Integrated Design of Autonomous Orbit Determination and Orbit Control for GEO Satellite Based on Neural NetworkRead the full article
International Journal of Aerospace Engineering serves the international aerospace engineering community through the dissemination of scientific knowledge on practical engineering and design methodologies pertaining to aircraft and space vehicles.
Chief Editor, Professor Zhao, is based at the University of Canterbury and his research interests include applying theoretical, numerical and experimental approaches to study combustion instability, thermoacoustics and aerodynamics.
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Study on Mechanical Properties of Submunition’s Ribbon Straightening Section
The humanitarian damage caused by the unexploded submunitions is one of the hot issues of concern to the international community at present. A portion of the submunition that did not explode was caused by a break at the connection between the ribbon riveting and the fuze. According to the physical structure of the submunition and the trajectory into which it was ejected, we analyzed the forces of the submunition in flight, deduced the related mathematical models, and clarify the key elements of the mechanics. In this paper, the commercial simulation software was used to calculate the mechanical properties of the ribbon. And the variation regularity between drop velocity and straightening force of ribbon are revealed. And the response characteristics of different material ribbon with different sizes of riveting holes and riveting joints under tensile action were simulated. The simulation results show that, in the trajectory environment with 30 m/s~55 m/s typical stream speed, the tensile force of the ribbon is less than 300 N, and the application concentration of the connecting parts of the riveting joint and the ribbon will not cause the failure of the kevlar ribbon, but it will cause the failure of the nylon ribbon. In order to verify the variation of the tension of kevlar ribbons in different trajectory environments, we designed the experimental scheme of tension test of the ribbon straightening section of submunition and conducted experiments. Experimental results and numerical simulation results revealed the same law. This paper provides effective technical support for solving the problem of unexploded submunitions.
Processing Technology Based on Radar Signal Design and Classification
It is well known that the application of radar is becoming more and more popular with the development of the signal technology progress. This paper lists the current radar signal research, the technical progress achieved, and the existing limitations. According to radar signal respective characteristics, the design and classification of the radar signal are introduced to reflect signal’s differences and advantages. The multidisciplinary processing technology of the radar signal is classified and compared in details referring to adaptive radar signal process, pulse signal management, digital filtering signal mode, and Doppler method. The transmission process of radar signal is summarized, including the transmission steps of radar signal, the factors affecting radar signal transmission, and radar information screening. The design method of radar signal and the corresponding signal characteristics are compared in terms of performance improvement. Radar signal classification method and related influencing factors are also contrasted and narrated. Radar signal processing technology is described in detail including multidisciplinary technology synthesis. Adaptive radar signal process, pulse compression management, and digital filtering Doppler method are very effective technical means, which has its own unique advantages. At last, the future research trends and challenges of technologies of the radar signals are proposed. The conclusions obtained are beneficial to promote the further promotion applications both in theory and practice. The study work of this paper will be useful for choosing more reasonable radar signal processing technology methods.
Development of Real-Time Maneuver Library Generation Technique for Implementing Tactical Maneuvers of Fixed-Wing Aircraft
This study develops the real-time maneuver library generation technique for performing aggressive maneuvers of fixed-wing aircraft. Firstly, the general maneuver libraries are defined, and then 7th-order polynomials are used to create the maneuver libraries. The attitude command attitude hold (ACAH) system, the rate command rate hold (RCRH) system, and the speed command speed hold (SCSH) system using the proportional-integral-derivative (PID) control technique are designed to minimize the complexity of the flight control system (FCS) and to reduce the weight and volume of the payload. Moreover, the FCS is used for implementing tactical maneuvers. Finally, flight simulations are implemented for the longitudinal loop and Immelmann-turn maneuvers to check the usefulness of the proposed maneuver library generation technique. This study can affect the development of flight techniques for aircraft tactical maneuvers and the modification of air force operational manuals.
Trajectory Tracking Control Study of a New Parallel Mechanism with Redundant Actuation
Parallel mechanisms with redundant actuation are attracting numerous scholars’ research interest due to their inherent advantages. In this paper, an efficient trajectory tracking control scheme for the new redundantly actuated parallel mechanism by integrating force/position hybrid control with the combination of inertia feed-forward control and back propagation (BP) neural network PID control is proposed. The dynamic models including the joint space and task space are formulated explicitly in efficient and compact form by means of the principle of virtual work and d’Alembert formulations. The force/position hybrid control is implemented to perform trajectory tracking and optimize the driving force configuration in MATLAB/Simulink environment, before being applied to an actual parallel mechanism. The illustrative simulation results demonstrate that the force/position hybrid control scheme is available to provide good trajectory tracking performance. Simultaneously, the feasibility of the proposed control scheme is verified by comparison analysis with the aforementioned conventional control method.
Foreign Object Damage Performance and Constitutive Modeling of Titanium Alloy Blade
Foreign object damage (FOD) to fan blades has been identified as one of the main factors affecting the safety of aeroengine operation. Numerical simulations are an important means of studying FOD, but the selection of the material’s parameters in modeling is a key problem. In this work, a FOD test was carried out with titanium alloy blades as the sample, and the damage types suffered by the blades subjected to impacts from foreign objects under different conditions are obtained. A blade material test was carried out to obtain its parameters in terms of the Johnson-Cook material model, and finite element models of the impacting foreign objects are constructed. When comparing the test results with the simulated results, excellent correlation between them is found.
Numerical and Experimental Failure Analysis of Carbon Fiber-Reinforced Polymer-Based Pyrotechnic Separation Device
Current pyrotechnic separation devices are mainly made of metal materials, limiting the capacity of lightweight design in advanced launching vehicles. With the outstanding mechanical properties, such as high mass-specific strength and modulus, carbon fiber-reinforced polymers (CFRPs) have the potential to replace metal materials in pyrotechnic seperaton devices. However, to improve the seperation reliability of these pyrotechnic separation devices, there still needs further understanding on the the failure mode of CFRP composites under linear shaped charge (LSC). In this paper, cutting tests were carried out on CFRPs for the failure analysis of CFRPs under LSC, and nonlinear finite element analysis (FEA) was performed to characterize the evolution of LSC cutting in CFRPs. According to experimental simulation and numerical simulation, it can be found that the three main failure modes in CERPs while subjected to LSC jet are shear failure, delamination failure, and tensile failure. In the early cutting stage, the initial time of damage of the fiber and the matrix near the shaped charge shows less difference and the laminate is directly separated by the energy of high-speed jet. When the jet velocity decreases, the jet morphology collapses and matrix damages precede into the fiber, which would cause tensile failure mode of CFRPs. Meanwhile, the delamination in low jet speed stages is larger than that in the high jet speed stages. These studies on the failure modes of CFRPs under LSC provide important basis for the future design of CFRP-based pyrotechnic separation devices, which is important to the lightweight design of launching vehicles.