Abstract
This study presents a coupled analytical approach to predict stiffness degradation in composite laminates affected by transverse cracking and delamination under asymmetrical environmental conditions. A modified shearlag model incorporating both parabolic and progressive shear stress distributions is used to quantify relative and total stiffness loss. The theoretical framework builds on Classical Laminate Theory (CLT), extended to include stress
perturbations and interface damage. This choice ensures compatibility with laminate-level mechanical behavior while
enhancing local damage representation. Model predictions are validated against experimental data for T800H/3631 laminates, showing strong agreement across varying crack densities and temperatures. The results confirm that fiber orientation, delamination ratio, and environmental gradients significantly influence stiffness degradation. Compared to previous models based solely on CLT or simplified degradation factors, the present approach captures the interactive effects of damage and asymmetric moisture diffusion more realistically. These insights inform the design of more durable aerospace composite structures operating in harsh hygrothermal environments.
Key Words
angle ply; asymmetrical environment; delamination; diffusivity; stiffness
Address
Mohamed Khodjet Kesba, B. Boukert, A. Benkhedda: Aeronautical Sciences Laboratory, Institute of Aeronautics and Space Studies, University of Blida 1, BP 270 Route de Soumaa, Blida 09000, Algeria
E.A. Adda Bedia: Laboratory of Materials and Hydrology, University of Sidi Bel Abbes, Sidi Bel Abbes, Algeria
Abstract
One of the ways to solve the problem of creating a modern telecommunications structure in hard-toreach areas of the Arctic, Asia, Latin America and a number of other territories is the introduction of communication networks of a new type of non-terrestrial networks (NTN), using not only satellite communication networks (SCN), but also various aerial systems. This article discusses the use of high altitude platform stations (HAPS) as a part of the architecture of NTN networks, which are capable of providing users with a wide range of communication services even in the absence of modern terrestrial telecommunications infrastructure. The options of NTN architecture using HAPS is described, in which they can perform the functions of repeaters or cellular base stations. The calculation of the energy characteristics of various radio links that are a part of a communication network based on HAPS is given. The example of the Arctic shows the feasibility of the proposed solution of using HAPS as a part of NTN and its high efficiency.
Key Words
3rd Generation Partnership Project (3GPP); 4G/5G; cellular base station; communications satellite (CS); heterogeneous networks; high altitude platform station (HAPS); non-terrestrial networks (NTN); satellite communication networks (SCN)
Address
Gennady V. Chechin and Valentin E. Kolesnichenko: Moscow Aviation Institute, Volokolamskoe Highway 4, 125993 Moscow, Russia
Abstract
Determining sector capacity is a fundamental pillar for ensuring safe and effective air traffic management. Sector capacity is usually expressed through the number of aircraft that are allowed to enter a given sector in one hour. Controlling the flow of aircraft and regulating their number in the space ensures that the air traffic controller is able to maintain safe distance between the aircraft and does not exceed the maximum level of permissible workload. Each air navigation services provider is thus looking for ways to increase sector capacity. One of the innovative approaches to optimizing sector capacity is the use of the Automatic Terminal Information Service (ATIS). When comparing the controller availability factor and terminal area capacity with and without ATIS, it was found that the controller availability factor increased by 2.5% after the introduction of ATIS, and the sector capacity increased by 36.2%. This evidence confirms that implementing ATIS has a positive effect on the overall capacity of the Terminal maneuvering area, with a probability greater than 95% that these changes did not arise due to random variation. Such an integrative approach is proving to be a promising path to more efficient and safer air traffic. The reduction in transmission duration means air traffic controllers spend less time communicating ATIS information, allowing more time for traffic control and separation planning. This increased efficiency translates to a higher sector capacity, enabling controllers to manage more aircraft simultaneously.
Key Words
air traffic; Automatic Terminal Information Service; safety; sector capacity; workload
Address
Tomáš Hoika, Jiří Jánský and Šárka Hošková-Mayerová: Faculty of Military Technology, University of Defence, Kounicova 65, 602 00, Brno, Czech Republic
Abstract
This paper investigates the parametric resonance of graphene-platelet reinforced metal foam (GPLRMF) beams under three typical boundary conditions. The Halpin-Tsai model and rule of mixture are employed to characterize the GPLRMF material properties, while the governing equations are established based on Euler-Bernoulli beam theory. Numerical results demonstrate that increased external excitation leads to significant amplification of vibration amplitudes. The modified variable amplitude method is adopted to ensure accurate prediction of system response across the entire frequency range, with validation against existing literature. Detailed parametric studies examine the effects of: (1) foam distributions (including Foam-I pattern), (2) porosity coefficients, (3) GPL dispersion patterns (Type-A to Type-X), and (4) GPL weight fractions. Furthermore, the influences of boundary constraints, thermal environments, external stimuli, and damping ratios on parametric resonance are systematically analyzed. Key findings indicate that Foam-I distribution with Type-A GPL arrangement exhibits negligible dynamic response, suggesting superior anti-vibration capacity. Both clamped boundaries and reduced temperature are shown to effectively shift resonance positions while enhancing beam stiffness.
Key Words
beams; boundary conditions; GPLRMF; parametric resonance; thermal environment
Address
W.B. Shan: Hunan Electrical College of Technology, Xiangtan, 411101, PR China; Changsha Environmental Protection College, Changsha, 410004, PR China
H. Li: Hunan Electrical College of Technology, Xiangtan, 411101, PR China
Q.M. Peng: Hunan Electrical College of Technology, Xiangtan, 411101, PR China
N.N. Zhang: Changsha Environmental Protection College, Changsha, 410004, PR China
Abstract
Low-thrust propulsion strategies for orbit circularization of small satellites have gained significant attention in recent years due to their potential to reduce propellant consumption and improve maneuverability. This study investigates the application of continuous low-thrust propulsion for achieving orbit circularization in small satellites. The spacecraft's dynamics are modeled using the Lagrange Planetary Equations, and an optimal control law is developed based on a Hamiltonian formulation. The control strategy includes optimal thrust integration, targeting changes in both the semi-major axis and eccentricity. The proposed control law is validated through highfidelity numerical simulations using STK Astrogator. Propagation is carried out with the High Precision Orbit Propagator (HPOP), which accounts for realistic environmental disturbances. The simulation results demonstrate that the designed low-thrust strategy effectively reduces both maneuver time and the required propellant while achieving successful orbit circularization. This work contributes to the development of efficient, accurate, and operationally feasible low-thrust guidance techniques for future small satellite missions.
Key Words
electric propulsion; space missions; high-precision orbit propagator; Lagrange planetary equations; low-thrust propulsion; spacecraft orbit
Address
Khouane Boulanouar: Department of Mission and Space Systems, Satellite Development Center, BP 4065, Ibn Rochd USTO, Oran, 31130, Algeria
Bekhadda Nacera, Benmansour J. Eddine: Department of Space Mechanics Research, Satellite Development Center, BP 4065, Ibn Rochd USTO, Oran, 31130, Algeria
