Abstract
The stiffness reduction of cross-ply composite laminates featuring a transverse cracking and delamination within the mid-layer is predicted through utilization of a modified shear-lag model, incorporating a stress perturbation function. Good agreement is obtained by comparing the prediction models and experimental data. The material characteristics of the composite are affected by fluctuations in temperature and transient moisture concentration distribution in desorption case, based on a micro-mechanical model of laminates. The transient and
non-uniform moisture concentration distribution induces a stiffness reduction. The obtained results demonstrate the
stiffness degradation dependence on factors such as cracks density, thickness ratio and environmental conditions. The
present study underscores the significance of comprehending the degradation of material properties in the failure
progression of laminates, particularly in instances of extensive delamination growth.
Key Words
delamination; desorption; hygrothermal effect; stiffness; transverse cracking; Tsai model
Address
B. Boukert, M. Khodjet-Kesba, 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
This paper addresses the enhancement of long-endurance solar-powered aircraft through the integration of a rechargeable battery and Maximum Power Point Tracking (MPPT) controller. Traditional long-endurance aircraft often rely on non-renewable energy sources such as batteries or jet fuel, contributing to carbon emissions. The proposed system aims to mitigate these environmental impacts by harnessing solar energy and efficiently managing its storage and utilization. The MPPT controller optimizes the power output of photovoltaic cells, enabling simultaneous charging and discharging of the battery for propulsion and servo control. A prototype is presented to illustrate the practical implementation and functionality of the proposed design, marking a promising step towards more sustainable and enduring solar-powered flight.
Key Words
long endurance; MPPT; renewable energy; solar panel; solar powered aircraft
Address
Leo Paul Amuthan George and Anju Anna Jacob: Faculty of Engineering, Emirates Aviation University, Dubai, UAE
Abstract
This paper presents a comprehensive investigation into the optimization of Flight Management Systems (FMS) with a particular emphasis on data processing efficiency by conducting a comparative study with conventional methods to edge-computing technology. The objective of this research is twofold. Firstly, it evaluates the performance of FMS navigation systems using conventional and edge computing methodologies. Secondly, it aims to extend the boundaries of knowledge in edge-computing technology by conducting a rigorous analysis of terrain data and its implications on flight path optimization along with communication with ground stations. The study employs a combination of simulation-based experimentation and algorithmic computations. Through strategic intervals along the flight path, critical parameters such as distance, altitude profiles, and flight path angles are dynamically assessed. Additionally, edge computing techniques enhance data processing speeds, ensuring adaptability to various scenarios. This paper challenges existing paradigms in flight management and opens avenues for further research in integrating edge computing within aviation technology. The findings presented herein carry significant implications for the aviation industry, ranging from improved operational efficiency to heightened safety measures.
Key Words
air traffic management; data transmission; edge computing; flight management system; image processing; MATLAB; terrain analysis
Address
Pradum Behl and S. Charulatha: School of Aeronautical Sciences, Hindustan Institute of Technology and Sciences, Rajiv Gandhi Salai (OMR), Padur, Kelambakkam, Tamil Nadu 603103, India
Abstract
This paper presents the exact solutions and closed forms for of nonlinear stability and vibration behaviors of straight and curved beams with nonlinear viscoelastic boundary conditions, for the first time. The mathematical formulations of the beam are expressed based on Euler-Bernoulli beam theory with the von Kármán nonlinearity to include the mid-plane stretching. The classical boundary conditions are replaced by nonlinear viscoelastic boundary conditions on both sides, that are presented by three elements (i.e., linear spring, nonlinear spring, and nonlinear damper). The nonlinear integro-differential equation of buckling problem subjected to nonlinear nonhomogeneous boundary conditions is derived and exactly solved to compute nonlinear static response and critical buckling load. The vibration problem is converted to nonlinear eigenvalue problem and solved analytically to calculate the natural frequencies and to predict the corresponding mode shapes. Parametric studies are carried out to depict the effects of nonlinear boundary conditions and amplitude of initial curvature on nonlinear static response and vibration behaviors of curved beam. Numerical results show that the nonlinear boundary conditions have significant effects on the critical buckling load, nonlinear buckling response and natural frequencies of the curved beam. The proposed model can be exploited in analysis of macrosystem (airfoil, flappers and wings) and microsystem (MEMS, nanosensor and nanoactuators).
Key Words
analytical solutions; curved beam; nonlinear viscoelastic boundary conditions; static and dynamic stability
Address
Nazira Mohamed, Salwa A. Mohamed: Department of Engineering Mathematics, Faculty of Engineering, Zagazig University, Egypt
Mohamed A. Eltaher: Mechanical Engineering Department, Faculty of Engineering, King Abdulaziz University,
Jeddah, Saudi Arabia; Mechanical Design and Production Department, Faculty of Engineering, Zagazig University, Egypt
Abstract
Adhesive bonding is currently widely used in many industrial fields, particularly in the aeronautics sector. Despite its advantages over mechanical joints such as riveting and welding, adhesive bonding is mostly used for secondary structures due to its low peel strength; especially if it is simultaneously exposed to temperature and humidity; and often presence of bonding defects. In fact, during joint preparation, several types of defects can be introduced into the adhesive layer such as air bubbles, cavities, or cracks, which induce stress concentrations potentially leading to premature failure. Indeed, the presence of defects in the adhesive joint has a significant effect on adhesive stresses, which emphasizes the need for a good surface treatment. The research in this field is aimed at minimizing the stresses in the adhesive joint at its free edges by geometric modifications of the ovelapping part and/or by changing the nature of the substrates. In this study, the finite element method is used to describe the mechanical behavior of bonded joints. Thus, a three-dimensional model is made to analyze the effect of defects in the adhesive joint at areas of high stress concentrations. The analysis consists of estimating the different stresses in an adhesive joint between two 2024-T3 aluminum plates. Two types of single lap joints (SLJ) were analyzed: a standard SLJ and another modified by removing 0.2 mm of material from the thickness of one plate along the overlap length, taking into account several factors such as the applied load, shape, size and position of the defect. The obtained results clearly show that the presence of a bonding defect significantly affects stresses in the adhesive joint, which become important if the joint is subjected to a higher applied load. On the other hand, the geometric modification made to the plate considerably reduces the various stresses in the adhesive joint even in the presence of a bonding defect.
Key Words
adhesive; bonding defect; modified lap joint; single lap joint; stresses
Address
Attout Boualem: Department of Mechanical Engineering, LMPM Laboratory, University of Djillali Liabes, Sidi Bel Abbes, Algeria
Sidi Mohamed Medjdoub: Department of Mechanical Engineering, LMSS Laboratory, University of Djillali Liabes, Sidi Bel Abbes, Algeria
Madani Kouider: Department of Mechanical Engineering, LMSS Laboratory, University of Djillali Liabes, Sidi Bel Abbes, Algeria
Kaddouri Nadia: Department of Mechanical Engineering, LMSS Laboratory, University of Djillali Liabes, Sidi Bel Abbes, Algeria
Elajrami Mohamed: Department of Mechanical Engineering, LMSS Laboratory, University of Djillali Liabes, Sidi Bel Abbes, Algeria
Belhouari Mohamed: Department of Mechanical Engineering, LMSS Laboratory, University of Djillali Liabes, Sidi Bel Abbes, Algeria
Amin Houari: Department of Mechanical Engineering, LMSS Laboratory, UMBB University Boumerdes, Algeria
Salah Amroune: Department of Mechanical Engineering, M'sila University, Algeria
R.D.S.G. Campilho: CIDEM, ISEP-School of Engineering, Polytechnic Institute of Porto, R. Dr. António Bernardino de Almeida, 431, 4200-072 Porto, Portugal; Institute of Science and Innovation in Mechanical and Industrial Engineering, Rua Dr. Roberto Frias, 400, 4200-465 Porto, Portugal
