Abstract
The effectiveness of structural repair using composite patches depends on both geometric and mechanical parameters, including the properties of the patch, the adhesive joint, and the repaired structure. In this study, the finite element method (FEM) was employed to investigate the influence of repaired structure parameters effect, specifically thickness and Young's modulus, on the repair efficiency. Unlike previous studies, which focus on aerospace applications, this work explores the potential to extend composite patch repair techniques to other domains such as hydrocarbon, marine, and civil engineering, where structures are characterized by higher Young's modulus and thicknesses. The analysis examines the stress intensity factor (SIF) at crack tips on both the repaired and unrepaired faces, as well as shear stresses within the adhesive layer. The results reveal that while single-patch repairs are effective for thinner structures (e.g., aircraft fuselages under 4 mm), double-patch repairs are necessary for thicker structures, such as those in hydrocarbon or marine engineering, to stabilize cracks on both faces. Furthermore, using a thinner double patch repair provides similar SIF reductions as a thicker patch, offering significant mass savings—a critical factor in engineering design. These findings highlight the adaptability of composite repair techniques across various industries, demonstrating the potential for broader application beyond aerospace, with implications for enhanced structural integrity and reduced weight.
Address
Mohammed Baghdadi: LMPM, Department of Mechanical Engineering, University of Sidi Bel Abbes, BP 89, Cité Ben M'hidi, 22000 Sidi Bel Abbes, Algeria
Abstract
The use of CubeSats as drones for inspecting the collaborative mothercraft is one of the most interesting
in-orbit service missions for this kind of small spacecraft. The most challenging operation in this context is the
retrieval of the CubeSat by the mothercraft after the inspection phase especially because any violation of safety
constraints must be avoided. A well-established docking strategy in nominal and off-nominal conditions is fundamental already during the preliminary design phases. The present paper shows drivers and requirements that
identify a set of design parameters on the state boundaries of the CubeSat, its main features, and the uncertainties due
to the space environment and the system uncertainties. After the choices of the guidance, navigation, and control
strategies and architectures, simulation sessions lead to an assessment of the robust performance in nominal
conditions. Then, the off-nominal conditions are deduced and new simulation sessions confirm the capability of the
system to react against discrepancies between actual state and desired state and system failures. The proposed
solution is applied to a 12U CubeSat mission that will be released and, in case, retrieved by a mothercraft for
observation purposes. The paper highlights the solution's effectiveness in nominal conditions, and when an error
occurs in the approach velocity and failures affect the propulsion system, as an example of the entire analysis.
Key Words
collision avoidance maneuvers; passively safe trajectory; small satellites docking
Address
Fabrizio Stesina, Sabrina Corpino and Antonio D'Ortona: Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino, Italy
Abstract
In this paper, we propose a coupled systematic reference model-related method for dynamic controller design of evolutionary processes to overcome the effects of model errors. To ensure a robust model, the stability criterion is directly proved by the Lyapunov method. NFA solves the problem based on a complex echolocation TS fuzzy model. Based on these standards and distributed control methods, the use of NFA is a cluster-based fuzzy control method for designing predictive signals and active controls. Finally, a numerical example is given in the presented results to show that the stability analysis can be applied to nonlinear responses and that the application of this principle depends on the precise degree of multi-degree-of-freedom (MDOF) vibration compensation. In addition to robust logic, control system effectiveness can also reduce risk in industrial applications.
Key Words
coupled systematic criterion; disordering; evolved control systems; predictive control; time delays
Address
C.C. Hung: School of Big Data, Fuzhou University of International Studies and Trade, No. 28, Yuhuan Road, Shouzhan New District, Changle District, Fuzhou City, Fujian Province, PR China
T. Nguyễn, N. Mohammed: Ha Tinh University, Dai Nai Ward, Ha Tinh City, Vietnam
C.Y. Hsieh: National Pingtung University, Education School,
No. 4-18, Minsheng Rd., Pingtung City, Pingtung County 900391, Taiwan
Abstract
This study develops a size-dependent model based on modified nonlocal strain gradient theory to
examine the effects of flexoelectricity and porosity distribution on the electromechanical bending behavior of
piezoelectric functionally graded (FG) nanocomposite beams on Winkler-Pasternak foundations under different
loading conditions. The nanocomposite comprises a porous FG core with piezoelectric face layers, using a nonlinear
power law for thorough-thickness FG material gradation. Various porosity distribution patterns are considered, and
closed-form solutions for electromechanical bending deflection are derived and validated. Results show that
nonclassical bending behavior can be optimized by adjusting FG gradation, porosity, flexoelectricity, and foundation
parameters, providing insights for MEMS and NEMS applications.
