052/1672-6553-2014-058
Abstract:Space docking mechanism was used to realize the space docking and separation for the aircraft and space station. In order to simulate the process of space separation, the buffering test table was developed to study the variety rule attitude angle and attitude angle velocity of the aircraft and space station. At the same time, the digital prototype model was built to analyze the movement characteristics of the space vehicles. Comparing the results obtained from the two analysis methods, this paper demonstrates the effect of the buffering test table on connection and separation experimentation.
2014, 12(3):269-273. DOI: 10.6052/1672-6553-2014-043
Abstract:Aiming at the problem that the longitudinal modes of structural system of rocket need to be identified from its integral modes in engineering, a method that automatically identifies the longitudinal modes of structural system of rocket was proposed according to the theory of modal effective mass. Taking the vibration characteristics of system with lumped mass as a computing example, applying the finite element software, the beam model of system with lumped mass was established, and the longitudinal modes of the system were automatically identified based on the method. Compared with the system modal information calculated by the method of modal analysis, this automatic identification method not only can accurately identify the longitudinal modes of vibrating system, but also has automatic and high efficiency identification feature. It provides a theoretical basis for the dynamic model of POGO vibrating system in liquid rockets and other model of engineering systems to be accurately and promptly established.
2014, 12(3):274-278. DOI: 10.6052/1672-6553-2014-045
Abstract:Traditional modal test of spacecraft is usually used to examine its finite element model, but the parameters of the finite element model are always modified through artificial adjustment, which isolates modal analysis from modal test, and influences the precision of subsequent analysis, research period and funds etc. In order to change the present situation of modal analysis and test of spacecraft, this paper introduces the feasibility of modal analysis-test system in theory, and based on the Virtualab-Nastran software platform, gives an example of a scaling cabin, implements the complete procedures of modal analysis-test system, including pretest analysis, modal test, model updating etc, which closely relates modal analysis to test, corrects the finite element model rapidly according to the test results, makes the analysis results close to test results, and achieves precise modeling.
2014, 12(3):279-282. DOI: 10.6052/1672-6553-2014-060
Abstract:This paper used outfield transient vibration time history to gain ESD envelope ; used random signal replication method in vibrator control theory to gain ESD amplitude time history and used vibrator time waveform replication method to take transient vibration test. This method provides technology support for vibrator ESD direct control test method.
2014, 12(3):283-288. DOI: 10.6052/1672-6553-2014-061
Abstract:A method was presented to analyze the nonlinear flutter. Based on this method, the flutter characteristics of the high aspect wing were illustrated. The numerical results show that the flutter speed is decreased when the first horizontal bending mode involved. Secondly, this study discussed how the main direction of the composite influenced the character of the nonlinear vibration and flutter, and established the method of the flutter clipping to the high aspect wing. And the result shows that the stiffness of structure can be changed by changing the main direction of the composite. It mainly changes the horizontal bending mode, makes the main direction tend to the trailing edge, and then makes the section line move to the leading edge. Further analyzing the nonlinear flutter reveals that it is the changing of the horizontal bending mode that causes the flutter speed change obviously. And by the section line of this mode moves ahead, the flutter speed will become larger. In the study, two examples were illustrated to validate its truthiness.
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